Module marlu::constants

Useful constants.

Constants

COTTER_MWA_HEIGHT_METRES

cotter’s MWA altitude in metres. Use MWA_HEIGHT_M unless you know what you’re doing.

COTTER_MWA_LATITUDE_RADIANS

cotter’s MWA latitude on Earth in radians. Use MWA_LAT_RAD unless you know what you’re doing.

COTTER_MWA_LONGITUDE_RADIANS

cotter’s MWA longitude on Earth in radians. Use MWA_LONG_RAD unless you know what you’re doing.

DAYSEC

Seconds per day (86400)

DH2R

Hour angle to radians (15 / 180 * PI).

DS2R

Seconds of time to radians (7.272205216643039903848712e-5).

HIFITIME_GPS_FACTOR

This is the number of seconds from 1900 Jan 1 and 1980 Jan 5. The GPS epoch is 1980 Jan 5, but hifitime uses 1900 for everything; subtracting this number from the result of hifitime::Epoch::as_gpst_seconds gives the expected GPS time.

MJD_TAI_EPOCH_DIFF

The number of seconds between 1858-11-17T00:00:00 (MJD epoch, used by casacore) and 1900-01-01T00:00:00 (TAI epoch) is 1297728000. I’m using the TAI epoch because that’s well supported by hifitime, and hifitime converts an epoch to many formats including JD, and accounts for leap seconds.

MWA_HEIGHT_M

MWA height (a.k.a. altitude) [metres]

MWA_LAT_DEG

MWA latitude [degrees]

MWA_LAT_RAD

MWA latitude [radians]

MWA_LONG_DEG

MWA latitude [degrees]

MWA_LONG_RAD

MWA longitude [radians]

SOLAR2SIDEREAL

Ratio of a solar day to a sidereal day (24/23.9344696 = 1.002737909).

VEL_C

Speed of light [metres/second]