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An Update on the COS Development Status

SPACE TELESCOPE SCIENCE INSTITUTE. Operated for NASA by AURA. TIPS 21 August 2003 (Last COS TIPS: Dec 2002). An Update on the COS Development Status. COS Integrated SI (Aft End). COS Timeline Summary. Instrument integration activities (Jan-Mar 2003)

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An Update on the COS Development Status

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  1. SPACE TELESCOPE SCIENCE INSTITUTE Operated for NASA by AURA TIPS21 August 2003 (Last COS TIPS: Dec 2002) An Update on the COS Development Status COS Integrated SI (Aft End)

  2. 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 l; “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

  3. 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

  4. COS: pre-acoustic test; packing for return to Ball

  5. COS Integrated SI and Enclosure

  6. COS Issues of Interest • Spectra in Bright Object Aperture (BOA) have coma • ND2 filter (2 mm cube) has 0.25o 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

  7. 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

  8. 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

  9. 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

  10. Sample COS FUV Spectrum External PtNe calibration lamp (no distortion correction)

  11. Sample COS NUV Spectrum External PtNe calibration lamp

  12. Initial FUV Spectral Resolution Results - G130M External PtNe calibration lamp R = l/

  13. Initial FUV Spectral Resolution Results - G160M External PtNe calibration lamp R = l/

  14. Initial NUV Spectral Resolution Results G185M External PtNe calibration lamp R = l/ G225M G285M

  15. Initial COS Efficiency Estimates From Wilkinson et al. (2003, SPIE)

  16. Initial Spatial Resolution Results TA1 Image (NUV) Double pinhole aperture 1” (~40 pixels) separation 40 30 Dispersion (pixels) 20 Images are clearly resolved 10 0 10 20 30 40 50 60 Cross Dispersion (pixels)

  17. Initial FUV Grating Motion Repeatability Results

  18. Initial NUV Grating Motion Repeatability Results

  19. 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) • Most modules are now complete • Spectral merging procedures for FP-POS positions in progress • Testing to occur on integrated SI data from T-Vac

  20. 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 • SMGTnow planned for late July 2004

  21. 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 Website • http://www.stsci.edu/instruments/cos

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