SPACE TELESCOPE SCIENCE INSTITUTE Operated for NASA by AURA TIPS / COS TV Update 21 December 2006 Agenda Agenda Testing Setup and Status Testing Setup and Status TV Testing Plans TV Testing Plans Summary Summary NUV Sensitivity NUV Sensitivity Last TIPS presentation: 15 June 2006 Last TIPS presentation: 15 June 2006

Keyes (TIPS) - 21 December 2006 Slide 2 of 14 Summary of Test Program to Date Completed Environmental Test (TV I) in 2003 Delivered COS to GSFC in April 2004 Semi-annual Functional Testing (2004-summer 2006) Removed, Inspected, Reworked, & Tested MEB boards from August-September 2006 – including replacing all LVPS Integrated all boards back in the MEBs in September COS sucessfully completed Thermal-Vacuum Testing (TV II) in November/December 2006

Keyes (TIPS) - 21 December 2006 Slide 3 of 14 Previous Ground Testing Status Summary  All major performance requirements met in TV I in 2003 – Spectral resolution – Sensitivity – Flatfield quality – Scattered light – Wavelength coverage  TV I testing revealed spectrum drift caused by OSM motions – TAGFLASH Mode – TAGFLASH Mode (OSM-drift operational correction) > Test at Thermal-Vac II > Lamp Lifetime Tests ongoing at NIST and CU OSM 1

Keyes (TIPS) - 21 December 2006 Slide 4 of 14 COS TV Pics

Keyes (TIPS) - 21 December 2006 Slide 5 of 14 New vacuum CDS installed in SES with RAS/Cal, COS 2006 COS Vacuum Test Configuration Original Relay Optics, RAS/Cal, TBF and COS installed in SES

Keyes (TIPS) - 21 December 2006 Slide 6 of 14 COS TV Pics -- courtesy of Dave Soderblom

Keyes (TIPS) - 21 December 2006 Slide 7 of 14 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 March 2007

Keyes (TIPS) - 21 December 2006 Slide 8 of 14 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

Keyes (TIPS) - 21 December 2006 Slide 9 of 14 TV II Science Cal Tests 29 test sequences; items in red are new tests for Total run time is approximately 11 days for required tests and 21 days for required+contingency. Required TestsContingency Tests

Keyes (TIPS) - 21 December 2006 Slide 10 of 14 Thermal Vac & Science Calibration  Initial thermal vacuum and thermal balance testing in November  STScI support at GSFC – Hartig, Wheeler, Soderblom, Keyes, Hartig, Friedman.  Detailed science calibration (“Appendix C”) 28 Nov – 8 Dec. – ~25 tests; 1233 data files; ~10 Gbytes raw data. – Included STScI-generated SMS for thorough TAGFLASH testing > First execution of an STScI SMS on SI.  All testing completed at GSFC  Science calibration complete – All primary instrument modes exercised.  Preliminary onsite assessment indicates performance remains nominal – Continuing assessment of resolution, sensitivity, alignment, image quality, focus. – Apparent decline in NUV sensitivity between 2200 and 2900 Å with ONLY the two bare aluminum-coated spectral elements (G225M and G285M)  Flight software and TAGFLASH performed as expected  Continued storage at GSFC; SMGT upcoming (30 March 2007)  Functional tests every 3 months; NUV throughput tests every 6 months  OPUS-processed data will be available with StarView.

Keyes (TIPS) - 21 December 2006 Slide 11 of 14 % change: 2006 Sensitivity compared with 2003 Sensitivity 2003 and 2006 test setup may have systematic differences Different PMT calibrations Red-leak in 2003 PMT measurements No common optic or detector between NUV TA1, G230L and FUV G140L, G160M yet show same ~10% decline decline in common wavelength region; implies external systematic offset

Keyes (TIPS) - 21 December 2006 Slide 12 of 14 NUV STIS sensitivities assume zero slit losses; typical loss is ≥20%.

Keyes (TIPS) - 21 December 2006 Slide 13 of 14 COS offset by apparent 20% NUV decline

Keyes (TIPS) - 21 December 2006 Slide 14 of 14 Sensitivity  Analysis of FUV and NUV sensitivity is very preliminary at this point  Statistically significant sensitivity degradation between 2003 and 2006 for only G225M and G285M spectral elements – These are the only gratings with bare aluminum coatings – 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 – Spare NUV gratings and witness samples will be evaluated  Possible amelioration? – very difficult to access OSM2 mechanism and NUV gratings

Keyes (TIPS) - 21 December 2006 Slide 15 of 14 Background information

Keyes (TIPS) - 21 December 2006 Slide 16 of 14 FUV Sensitivity

Keyes (TIPS) - 21 December 2006 Slide 17 of 14 COS Optical Layout

Keyes (TIPS) - 21 December 2006 Slide 18 of 14 COS Detectors – FUV XDL Top View 170 mm

Keyes (TIPS) - 21 December 2006 Slide 19 of 14 COS Detectors – NUV MAMA in the enclosure

Keyes (TIPS) - 21 December 2006 Slide 20 of 14 CBA CBA PtNeWavecalExternalScienceNUVMAMA FUV MCP (1 of 2 segments) External Science Internal PtNe Wavecal COS Spectral Layout for Simultaneous Internal Wavecals and Science Spectra – Obtain (continuous or flashed) internal PtNe spectra at same time as science exposure – Track internal PtNe lines and apply shifts to science spectrum (all events time-tagged) in COS data pipeline