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< < | <!-- * Set CURRENT_DOC_BUILD = hcss-doc-14.0 --> | > > | <--
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Data Products Known Issues | |
- Observations during the steep rise of the sub-K temperature
- This issue is fixed since HIPE v13, except for a handful of observations made before OD400: contact the HSC Helpdesk if you think data processed with HIPE v13 or later still needs correcting for this issue.
- During the first few hours after the cooler was recycled the bolometers' temperature (the sub-K temperature) undergoes a steep rise before it reaches a stable plateau. Observations during this period suffer overcorrection of the instrument/telescope emission. This is more significant for faint targets and can be identified as an unphysical slope of the SLW spectrum, with an important negative gap in the region that overlaps with SSW, i.e. a droop at the high-frequency end of SLW (see the figure below). One way to check if your observation is within this problematic category is to get the median sub-K temperature for the first building block: print MEDIAN(obs.level0_5.get(0xA1060001).nhkt['signal']['SUBKTEMP'].data), where obs is the pre-loaded observational context. If the result is less than 0.2869 K then the observation is affected by this.
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> > |
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A possible fix to this problem is to subtract the smoothed off-axis detectors, because they are also subject to the same overcorrection. The Background Subtraction script from the HIPE Useful Scripts can be used for this investigation, the output of this script is shown in the Figure below.
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< < |  | > > |  | |
- Calibration/pipeline problems/needs
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META FILEATTACHMENT |
attachment="cpCubesPartialSpecIssue.png" attr="" comment="" date="1458766760" name="cpCubesPartialSpecIssue.png" path="cpCubesPartialSpecIssue.png" size="131932" user="RosalindHopwood" version="1" |
META FILEATTACHMENT |
attachment="unchoppedwrong.txt" attr="" comment="temporary mssg about pacs spec unchopped foul" date="1462284207" name="unchoppedwrong.txt" path="unchoppedwrong.txt" size="803" user="KatrinaExter" version="1" |
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attachment="unimap_special_cases.txt" attr="" comment="" date="1476185755" name="unimap_special_cases.txt" path="unimap_special_cases.txt" size="851" user="LucaCalzoletti" version="1" |
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attachment="Off-axis-subtracted.png" attr="" comment="Off-axis subtracted spectrum fixing the SLW dip" date="1486635646" name="Off-axis-subtracted.png" path="Off-axis-subtracted.png" size="21667" user="IvanV" version="1" |
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-
- The release of the interactive pipeline script in HIPE 14.2 (and possibly 14.0.1) for unchopped range scans (called "...with transient correction" in the Pipelines menu) contains an overactive smoothing that can clip away spectral lines. We strongly recommend not using this script for your reductions. The script from HIPE track 15 (which is currently the development track) can be used instead. This does not affect the SPG reductions of these observations.
- Warning for a subset of unchopped range scan PACS spectroscopy observations in HIPE/SPG 14.0.1.
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< < |
-
- PACS spectroscopy observations reported in this text file are affected by a problem that occurred at end of the pipeline processing for SPG 14.0.1. For this observing mode, the off-source observation is a separate obsid to the on-source observation. The on-source and off-source obsids are processed separately and the results placed in the Level 2 of the observation data. Normally the off-source data are then subtracted from the on-source data and these results placed in the Level 2.5 of the on-source observation. Unfortunately, for a subset of unchopped range scans this did not happen, but instead the on-source data were subtracted from the off-source data and placed in the Level 2.5 of the off-source observation. However, this has now been fixed and all SPG 14.2.2 products will be correct.
| > > |
-
- PACS spectroscopy observations reported in this text file are affected by a problem that occurred at end of the pipeline processing for SPG 14.0.1. For this observing mode, the off-source observation is a separate obsid to the on-source observation. The on-source and off-source obsids are processed separately and the results placed in the Level 2 of the observation data. Normally the off-source data are then subtracted from the on-source data and these results placed in the Level 2.5 of the on-source observation. Unfortunately, for a subset of unchopped range scans this did not happen, but instead the on-source data were subtracted from the off-source data and placed in the Level 2.5 of the off-source observation. However, this will be fixed in the final bulk processing (early 2017) and the SPG 14.2.2 products will be correct.
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- Flat fluxes for certain spectral ranges
- The pipeline task extractCentralSpectrum is used to created point-source calibrated spectra for pointed observations, working on the rebinned cubes to do this. This task does a spectral interpolation over NaNs (this is to avoid having jumps in summed spectra where one spaxel may have a NaN). The output spectra are improved as a result of this, however the central 9 spaxels of the input rebinned cubes are modified by this interpolation. The result of this modification is that for the rebinned cubes, the fluxes in the spectra in the ranges that were not flatfielded are nearly flat. In SPG 14.0.1-reduced observations, this affects those of the the pointed range scan mode, and specifically in the spectral ranges affected by leakage in the different bands. As an additional side effect, the interpolated cubes (which are created from the rebinned cubes) also show these extended flat-valued spectral ranges at some central locations. However, this has been fixed in SPG 14.2.
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Data Products Known Issues | |
-
- Processing an observation in HIPE 15 and HIPE 14.2 will produce the same results. However, marginal differences may appear in these processing results compared to the SPG 14.2(.0,1,2) gotten from the HSA. There is no fix for this, but the impact on the science data is insignificant.
- SPG 14.2.0 red leak range
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< < |
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- With products processed by SPG 14.2.0, for observations with a small range falling mostly in the red leak region (>190 microns) but with a short stretch shortward of 190 microns, the entire Level 2 red spectral range was lost. This has been fixed in 14.2.2 and only the spectral ranges that fall within the red leak are suppressed.
| > > |
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- With products processed by SPG 14.2.0, for observations with a small range falling mostly in the red leak region (>190 microns) but with a short stretch shortward of 190 microns, the entire Level 2 red spectral range was lost. This has been fixed in 14.2.2 and only the spectral ranges that fall within the red leak are suppressed.
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General notes | | print cal.phot.beamProfList[5].meta['FWHM_majorPsw'] This works in build 15. Note that the parameter (and a few others) are actually present in the product, but in 14, they are renamed to META_1, META_2...
- Incorrect WCS in the primary header of Level 2.5 and Level 3 maps
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< < |
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- The correct WCS for Level 2.5 and Level 3 maps is in the header of the
image , error and coverage extensions. The WCS in the primary header corresponds to one of the individual maps and it is not updated for the combined or mosaicked map.
| > > |
-
- The correct WCS for Level 2.5 and Level 3 maps is in the header of the image, error and coverage extensions. The WCS in the primary header corresponds to one of the individual maps and it is not updated for the combined or mosaicked map.
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- Reprocessing with the level-2.5 pipeline
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< < |
-
- Processing a list of observations with the
level25_pipeline.py SPG script may lead to tiny differences (1.0e-4, 1.e-5 Jy/beam or MJy/sr) with respect to the same products in the Herschel Science Archive. This is due to the way the current pipeline incorporates the last turnaround building block of concatenated observations in order to proceed with the the deglitching. There is currently no fix, although exactly the same results, as in the archive, can be obtain by individually processing each observation with the two-pass pipeline and then running the level25_pipeline.py script.
| > > |
-
- Processing a list of observations with the level25_pipeline.py SPG script may lead to tiny differences (1.0e-4, 1.e-5 Jy/beam or MJy/sr) with respect to the same products in the Herschel Science Archive. This is due to the way the current pipeline incorporates the last turnaround building block of concatenated observations in order to proceed with the the deglitching. There is currently no fix, although exactly the same results, as in the archive, can be obtain by individually processing each observation with the two-pass pipeline and then running the level25_pipeline.py script.
