Difference: StrSwitchOversAndSvvResets (1 vs. 11)

Revision 112016-04-12 - MiguelSanchez

Line: 1 to 1
 
META TOPICPARENT name="ImprovedPointing"

Periods of anomalous pointing during the Herschel mission due to star-tracker switch-overs and lack of aberration correction.

Line: 17 to 17
  If you have observations in one of the ODs referred below please contact the HSC Helpdesk for more information and support. Please refer to the HSC Helpdesk web link
Changed:
<
<		The problem has been addressed in HCSS 14.0 and the tests carried out with several observations, including pointing calibration targets, indicate that the problem has been correctly fixed. However, large offsets have been reported on individual observations (e.g. obsid 1342183075 in OD 112) so in case that you find any problem with the astrometry of your observation, please contact the HSC Helpdesk.
>
>		 The problem was been addressed in HCSS 14.0 . The tests performed indicated that the STR misalignment was not properly handled in early ODs (<= 113) and has been fixed in HCSS 14.1. (see SPR HCSS-20990). However, some issues still exist for a small set of SPIRE parallel observations in OD 111 (investigation on-going). In case that you find any problem with the astrometry of your observation, please contact the HSC Helpdesk.
 

STR switch-overs

Revision 102015-12-15 - MiguelSanchez

Line: 1 to 1
 
META TOPICPARENT name="ImprovedPointing"

Periods of anomalous pointing during the Herschel mission due to star-tracker switch-overs and lack of aberration correction.

Changed:
<
<
<--
  

-->
>
>
 

Rationale

Line: 17 to 17
  If you have observations in one of the ODs referred below please contact the HSC Helpdesk for more information and support. Please refer to the HSC Helpdesk web link
Changed:
<
<
NEW Contrary to previous statements, the problem with STR switch-overs still persists in HCSS 14.0. It is under investigation.
>
>		The problem has been addressed in HCSS 14.0 and the tests carried out with several observations, including pointing calibration targets, indicate that the problem has been correctly fixed. However, large offsets have been reported on individual observations (e.g. obsid 1342183075 in OD 112) so in case that you find any problem with the astrometry of your observation, please contact the HSC Helpdesk.
 

STR switch-overs

Revision 92015-12-15 - MiguelSanchez

Line: 1 to 1
 
META TOPICPARENT name="ImprovedPointing"

Periods of anomalous pointing during the Herschel mission due to star-tracker switch-overs and lack of aberration correction.

Line: 11 to 11
 
  1. Switch from the main star-tracker (STR1) to the backup unit (STR2) either driven by the autonomous Failure Detection, Isolation and Recovery (FDIR) or commanded from ground for testing and calibrating the backup unit. This produces an offset of some 15 arcsec between the desired (nominal) and actually commanded coordinates.
  2. Incorrect upload of the Spacecraft Velocity Vector (SVV) to the star-tracker (STR) resulting in a lack of light aberration correction in the coordinates of the STR guide stars. This produces a variable error in the range 0 - 20 arcsec between the desired (nominal) and actually commanded coordinates.
Changed:
<
<		NEW In HCSS 13.0, the auxiliary processor that creates the pointing product was updated to automatically check for those events and apply the corrections whenever appropriate. However, this was only implemented for the "simple-corrected" attitude (column simpleCorrFilterQuat) and not for the "gyro-propagated" one (column filterQuat). Hence, the astrometry of the products retrieved from the archive (processed with the gyro-propagated attitude) are still affected by the problems outlined above. If you want to reprocess the data by your own, you will need to overwrite the column filterQuat of the pointing product with the simpleCorrFilterQuat and then launch the pipeline processing ensuring that you use the new pointing product. However, in case of doubt of if you have observations in one of the ODs referred below and processed with SPG < 13.0, please contact the HSC Helpdesk for more information and support. Please refer to the HSC Helpdesk web link
>
>		NEW In HCSS 13.0, the auxiliary processor that creates the pointing product was updated to automatically check for those events and apply the corrections whenever appropriate. However, this was only implemented for the "simple-corrected" attitude (column simpleCorrFilterQuat) and not for the "gyro-propagated" one (column filterQuat). Hence, the astrometry of the products retrieved from the archive (processed with the gyro-propagated attitude) are still affected by the problems outlined above.
 
Changed:
<
<		NEW The problem has been fully solved in HCSS 14.0. Hence, future HSA products will be free of anomalies.
>
>
<--If you want to reprocess the data by your own, you will need to overwrite the column filterQuat of the pointing product with the simpleCorrFilterQuat and then launch the pipeline processing ensuring that you use the new pointing product.-->

If you have observations in one of the ODs referred below please contact the HSC Helpdesk for more information and support. Please refer to the HSC Helpdesk web link


NEW Contrary to previous statements, the problem with STR switch-overs still persists in HCSS 14.0. It is under investigation.

