Sometimes we may have only an approximate estimate of the HET structure azimuth. To get a better (although not exact) estimate, we can use estimate_azhet_hetq:
Usage: estimate_azhet_hetq 02:35:27.90 +39:39:52.0 63 arg1 - RA in sexigecimal format (hh:mm:ss.ss) arg2 - DEC in sexigecimal format (+dd:mm:ss.s) arg3 - approximate AZ % estimate_azhet_hetq 02:35:27.90 +39:39:52.0 63 63.461 88.34672The first number is the estimated structure azimuth, and the second is the HET parallactic angle for the observation. Using some of the tcs query tools on guider, we could find the exact structure azimuth that was used. For example, the first records we collected in that way for the above observation were as follows:
Wed Sep 16 07:02:51 GMT 2015 el 55.036564 lst 23.774898 itf.phi 0.176546 az 63.359416 ra 2.6077 itf.rho 0.463Hence, our estimated value of AZstruc=63.461 is fairly close to the tcs value of AZstruc=63.359.
A more vebose local file is made that lists some supplemental information:
% cat estimate_azhet_hetq.out Ra,Dec = 02:35:27.90 +39:39:52.0 Approximate AZ = 63 Track = E DEC in floating point (degrees) = 39.664444444 HET structure azimuth = 63.461 HET parallactic angle = 88.34672