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- Interactive analysis
- SourceTimelineFitter: the errors on the fitted RA, Dec positions from the task are wrong near the poles.
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- Other calibration/pipeline problems/needs
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< < | Useful Scripts | > > | Pointing | | | |
< < | Thermoelastic | > > | Observations performed at the the so-called 'warm' attitude range (Star Tracker 2 temperature > -15 C), could present a degradation of the pointing performance due to thermoelastic effects. These would include a larger APE and a pointing drift. | | | |
> > | In order to estimate such astrometry shifts, we have created a General Useful Scripts named Astrometry Thermoelastic Drift Correction, available in HIPE 15. The script calculates the average temperature of STR2 sensors during the mid-point of the observation and, if that is > -15 C, it uses an established STR2-Z-axis offset correlation function to get the Z-axis offset and derive RA and DEC offsets. Two possible outputs are provided: (1) A new pointing product that takes into account the updated rotation matrix/quaternion and corrects the filtered attitude. This product can be used by the user to reprocess the observation. (2) New Level 2 products (only applicable to Photometry) where the offsets in RA y DEC (derived from the Z-axis offset) have been used to adjust the WCS. | | Additional Information
HIFI documents: see the HIFI Instrument and Calibration webpage |
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Data Products Known Issues |
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- JScanam
- JScanam (an HCSS implementation of the Scanamorphos IDL map-maker) maps are available in level 2.5 and level 3 as of SPG 12 onwards. The JScanam ipipe script to process the maps is available in Hipe 11 onwards. Significant improvements have been achieved in the latest HIPE release, in terms of memory requirement, processing speed, and final map quality. Within the HSA, the JScanam Level2.5 maps are used as the Stand-alone Browse Products for the PACS Photometer scan-maps.
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In the JScanam pipeline for the the generation of the Level 2.5 maps, a random number generator is used for filling the masked signal pixels (within the scanamorphosNoiseSpectrum task, called internally by the scanamorphosIndividualDrifts task, just before the final projection). The random number generator is inizialized at each run and this means that calling twice the task on the same input frames (i.e. by running the same SPG version twice), the maps finally generated are slightly different. This difference can be considered negligible (remember that none PACS maps is absolute calibrated), being the percentage differences pixel-to-pixel of the order of few 0.1%, and well below the level of the standerd deviation map.
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- Unimap
- Unimap (a GLS mapmaker) maps are available in level 2.5 and level 3 as of SPG 13 onwards. The Unimap interactive pipeline script to reprocess the maps is available in HIPE 13 onwards. Unimap is Matlab software and it is invoked by a jython task. When running the interactive pipeline script, the Unimap release must be locally installed (instructions are given at the beginning of ipipe script).
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Data Products Known Issues | |
METADATA AND FITS KEYWORDS | |
< < |
- Message about DATE-OBS: Some internal HCSS metadata are renamed by the HCSS software when translating to FITS. One special case is startDate which gets written to FITS as both DATE-OBS and DATE_OBS. This is done for compatibility with legacy Spitzer software (namely MOPEX).
| > > |
- Message about DATE-OBS: Some internal HCSS metadata are renamed by the HCSS software when translating to FITS. One special case is startDate which gets written to FITS as both DATE-OBS and DATE_OBS. This is done for compatibility with legacy Spitzer software (namely MOPEX).
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PACS Photometer (scan mapping)
General notes | |
< < |
- Important note: PACS maps from any map-maker are in essence differential maps: the absolute level is undefined due to the dominating telescope background removed by map-makers. Hence it is not unusual if your background level is negative.
| > > |
- Important note: PACS maps from any map-maker are in essence differential maps: the absolute level is undefined due to the dominating telescope background removed by map-makers. Hence it is not unusual if your background level is negative.
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- To produce the highest quality maps, you should consider re-processing or fine-tuning the observations with the latest HIPE User Release. Maps available from the HSA are created within a bulk processing framework, and a reprocessing while fine-tuning the mapper parameters, according to the characteristics of the observed sky region, could enhance the quality of the final maps.
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-
- Unimap maps into HSA were generated with the release 6.4.4, while interactive script is compatible with Unimaps versions 6.5.3 and below.
- Distortions introduced by the Unimap GLS algorithm are generally removed by the Unimap post-processing or by the Pixel Noise compensation (see the PACS Data Reduction Guide for photometry). If you are not happy of the SPG archival results, you can run the interactive script by fine tuning the parameters.
- In some cases, drifts due to the calibration blocks persistence and strips due to strong saturated pixels can be observed, because not properly corrected by the Unimap pre-processing.
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> > |
-
- For the pairs of observations (obsIDs) reported into this list unimap_special_cases.txt, the SPG 14.2.0 fails because of a bug in the Unimap release 6.4.4. They are processed with SPG 14.2.1 by using the same Unimap release (6.4.4), but by modifying the values of some Unimap parameters (wrt the default ones) according the fourth (name of parameter) and fifth (adopted value) columns of the list unimap_special_cases.txt
.
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- Highpass-filtered maps (and their intrinsic limitations)
- High-pass filtered maps in SPG14 are available at level 2 and level 2.5. The extended emission is filtered out in the maps since a rather small filter width is used to remove 1/f noise stripping: this is done to allows us to obtain the best sensitivity for point-sources. Bright sources are masked out during the highpass filtering, hence their flux is not too much affected by filtering. But faint sources are not or are inadequately masked out by the SPG processing, hence the flux loss for these point-source can reach up to 20--30%. Re-processing your data, using customised masks, is recommended here.
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-
- Level 2.5 maps combine parallel mode as well as SPIRE-only maps into larger maps using the standard two-pass pipeline, see The SPIRE Data Reduction Guide, sections 4.2.3.
- Level 3 maps are mosaics of overlapping Level 2 and/or Level 2.5 maps, see The SPIRE Data Reduction Guide, sections 4.2.4.
-
No astrometry correction is applied on the individual maps used in Level 2.5 or Level 3 processing. This may result in broadened PSFs (or double sources in the extreme case) if some individual maps are affected by astrometry offsets.
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< < |
-
- Before HIPE 14.2.1, the
mosaic() task calculated incorrectly the SPIRE Photometer Level-3 maps: the image and error extensions.
| > > |
-
- Before HIPE 14.2.1, the mosaic() task calculated incorrectly the SPIRE Photometer Level-3 maps: the image and error extensions.
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- Stripes in PSW, PMW and/or PLW maps
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< < |
-
- All SPIRE photometry pipelines use the iterative
destriper method with a constant baseline (polynomial of zeroth order). This is the best method for SPIRE maps as reported in The SPIRE Map-Making Test Report , Xu et al, 2013 (arXiv:1401.2109). In some cases there could be a residual striping due to a combination of thermal drifts, bolometer jumps and/or improper baseline subtraction. Suggested solutions is to reprocess the map using a first order polynomial for the baseline estimation in the destriper .
| > > |
-
- All SPIRE photometry pipelines use the iterative destriper method with a constant baseline (polynomial of zeroth order). This is the best method for SPIRE maps as reported in The SPIRE Map-Making Test Report
, Xu et al, 2013 (arXiv:1401.2109). In some cases there could be a residual striping due to a combination of thermal drifts, bolometer jumps and/or improper baseline subtraction. Suggested solutions is to reprocess the map using a first order polynomial for the baseline estimation in the destriper.
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- De-glitchter masks faint sources
- Removing glitches from the data is a very delicate process. In particular, for data taken in Parallel Mode (sampling at 10Hz) and at high speed (60"/s) the de-glitcher with standard parameters may flag very faint sources as glitches. Bright sources are different from glitches in that they have a gaussian (i.e. beam/PSF) shape. For faint sources, the sampling rate could be not high enough and hence they have a "delta" shape, which is similar to a small glitch. The user might try to modify the correlation parameter to 0.95: this will decrease the number of detected glitches.
