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