transit_RA#
- caput.astro.observer.Observer.transit_RA(time)[source]#
Transiting RA for the observer at given Unix Time.
Because the RA is defined with respect to the specified epoch (J2000 by default), the elevation actually matters here. The elevation of the equator is used, which minimizes this effect.
- Parameters:
- timearray_like
Time as specified by the Unix/POSIX time.
- Returns:
- RA
float Transiting RA in degrees.
- RA
Notes
It is not clear that this calculation includes nutation and stellar aberration. See the discussion on stackoverflow. Some testing does seem to indicate that these effects are accounted for.
This calculates the RA in the given epoch which by default is J2000, but it might be more appropriate to use an epoch that is closer to the observation time. The mismatch in the celestial poles is not insignificant (~5 arcmin from J2000 to J2016).
PyEphem uses all geocentric latitudes, which I don’t think affects this calculation.