 

STR switch-overs

Line: 47 to 50
 
1308 2012-12-11T14:41:58.644 2012-12-11T19:56:45.000 5.246
The full list of observations affected by SVV resets, including science, calibration and engineering ones can be found here.
Changed:
<
<
Miguel Sanchez - 2015-11-26
>
>		-- Miguel Sanchez - 2015-12-15
 
META FILEATTACHMENT attachment="SVV_resets_aberration_shift_all_spg_versions.txt" attr="h" comment="" date="1448529955" name="SVV_resets_aberration_shift_all_spg_versions.txt" path="SVV_resets_aberration_shift_all_spg_versions.txt" size="8849" user="MiguelSanchez" version="1"
META FILEATTACHMENT attachment="STR_switch_shift_all_spg_versions.txt" attr="h" comment="" date="1448529955" name="STR_switch_shift_all_spg_versions.txt" path="STR_switch_shift_all_spg_versions.txt" size="78063" user="MiguelSanchez" version="1"

Revision 82015-11-26 - MiguelSanchez

Line: 1 to 1
 
META TOPICPARENT name="ImprovedPointing"

Periods of anomalous pointing during the Herschel mission due to star-tracker switch-overs and lack of aberration correction.

Line: 34 to 34
 
732 23.23
733 0.56
Added:
>
>		The full list of observations affected by STR switch-overs, including science, calibration and engineering ones can be found here.
 

SVV resets

OD Last_DPT_update_TC_time (UTC) First_SVV_update_TC_time (UTC) Duration (h)
Line: 44 to 45
 
499 2010-09-24T17:51:15.752 2010-09-25T00:49:03.000 6.963
543 2010-11-07T17:15:11.854 2010-11-08T00:09:32.000 6.906
1308 2012-12-11T14:41:58.644 2012-12-11T19:56:45.000 5.246
Deleted:
<
<		-- MiguelSanchez - 02 Jun 2014
 \ No newline at end of file
Added:
>
>		The full list of observations affected by SVV resets, including science, calibration and engineering ones can be found here.

Miguel Sanchez - 2015-11-26

META FILEATTACHMENT attachment="SVV_resets_aberration_shift_all_spg_versions.txt" attr="h" comment="" date="1448529955" name="SVV_resets_aberration_shift_all_spg_versions.txt" path="SVV_resets_aberration_shift_all_spg_versions.txt" size="8849" user="MiguelSanchez" version="1"
META FILEATTACHMENT attachment="STR_switch_shift_all_spg_versions.txt" attr="h" comment="" date="1448529955" name="STR_switch_shift_all_spg_versions.txt" path="STR_switch_shift_all_spg_versions.txt" size="78063" user="MiguelSanchez" version="1"

Revision 72015-11-25 - MiguelSanchez

Line: 1 to 1
 
META TOPICPARENT name="ImprovedPointing"

Periods of anomalous pointing during the Herschel mission due to star-tracker switch-overs and lack of aberration correction.

Line: 12 to 11
 
  1. Switch from the main star-tracker (STR1) to the backup unit (STR2) either driven by the autonomous Failure Detection, Isolation and Recovery (FDIR) or commanded from ground for testing and calibrating the backup unit. This produces an offset of some 15 arcsec between the desired (nominal) and actually commanded coordinates.
  2. Incorrect upload of the Spacecraft Velocity Vector (SVV) to the star-tracker (STR) resulting in a lack of light aberration correction in the coordinates of the STR guide stars. This produces a variable error in the range 0 - 20 arcsec between the desired (nominal) and actually commanded coordinates.
Changed:
<
<		NEW In HCSS 13.0, the auxiliary processor that creates the pointing product has been updated to automatically check for those events and apply the corrections whenever appropriate. Hence, if your observation has been processed with SPG 13.0 or later, you don't need to worry about this. Otherwise, the correction can be applied manually using scripts developed at the HSC. Therefore in case that you have observations in one of the ODs referred below and processed with SPG < 13.0, please contact the HSC Helpdesk for more information and support. Please refer to the HSC Helpdesk web link
>
>		NEW In HCSS 13.0, the auxiliary processor that creates the pointing product was updated to automatically check for those events and apply the corrections whenever appropriate. However, this was only implemented for the "simple-corrected" attitude (column simpleCorrFilterQuat) and not for the "gyro-propagated" one (column filterQuat). Hence, the astrometry of the products retrieved from the archive (processed with the gyro-propagated attitude) are still affected by the problems outlined above. If you want to reprocess the data by your own, you will need to overwrite the column filterQuat of the pointing product with the simpleCorrFilterQuat and then launch the pipeline processing ensuring that you use the new pointing product. However, in case of doubt of if you have observations in one of the ODs referred below and processed with SPG < 13.0, please contact the HSC Helpdesk for more information and support. Please refer to the HSC Helpdesk web link
 
Added:
>
>		NEW The problem has been fully solved in HCSS 14.0. Hence, future HSA products will be free of anomalies.
 

