MAMA Flat-field Status and Plans
نویسندگان
چکیده
An on-orbit flat-field monitoring program was initiated for the MAMA detectors with the goals of comparing the pre-launch flat-field characteristics with those observed on-orbit, measuring the stability of the FUVand NUV-flats, and creating updates to the reference flats. We found that the NUV-MAMA flat-field images at nominal (1024x1024) resolution are well corrected with pre-launch flats. That same comparison for the FUV-MAMA shows features in the pre-launch flat that make it unsuitible for generic pipeline use, although it resolves some important questions. The output of the flat-field lamps has declined ~15– 20% in less than 12 hours of on-orbit use, which is much larger than that expected. A plan is described for obtaining further on-orbit flat-field exposures in view of potentially much shorter lamp lifetimes, and for exploring alternatives for using the Kr and D2 lamps.
منابع مشابه
Absolute Flux Calibration of STIS MAMA Imaging Modes
The absolute flux calibration of STIS MAMA imaging modes is tested by comparison of observed and predicted count rates. As part of this work, we have derived new, wavelength-dependent aperture corrections for MAMA imaging, and have revised the NUVMAMA imaging throughput at short wavelengths. FUV-MAMA imaging modes clearly show a time dependent sensitivity loss that is consistent with the time d...
متن کاملUse of FP-SPLIT Slits for Reaching High Signal-to-Noise with MAMA Detectors
A pre-flight uncertainty for STIS was the extent to which the MAMA detectors would support high signal-to-noise observations given inherently low count rates, limitations on available flat fields, and the possibility of evolution in pixel-to-pixel response stability. This ISR reports on results from STIS/SMOV-7091 Pixel-to-pixel Response Stability in which spectra were acquired at high count le...
متن کاملThe Flat Fielding and Achievable Signal-to-Noise of the MAMA Detectors
The Space Telescope Imaging Spectrograph (STIS) was designed to achieve a signal-to-noise of at least 100:1 per resolution element. MAMA observations during Servicing Mission Orbital Verification (SMOV) confirm that this specification can be met. From analysis of a single spectrum of GD153, with counting statistics of ∼ 165 a S/N of ∼ 125 is achieved per spectral resolution element in the FUV o...
متن کاملA New Geometric-Distortion Solution for the STIS NUV- MAMA
We have obtained a new geometric-distortion solution for the STIS NUV-MAMA using two fields in NGC 4214 and NGC 604 which were imaged using three filters (CN182, CN270, SrF2) for GO program 9096. (WF)PC2 images of the same objects in F170W and F336W were used as an astrometric reference. Different polynomial degrees and weighting mechanisms for the geometric distortion were tested until an adeq...
متن کاملPhyllodes Tumor of the Breast: 307 Treated Cases, the Largest Mexican Experience at a Single Breast Disease Institution
Background: Phyllodes tumor (PT) of the breast in Hispanic patients is more frequently reported with large tumors and with more borderline/malignant subtypes compared with other populations. The objective of this study was to describe characteristics of patients with PT and to identify differences among subtypes in a Mexican population. <...
متن کامل