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-
- The extended calibrated maps (extdPxW in Level 2, 2.5 or 3) incorporate zero level offsets derived from Planck-HFI. For small size SPIRE maps, smaller than ~30 arcmin, the zero-offset can be rather uncertain, due to the large Planck beam (8 arcmin). In such cases the interpretation of the zero offset as the absolute zero level must to be treated with extreme caution.
- Missing keywords in calTree
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< < |
-
- In HIPE 14.x: trying to access
beamProf meta parameter 'FWHM_majorPsw' from the spireCal tree crashes with "parameter not found" exception
| > > |
-
- In HIPE 14.x: trying to access beamProf meta parameter 'FWHM_majorPsw' from the spireCal tree crashes with "parameter not found" exception
| | cal = spireCal(pool="spire_cal_14_3") | |
< < | print cal.phot.beamProfList[5].meta['FWHM_majorPsw']
This works in build 15. Note that the parameter (and a few others) are actually present in the product, but in 14, they are renamed to META_1 , META_2 ... | > > | print cal.phot.beamProfList[5].meta['FWHM_majorPsw'] This works in build 15. Note that the parameter (and a few others) are actually present in the product, but in 14, they are renamed to META_1, META_2... | | | |
< < |
-
-
SourceTimelineFitter : the errors on the fitted RA, Dec positions from the task are wrong near the poles.
| > > |
-
- SourceTimelineFitter: the errors on the fitted RA, Dec positions from the task are wrong near the poles.
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META FILEATTACHMENT |
attachment="lrBeforeAfter.png" attr="" comment="" date="1456522197" name="lrBeforeAfter.png" path="lrBeforeAfter.png" size="225688" user="RosalindHopwood" version="2" |
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attachment="cpCubesPartialSpecIssue.png" attr="" comment="" date="1458766760" name="cpCubesPartialSpecIssue.png" path="cpCubesPartialSpecIssue.png" size="131932" user="RosalindHopwood" version="1" |
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attachment="unchoppedwrong.txt" attr="" comment="temporary mssg about pacs spec unchopped foul" date="1462284207" name="unchoppedwrong.txt" path="unchoppedwrong.txt" size="803" user="KatrinaExter" version="1" |
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attachment="unimap_special_cases.txt" attr="" comment="" date="1476185755" name="unimap_special_cases.txt" path="unimap_special_cases.txt" size="851" user="LucaCalzoletti" version="1" |
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< < | <!-- * Set CURRENT_DOC_BUILD = hcss-doc-14.0 --> | > > | <--
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Data Products Known Issues | |
General notes | |
< < |
- In order to obtain the best possible Level 2 SPIRE photometry data, the observations might have to be reprocessed with the latest HIPE User Release.
| > > |
- The best science quality Level 2 and Level 2.5 SPIRE photometry products are created with version 14.1 of the Herschel Systematic Product Generation pipelines. These data are available in the Herschel Science Archive. Reprocessing SPIRE observations with HIPE v14.2 or above will result in almost identical products.
| | | |
< < |
- SPIRE-P level 2.5 and level 3 maps
- For the definitions of the new product levels, introduced with HIPE v11, see The SPIRE Data reduction Guide, sections 3.2.3 and 3.2.4
- These new levels will be available in the Herschel Science Archive when the observations will be bullk-reprocessed with HIPE v11. The useful user script Photometer_MapMerge.py can be used to make level 2.5 (parallel mode) or level 3 (mosaic) maps, see Section 5.8.3 in the SPIRE Data Reduction Guide.
- Stripes in PSW, PMW and/or PLW (Level 2) maps
- All SPIRE photometry pipelines now use by default the destriper, which improves the issue of striping in level 2 maps. Hence observers should expect potential improvements in that respect with version 9.
-
Please note that there was a bug in the destriper task included in HIPE 9.0 that may affect your final map, especially if there are bright objects in the observed field. This has been corrected since HIPE 9.1. If your observation falls in the mentioned category, you are strongly advised to update your HIPE installation.
-
In HIPE 10.0 the flagging of thermistor jumps in the level 0.5 to 1 data reduction is not set properly. This induces the destriper to work improperly and to leave stripes in the final map. It has been solved starting with HIPE 10.1.
<!--<br /> * Most of the stripes that are present in the final maps are due to a combination of thermal drifts (which in few cases are not efficiently removed) and median baseline subtraction. A similar effect is caused by very bright sources: in this case, the problem resides in the median baseline subtraction only. Suggested solutions:<br /> * switch to a baseline subtraction using a polynomial fitting using the optional task baselineRemovalPolynomial. If there are no jumps in the timelines, you may also try to run the baseline removal on the entire timeline;<br /> * in the case of bright sources, you may try to mask them before running the baseline removal (either median or polynomial): you can use this script as a template<br />--> | > > |
- SPIRE-P Level 2.5 and Level 3 maps
- Level 2.5 maps combine parallel mode as well as SPIRE-only maps into larger maps using the standard two-pass pipeline, see The SPIRE Data reduction Guide, sections 4.2.3.
- Level 3 maps are mosaics of overlapping Level 2 and/or Level 2.5 maps, see The SPIRE Data reduction Guide, sections 4.2.4.
-
The individual maps used in Level 2.5 or Level 3 processing are not registered onto the same astrometry reference frame and may result in blurred PSFs if some individual maps are subject to astrometry offsets.
- Stripes in PSW, PMW and/or PLW maps
- All SPIRE photometry pipelines use the iterative
destriper method with a constant baseline (polynomial of zeroth order). This is the best method for SIRE maps as reported in The SPIRE Map-Making Test Report , Xu et al, 2013 (arXiv:1401.2109). In some cases there could be a residual striping due to a combination of thermal drifts, bolometer jumps and/or improper baseline subtraction. Suggested solutions is to reprocess the map using a first order polynomial for the baseline estimation in the destriper .
| |
- De-glitchter masks faint sources
| |
< < |
-
- The de-glitcher is a very delicate process. In particular, for data taken in Parallel Mode (sampling at 10Hz) and at high speed (60"/s) the de-glitcher with standard parameters may flag very faint sources as glitches. Bright sources are different from glitches in that they have a gaussian (i.e. beam/PSF) shape. For faint sources, the sampling rate could be not high enough and hence they have a "delta" shape, which is similar to a small glitch. The user might try to modify the correlation parameter to 0.95: this will decrease the number of detected glitches.
| > > |
-
- Removing glitches from the data is a very delicate process. In particular, for data taken in Parallel Mode (sampling at 10Hz) and at high speed (60"/s) the de-glitcher with standard parameters may flag very faint sources as glitches. Bright sources are different from glitches in that they have a gaussian (i.e. beam/PSF) shape. For faint sources, the sampling rate could be not high enough and hence they have a "delta" shape, which is similar to a small glitch. The user might try to modify the correlation parameter to 0.95: this will decrease the number of detected glitches.
| |
- Some sources have saturated the ADC and the corresponding data have been masked
- There is nothing a user can do: the source was simply too bright. If the user has other sources still not observed and of the same intensity, it is suggested to change the AORs to use the bright source mode.
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< < | <!-- * <b>Thermistor jumps*<br /> </b> As of HIPE 6.0.3, a new module together called signalJumpDetector in place to identify the jump and to exclude the affected thermistor(s). <br />--> | |
- Cooler temperature variations
| |
< < |
-
- The cooler temperature variations, as explained in greater details in the SPIRE Data Reduction Guide, section 6.4, can affect observations performed soon after the cooler recycle. The steep rise of the sub-K detector temperature is also known as the cooler burp and there is a quality flag coolerBurpDetected in HIPE v11 or later that indicates if the observation was performed during this period.
