Like the G230L
grating, the G230M
grating is used with the NUV-MAMA
; it has a spectral range from 1650-3100 Å, however, with a resolving power R~10,000 a single exposure with the G230M
grating covers only 90 Å, and the grating must be scanned, with a series of exposures taken at 18 distinct settings to cover the full spectral range.
grating mode is designed for observations where spatially resolved, long slit, spectroscopy is desired at relatively high spectral resolution covering a limited region of the NUV spectrum.
Notice that the CCD G230MB
grating mode also covers the NUV with comparable resolution. See “Comparison of G230MB and G230M”
for a detailed comparison of these two grating modes in that wavelength regime.
The top axis displays constant Fλ
values corresponding to the STMAG units (V+STMAGλ
) on the bottom axis. Recall that STMAG=0 is equivalent to Fλ
= 3.63E-9 erg/cm2
/s/Å. The curves are labeled with exposure times in seconds.