calc_zd_pa

calc_zd_pa(ra: QuantityDict, dec: QuantityDict, obs_long: QuantityDict, obs_lat: QuantityDict, date_time: EpochDict) → tuple[float, float][source]

Computes the zenith distance and parallactic angle chi.

Parameters:

  • ra -- Uncorrected Right Ascension.

  • dec -- Uncorrected Declination.

  • obs_long -- Geographic longitude of observatory.

  • obs_lat -- Geographic latitude of observatory.

  • date_time -- Date and time of observation.

The arguments are all in casa_tools.quanta format (dictionary containing value (float) and unit (str)). The function internally uses radian units for computation. The arguments may have any convertible units.

Returns:

zd -- zenith distance in radians chi: parallactic angle in radians

Examples: >>> ra, dec = {'unit': 'deg', 'value': 239.9618166667}, {'unit': 'deg', 'value': 33.5} >>> obslong, obslat = {'unit': 'deg', 'value': -107.61833}, {'unit': 'deg', 'value': 33.90049}, >>> datetime = {'m0': {'unit': 'd', 'value': 58089.82306510417}, 'refer': 'UTC', 'type': 'epoch'} >>> zd, chi = calc_zd_pa(ra=ra, dec=dec, obs_long=obslong, obs_lat=obslat, date_time=datetime) >>> '{}rad,{}rad'.format(zd, chi) 0.2981984027696312rad, 1.4473222298324353rad