Bruno Altieri 21-22 Jan. 2009

http://herschel.esac.esa.int/ # 1

Pointing calibration plan

Bruno Altieri (HSC)

PACS PV phase reviewMPE, January 2008

Bruno Altieri 21-22 Jan. 2009

http://herschel.esac.esa.int/ # 2

Pointing Working Group• A pointing working group was set-up early 2008, by the

SciOps WG between Project, MOC (FD), HSC and ICCs.

• A pointing calibration plan was issued– T. Marston, HERSCHEL-HSC-DOC-1139, v1.0, 5/8/2008– Herschel relies on PACS (blue) photometer for spacecraft

pointing performance assessment

• The plan was later de-scoped to only use Star Tracker 1

Bruno Altieri 21-22 Jan. 2009

http://herschel.esac.esa.int/ # 3

Pointing calibration plan• Pointing cal. plan became part of PV phase to a large

fraction, hence now in PACS PV plan– But time budget counted separately– Obviously must be scheduled as early as possible.– Preceded by in commissioning :

• ACMS commissioning in CoP• Photometer bias set-up (BOLO_BIAS_2)• PACS search scan map (CoP)• Check of derived SIAM update (CoP)

• Total estimated time : ~30 hours– In the PVPhotFPG program– Does not include 7.5 hours of spectrometer FPG.

Bruno Altieri 21-22 Jan. 2009

http://herschel.esac.esa.int/ # 4

Pointing calibration CoP• Initial search map

– 40’x40’ scan map: wide search to include STR structure bending, M2 misalignment ..

– M51 ? ISO first light• Advantages:

– Visible 23/04 – 09/08– Hint about orientation

• Drawback– Not point-like, but companion is !

• Derive SIAM• Check SIAM update

– Standard PS mode– HIP 21479 (always visible) 140 Jy

• Already a scan map at the end of BOLO_BIAS_2 ?

Bruno Altieri 21-22 Jan. 2009

http://herschel.esac.esa.int/ # 5

Pointing calibration PV• Pointing cal. plan became part of PV phase to a large

fraction, hence now in PACS PV plan– But time budget counted separately– Obviously must be scheduled as early as possible.– Preceded by in commissioning :

• ACMS commissioning in CoP• Photometer bias set-up (BOLO_BIAS_2)• PACS search scan map (CoP)• Check of derived SIAM update (CoP)

• Total estimated time : ~30 hours– In the PVPhotFPG program– Does not include 7.5 hours of spectrometer FPG.

Bruno Altieri 21-22 Jan. 2009

http://herschel.esac.esa.int/ # 6

Pointing calibration• Stars sample selected by Markus Nielbock

– PACS pointing calibration stars (PICC-MA-TN-003)

• Measure APE statistically with “many” stars– 40 stars, 5mn AORs, for standard SAA range [-10,30]– Duration :~4 hours

• Tune SIAM• Explore the full SAA range after a long stabilisation

– [-20,-10]– [-30, -20]

• SRPE measurement assessment,– Making use of on-ground gyro propagation

Bruno Altieri 21-22 Jan. 2009

http://herschel.esac.esa.int/ # 7

Pointing observation plan (1)

Bruno Altieri 21-22 Jan. 2009

http://herschel.esac.esa.int/ # 8

Pointing observation plan (2)

Bruno Altieri 21-22 Jan. 2009

http://herschel.esac.esa.int/ # 9

Tests and CAP• SOVT-1: standard AORs• SOVT-2

– OD 60, 63 & 64– Only looked at OD 60 so far

• Dithering was not put (gain?)

• SIMS-1– OD 65 already delivered (standard AORs)

• CAP from Dieter• Tested 2D gaussian fitting in dp-pacs

– Though not as robust as in IDL