A.4 STIS

Suppose that you wish to use the STIS to observe a target at a declination of +15 degrees, so that there are 52 minutes of visibility time per orbit (see Table 6.1). Your desired exposures are listed in Table A.10, and the associated overheads are listed in Table A.11. In Table A.12 you can see how this fits into a total of 2 orbits.

Table A.10: STIS Example: Planned Exposures

Config

Mode

Spectral

Element

Number of Exp

Time per Exp [m]

Notes

STIS/CCD

ACQ

target acquisition

STIS/CCD

ACQ/PEAK

peakup acquisition (necessary because of use of 0.1" wide slit for subsequent spectra)

STIS/CCD

IMAGING

F28X50OII

2

2

STIS/NUV

IMAGING

F25QTZ

1

19

STIS/NUV

SPECTROSCOPIC

G230L

1

13

with 52X0.1 slit

STIS/FUV

SPECTROSCOPIC

G140L

1

17

with 52X0.1 slit

Config	Mode	Spectral Element	Number of Exp	Time per Exp [m]	Notes
STIS/CCD	ACQ				target acquisition
STIS/CCD	ACQ/PEAK				peakup acquisition (necessary because of use of 0.1" wide slit for subsequent spectra)
STIS/CCD	IMAGING	F28X50OII	2	2
STIS/NUV	IMAGING	F25QTZ	1	19
STIS/NUV	SPECTROSCOPIC	G230L	1	13	with 52X0.1 slit
STIS/FUV	SPECTROSCOPIC	G140L	1	17	with 52X0.1 slit

Table A.11: STIS Example: Incurred Overheads

Overhead

Overhead Time [m]

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

ACQ

6

target acquisition

6.3

ACQ/PEAK

6

peakup target acquisition

6.3

CCD imaging

5

but only 1m if no change from previous exposure

6.11

MAMA imaging

5

but only 1m if no change from previous exposure

6.11

MAMA spectroscopy

8

but only 1m if no change from previous exposure

6.11

Overhead	Overhead Time [m]	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
ACQ	6	target acquisition	6.3
ACQ/PEAK	6	peakup target acquisition	6.3
CCD imaging	5	but only 1m if no change from previous exposure	6.11
MAMA imaging	5	but only 1m if no change from previous exposure	6.11
MAMA spectroscopy	8	but only 1m if no change from previous exposure	6.11

Table A.12: STIS Example: Orbit Planning

Activity

Duration [m]

Elapsed Time [m]

Orbit 1

Guide star acquisition

6

6

ACQ

6

12

ACQ/PEAK

6

18

F28X50OII Exp Time

2x2

22

F28X50OII Overhead

5+1

28

F25QTZ Exp Time

19

47

F25QTZ Overhead

5

52

Orbit 2

Guide star re-acquisition

5

5

G230L Exp Time

13

18

G230L Overhead

8

26

G140L Exp Time

17

43

G140L Overhead

8

51

Unused

1

52

Activity	Duration [m]	Elapsed Time [m]
Orbit 1
Guide star acquisition	6	6
ACQ	6	12
ACQ/PEAK	6	18
F28X50OII Exp Time	2x2	22
F28X50OII Overhead	5+1	28
F25QTZ Exp Time	19	47
F25QTZ Overhead	5	52
Orbit 2
Guide star re-acquisition	5	5
G230L Exp Time	13	18
G230L Overhead	8	26
G140L Exp Time	17	43
G140L Overhead	8	51
Unused	1	52