The current list of observations known to have cooler temperature effects is here. Note that not all observations in this list raised the coolerBurpDetected flag.
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- The cooler temperature variations, as explained in greater details in the SPIRE Data Reduction Guide, section 6.4, can affect observations performed soon after the cooler recycle. The steep rise of the sub-K detector temperature is also known as the cooler burp and there is a quality flag coolerBurpDetected (as of HIPE v11 or later) that indicates if the observation was performed during this period.
The current list of observations known to have cooler temperature effects is here. Note that not all observations in this list raised the coolerBurpDetected flag.
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- NaNs pixels present in the PSW, PMW and/or PLW (Level 2) maps
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- NaNs pixels present in the PSW, PMW and/or PLW maps
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- This effect, related to data masked for various reasons and poor coverage (not enough redundancy), is more evident in single fast-scan Parallel Mode maps. To avoid NaNs, increase the pixel's dimension (i.e., decrease the map's resolution)
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< < | <!-- * <b>WCS in 3-colour images*<br /> </b> In all observation reduced with HIPE 8, the task createRgbImage puts wrong WCS in the output. Instead of using the WCS provided by the WCS input parameter, this task uses the WCS of one of the input images. This has been fixed in HIPE 9<br />--> | |
- Quality flags
- Currently, the quality flags at the quality context inside the observation context are just meant for HSC/ICC internal evaluation of the quality of the products and not for the users. In case the data had some serious quality problem, the PI of the program has been contacted about it. Otherwise, only information in the quality summary, when available, should concern the observers.
- Planck derived zero offsets
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< < |
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- The extended calibrated maps (extdPxW in level-2, 2.5 or 3) incorporate zero level offsets derived from Planck-HFI. For small size SPIRE maps, smaller than ~30 arcmin, the zero-offset can be rather uncertain, due to the large Planck beam (8 arcmin). In such cases the interpretation of the zero offset as the absolute zero level must to be treated with extreme caution.
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- The extended calibrated maps (extdPxW in Level 2, 2.5 or 3) incorporate zero level offsets derived from Planck-HFI. For small size SPIRE maps, smaller than ~30 arcmin, the zero-offset can be rather uncertain, due to the large Planck beam (8 arcmin). In such cases the interpretation of the zero offset as the absolute zero level must to be treated with extreme caution.
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SPIRE Small Scan Map AOT release note: 17 Mar 2010 | |
< < | <!--<br /><a class="red" href="http://herschel.esac.esa.int/Docs/AOTsReleaseStatus/SPIRE_PointSource_AOT_ReleaseNote_30Apr2010.pdf">SPIRE Point Source Mode release note</a>: 30 Apr 2010 <br />--> | | SPIRE Spectroscopy | |
< < |
- In order to obtain the best possible Level 2 SPIRE FTS data, the observations should be reprocessed with the latest HIPE User Release.
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- The best science quality Level 2 and Level 2.5 SPIRE photometry products are created with version 14.1 of the Herschel Systematic Product Generation pipelines. These data are available in the Herschel Science Archive. Reprocessing SPIRE observations with HIPE v14.2 or above will result in almost identical products.
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Extended calibrated spectra and spectral cubes: prior to SPG 14.0 all extended calibrated spectra, including the spectral cubes (as these are built by extended calibrated spectra) were affected by a missing correction for the far-field feed horn efficiency (ηff ). This correction is significant - a factor of 1.3-1.5 in SSW and 1.3-2.2 in SLW, as shown in the figure, where the red dashed line shows ηff , the blue squares are the average ratios of uncorrected FTS synthetic photometry to the corresponding photometry extracted from extended-calibrated photometer maps and the green circles are ground based measurements, taken pre-launch. More details on this critical problem will be available in a dedicated paper (Valtchanov et al, in preparation).
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< < | <!-- * <b>FTS Array footprint user script*<br /> </b> For very large area maps the script produces wrong overlay (offset from the real position) if the default map projections (tangential) is used. The workaround is to use smaller map where the tangential projection centre is near the FTS target position.<br /> --> | |
- Calibration/pipeline problems/needs
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SPIRE Spectroscopy Release Notes |
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- Set CURRENT_DOC_BUILD = hcss-doc-14.0
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Data Products Known Issues | |
In what follows, we provide a summary of the known issues that you may encounter when inspecting data processed with the automatic pipelines SPG versions 6.1 to 13.0. Most can be resolved by running the pipelines within HIPE and optimizing their parameters as explained below. | |
< < | <--This is a comment: it will be ignored by the browser --> | > > | <!--This is a comment: it will be ignored by the browser --> | |
Note that some of this information can also be found in the quality report of the observation (QC Report) and as metadata with the FITS keyword "PCAVEATS". | |
- Intrinsic limitation of highpass filter maps
- High-pass filtered maps in SPG13 are available at level 2 and level 2.5. The extended emission is filtered out in the maps since a rather small filter width is used to remove 1/f noise stripping: this is done to allows us to obtain the best sensitivity for point-sources. Bright sources are masked out during the highpass filtering, hence their flux is not too much affected by filtering. But faint sources are not or are inadequately masked out by the SPG processing, hence the flux loss for these point-source can reach up to 20--30%. Re-processing your data is recommended here.
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< < | <-- * These are due to a non-optimal estimate of background by the high-pass filter close to a bright source. The current masked high-pass filter pipeline is a trade-off, designed to get a good sensitivity on point-sources and preserve some extended emission up to a few arcmin scale. However due to the relatively large width in the second high-pass filtering, significant stripping from the 1/f noise is still present in the level 2 maps. On the other hand a large fraction of the extended emission is filtered out. The observer is advised to play with the threshold to define the mask and with the width of the high-pass filter to reduce these effects or move to MADmap scanamorphos to preserve extended emission at all scales. Level 2.5 MADmap maps, combining scans and crossed-scans on the other hands do preserve extended emission at all spatial scales. --> | > > | <!--<br /> * These are due to a non-optimal estimate of background by the high-pass filter close to a bright source. The current masked high-pass filter pipeline is a trade-off, designed to get a good sensitivity on point-sources and preserve some extended emission up to a few arcmin scale. However due to the relatively large width in the second high-pass filtering, significant stripping from the 1/f noise is still present in the level 2 maps. On the other hand a large fraction of the extended emission is filtered out. The observer is advised to play with the threshold to define the mask and with the width of the high-pass filter to reduce these effects or move to MADmap scanamorphos to preserve extended emission at all scales. Level 2.5 MADmap maps, combining scans and crossed-scans on the other hands do preserve extended emission at all spatial scales.<br />--> | |
- MADmap issues
- MADmap -- a GLS (Generalized Least Square) map-maker -- maps are no longer created by SPG13 and beyond. However, the pipeline script to do this yourself is provided in HIPE 13.
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- One matrix (fully half of) of the red channel array was lost at the end of the mission, so from OD1375 onwards this matrix is masked out automatically in the SPG processing.
- The quality flags in the quality context ("quality" or "qualitySummary") inside the observation context are meant for HSC/ICC internal evaluation of the quality of the products: when an observation had a serious quality problem, the PI of the program would have been contacted about it. For archive users, only the information in the "qualitySummary", when available, is useful.
