space telescope science institute operated for nasa by aura an update on the cos development status...
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SPACETELESCOPESCIENCEINSTITUTE
Operated for NASA by AURA
An Update on the COS Development Status
TIPS21 August 2003
(Last COS TIPS: Dec 2002)
COS Integrated SI (Aft End)
Sembach 2 of 21TIPS - 21 August 2003
COS Timeline Summary
• Instrument integration activities (Jan-Mar 2003)– Calibration platform installed, electronics, enclosure, etc– FUV02 (flight spare) detector qualifications completed
• FUV detector swap and alignment (March-April 2003)– FUV02 performance better at longer ; “flatter” throughput– Alignment checked under N2 purge with CAOS/HOMS
• Environmental tests of integrated instrument (April 2003)– GSFC: EMI/EMC, acoustics, vibration, metrology
• Initial thermal balance, alignment, and testing in vacuum completed in July 2003– To confirm focus/spectral resolution/throughput/operations
Sembach 3 of 21TIPS - 21 August 2003
COS Timeline Summary (con’t)
• Instrument currently out of vacuum chamber at Ball– Working issues discovered during initial testing
• T-Vac activities to begin September 11• Science calibration to occur September 18 - October 12• Delivery to GSFC expected in late October 2003• Integrated pipeline testing in May 2004• SMGT planned for late July 2004• Working to launch date of May 2005
Sembach 4 of 21TIPS - 21 August 2003
COS: pre-acoustic test; packing for return to Ball
Sembach 5 of 21TIPS - 21 August 2003COS Integrated SI and Enclosure
Sembach 6 of 21TIPS - 21 August 2003
COS Issues of Interest
• Spectra in Bright Object Aperture (BOA) have coma– ND2 filter (2 mm cube) has 0.25
o wedge
– Resolution degraded by factor of ~4 in NUV, less in FUV
– No serious science impact
• Spectral lines sometimes found to be “tilted” under N2 purge in CAOS/HOMS after FUV02 detector swap
– Time variable, observed for FUV external lamp spectra
– Most likely related to failing PtNe calibration lamp
– Not seen after new lamp installed or in later vacuum tests
Sembach 7 of 21TIPS - 21 August 2003
Removal of COS from Vacuum Chamber
• Internal ion pressure gauge not functioning– Problem traced to incorrect signals fed to electronics box; fixed
• RASCAL chief ray not aligned as it was prior to pump down– Chief ray remeasured; tip/tilt mirrors corrected
• Interpoint converter found to be faulty after check of calibration lamp voltage and current telemetry– LVPS board removed, x-rayed at GSFC– Solder leads lift from solder joints under vacuum– Other converters (5) x-rayed to ensure sufficient strain relief– Spares also being checked– Stiffener plates (Kovar) being bonded to tops to prevent stress
Sembach 8 of 21TIPS - 21 August 2003
STScI Thermal Vacuum Activities
• Instrument scientists supported initial science verification activities in late June - early July in Boulder, CO– Hartig, Leitherer, Sembach participated on-site– Friedman analyzed spectral repeatability data– Approx. 500 datasets produced in two week period
• Science calibration data archived in MAST– All data run through OPUS and initial CALCOS processing– T-Vac retrieval screen available– Automated data transfer algorithms developed and implemented– Data also stored locally on COS machines for rapid analysis
• Keyword consistency checking– Fidelity of FITS keywords being checked with help from Rose/Hodge
Sembach 9 of 21TIPS - 21 August 2003
COS Initial Testing Summary
• Instrument is performing as expected optically– Spectral resolution ~ 20,000 in medium resolution modes– Throughput meets/exceeds CEI specifications– Geometric distortion can be corrected accurately– Grating motion repeatability is as good as expected– Spatial resolution ~ 1 arc sec
• Final calibration activity plan being finalized by CU/Ball– Close cooperation with STScI
• Testing to resume in mid-September
Sembach 10 of 21TIPS - 21 August 2003
Sample COS FUV Spectrum
External PtNe calibration lamp
(no distortion correction)
Sembach 11 of 21TIPS - 21 August 2003
Sample COS NUV Spectrum
External PtNe calibration lamp
Sembach 12 of 21TIPS - 21 August 2003
Initial FUV Spectral Resolution Results - G130M
External PtNe calibration lamp
R =
Sembach 13 of 21TIPS - 21 August 2003
Initial FUV Spectral Resolution Results - G160M
External PtNe calibration lamp
R =
Sembach 14 of 21TIPS - 21 August 2003
Initial NUV Spectral Resolution
Results
G185M
G225M
G285M
External PtNe calibration lamp
R =
Sembach 15 of 21TIPS - 21 August 2003
Grating Wavelength (Å) Efficiency RequirementG130M-B 1248 0.174±0.018 >0.103
G130M-A 1327 0.113±0.017
G160M-B 1430 0.120±0.011 >0.077
G160M-A 1621 0.075±0.016
G140L 1327 0.083±0.014 >0.07G185M 1846 0.0355±0.0043 >0.018G225M 2487 0.0248±0.0023 >0.023G285M 2695 0.0189±0.0014 >0.017G230L 2262 0.0246±0.029 >0.021TA1 2487 0.0424±0.0043 No reqTA1-Brt 2487 0.0031±0.0003 No req
Initial COS Efficiency Estimates
From Wilkinson et al. (2003, SPIE)
Sembach 16 of 21TIPS - 21 August 2003
Initial Spatial Resolution Results
TA1 Image (NUV)Double pinhole aperture
1” (~40 pixels) separation
0
10
20
30
40
2010 30 40 50 60
Dis
pers
ion
(pix
els)
Cross Dispersion (pixels)
Images are clearly resolved
Sembach 17 of 21TIPS - 21 August 2003
Initial FUV Grating Motion Repeatability Results
Sembach 18 of 21TIPS - 21 August 2003
Initial NUV Grating Motion Repeatability Results
Sembach 19 of 21TIPS - 21 August 2003
STScI Ground System Development and COS Pipeline
• Bright object screening tool (ROBOT) in progress
• Flatfield commanding rework complete
• HST data volume study – COS on-orbit and pipeline estimates updated
• Bench testing of command certification SMS (T. Wheeler)
• Planning of Integrated Pipeline Test started
• COS Pipeline (CALCOS)COS Pipeline (CALCOS)– Most modules are now complete– Spectral merging procedures for FP-POS positions in progress– Testing to occur on integrated SI data from T-Vac
Sembach 20 of 21TIPS - 21 August 2003
SMOV & SMGT
• Successful SMOV4 requirements review 30 July 2003 at GSFC
• Special commanding definition required by Oct 2003– COS Operations Working Group will establish requirements
• SMOV activity summaries (Phase 1 proposals) definition Nov-Dec 2003– Review presently scheduled for late Jan 2004
• SMGT now planned for late July 2004
Note: Carl Biagetti says that the SMOV dates have moved out 6 months relative to those listed here.
Sembach 21 of 21TIPS - 21 August 2003
STScI User Support
STScI Instrument Division COS Staff– IS: Keyes, Sembach, Friedman; DA: McMaster
– Leitherer transferred from COS to JWST in July 2003 (supporting T-Vac)
COS Handbooks– Mini-handbook for Cycle 13 being revised (August 2003)– Instrument handbook outline exists, work to continue after T-Vac
COS Exposure Time Calculators– Spectroscopic ETC software development in progress– Target acquisition ETC requirements delivered to APT group– Completion of ETCs expected in January 2004
COS Websitehttp://www.stsci.edu/instruments/cos