|STIS Instrument Handbook for Cycle 26|
The 25MAMA mode with the NUV-MAMA provides high-throughput broad-band near-ultraviolet (NUV) imaging with excellent pixel sampling and very high throughput at ~2500 Å.NUV-MAMA clear images will be somewhat out of focus because the mirror optimally focuses for use of a filter. Whenever possible, use F25SRF2 or F25QTZ instead of 25MAMA for NUV-MAMA imaging.For long exposures of faint targets, sky background is likely to be a limiting factor. Observers should consider the use of DARKTIME or (preferably) use the F25QTZ filter, which has nearly the same throughput but rejects geocoronal Lyman-α and [O I] 1302+1306 Å air glow.Users should also consider whether WFC3 with the F225W, the F300X or the F275W filters might be a better choice for their science goals.
Pivot λ (Å) Speak Bλ R80 (arcsec) Figure 14.23: 25MAMA NUV-MAMA Integrated System Throughput and RedleakTable 14.10: 25MAMA NUV-MAMA Sensitivity & Throughput
Figure 14.24: Point Source S/N vs. V+ABν for the 25MAMA NUV-MAMA mode. Top curves are for DARKTIME. Bottom curves are for average sky. Curves are labeled by required exposure time (sec.).Figure 14.25: Extended Source S/N vs. V+ABν for the 25MAMA NUV-MAMA mode. Top curves are for an area of 0.2 arcsec2; bottom curves are for 1 arcsec2. Average sky assumed. Curves are labeled by required exposure time (seconds).Table 14.11: Radial Profile for 25MAMA*
Figure 14.26: Point Source Encircled Energy for 25MAMA NUV-MAMAFigure 14.27: Point Source Intensity vs. Radius for 25MAMA NUV-MAMA