STIS Status TIPS, September 17, 2009 Charles Proffitt for the STIS team
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STIS Status TIPS, September 17, 2009 Charles Proffitt for the STIS team STIS Status: Topics • STIS SMOV & Calibration Overview • STIS CCD status summary • NUV Dark current update STIS SMOV Status • All STIS SMOV observations complete as of September 6, 2009 • Most STIS SMOV analysis complete – Final superbias & super-dark reference files for SMOV period have been delivered – New CCD reference file delivered • Readnoise, gain, and CTE parameters – CCD TDS reference files delivered • Time-dependent sensitivity corrections to flux calibration • Open issues in STIS SMOV analysis – Waiting for additional Cycle 17 calibration observations to finalize MAMA TDS updates • Changes from pre-repair predictions appear to be small (< 3%) – Monitoring of NUV MAMA dark is being continued by cycle 17 calibration program 11857 – Detailed writeups still pending for most activities STIS Activity PropID STIS SMOV Program Title Analysis Lead Visits Done Total Visits STIS02 11347 STIS03 Status Memory Load and Dump BS 1 1 Complete 11348 Science Data Buffer Check BS 3 3 Complete STIS04 11349 Mechanism Mini-Functional TW 1 1 Complete STIS05 11399 CCD Anneal (two anneal iterations) MW 6 6 Complete STIS06 11382 CCD Functional DL 4 4 Complete STIS07 11404 CCD Dark & Bias Monitor MW 90 105 Complete STIS08 11383 Aperture Wheel & Lamp Functional WZ 2 2 Complete STIS09 11384 STIS-to-FGS Alignment CP 1 1 Complete STIS10 11385 CCD Spectral Format Verification WZ 1 1 Complete STIS11 11386 External Focus Check CP 4 3+1 Complete STIS12 11387 Corrector and Focus Alignment CP - 8 Contingency STIS13 11388 CCD External Spectroscopic Quality TG 1 1 Complete STIS14 11400 CCD CTI Check PG 1 1 Complete STIS15 11401 CCD Spectroscopic Throughputs DL 3 3 Complete STIS16 11389 CCD Image and Pointing Stability TG 1 1 Complete STIS17 11350 FUV MAMA HV Recovery TW 4 4 Complete STIS18 11351 NUV MAMA HV Recovery TW 4 (+2F) 4 (+2F) Complete STIS19 11390 FUV MAMA Dark Measure CP 10 10 Complete STIS20 11402 NUV Dark Monitor CP 42(+3F) 20+52 Complete STIS21 11391 FUV Optical Format Verification WZ 2 2 Complete STIS22 11392 NUV Optical Format Verification WZ 2 (+2F) 2 (+2F) Complete STIS23 11393 FUV MAMA Spectroscopic Quality TG 1 1 Complete STIS24 11394 NUV MAMA Spectroscopic Quality TG 1 1 Complete STIS25 11403 MAMA Spectroscopic Throughputs DL 3 3 Analysis being finalized STIS26 11395 MAMA Image Stability TG 2 2 Complete STIS Cycle 17 Calibration • Analysis leads assigned for all programs – New leads will also track execution • Most Calibration Programs have started – Routine dark monitors have begun • Routine delivery of weekly bias and dark reference files – Automated Bias & Dark Pipeline still under work – P-flat data collection has begun • SMOV plan deferred this calibration to cycle 17 – Data being combined with SMOV results to improve calibration • Cycle 17 data especially important for CTE calibration STIS Calibration Plan PropID STIS SMOV Program Title Analysis Lead Start Date 11843 CCD Performance Monitor VD 01-Sep-2009 11844/11845 CCD Dark Monitor (part 1 & 2) MW 03-Aug-2009 11846/11847 CCD Bias Monitor (part 1 & 2) MW 03-Aug-2009 11848 CCD Read-noise Monitor VD 10-Sep-2009 11849 CCD Hot-pixel Annealing MW 23-Jul-2009 11852 CCD Spectroscopic Flats SN 10-Aug-2009 11853 CCD Imaging Flats SN 27-Aug-2009 11858 CCD Spectroscopic Dispersion IP 20-Aug-2009 11850 CCD Sparse Field CTE Internal VD 03-Jul-2009 11854 CCD Full Field Sensitivity VD Jan-Mar, 2010 11851 Slit Wheel Repeatability WZ 17-Aug-2009 11855 CCD Spectroscopic Sensitivity Monitor RO 10-Aug-2009 11859 MAMA Dispersion Solutions IP 20-Aug-2009 11856 MAMA Full Field Sensitivity VD May, 2010 11860 MAMA Sensitivity and Focus Monitor RO 03-Sep-2009 11857 MAMA Dark Monitor WZ 09-Sep-2009 11863 MAMA Fold Distribution TW Nov, 2009 11861 MAMA FUV Flats TA 17-Aug-2009 11862 MAMA NUV Flats TA 17-Aug-2009 11864 MAMA Anomalous Recovery TW contingency 11865 COS Flux Standard RB Oct, 2009 11866 Echelle Grating Blaze Function Zero Points PG Nov, 2009 11999 JWST Calibration from a Consistent Absolute Calibration of Spitzer & Hubble RB Oct, 2009 - Sep 2010 STIS CCD Status • • Dark current, read-noise, and CTE measured Read noise slightly greater than pre-repair – Gain = 1 was 5.3 now 5.8 e– Gain = 4 was 7.8 now 8.3 e- • Observed charge Transfer Efficiency (CTE) in 2009 close to extrapolation of old trend (CTI = 1 - CTE). – CTE losses becoming very large for faint sources STIS CCD Status - cont • Current pipeline CTE algorithm assumes constant “spurious charge” over detector at a given time – Can get better CTE correction if this allowed to vary over detector – This will require modest changes to CALSTIS – For now will use compromise value with old algorithm CCD Dark Current Behavior • Median CCD dark current in 2009 slightly above extrapolated trend from 2004 • CCD Dark shows increasing spatial dependence over time – about 40% lower near row 900 as compared to center of chip! CCD Sensitivity Changes Advantages of E1 position • For many years, we have had defined “E1” positions for CCD near row 900 of STIS long slit – – – – Closer to default readout amplifier Reduced CTI losses Reduced effective dark current Less contamination by CTE tails of CR & hot pixels • While we have advertised advantages of E1 position for years in IHB and other documentation, ETC does not distinguish between center and E1 posistion – GO need to manually estimate CTE losses • Re-emphasize importance of using E1 position to GOs • For cycle 19 ETC, should include variations in dark current & CTE as function of slit position NUV dark update • Post SM4 NUV dark current (black dots) much higher than expected – model as “expected dark” + “something extra” • Model as the “expected dark” (orange curve below) declining according to old behavior + an extra component Ae-(E/T) e-t/ • “extra” term appears to have stronger T dependence (E ≈ 1.8 eV vs 1.5 eV) • Plot below compares different e-folding times for extra component =100 d (red) & = ∞ (blue)
