Difference: DataProcessingWorkshop2013 (33 vs. 34)

Revision 342013-06-26 - PedroGarciaLario

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Herschel Data Processing Workshop for Newcomers, 24-27 June 2013

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 For full science quality you need to re-pipeline the data - take advantage of the latest calibrations as the HSA products don't run all the pipeline tasks. This is documented in chp 1 of the PDRG. You can get fluxes (Jy/spaxel) and wavelengths (microns). Though the fits files do have a rather awkward format. They can be hard to read directly into other software - we are working on this and if you have problems it is fastest to raise a helpdesk ticket. One last thing: for unchopped mode, the flux level of the continuum is not guaranteed to be correct. That mode was never intended for continuum studies.
Q3: where can I find the sky background contamination?

A3: If the question means: where can I find the spectra of the sky (+telescope) then for chop-nod observations these are the spectra taken in the off-chop positions. The easiest way to see these data is to run the script Split On-Off, which you find in the HIPE Pipelines menu (Spectroscopy->both chopped menus -> Split On-Off. This is also explained in the pipeline chapters (chp 3) of the PACS Data Reduction Guide. This script will produce separate cubes of the on-source spectra and the off-source spectra.

Q4: can you subtract a baseline to spectra? Could it be included in the script?

A4: The currently best documented way is to fit the continuum with a poly and then get the residual (data - fit). This is explained in chapter 7 of the "Data Analysis Guide" (about the SpectrumFitter and SpectrumFitterGUI), which you can get via the HIPE Help->Help contents menu. The baseline fitter is a PACS specific task that you can also use but it is not well documented. This takes the data and identifies where the baseline is, i.e. it ignores lines, and then that baseline can be subtracted from the spectrum. If someone wants to use this task, or know more details, then please raise a helpdesk ticket to ask specifically for that.

Q5: is the split on-off applicable to unchopped observations?

A5: For the unchopped line scan mode, the off-source spectra are separated out from the on-source spectra within the pipeline (it will be very clear when this happens as you follow the interactive pipeline script Spectroscopy->unchopped line scan->"lineScan") and you can then compare them by plotting them together (this is also explained in the PDRG pipeline chap 4 and some additional information in chp 8). For the unchopped range scan, on and off (ie source and sky) are separate observations and once you have reduced each through to Level 2, you can compare them e.g. as cubes in the Spectrum Explorer.

 PACS Photometry


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