|
|
|
____________________
|
|
|
|
|
CGS4 flat fields
Suggested Flat Exposure Times
40 l/mm grating:
| Wavelength |
Order |
BB Aperture |
Exposure Tim (secs) |
| 1.15 |
2 |
5.0 |
2.0 |
| 1.30 |
2 |
5.0 |
2.0 |
| 1.70 |
1 |
1.3 |
0.6 |
| 2.20 |
1 |
1.3 |
0.25 |
| 3.10 |
1 |
3.2 |
0.75 |
| 3.80 |
1 |
2.0 |
2.0 |
| 4.90 |
1 |
1.3 |
1.0 |
150 l/mm grating:
| Wavelength |
Order |
BB Aperture |
Exposure Time (secs) |
| 1.15 |
3 |
5.0 |
5.0 |
| 1.30 |
3 |
5.0 |
2.5 |
| 1.70 |
2 |
2.0 |
1.0 |
| 2.20 |
2 |
3.2 |
0.25 |
| 2.20 |
1 |
3.2 |
0.12 |
Echelle:
Because of the extremely small wavelength coverage of the echelle, it is
fairly impracticable to provide a table of suggested blackbody apertures
and exposure times. The quickets way to determine an appropriate exposure
time and aperture is as follows (this technique can be used with any grating):
-
Write an astronomical config for the wavelength you wish to observe at.
-
Set to this config using the Set_Single_Observation menu in the CGS4 software
and specify a flat observation.
-
Select "Movie", select an exposure time in "Set_Movie" (e.g., 0.5 secs)
and then "Run_Movie"
-
Note the counts on the movie screen.
-
Select "Direct_Motor_Control" and select another blackbody aperture. You
will see the counts change.
-
When you are happy with your selection (i.e., 3000 - 4000 counts) abort
the movie and edit your config with the appropriate numbers.
|
|
