Cosmic Origins Spectrograph Instrument Handbook for Cycle 17

9.6 Examples of Orbit Estimates

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9.6.1 Example 1: NUV TIME-TAG

In this example we start with an NUV ACQ/IMAGE target acquisition, then add two NUV TIME-TAG exposures with the same grating, but different central wavelengths, both utilizing default FP-POS and FLASH=YES.

Table 9.9: Overhead values for NUV TIME-TAG

Table 9.10:
 

Action	Time required	Comment
Initial guide star acquisition	6 min	Required at start of a new visit
NUV ACQ/IMAGE with 2 sec exposure time	7 min + 4 sec	ACQ/IMAGE is first exposure in visit, thus we include OSM1 change to NCM1 and OSM2 move to MIRRORA
NUV G185M at 1850 Å, TIME-TAG, FLASH=YES, FP-POS=3, 1200 sec exp.	36 + 60 + 112 + 110 + 1200 = 1518 sec = 25.3 min	Generic NUV TIME-TAG setup; change from MIRRORA to G185M [60+112]; no central wavelength change (default value); no FP-POS change (3=default); no aperture change from PSA; no SEGMENT change; TIME-TAG memory readout; exp time
NUV G185M at 1812 Å, TIME-TAG, FLASH=YES, FP-POS=3, 600 sec exp.	36 + 73 + 110 + 600 = 783 sec = 13.1 min	Only change central wavelength, so generic NUV TIME-TAG exposure setup; no grating change; central wavelength change [73 sec]; no FP-POS change; no SEGMENT change; TIME-TAG memory readout; exp time
Total science time	38.4 min
Total time used in orbit	51.4 min

9.6.2 Example 2: NUV plus FUV TIME-TAG

In this example we start with an NUV ACQ/SEARCH followed by an ACQ/IMAGE target acquisition, then add an NUV TIME-TAG exposure followed by a switch to the FUV channel and an FUV TIME-TAG exposure.

Table 9.11: Overhead values for NUV ACCUM with FUV TIME-TAG

Table 9.12:
 

Action	Time required	Comment
Initial guide star acquisition	6 min	Required at start of a new visit
NUV ACQ/SEARCH, MIRRORA, 3 × 3 pattern, 10 sec exp.	60 + 54 + 107 + 9×(20+10) = 270 sec = 2.5 min	COS starts at G130M on OSM1, so move to NCM1 requires 60+54 sec; OSM2 home position is G185M, so move to MIRRORA takes 107 sec; 9 ACQ/SEARCH sub-exposures, so overhead includes 9 slews (20 sec each) plus 9 exposures (10 sec each)
NUV ACQ/IMAGE with 10 sec exposure time	2 min + 2×10 sec = 140 sec = 2.3 min	No OSM2 movement; so overhead includes only ACQ/IMAGE setup and twice exp. time
NUV G225M at 2250 Å, TIME-TAG, FLASH=YES, FP-POS=3, 1200 sec exp.	36 + 60 + 43 + 110 + 1200 = 1449 sec = 24.2 min	Generic NUV TIME-TAG setup; change from MIRRORA to G225 [60+43]; no central wavelength change (default value); no FP-POS change (3=default); no aperture change from PSA; no SEGMENT change; TIME-TAG memory readout; exp time
FUV G130M at 1309 Å, TIME-TAG, FLASH=YES, FP-POS=3, 600 sec exp.	71 + 47 + 110 + 600 = 838 sec = 14.0 min	Switch from FUV to NUV adds no overhead (OSM2 not moved); generic FUV TIME-TAG setup; OSM1 move from NCM1 to G130M; no central wavelength change; no FP-POS change; no SEGMENT change; TIME-TAG memory readout; exp time
Total science time	38.2 min
Total time used in orbit	51.0 min

9.6.3 Example 3: FUV Acquisition plus FUV TIME-TAG

In this example we start with an FUV ACQ/SEARCH followed by an ACQ/PEAKXD, then ACQ/PEAKD target acquisition, then add an FUV TIME-TAG exposure with G140L and SEGMENT=A.

