Pointing Calibration Plan for PACS in the Herschel PV Phase Review
In January 2008, a pointing working group was established between SciOps WG, MOC (FD), and HSC to create a pointing calibration plan for the PACS instrument. This effort is crucial for spacecraft pointing performance assessment, initially relying on the PACS photometer. The plan evolved to primarily utilize Star Tracker 1 and became integral to the PACS PV phase. A total of approximately 30 hours was estimated for calibration activities, which included commissioning procedures and observational plans to improve pointing accuracy.
Pointing Calibration Plan for PACS in the Herschel PV Phase Review
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Presentation Transcript
Pointing calibration plan PACS PV phase review MPE, January 2008 Bruno Altieri (HSC)
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
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.
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 ?
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.
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
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
