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 are not seeing 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
|
Filter
|
Default exposure time (secs)
|
Recommended exposure time (secs)
|
Available alternatives (secs)
|
|
10.5 (broad)
|
0.01
|
0.01
|
0.01
|
|
7.9
|
0.08
|
0.08
|
0.02, 0.03, 0.04, 0.06, 0.1
|
|
8.8
|
0.08
|
0.1
|
0.02, 0.03, 0.04, 0.06, 0.08
|
|
9.7
|
0.08
|
0.06
|
0.02, 0.03, 0.04, 0.08, 0.1
|
|
10.3
|
0.08
|
0.08
|
0.02, 0.03, 0.04, 0.06, 0.1
|
|
11.6
|
0.08
|
0.08
|
0.02, 0.03, 0.04, 0.06, 0.1
|
|
12.5
|
0.08
|
0.08
|
0.02, 0.03, 0.04, 0.06, 0.1
|
|
18.5
|
0.08
|
0.03
|
0.02, 0.04
|
Spectroscopy
|
Grating (+ wavelength)
|
Default exposure time (secs)
|
Recommended exposure time (secs)
|
Available alternatives (secs)
|
|
LowN (10.5 microns)
|
0.21
|
0.21
|
0.16, 0.18, 0.24, 0.27
|
|
MedN1 (10 microns)
|
1.05
|
1.05
|
0.84, 0.94, 1.16, 1.26, 1.37
|
|
MedN1 (12 microns)
|
1.26
|
1.26
|
0.84, 0.94, 1.05, 1.16, 1.37
|
|
MedN1 (18 microns)
|
1.90
|
1.90
|
1.79, 2.01, 2.11, 2.22, 2.33
|
|
MedN1 (21 microns)
|
2.22
|
2.22
|
1.79, 1.90, 2.01, 2.11, 2.33,
|
|
LowQ (21 microns)
|
0.36
|
0.36
|
0.21, 0.29, 0.34, 0.4
|
|
Echelle (10 microns)
|
6.0
|
6.0
|
3.0
|
|
Echelle (21 microns)
|
6.0
|
1.0
|
3.0
|
|
