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Hubble Space Telescope Primer for Cycle 22 > Appendix A: Orbit Calculation Examples > A.2 COS Examples

A.2 COS ExamplesThis section illustrates two examples of COS Phase I observations. Additional details are available in the COS Instrument Handbook.The COS NUV channel is used to observe an object at declination -10o. First, an image is taken, followed by obtaining a TIME-TAG spectrum with two exposures using different gratings. The specific observations, as requested by the user, are summarized in Table A.4.

• Based on information in Table 6.1, there are 54 minutes of orbital visibility per orbit.

• Therefore, a preliminary observing strategy can be created by the user to fit the observations in one orbit, as shown in Table A.6. In this example, we assume that the coordinates of the object are known to an accuracy of 0.4 arcsec or better. See the COS Instrument Handbook for details.Table A.4: COS Example 1: Planned Exposures

Table A.6: COS Example 1: Orbit Planning

The COS NUV channel is used to acquire the same object as in Example 1, in imaging mode, then uses the FUV channel to obtain a TIME-TAG spectrum with two exposures using the same grating and central wavelength. The planned exposures are summarized in Table A.7.

• Based on information in Table 6.1, there are 54 minutes of orbital visibility time per orbit.

• Therefore, a preliminary observing strategy can be created by the user to fit the observations in two orbits, as shown in Table A.9. In this example, we assume that the coordinates of the object are known to an accuracy of 0.4 arcsec or better. See the COS Instrument Handbook for details.Table A.7: COS Example 2: Planned Exposures

Table A.8: COS Example 2: Incurred Overheads

Table A.9: COS Example 2: Orbit Planning

Hubble Space Telescope Primer for Cycle 22 > Appendix A: Orbit Calculation Examples > A.2 COS Examples