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< < | <--- * Calibration block transient in L2 maps* Several red (160um) scan maps are affected by a calibration block downwards transient when scheduled immediately before the science observation. This can be mitigated by running a high-pass filter with a smaller width, fitting the transient or just masking the affected frames at the start of the observation. --> | > > | <!---<br /> * <b>Calibration block transient in L2 maps*<br /> </b> Several red (160um) scan maps are affected by a calibration block downwards transient when scheduled immediately before the science observation. This can be mitigated by running a high-pass filter with a smaller width, fitting the transient or just masking the affected frames at the start of the observation.<br />--> | | | |
< < | <-- * Scan maps processed with SPG v4.1.0 were deglitched with "MMT deglitching", a temporal deglitching of the pixel timelines. This deglitching technique works very well for deep fields (e.g. cosmological fields) but fails at high scan speed (60"/s) or even medium scan speeds on bright (>~1Jy) sources, wrongly identified as glitches. --> | > > | <!-- * Scan maps processed with SPG v4.1.0 were deglitched with "MMT deglitching", a temporal deglitching of the pixel timelines. This deglitching technique works very well for deep fields (e.g. cosmological fields) but fails at high scan speed (60"/s) or even medium scan speeds on bright (>~1Jy) sources, wrongly identified as glitches.<br />--> | | | |
< < | <-- * Deglitching* The deglitching was changed to a so-called "2nd level deglitching" in SPG v6.1.0 that makes use of the spatial redundancy (a sky pixel being seen by several detector pixel readouts). Large scan maps (e.g. galactic fields) processed with SPG v6.1 are therefore of much better quality than earlier ones (SPG v4.1.0), however some low level glitches are left as a high threshold was set in the pipeline. As the deglitching is now run from level 1 to level 2 after highpass filtering, the level 1 cubes in HSA processed with SPG 6.1 do not contain anymore glitch masks. For interactive processing, several hints and methods are given in the ipipe scripts. --> | > > | <!-- * <b>Deglitching*<br /> </b> The deglitching was changed to a so-called "2nd level deglitching" in SPG v6.1.0 that makes use of the spatial redundancy (a sky pixel being seen by several detector pixel readouts). Large scan maps (e.g. galactic fields) processed with SPG v6.1 are therefore of much better quality than earlier ones (SPG v4.1.0), however some low level glitches are left as a high threshold was set in the pipeline. As the deglitching is now run from level 1 to level 2 after highpass filtering, the level 1 cubes in HSA processed with SPG 6.1 do not contain anymore glitch masks. For interactive processing, several hints and methods are given in the ipipe scripts.<br />--> | | | |
< < | <-- * Brightest sources core deglitched in the Level 2 map processed with old pipeline version (SPG v4.1.0)* This is due to the MMT deglitching at high speed (60"/s), which can wrongly identify bright sources as glitches. A possible solution in these cases is to use 2nd order deglitching in the interactive pipeline, now the default in the HCSS pipeline.
* Glitches from Cosmic ray hits* Level 2 maps in the archive (HSA) processed with SPG 4.1.0 are affected by glitches as a side effect of disabling the deglitching on bright sources. This has been corrected in SPG version 6.1.0 and above. Interactive HIPE sessions shall get rid off of all these glitches by playing with the deglitching thresholds or using the 2nd order deglitching (memory consuming). * At 20"/s scan speed, the MMT deglitching does fine if there are no bright sources (>~1Jy), for instance for cosmological survey observations. For brighter sources (nearby galaxies or galactic fields) it is better to switch to second order deglitching. For more information see the PACS Data Reduction Guide (PDRG). --> | > > | <!--<br /> * <b>Brightest sources core deglitched in the Level 2 map processed with old pipeline version (SPG v4.1.0)*<br /> </b> This is due to the MMT deglitching at high speed (60"/s), which can wrongly identify bright sources as glitches. A possible solution in these cases is to use 2nd order deglitching in the interactive pipeline, now the default in the HCSS pipeline.<br /><br /> * <b>Glitches from Cosmic ray hits*<br /> </b> Level 2 maps in the archive (HSA) processed with SPG 4.1.0 are affected by glitches as a side effect of disabling the deglitching on bright sources. This has been corrected in SPG version 6.1.0 and above. Interactive HIPE sessions shall get rid off of all these glitches by playing with the deglitching thresholds or using the 2nd order deglitching (memory consuming).<br /> * At 20"/s scan speed, the MMT deglitching does fine if there are no bright sources (>~1Jy), for instance for cosmological survey observations. For brighter sources (nearby galaxies or galactic fields) it is better to switch to second order deglitching. For more information see the PACS Data Reduction Guide (PDRG).<br />--> | | | |
< < | <-- The astrometry of several PACS scan maps acquired between ODs 320 and 761 has been reported to be off by 4 arcsec (solid offset of the whole map) or even above for a few fields where the tracking stars are not homogeneously distributed in the star-tracker field-of-view. It is intended to improve the a posteriori reconstructed pointing for all observations in the future. --> | > > | <!--<br />The astrometry of several PACS scan maps acquired between ODs 320 and 761 has been reported to be off by 4 arcsec (solid offset of the whole map) or even above for a few fields where the tracking stars are not homogeneously distributed in the star-tracker field-of-view. It is intended to improve the a posteriori reconstructed pointing for all observations in the future.<br />--> | | | |
< < | <-- * The absolute astrometry of Level 2 maps on Solar System Objects (SSO), projected in the SSO reference frame is not reliable and can be off up to 20 arcsec. This a data processing issue only (aberration & light travel time correction), while the observations themselves were correctly performed (uplink). This issue is under investigations at HSC and PACS ICC. --> | > > | <!--<br /> * The absolute astrometry of Level 2 maps on Solar System Objects (SSO), projected in the SSO reference frame is not reliable and can be off up to 20 arcsec. This a data processing issue only (aberration & light travel time correction), while the observations themselves were correctly performed (uplink). This issue is under investigations at HSC and PACS ICC.<br />--> | | | |
< < | <-- * Full noise propagation in the HSC pipelines will be available at later HCSS versions, so the current noise map is relatively but not absolutely correct. Furthermore, the default pipeline results in correlated noise in individual pixels. In order to estimate a proper background standard deviation, the observers are advised to make 10+ aperture photometry measurements in different sky patches around the source and to estimate the absolute standard deviation of the image as the sigma of those photometric points. --> | > > | <!--<br /> * Full noise propagation in the HSC pipelines will be available at later HCSS versions, so the current noise map is relatively but not absolutely correct. Furthermore, the default pipeline results in correlated noise in individual pixels. In order to estimate a proper background standard deviation, the observers are advised to make 10+ aperture photometry measurements in different sky patches around the source and to estimate the absolute standard deviation of the image as the sigma of those photometric points. <br />--> | | | |
< < | <-- * Quality flags in the quality*
Currently, the quality flags at the quality context inside the observation context are just meant for HSC/ICC internal evaluation of the quality of the products and not for the users. In case the data had some serious quality problem, the PI of the program has been contacted about it. Otherwise, only information in the quality summary, when available, should concern the observers. --> | > > | <!--<br /> * <b>Quality flags in the quality*<br /><br /> </b> Currently, the quality flags at the quality context inside the observation context are just meant for HSC/ICC internal evaluation of the quality of the products and not for the users. In case the data had some serious quality problem, the PI of the program has been contacted about it. Otherwise, only information in the quality summary, when available, should concern the observers.<br />--> | |
- Other calibration/pipeline problems/needs
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PACS photometer AOT release notes see PACS Instrument and Calibration webpage | |
< < | <--- PACS Scan Map AOT release note: 23 Feb 2010
PACS Photometer - Point/Compact Source Observations: Mini Scan-Maps & Chop-Nod AOT release note: 12 Nov 2010 --> | > > | <!---<br /><a class="red" href="http://herschel.esac.esa.int/Docs/AOTsReleaseStatus/PACS_ScanMap_ReleaseNote_23Feb2010.pdf">PACS Scan Map AOT release note</a>: 23 Feb 2010<br /><br /><a class="red" href="http://herschel.esac.esa.int/Docs/AOTsReleaseStatus/PACS_PhotMiniScan_ReleaseNote_12Nov2010.pdf">PACS Photometer - Point/Compact Source Observations: Mini Scan-Maps & Chop-Nod AOT release note</a>: 12 Nov 2010<br />--> | |
PACS Spectroscopy | |
For more information about the standard and the standalone browse cubes provided for PACS spectroscopy, see the PACS Products Explained HIPE help document, which is also available from the PACS documentation webpage and the HIPE download webpage, both off the Herschel Science Centre webpage. | |
< < | General notes
| > > | Warning for a subset of unchopped range scan PACS spectroscopy observations in HIPE/SPG 14 | | | |
< < |
- To produce the highest quality cubes possible, you should consider re-processing or fine-tuning the observations with the latest HIPE User Release. Cubes available from the HSA are created within a bulk processing framework, and a reprocessing while fine-tuning the important pipeline task parameters, according to the characteristics of the observation and source, could enhance the quality of the final results. The first two chapters of the PACS Data Reduction Guide for spectroscopy (HIPE 13) give information about the need to reprocess, and about what to do with HSA-obtained cubes before using them for science.
