Appendix A:
Orbit Calculation Examples
In this appendix . . .Chapter 6 described the issues involved in the construction of an observing program, and in the calculation of the total orbit request for a Phase I proposal. As an illustration, this Appendix contains some specific, simple example orbit calculations for each of the SIs offered in Cycle 12.
A.1 ACS
Suppose that you wish to use the ACS to observe a target at a declination of +35 degrees, so that there are 54 minutes of visibility time per orbit (see Table 6.1). Your desired exposures are listed in Table A.1, and the associated overheads are listed in Table A.2. In Table A.3 you can see how the observations fit into a total of 2 orbits.
Table A.1: ACS Example: Planned Exposures
Config Mode SpectralElement Number of Exp Time per Exp [m] Notes ACS/WFC IMAGING F606W 4 8.5 Pattern (see Section 5.4) with an offset of 25" between positions ACS/HRC IMAGING F814W 2 6 CR-SPLIT ACS/HRC IMAGING F606W 2 6 CR-SPLIT ACS/HRC IMAGING F435W 2 7 CR-SPLITTable A.2: ACS Example: Incurred OverheadsTable A.3: ACS Example: Orbit PlanningA.2 FGS
Suppose that you wish to use the FGS to observe a binary star named Binary01, as well as five reference stars ref1,......,ref5. All stars are in the same FGS field of view, and can therefore be observed in one and the same visit (see Section 6.2.3). Stars ref4 and ref5 have magnitude V=14.6, and all the other targets have 13.0<V<14.0. The targets have a declination of +42 degrees, so that there are 54 minutes of visibility time per orbit (see Table 6.1). To enable the removal of drift and jitter in the post observation analysis of the data, the binary is observed in POS mode three times and the reference stars are each observed twice. Your desired exposures are listed in Table A.4, and the associated overheads are listed in Table A.5. In Table A.6 you can see how this fits into a total of 1 orbit.
Table A.4: (Continued)FGS Example: Planned Exposures
Config Mode Spectral Element Number of Exp Time per Exp [m] Notes FGS POS F583W 8 0.2 2 exposures of target Binary01, and 2 exposures for each of the targets ref1, ref2 and ref3 FGS POS F583W 4 0.7 2 exposures for each of the targets ref4 and ref5 FGS TRANS F583W 1 13.3 20 scans of 40 sec each (see Table 6.8) for Binary01Table A.5: FGS Example: Incurred OverheadsTable A.6: FGS Example: Orbit PlanningA.3 NICMOS
Suppose that you wish to use the NICMOS to observe a target at a declination of -50 degrees, so that there are 56 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 SpectralElement Number of Exp Time per Exp [m] Notes NIC2 IMAGING F110W 4 2.1 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 positionsTable A.8: NICMOS Example: Incurred OverheadsTable A.9: NICMOS Example: Orbit PlanningA.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 ExposuresTable A.11: STIS Example: Incurred OverheadsTable A.12: STIS Example: Orbit PlanningA.5 WFPC2
Suppose that you wish to use the WFPC2 to observe a target at a declination of -45 degrees, so that there are 55 minutes of visibility time per orbit (see Table 6.1). Your desired exposures are listed in Table A.13 and the associated overheads are listed in Table A.14. In Table A.15 you can see how the observations fit into a total of 3 orbits.
Table A.13: WFPC2 Example: Planned Exposures
Config Mode SpectralElement Num of Exp Time per Exp [m] Notes WFPC2 IMAGING F814W 1 40 CR-SPLIT WFPC2 IMAGING F450W 1 43 CR-SPLIT WFPC2 IMAGING F555W 4 9 Pattern (see Section 5.4 ) with an offset of 1" between positionsTable A.14: WFPC2 Example: Incurred OverheadsTable A.15: WFPC2 Example: Orbit Planning
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