SPACE TELESCOPE SCIENCE INSTITUTE Operated for NASA by AURA COS Status FUV Detector “1-bounce design” NUV Detector HST aberration fully-corrected Calibration Platform

COS Status  SI stored at GSFC since April 2004; periodic functional testing  Removed, inspected, reworked, & tested MEB boards from August-September 2006 – including replacing all LV power converters  COS successfully completed Thermal-Vacuum Testing (TV II) in November/December 2006

COS Status: SI testing-related   Thermal-Vac testing at GSFC – –Demonstrated continued nominal performance of COS – –Exercised new modes and capabilities: e.g., “TAGFLASH” observing mode   STScI participated on-site in Thermal-Vac II activities – –supported alignment and science calibration activities – –Prepared and executed comprehensive test of TAGFLASH mode   All TV data (~10 Gbytes from 1200 exposures) tranferred to STScI – –will be processed through OPUS and archived in MAST for retrieval via StarView   Wavelength-dependent NUV sensitivity decline observed – –Up to 15% decline only for bare Al-coated gratings and λ > 2100 Ǻ > >may be due to systematic differences in test setup – –Witness sample mirrors show no degradation; surrogate spare gratings are presently being tested at GSFC – –All sensitivities measured in 2006 testing are within spec and remain at least 3x more efficient than equivalent STIS E230M modes  Continued storage at GSFC –Functional tests every 3 months; NUV throughput tests every 6 months –Test data will be archived in MAST

COS Status: STScI   TAGFLASH : – –Thorough successful testing by STScI at Thermal-Vac II – –Program prepared entirely with GO tools (APT); first execution of STScI SMS on SI – –Obtains wavelength calibration data by flashing cal lamp during TIME-TAG exposures rather than as a separate exposure; achieves greater observing efficiency and allows removal of any mechanism motions FUV MCP (1 of 2 segments) External Science Internal PtNe Wavecal  Exposure Time Calculator (ETC) –Spectroscopic ETC: now in testing through April 2007 –Target Acquisition and Imaging ETC: summer 2007  Bright Object Protection –User tool in APT: testing now through April 2007; incorporates GALEX  Documentation –Distributed mini-HB version 3 with Cycle 17 CfP –Instrument Handbook being drafted in preparation for release in Cycle 17

COS Status: STScI  STScI preparing SMS for SMGT testing –Test will occur in late July 2007 –SMS will exercise all COS science and calibration-related modes in realistic usage scenarios –Resultant data will be processed through pipeline and archived  SMOV4 preparations –STScI, in consultation with COS IDT, prepared updated set of comprehensive requirements; formal review mid-March 2007 –Activity summaries (program phase I) to be prepared in summer 2007; review in fall 2007

Backup Slides

STScI COS Team Activities FY07   Instrument Handbook completion and delivery   Thermal-Vac II support; TAGFLASH analysis   SMGT program preparation and test support   Pipeline testing, special commanding, reference files   SMOV4 verification, calibration proposal development   Data Handbook preparation   Aperture definition and world coordinate system development   ETC/BOP completion and delivery   Cumulative Image development   Associations testing   Keyword updates   Cycle 17 Call for Proposals   GTO Target Review

Ground Science Calibration 2006  Science calibration tests in Nov/Dec 2006 TV II test at GSFC  Goals of 2006 test plan (“Appendix C”): –Demonstrate continued nominal performance of COS –Exercise new modes and capabilities: e.g., “TAGFLASH” observing mode –Obtain additional information needed to reduce and interpret science data: external FUV flat-field observations  Did not repeat all tests from 2003; only those required to meet above goals  Two-tiered test plan: required tests and optional tests to be executed only if questions arise about the current performance of COS  Close STScI Thermal-Vac Coordination with IDT – –Coordinating Thermal-Vac staffing resources and schedules – –FUV and NUV Thermal-Vac data processed by OPUS and ingested in MAST – –Initial reference file delivery from IDT prior to SMGT in July 2007

Science Calibration Test Categories  Alignment, focus, image quality, resolution  Sensitivity  Wavelength scales  Flat field and S/N  Detector functions  Optical stability & repeatability  Target acquisition algorithms  TAGFLASH

Sensitivity  Statistically significant sensitivity degradation between 2003 and 2006 for only G225M and G285M spectral elements –These are the only gratings with bare aluminum coatings –Test-related systematics can not be ruled out as source of differences between 2003 and 2006 measurements –Degradation is not uniform with wavelength >No degradation since 2003 at 2100 Å where degradation may have stabilized –Even with measured degradation, COS retains significantly higher throughput than STIS E230M and the COS MAMA is predicted to have a factor of 4 lower background –Witness samples show NO degradation –Spare NUV gratings presently being evaluated at GSFC  Possible amelioration? –very difficult to access OSM2 mechanism and NUV gratings