Table 9.13: Overhead values for FUV Acquisition with FUV TIME-TAG

Table 9.14:
 

Action	Time required	Comment
Initial guide star acquisition	6 min	Required at start of a new visit
FUV ACQ/SEARCH, G130M at 1309 Å, 3 × 3 pattern, 15 sec exp.	9×(20+15) = 315 sec = 5.3 min	COS starts from G130M home on OSM1 so no initial move; 9 ACQ/SEARCH sub-exposures, so overhead includes 9 slews (20 sec each) plus 9 exposures (15 sec each)
FUV ACQ/PEAKXD, G130M at 1309 Å, 20 sec exp.	80 + 20 sec = 100 sec = 1.7min	No OSM1 movement; generic PEAKXD overhead; exp time
FUV ACQ/PEAKD, G130M at 1309 Å, 5 steps, 25 sec exp.	5×(20+25) = 220 sec = 3.7 min	No OSM1 move; five slews (20 sec each) plus 5 exp (25 sec each)
FUV G140L at 1235 Å, TIME-TAG, FLASH=YES, FP-POS=3, SEGMENT=A, 600 sec exp.	71 + 60 + 102 + 330 + 110 + 600 = 1273 sec = 21.2 min	Generic FUV TIME-TAG setup; OSM1 grating change (60+102); no central wavelength change; no FP-POS change; SEGMENT reconfiguration change; TIME-TAG memory readout; exp time
Total science time	21.2 min
Total time used in orbit	31.9 min

9.6.4 FUV TIME-TAG with BOA and FLASH=NO

In this example we start with an FUV ACQ/SEARCH followed by an ACQ/PEAKXD, then ACQ/PEAKD target acquisition, then add an FUV TIME-TAG exposure with G140L and SEGMENT=A.

Table 9.15: Overhead values for FUV TIME-TAG using the BOA and FLASH=NO

Table 9.16:
 

Action	Time required	Comment
Initial guide star acquisition	6 min	Required at start of a new visit
NUV ACQ/IMAGE, 2 sec exp.	7 min + 4 sec	ACQ/IMAGE is first exposure in visit, so overhead includes OSM1 change to NCM1; OSM2 move to MIRRORA
FUV G160M at 1600 Å, TIME-TAG, BOA, FLASH=NO, FP-POS=1, 3000 sec exp.	71 + 60 + 112 + 68 + 8 + 110 + 1800 sec = 2229 sec = 37.1 min	Generic FUV TIME-TAG setup; NUV to FUV adds no overhead; change from NCM1 to G160M [60+92]; no central wavelength change (default value); non-preferred direction FP-POS change [68 sec] (3=default to 1); aperture change from PSA to BOA; no SEGMENT change; TIME-TAG memory readout; exp time
FUV G160M at 1600 Å, TIME-TAG, AUTO WAVECAL, WCA, FP-POS=1, 10 sec exp.	71 + 8 + 110 = 199 sec = 3.3 min	AUTO WAVECAL to be inserted as FLASH=YES not allowed with BOA; generic FUV TIME-TAG setup; no OSM1 move, no central wavelength change; no FP-POS change; aperture change from BOA to WCA; no SEGMENT change; TIME-TAG memory readout; exp time
end of orbit 1
Guide star re-acquisition	6 min	required at start of additional orbit
FUV G160M at 1600 Å, TIME-TAG, BOA, FLASH=NO, FP-POS=1, 2400 sec exp.	71 + 8 + 110 + 2400 = 2589 sec = 43.2 min	Generic FUV TIME-TAG setup; continue at same OSM1 position, same central wavelength and FP-POS; aperture change to BOA [8 sec]; no SEGMENT change; TIME-TAG memory readout; exp time
FUV G160M at 1600 Å, TIME-TAG, AUTO WAVECAL, WCA, FP-POS=1, 10 sec exp.		Another AUTO WAVECAL required as more than 40 min have elapsed since last one; again generic FUV TIME-TAG exposure setup; no grating change; no central wavelength change; no FP-POS change; aperture change to BOA [8 sec]; no SEGMENT change; TIME-TAG memory readout; exp time
Total science time	38.4 min
Total time used in orbit	51.4 min