STR switch-overs

Revision 62015-04-10 - MiguelSanchez

Line: 1 to 1
 
META TOPICPARENT name="ImprovedPointing"

Periods of anomalous pointing during the Herschel mission due to star-tracker switch-overs and lack of aberration correction.

Line: 12 to 12
 
  1. Switch from the main star-tracker (STR1) to the backup unit (STR2) either driven by the autonomous Failure Detection, Isolation and Recovery (FDIR) or commanded from ground for testing and calibrating the backup unit. This produces an offset of some 15 arcsec between the desired (nominal) and actually commanded coordinates.
  2. Incorrect upload of the Spacecraft Velocity Vector (SVV) to the star-tracker (STR) resulting in a lack of light aberration correction in the coordinates of the STR guide stars. This produces a variable error in the range 0 - 20 arcsec between the desired (nominal) and actually commanded coordinates.
Changed:
<
<		While a definitive fix for this problem is being implemented (automatically checking for such events and applying the required corrections upon creation of the pointing product), currently whenever a bulk reprocessing is performed, the corrections get lost. Several scripts developed at HSC can provide a correct pointing but require manual intervention. So in case that you have observations in one of the ODs referred below, please contact the HSC Helpdesk for more information and support. Please refer to the HSC Helpdesk web link
>
>		NEW In HCSS 13.0, the auxiliary processor that creates the pointing product has been updated to automatically check for those events and apply the corrections whenever appropriate. Hence, if your observation has been processed with SPG 13.0 or later, you don't need to worry about this. Otherwise, the correction can be applied manually using scripts developed at the HSC. Therefore in case that you have observations in one of the ODs referred below and processed with SPG < 13.0, please contact the HSC Helpdesk for more information and support. Please refer to the HSC Helpdesk web link
 

Revision 52014-06-02 - MiguelSanchez

Line: 1 to 1
 
META TOPICPARENT name="ImprovedPointing"
Changed:
<
<

Anomalies in pointing products due to STR switch-overs and SVV resets

>
>

Periods of anomalous pointing during the Herschel mission due to star-tracker switch-overs and lack of aberration correction.

 
Changed:
<
<
>
>
<--
  

-->
 

Rationale

Added:
>
>		The pointing data of several ODs are affected by offsets due to two causes:

  1. Switch from the main star-tracker (STR1) to the backup unit (STR2) either driven by the autonomous Failure Detection, Isolation and Recovery (FDIR) or commanded from ground for testing and calibrating the backup unit. This produces an offset of some 15 arcsec between the desired (nominal) and actually commanded coordinates.
  2. Incorrect upload of the Spacecraft Velocity Vector (SVV) to the star-tracker (STR) resulting in a lack of light aberration correction in the coordinates of the STR guide stars. This produces a variable error in the range 0 - 20 arcsec between the desired (nominal) and actually commanded coordinates.

While a definitive fix for this problem is being implemented (automatically checking for such events and applying the required corrections upon creation of the pointing product), currently whenever a bulk reprocessing is performed, the corrections get lost. Several scripts developed at HSC can provide a correct pointing but require manual intervention. So in case that you have observations in one of the ODs referred below, please contact the HSC Helpdesk for more information and support. Please refer to the HSC Helpdesk web link

 

STR switch-overs

Line: 42 to 50
 
543 2010-11-07T17:15:11.854 2010-11-08T00:09:32.000 6.906
1308 2012-12-11T14:41:58.644 2012-12-11T19:56:45.000 5.246
Changed:
<
<		-- MiguelSanchez - 30 May 2014
>
>		-- MiguelSanchez - 02 Jun 2014

Revision 42014-06-02 - MiguelSanchez

Line: 1 to 1
 
META TOPICPARENT name="ImprovedPointing"

Anomalies in pointing products due to STR switch-overs and SVV resets

Line: 11 to 11
 

STR switch-overs

Changed:
<
<
OD Time (h)
>
>
OD Duration (h)
 
44 0.0001
81 11.31
82 19.64
Line: 33 to 33
 

SVV resets

Added:
>
>
OD Last_DPT_update_TC_time (UTC) First_SVV_update_TC_time (UTC) Duration (h)
399 2010-06-16T16:43:53.432 2010-06-16T23:25:47.000 6.698
427 2010-07-14T16:02:01.681 2010-07-14T22:31:16.000 6.487
448 2010-08-04T15:21:47.767 2010-08-04T22:06:17.000 6.741
480 2010-09-05T18:07:30.264 2010-09-06T01:04:48.000 6.955
499 2010-09-24T17:51:15.752 2010-09-25T00:49:03.000 6.963
543 2010-11-07T17:15:11.854 2010-11-08T00:09:32.000 6.906
1308 2012-12-11T14:41:58.644 2012-12-11T19:56:45.000 5.246
  -- MiguelSanchez - 30 May 2014 \ No newline at end of file

