Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 14
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| Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 14 | |||||
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F25ND5-NUV-MAMA
Description
The
F25ND5mode with the NUV-MAMA provides broad band imaging with an attenuation of 5 x 10-6. The field of view is 25 x 25 arcsec. The value of R80 and the central pixel flux are unmeasured but assumed to be approximately the same as produced by theF25QTZfilter.Recommended Uses
Recommended for broad-band near-UV imaging of objects too bright by 2 x 105 for clear mode.
Special Considerations
The throughput of the ND5 filter and NUV-MAMA combination relative to the unfiltered NUV-MAMA varies strongly as a function of wavelength. At wavelengths between 3000 and 5000 Å the attenuation factor is close to 5 x 106. At shorter wavelengths the relative throughput can be a factor of ten or more smaller, while at longer wavelengths it is considerably larger, so special care should be taken for red sources. To make an accurate prediction of the expected count rate, observers should use a good approximation of the source spectrum as input for the STIS ETC.
Figure 14.31: F25ND5 NUV-MAMA Integrated System Throughput and Redleak
Table 14.13: Throughput and Sensitivity for F25ND5 NUV-MAMA
Figure 14.32: Point Source S/N vs. V+ABfor the F25ND5 NUV-MAMA mode. Top curves are for DARKTIME. Bottom curves are for average sky. Top curves are for DARKTIME. Bottom curves are for average sky. Curves are labeled by required exposure time (sec).
Figure 14.33: Extended Source S/N vs. V+AB
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