grating is used with the NUV-MAMA
and provides echelle spectra at a resolving power of ~114,0001
from 1620 to 3150 Å.
A single E230H
echellogram covers ~267 Å, over ~20-70 orders. The orders are spaced by only ~ 12.7 pixels (0.37 arcseconds) at 1650 Å and 47.2 pixels (~1.38 arcseconds) at 3100 Å. The grating must be scanned, with exposures taken at six distinct settings to cover the full spectral range of the grating.
Point source sensitivity assumes full transmission (zero slit losses). Diffuse source
sensitivity assumes a 0.1” wide slit. To convert point source sensitivities to diffuse source sensitivities multiply the point source values by the grating spatial (cross dispersion) plate scale in units of arcseconds per pixel and by the width of the desired slit in units of arcseconds.
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.