| > > | PACS spectroscopy observations reported in this text file are affected by a problem that occurred at end of the pipeline processing for SPG 14. For this observing mode, the off-source observation is a separate obsid to the on-source observation. The on-source and off-source obsids are processed separately and the results placed in the Level 2 of the observation data. Normally the off-source data are then subtracted from the on-source data and these results placed in the Level 2.5 of the on-source observation. Unfortunately, for a subset of unchopped range scans this did not happen, but instead the on-source data were subtracted from the off-source data and placed in the Level 2.5 of the off-source observation.
If you wish to work with the on-source observations that have been background subtracted, you can run a useful script in HIPE that starts from the Level 2 products gotten from the HSA (i.e. you do not need to re-run the entire pipeline). Contact the Helpdesk for assitance. | | | |
< < | <-- * Off-subtraction for unchopped long-range scan observations* Range Spectroscopy unchopped observation require off-position scans observed in a separate AOR. The off-source observation need to be subtracted from the on-scan after producing Level 2 rebinned spectra, this results a Level 2.5 product. The pipeline only generates Level 2 data products for unchopped spectroscopy in SPG 8.0. You need to combine interactively the on and off positions using the dedicated multi-observation unchopped pipeline script under the PACS pipeline menu. --> | > > | This will be fixed in SPG 14.2. | | | |
< < | <-- * Unchopped grating scan flux calibration* The absolute flux calibration of the PACS spectrometer is based on observations of flux calibration standards using chopped spectroscopy modes. There are hints of systematic differences in the response scaling between chopped and unchopped mode due to response transients within the chopping pattern. In SPG 8.0 the flux calibration of unchopped data relies on the system response derived chopped scheme, therefore absolute flux values need to be carefully interpreted. Please contact Helpdesk for guidelines on the specific observation you have to deal with. --> | > > | General notes | | | |
> > |
- To produce the highest quality cubes possible, you should consider re-processing or fine-tuning the observations with the latest HIPE User Release. Cubes available from the HSA are created within a bulk processing framework, and a reprocessing while fine-tuning the important pipeline task parameters, according to the characteristics of the observation and source, could enhance the quality of the final results. The first two chapters of the PACS Data Reduction Guide for spectroscopy (HIPE 13) give information about the need to reprocess, and about what to do with HSA-obtained cubes before using them for science.
- Off-subtraction for unchopped long-range scan observations. Range Spectroscopy unchopped observation require off-position scans observed in a separate AOR. The off-source observation need to be subtracted from the on-scan after producing Level 2 rebinned spectra, this results a Level 2.5 product. The pipeline only generates Level 2 data products for unchopped spectroscopy in SPG 8.0. You need to combine interactively the on and off positions using the dedicated multi-observation unchopped pipeline script under the PACS pipeline menu.
- Unchopped grating scan flux calibration The absolute flux calibration of the PACS spectrometer is based on observations of flux calibration standards using chopped spectroscopy modes. There are hints of systematic differences in the response scaling between chopped and unchopped mode due to response transients within the chopping pattern. In SPG 8.0 the flux calibration of unchopped data relies on the system response derived chopped scheme, therefore absolute flux values need to be carefully interpreted. Please contact Helpdesk for guidelines on the specific observation you have to deal with.
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- Spectral leakage
- The order selection filters of the PACS spectrometer have a steep but not perfectly vertical transmission profile at the cutoff wavelengths of the spectral bands. PACS spectra near the band borders of bands R1, B3A and B2B are therefore affected by higher- or lower-order wavelengths leaking into the spectra -- both continuum and spectral lines! Consult the PACS Calibration Document for more information on the leakage regions.
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< < |
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- For the leak in band R1, it is possible to reduce these data with a specific relative spectral response function calibration file in HIPE to obtain correct line fluxes (but an incorrect continuum level). How to do this is explained in the PACS Data Reduction Guide for spectroscopy (chps 5 and 6 in the HIPE 13 version). This RSRF is not applied by default since it increases the noise in the resulting spectrum, but can be used interactively within HIPE.
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- For the leak in band R1, it is possible to reduce these data with a specific relative spectral response function calibration file in HIPE to obtain correct line fluxes (but an incorrect continuum level). How to do this is explained in the PACS Data Reduction Guide for spectroscopy (chps 5 and 6 in the HIPE 13 version). This RSRF is not applied by default since it increases the noise in the resulting spectrum, but can be used interactively within HIPE. Note that for range scan observations, this wavelength range is cut out by the SPG pipeline (i.e. they will not be present in these observations that you download from the HSA), but for line scan observation is it not (and they will be present): do not use these data for your science!
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- Second-pass ghosts
- A second pass in the optics of the PACS spectrometer can cause a ghost image to appear on most spaxels (but never in the central spaxel). If a source located in one of these "originating" spaxels shows a strong spectral line (typically an atomic fine-structure line), then a weak, broadened line can be seen at an offset wavelength in its corresponding "destination" spaxel affected by the 2nd-pass ghost. The peak flux of this line is typically ~5% of the peak of the originating line. The most prominent ghost is the 122 micron feature, which originates from the usually strong CII+ 157.7 micron line. A list of strong ghosts and an image showing the directions of the projected passes on the 5x5 IFU footprint can be found in the PACS Calibration Document.
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- Check for contaminating flux in chop-off positions
- To check for the presence of contamination from unwanted astronomical sources in the off positions of chopNod mode observations, you can use a Split On-Off pipeline script to produce an off-source and on-source cube. These cubes can then be compared to each other to check for contamination in spectral lines or by strong continuum emission, e.g. by over-plotting the respective spectra. Note that the on-source and off-source cubes produced by this task will not allow you to detect faint levels of contamination because wriggles from the RSRF are not removed by this process. For faint targets (line peak-to-continuum emission ~<5-10 Jy) you should also check the differential signal between the nodA and B on-source cubes. This is documented in the PACS Data Reduction Guide for spectroscopy. In this guide you can also find advice on checking for contamination in the unchopped mode observations, which is done either by comparing companion observations (unchopped range) or with a small script provided in the PDRG (unchopped line).
