STIS Status Report Kailash C. Sahu Apr 18, 2002 TIPS

OUTLINE STIS Time Dependent Sensitivity Correction Sensitivities after SM3B Echelle Blaze Shift Correction Improved NUV-MAMA Darks Phase-II Proposal Reviews

Time Dependent Sensitivity Correction Symptoms STIS sensitivities are found to slowly change with time Change is as much as 10% in the last 5 years for some modes This depends on the detector, and also has a wavelength dependence The change is not always monotonic in time Changes in L and M-modes are similar

Time Dependent Sensitivity Correction Time dependence can be corrected by applying a wavelength dependent correction in linear segments of time ( Stys and Walborn). Algorithm developed by Busko, Hodge, Sahu, Valenti (and the pipeline group) Implemented in CALSTIS and tested Residual less than ~2% Ready to be implemented in the pipeline calibrations.

Time Dependent Sensitivity Correction 4/14/2002 4/16/2002 4/16/2002

Sensitivities after SM3B OBSERVATIONS Sensitivity measurements were taken on April 3 for G230LB, G430L and G750L modes (CCD modes) On April 14 and April 16 for G140L On April 16 for G230L RESULTS G140L: 1.8% higher on 14th April, but 0.3% higher on 16th April G230L: Consistent with extrapolated sensitivity. G750L: -0.6 ± 1.0% (compared to a single measurement 6 months earlier) G430L: +0.1 ± 1.0% G230LB: -0.8 ± 1.0% SUMMARY All measurements are consistent with the expectations.

Echelle Blaze Shift Correction

Echelle Blaze Shift Correction Symptoms Redundant flux information at ends of echelle orders Flux discrepancies as large as 10% (see example) Flux errors correlate with time and monthly offset in X Grating angle affects wavelength and blaze differently First Order Correction Algorithm developed by Don Lindler (calibration outsourcing) Measured blaze shifts for 600+ datasets (primary cenwaves) Linear fit of blaze shift vs. time and offsets in X and Y Fit coefficients added to new columns in _pht reference file Calstis enhanced by Ivo Busko; tested by Jeff Valenti Blaze shift estimated from coefficients; good but not perfect Data may be reprocessed by hand using arbitrary blaze shift Still need to add support for secondary wavelength settings

Improved NUV-MAMA Darks Changes in the mean operating temperature of the NUV-MAMA causes dark current to deviate from the scaling law used. Time and temperature dependent correction algorithm was developed by Charles Proffitt Implemented in CALSTIS with an option to scale the dark to a user-input value (Busko) Ready to be implemented in the pipeline

Phase-II Proposal Reviews Instrument review of ~2/3rd of the proposals have been completed. A majority of the remaining are due to PI input, and TOO proposals which cannot be reviewed at this moment. There are > 500 snapshot observations with MAMA (many of which are for imaging). BOP checking of these observations are time-consuming, and will clearly need more time for completion of the review.