Exposure Times for Michelle

Exposure Times for Michelle

Because the atmosphere is the limiting factor in setting exposure times for Michelle, changes in the column density of precipitable water or the presence of thin cloud will often mean that the default times for Michelle observations will not be optimal, especially for imaging. Typically, the observer will want about 40,000 counts in a single chop beam for imaging. If you do not see this, you may adjust the exposure time in the Michelle component in the OT, but not all exposure times are guaranteed to work. Some will crash Edict. Please find below some exposure times that are known to work.

Imaging

FilterDefault Exposure Time (secs)Recommended Exposure Time (secs)Available Alternatives (secs)
10.5 (broad)0.010.010.01
7.90.080.080.02, 0.03, 0.04, 0.06, 0.1
8.80.080.10.02, 0.03, 0.04, 0.06, 0.08
9.70.080.060.02, 0.03, 0.04, 0.08, 0.1
10.30.080.080.02, 0.03, 0.04, 0.06, 0.1
11.60.080.080.02, 0.03, 0.04, 0.06, 0.1
12.50.080.080.02, 0.03, 0.04, 0.06, 0.1
18.50.080.030.02, 0.04

Spectroscopy

Grating (+ Wavelength)Default Exposure Time (secs)Recommended Exposure Time (secs)Available Alternatives (secs)
LowN (10.5 microns)0.210.210.16, 0.18, 0.24, 0.27
MedN1 (10 microns)1.051.050.84, 0.94, 1.16, 1.26, 1.37
MedN1 (12 microns)1.261.260.84, 0.94, 1.05, 1.16, 1.37
MedN1 (18 microns)1.901.901.79, 2.01, 2.11, 2.22, 2.33
MedN1 (21 microns)2.222.221.79, 1.90, 2.01, 2.11, 2.33
LowQ (21 microns)0.36 0.360.21, 0.29, 0.34, 0.4
Echelle (10 microns)6.06.03.0
Echelle (21 microns)6.01.03.0