Space Telescope Science Institute  A.2 FGS A.4 WFPC2

A.3 NICMOS

Suppose that you wish to use the NICMOS to observe a target at a declination of -50 degrees, so that there are 54 minutes of visibility time per orbit (see Table 6.1). Your desired exposures are listed in Table A.7, and the associated overheads are listed in Table A.8. In Table A.9 you can see how the observations fit into a total of 1 orbit.


Table A.7: NICMOS Example: Planned Exposures
Config
Mode
Spectral
Element
Number of Exp
Time per Exp [min.]
Notes
NIC2
IMAGING
F110W
4
2.2
Pattern (see Section 5.4) of MULTIACCUM exposures with an offset of 1" between dither positions
NIC2
IMAGING
F160W
4
4
Pattern (see Section 5.4) of MULTIACCUM exposures with an offset of 1" between dither positions
NIC2
IMAGING
F222M
4
4
Pattern (see Section 5.4) of MULTIACCUM exposures with an offset of 1" between dither positions

Table A.8: NICMOS Example: Incurred Overheads
Overhead
Overhead Time [min.]
Notes
see Table
Guide star acquisition
6
First orbit in new visit
MULTIACCUM exposure
0.07

Instrument Setup
0.3
Beginning of each orbit
Filter change
0.3

SAM of 1"
0.33
Small Angle Maneuver between positions in the pattern

Table A.9: NICMOS Example: Orbit Planning
Activity
Duration [min.]
Elapsed Time [min.]
Orbit 1


Guide star acquisition
6
6
Instrument Setup
0.3
6.3
F110W Exp Time
2.2
8.5
F160W Exp Time
4
12.5
F222M Exp Time
4
16.5
Overhead
(3x0.07) + (2x0.3) + (1x0.33)
17.6
F110W Exp Time
2.2
19.8
F160W Exp Time
4
23.8
F222M Exp Time
4
27.8
Overhead
(3x0.07) + (3x0.3) + (1x0.33)
29.3
F110W Exp Time
2.2
31.5
F160W Exp Time
4
35.5
F222M Exp Time
4
39.5
Overhead
(3x0.07) + (3x0.3) + (1x0.33)
40.9
F110W Exp Time
2.2
43.1
F160W Exp Time
4
47.1
F222M Exp Time
4
51.1
Overhead
(3x0.07) + (3x0.3) + (1x0.33)
52.6
Unused
1.4
54
A.2 FGS A.4 WFPC2
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