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Hubble Performance Monitoring and Assessment meeting #5, Goddard: minutes (excerpt)
5 June 1990 (file dated 11 June 1990)
Official minutes of the weekly HST performance meeting at Goddard, from Chris’s STScI files. Six days after Chris’s 30 May memorandum giving about half a wave rms of spherical aberration, the optics contractor (Hughes Danbury) reported its own phase-retrieval result from a 3 June image: spherical only ~0.2 wave peak-to-valley, with ~4 waves of coma attributed to secondary-mirror misalignment. The same minutes schedule the joint SWG/Users Committee/PMA meeting of 27 June at which Chris presented the diagnosis. Excerpt; attendee contact details omitted.
Plain textRelated: Diagnosing Hubble’s spherical aberration
PERFORMANCE MONITORING AND ASSESSMENT WEEKLY MEETING #5 Tuesday June 5, 1990, 1:30 - 3:30 p.m. Goddard Space Flight Center, Building 8, 3rd Floor Management Conference Center N303
[Excerpt from the minutes as circulated by e-mail, file dated 11 June 1990. Only the OTA/wavefront items and the meeting schedule are reproduced; attendee contact details omitted.]
PMA Status - Keith Kalinowski
... The first monthly PMA meeting will be a joint SWG/HST Users Committee/PMA monthly to be held June 27 in Building 22 Room 365. ...
Executive Summary (extract)
Bob Basedow reported on the current OTA status. He presented results of analysis on the FGS's, the Optical Control System/Wavefront Sensors and the Thermal system. ... The Image size is ~ 0.7 arcsecs and the wavefront is estimated at: Focus ~ 2 waves, astigmatism ~.2 waves, coma ~ 4 waves, and spherical is ~ .2 waves. There are currently no significant thermal anomalies.
OTA STATUS - Bob Basedow, HDOS
OCS/WAVEFRONT Status
o Focus currently best achievable using FGSs (Bootstrap Phase A) o FGS data indicates image size ~0.7 asecs o WFPC data consistent with this, but shows central 0.15 asec core o HDOS Phase retrieval algorithm applied to PC image of 6/3/90 o Wavefront estimated at: FOCUS ~ 2 WAVES o-p ASTIGMATISM ~0.2 WAVES o-p COMA ~4 WAVES o-p SPHERICAL ~0.2 WAVES o-p o Estimate probably significantly affected by WFPC optics, especially central obscuration alignment
The phase retrieval model does not account for the WFPC optics, and therefore cannot reproduce the PSF's. Nutuation of the annulus around the peak of the PSF, is attributed to the mis-alignment of the secondary mirror.
OBA is a package which finds the aberrations given a PSF Measured PSF's are taken from the WF/PC Have Fit "1st Light" WFC PSF and a PC PSF
Ongoing Analysis: Find cause of skirt around PSF (pupil vignette) Field Dependence in WF/PC CCD arrays Further algorithm refinement
WFPC REPORT There was no one available to report on the status of the WFPC.