A.1 ACS Example

The ACS WFC channel is used to observe a target at declination +35°. The requested exposures are listed in Table A.1.

•	According to Table 6.1, there are 55 minutes of visibility time per orbit.

•	Overheads for the observations, documented in Chapter 6, are compiled in Table A.2.

Therefore, a preliminary observing strategy can be created by the user to fit the observations in two orbits, as shown in Table A.3.

Table A.1: ACS Example: Planned Exposures

Config	Mode	Spectral Element	Number of exposures	Time per exposure (minutes)	Notes
ACS/WFC	IMAGING	F606W	4	8.75	Pattern (see Section 5.4) with an offset of 25" between positions

Table A.2: ACS Example: Incurred Overheads

Overhead	Overhead time (minutes)	Notes	see Table
Guide star acquisition	6	First orbit in new visit	6.2
Guide star re-acquisition	5	Per orbit after first orbit	6.2
WFC exposure (first)	4	First exposure in a series of identical exposures	6.4
WFC exposure (not first)	2.5	Per exposure after the first exposure in a series	6.4
SAM of 25"	0.67	Small Angle Maneuver between positions in the pattern	6.12

Table A.3: ACS Example: Orbit Planning

Activity	Duration (minutes)	Elapsed Time (minutes)
Orbit 1
Guide star acquisition	6	6
WFC/F606W Exp Time	4x8.75	41
WFC/F606W Overhead	4+(3x2.5)+(3x0.67)	54.5
Unused time	0.5	55
Orbit 2
Guide star re-acquisition	5	5
HRC/F814W Overhead	2.5+1	19.5
HRC/F606W Exp Time	2x7	33.5
HRC/F606W Overhead	2.5+1	37
HRC/F435W Exp Time	2x7	51
HRC/F435W Overhead	2.5+1	54.5
Unused time	0.5	55