Revision 32014-06-02 - MiguelSanchez

Line: 1 to 1
 
META TOPICPARENT name="ImprovedPointing"

Anomalies in pointing products due to STR switch-overs and SVV resets

Line: 17 to 17
 
82 19.64
83 24.01
84 1.67
Added:
>
>
93 24.04
94 24.04
95 24.04
111 10.21
112 22.70
161 2.08
585 14.10
586 2.12
732 23.23
733 0.56
 
Deleted:
<
<		!!! STR 2 found during 86529.00 seconds in AHF 0093_0001.AHF!!! Total records in AHF = 346117, Count = 346116 !!! STR 2 found during 86529.00 seconds in AHF 0093_0002.AHF!!! Total records in AHF = 346125, Count = 346124 !!! STR 2 found during 86531.00 seconds in AHF 0094_0001.AHF!!! Total records in AHF = 346125, Count = 346124 !!! STR 2 found during 86531.00 seconds in AHF 0094_0002.AHF!!! Total records in AHF = 346137, Count = 346136 !!! STR 2 found during 86534.00 seconds in AHF 0095_0001.AHF!!! Total records in AHF = 367897, Count = 147096 !!! STR 2 found during 36774.00 seconds in AHF 0111_0002.AHF!!! Total records in AHF = 326937, Count = 326936 !!! STR 2 found during 81734.00 seconds in AHF 0112_0001.AHF!!! Total records in AHF = 344825, Count = 30016 !!! STR 2 found during 7504.00 seconds in AHF 0161_0002.AHF!!! Total records in AHF = 343841, Count = 203099 !!! STR 2 found during 50774.75 seconds in AHF 0585_0002.AHF!!! Total records in AHF = 343201, Count = 30518 !!! STR 2 found during 7629.50 seconds in AHF 0586_0002.AHF!!! Total records in AHF = 345268, Count = 334535 !!! STR 2 found during 83633.75 seconds in AHF 0732_0003.AHF!!! Total records in AHF = 342104, Count = 8120 !!! STR 2 found during 2030.00 seconds in AHF 0733_0003.AHF!!!
 

Revision 22014-05-31 - MiguelSanchez

Line: 1 to 1
 
META TOPICPARENT name="ImprovedPointing"

Anomalies in pointing products due to STR switch-overs and SVV resets

Line: 11 to 11
 

STR switch-overs

Added:
>
>
OD Time (h)
44 0.0001
81 11.31
82 19.64
83 24.01
84 1.67

!!! STR 2 found during 86529.00 seconds in AHF 0093_0001.AHF!!! Total records in AHF = 346117, Count = 346116 !!! STR 2 found during 86529.00 seconds in AHF 0093_0002.AHF!!! Total records in AHF = 346125, Count = 346124 !!! STR 2 found during 86531.00 seconds in AHF 0094_0001.AHF!!! Total records in AHF = 346125, Count = 346124 !!! STR 2 found during 86531.00 seconds in AHF 0094_0002.AHF!!! Total records in AHF = 346137, Count = 346136 !!! STR 2 found during 86534.00 seconds in AHF 0095_0001.AHF!!! Total records in AHF = 367897, Count = 147096 !!! STR 2 found during 36774.00 seconds in AHF 0111_0002.AHF!!! Total records in AHF = 326937, Count = 326936 !!! STR 2 found during 81734.00 seconds in AHF 0112_0001.AHF!!! Total records in AHF = 344825, Count = 30016 !!! STR 2 found during 7504.00 seconds in AHF 0161_0002.AHF!!! Total records in AHF = 343841, Count = 203099 !!! STR 2 found during 50774.75 seconds in AHF 0585_0002.AHF!!! Total records in AHF = 343201, Count = 30518 !!! STR 2 found during 7629.50 seconds in AHF 0586_0002.AHF!!! Total records in AHF = 345268, Count = 334535 !!! STR 2 found during 83633.75 seconds in AHF 0732_0003.AHF!!! Total records in AHF = 342104, Count = 8120 !!! STR 2 found during 2030.00 seconds in AHF 0733_0003.AHF!!!

 

SVV resets

Revision 12014-05-30 - MiguelSanchez

Line: 1 to 1
Added:
>
>
META TOPICPARENT name="ImprovedPointing"

Anomalies in pointing products due to STR switch-overs and SVV resets

Rationale

STR switch-overs

SVV resets

-- MiguelSanchez - 30 May 2014

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