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< < |
<-- * RSRF at wavelengths below 53 microns* The relative spectral response function (used by the pipeline task rsrfCal) is an extrapolation at wavelengths below 53 microns. This will cause problems in the spectra from module 3 (=spaxel 3,0, i.e. in the cube image you see when you look at a PacsCube or PacsRebinnedCube with the Standard Cube Viewer or the Spectrum Explorer, it is the 4th up and on the very left): the extrapolation is too steep and makes the pixel-spectra similarly follow a very steep curve. This is being corrected. --> | > > |
- RSRF at wavelengths below 53 microns The relative spectral response function (used by the pipeline task rsrfCal) is an extrapolation at wavelengths below 53 microns. This will cause problems in the spectra from module 3 (=spaxel 3,0, i.e. in the cube image you see when you look at a PacsCube or PacsRebinnedCube with the Standard Cube Viewer or the Spectrum Explorer, it is the 4th up and on the very left): the extrapolation is too steep and makes the pixel-spectra similarly follow a very steep curve. This is being corrected.
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- Unstable/incorrect broad-band (dust) features
- Broad spectral features (of a few micrometer width) and continuum shape variations can be introduced by transient effects (for chopNod mode and more so for unchopped mode observations) and by pointing offsets distorting the Relative Spectral Response Function. The "background normalisation" pipeline script for chopNod observations is recommended for observations looking for such features, as it minimises the effect -- this is the SPG pipeline for HIPE 13 and onwards. For unchopped mode observations you could reprocess the observation with the "transients correction" pipeline script that is new to HIPE 13. However, neither of these pipelines will completely negate the effect of transients and pointing jitter-induced RSRF distortions.
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- Limitations on absolute spectrophotometric accuracy
- The PACS spectrometer flux calibration accuracy is limited by detector response drifts and slight pointing offsets arising from the standard 1.2" (1-sigma) pointing error occurring within each and every observation. These limit both the absolute flux accuracy and relative accuracy within a band. Various pipelines deal better with these than others (see the advice in the PACS Data Reduction Guide for spectroscopy) but they can never be entirely negated. Hence the calibration uncertainty for any particular observation is a combination of the general calibration uncertainties (given in the PACS Observers Manual), the noise on the spectrum (explained in more detail in the PDRG chp 7.6), and the "activity" during any single observation.
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< < |
<-- * Line flux correction due to strong wings in the instrumental profile (IP)* Pre-flight ground-based monochromatic measurements indicated the PACS spectrometer instrumental profile distributes measurable power in spectral line wings. The effect is below ~10% and only noticeable for wavelengths longer than ~150 micrometers. Future HIPE releases will provide a correction factor to apply on a Gaussian fit in order to compensate for line power lost in the IP wings. --> | > > |
- Line flux correction due to strong wings in the instrumental profile (IP) Pre-flight ground-based monochromatic measurements indicated the PACS spectrometer instrumental profile distributes measurable power in spectral line wings. The effect is below ~10% and only noticeable for wavelengths longer than ~150 micrometers. Future HIPE releases will provide a correction factor to apply on a Gaussian fit in order to compensate for line power lost in the IP wings.
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- NaN's in the final cubes
- It is normal to have NaNs at the very edges of the spectral ranges of SED mode observations: this is due to gaps in the spectral sampling.
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PACS Spectrometer Release Notes | |
< < | PACS spectrometer AOT release notes see PACS Instrument and Calibration webpage <--- PACS chopped line scan and high sampling range scan AOT release note: 19 Jan 2010
PACS Wavelength Switching AOT release note: 20 Jan 2009
PACS SED and large range scan AOT release note: 10 Mar 2010
PACS Unchopped Mode AOT Release Note: 20 Sep 2010 --> | > > | PACS spectrometer AOT release notes see PACS Instrument and Calibration webpage <!---<br /><a class="red" href="http://herschel.esac.esa.int/Docs/AOTsReleaseStatus/PACS_ChoppedLineRange_ReleaseNote_19Jan2010.pdf">PACS chopped line scan and high sampling range scan AOT release note</a>: 19 Jan 2010 <br /><br /><a class="red" href="http://herschel.esac.esa.int/Docs/AOTsReleaseStatus/PACS_WaveSwitching_ReleaseNote_20Jan2010.pdf">PACS Wavelength Switching AOT release note</a>: 20 Jan 2009<br /><br /><a class="red" href="http://herschel.esac.esa.int/Docs/AOTsReleaseStatus/PACS_SEDRange_ReleaseNote_10Mar2010.pdf">PACS SED and large range scan AOT release note</a>: 10 Mar 2010<br /><br /><a class="red" href="http://herschel.esac.esa.int/Docs/AOTsReleaseStatus/PACS_Unchopped_ReleaseNote_20Sep2010.pdf">PACS Unchopped Mode AOT Release Note</a>: 20 Sep 2010<br />--> | |
SPIRE Photometry | |
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- All SPIRE photometry pipelines now use by default the destriper, which improves the issue of striping in level 2 maps. Hence observers should expect potential improvements in that respect with version 9.
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Please note that there was a bug in the destriper task included in HIPE 9.0 that may affect your final map, especially if there are bright objects in the observed field. This has been corrected since HIPE 9.1. If your observation falls in the mentioned category, you are strongly advised to update your HIPE installation.
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In HIPE 10.0 the flagging of thermistor jumps in the level 0.5 to 1 data reduction is not set properly. This induces the destriper to work improperly and to leave stripes in the final map. It has been solved starting with HIPE 10.1.
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< < | <-- * Most of the stripes that are present in the final maps are due to a combination of thermal drifts (which in few cases are not efficiently removed) and median baseline subtraction. A similar effect is caused by very bright sources: in this case, the problem resides in the median baseline subtraction only. Suggested solutions: * switch to a baseline subtraction using a polynomial fitting using the optional task baselineRemovalPolynomial . If there are no jumps in the timelines, you may also try to run the baseline removal on the entire timeline; * in the case of bright sources, you may try to mask them before running the baseline removal (either median or polynomial): you can use this script as a template --> | > > | <!--<br /> * Most of the stripes that are present in the final maps are due to a combination of thermal drifts (which in few cases are not efficiently removed) and median baseline subtraction. A similar effect is caused by very bright sources: in this case, the problem resides in the median baseline subtraction only. Suggested solutions:<br /> * switch to a baseline subtraction using a polynomial fitting using the optional task baselineRemovalPolynomial. If there are no jumps in the timelines, you may also try to run the baseline removal on the entire timeline;<br /> * in the case of bright sources, you may try to mask them before running the baseline removal (either median or polynomial): you can use this script as a template<br />--> | |
- De-glitchter masks faint sources
- The de-glitcher is a very delicate process. In particular, for data taken in Parallel Mode (sampling at 10Hz) and at high speed (60"/s) the de-glitcher with standard parameters may flag very faint sources as glitches. Bright sources are different from glitches in that they have a gaussian (i.e. beam/PSF) shape. For faint sources, the sampling rate could be not high enough and hence they have a "delta" shape, which is similar to a small glitch. The user might try to modify the correlation parameter to 0.95: this will decrease the number of detected glitches.
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- Some sources have saturated the ADC and the corresponding data have been masked
- There is nothing a user can do: the source was simply too bright. If the user has other sources still not observed and of the same intensity, it is suggested to change the AORs to use the bright source mode.
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< < | <-- * Thermistor jumps* As of HIPE 6.0.3, a new module together called signalJumpDetector in place to identify the jump and to exclude the affected thermistor(s). --> | > > | <!-- * <b>Thermistor jumps*<br /> </b> As of HIPE 6.0.3, a new module together called signalJumpDetector in place to identify the jump and to exclude the affected thermistor(s). <br />--> | |
- Cooler temperature variations
- The cooler temperature variations, as explained in greater details in the SPIRE Data Reduction Guide, section 6.4, can affect observations performed soon after the cooler recycle. The steep rise of the sub-K detector temperature is also known as the cooler burp and there is a quality flag coolerBurpDetected in HIPE v11 or later that indicates if the observation was performed during this period.
