get_geomagnetic_delta

lstchain.reco.utils.get_geomagnetic_delta(zen, az, geomag_dec=None, geomag_inc=None, time=None)

From a given geomagnetic declination and inclination angle along with telescope zenith and azimuth pointing to get the angle between the geomagnetic field and the shower axis, for a single telescope.

If no geomagnetic parameters are provided, use default for LST-1 by estimating the predicted values as per https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml?#igrfwmm for the current time.

Parameters:

zen: astropy.units.Quantity[angle]

Zenith pointing angle

az: astropy.units.Quantity[angle]

Azimuth pointing angle.

geomag_dec: astropy.units.Quantity[angle]

Geomagnetic declination measures the difference between the measurement of true magnetic north and the geographical north, eastwards. Hence we add to the azimuth measurement as it is measured westwards.

geomag_inc: astropy.units.Quantity[angle]

Geomagnetic inclination, ‘dip angle’ is the angle between the geomagnetic field and the horizontal plane.

time: astropy.time.Time

If geomag_inc or geomag_dec are not give, use this time to calculate them using get_geomagnetic_field_orientation. If time is None, use the current time.

Returns:

delta: Angle between geomagnetic field and the shower axis.