When used with a central wavelength of 1222 Å, grating G130M samples wavelengths between about
1065 and 1365 Å with a resolving power R
> 10,000. Its sensitivity is comparable to that of other G130M modes and considerably higher than G140L. Preliminary measurements indicate that the resolving power of this mode is R
> 13,000 at 1135 Å and R
> 10,000 at 1340 Å, but this is a lower limit; predicted values exceed 14,000 at 1065 Å and 17,000 at 1135 Å.
A key advantage of this observing mode is that it places the Lyman α
airglow line in the gap between detector segments A and B, eliminating this source of damaging high-intensity flux.
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 cm-2
. Colors refer to exposure times in seconds. The edge of the shaded area corresponds to the bright-object screening limit. Use of the PSA is assumed.