The current list of observations known to have cooler temperature effects is here. Note that not all observations in this list raised the coolerBurpDetected flag.
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- NaNs pixels present in the PSW, PMW and/or PLW (Level 2) maps
- This effect, related to data masked for various reasons and poor coverage (not enough redundancy), is more evident in single fast-scan Parallel Mode maps. To avoid NaNs, increase the pixel's dimension (i.e., decrease the map's resolution)
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< < | <-- * WCS in 3-colour images* In all observation reduced with HIPE 8, the task createRgbImage puts wrong WCS in the output. Instead of using the WCS provided by the WCS input parameter, this task uses the WCS of one of the input images. This has been fixed in HIPE 9 --> | > > | <!-- * <b>WCS in 3-colour images*<br /> </b> In all observation reduced with HIPE 8, the task createRgbImage puts wrong WCS in the output. Instead of using the WCS provided by the WCS input parameter, this task uses the WCS of one of the input images. This has been fixed in HIPE 9<br />--> | |
- Quality flags
- Currently, the quality flags at the quality context inside the observation context are just meant for HSC/ICC internal evaluation of the quality of the products and not for the users. In case the data had some serious quality problem, the PI of the program has been contacted about it. Otherwise, only information in the quality summary, when available, should concern the observers.
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SPIRE Small Scan Map AOT release note: 17 Mar 2010 | |
< < | <-- SPIRE Point Source Mode release note: 30 Apr 2010 --> | > > | <!--<br /><a class="red" href="http://herschel.esac.esa.int/Docs/AOTsReleaseStatus/SPIRE_PointSource_AOT_ReleaseNote_30Apr2010.pdf">SPIRE Point Source Mode release note</a>: 30 Apr 2010 <br />--> | |
SPIRE Spectroscopy | |
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- Very small repetition numbers (e.g. 2 or 4) make 2nd level deglitching, which is based on a statistical outlier criterion, more challenging. The deglitching module may either not identify a glitch at all or it may not remove it completely. In cases where the glitch is located within the double-sided portion of the interferogram, the additional energy from the glitch will translate into artefacts of the continuum level. This kind of problem can be identified by inspecting all detectors from all scans in the level-1 spectral products. For some detectors, one or several scans may appear to be outliers. As a work-around, it is recommended to reprocess the data with a lower thresholdFactor when calling deglitchIfgm(). If the problem persists, the identified detector should be removed from the applicable scan in the SDI product.
(NB: This affects HIPE 6 and higher)
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< < |
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- Unresolved lines should be fitted using a sinc model with the width fixed. For the sinc model implemented in the
SpectrumFitterGUI , the sinc width can be set equal to resolution/π, which, for HR is 1.2/π = 0.382 GHz. For partially resolved lines, with widths greater than 200 km/s, the sincGauss model can be used, keeping the sinc width fixed.
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- Unresolved lines should be fitted using a sinc model with the width fixed. For the sinc model implemented in the SpectrumFitterGUI, the sinc width can be set equal to resolution/π, which, for HR is 1.2/π = 0.382 GHz. For partially resolved lines, with widths greater than 200 km/s, the sincGauss model can be used, keeping the sinc width fixed.
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- Point-source and extended-source calibrated spectra
- If your level-2 spectra show characteristic jumps at ~1250 GHz and ~750 GHz, so the spectra from the two bands SSW and SLW do not match, then your target may be extended or semi-extended in the SPIRE beam. You may need to use the semi-extended correction tool (SECT), available since HIPE v10. Check the SPIRE Data Reduction Guide (SDRG), section 7.6.2 "Does my spectrum need correcting?".
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< < | <-- * FTS Array footprint user script* For very large area maps the script produces wrong overlay (offset from the real position) if the default map projections (tangential) is used. The workaround is to use smaller map where the tangential projection centre is near the FTS target position. --> | > > | <!-- * <b>FTS Array footprint user script*<br /> </b> For very large area maps the script produces wrong overlay (offset from the real position) if the default map projections (tangential) is used. The workaround is to use smaller map where the tangential projection centre is near the FTS target position.<br /> --> | |
- Calibration/pipeline problems/needs
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Other Technical Notes | |
< < | PACS documents: see PACS Instrument and Calibration webpage <-- PACS Spectroscopy AOR Update Guide for Routine Phase Observations: 10 Mar 2010 --> | > > | PACS documents: see PACS Instrument and Calibration webpage <!-- <br /><a class="red" href="http://herschel.esac.esa.int/Docs/TechnicalNotes/PACS_Spectroscopy_AOR_Update_Guide_10Mar2010.pdf">PACS Spectroscopy AOR Update Guide for Routine Phase Observations</a>: 10 Mar 2010<br />--> | |
HIFI Information note on Mapping Modes: 30 Jun 2010 | |
PACS photometer and spectrometer calibration documents: see PACS Instrument and Calibration webpage | |
< < | <-- PACS Spectroscopy Performance and Calibration: 11 Mar 2010
PACS Photometer Point Spread Function (PSF): 03 Nov 2010 --> | > > | <!-- <a class="red" href="http://herschel.esac.esa.int/Docs/Calibration/PACS_SpectroscopyPerformanceCalibration_11Mar2010.pdf">PACS Spectroscopy Performance and Calibration</a>: 11 Mar 2010 <br /><br /><a class="red" href="http://herschel.esac.esa.int/Docs/Calibration/PACS_Point_Spread_Function_03Nov2010.pdf">PACS Photometer Point Spread Function (PSF)</a>: 03 Nov 2010 <br />--> | |
SPIRE Photometer Beams (FTP repository)
HIFI System noise temperature IF spectra (FTP repository) | |
< < | <-- * Set ALLOWTOPICCHANGE = DpMgGroup, HscCommunitySupportGroup --> | > > | <!--<br />* Set ALLOWTOPICCHANGE = DpMgGroup, HscCommunitySupportGroup<br />--> | |
META FILEATTACHMENT |
attr="h" autoattached="1" comment="" date="1437490181" name="obsSVVanomaly.csv" path="obsSVVanomaly.csv" size="2980" user="Main.LucaCalzoletti" version="1" |
META FILEATTACHMENT |
attr="" autoattached="1" comment="" date="1437489475" name="ngc253_1342221743_blue.jpeg" path="ngc253_1342221743_blue.jpeg" size="957526" user="Main.LucaCalzoletti" version="1" |
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META FILEATTACHMENT |
attachment="spec_extCalCorr_curve.png" attr="" comment="" date="1456503057" name="spec_extCalCorr_curve.png" path="spec_extCalCorr_curve.png" size="120905" user="RosalindHopwood" version="1" |
META FILEATTACHMENT |
attachment="lrBeforeAfter.png" attr="" comment="" date="1456522197" name="lrBeforeAfter.png" path="lrBeforeAfter.png" size="225688" user="RosalindHopwood" version="2" |
META FILEATTACHMENT |
attachment="cpCubesPartialSpecIssue.png" attr="" comment="" date="1458766760" name="cpCubesPartialSpecIssue.png" path="cpCubesPartialSpecIssue.png" size="131932" user="RosalindHopwood" version="1" |
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META FILEATTACHMENT |
attachment="unchoppedwrong.txt" attr="" comment="temporary mssg about pacs spec unchopped foul" date="1462284207" name="unchoppedwrong.txt" path="unchoppedwrong.txt" size="803" user="KatrinaExter" version="1" |
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