Allow for passing the target coordinates to `extract_source_position`

[morcuended]

cta-lstchain/lstchain/reco/utils.py

Lines 104 to 132 in 9aaa78b

	def extract_source_position(
	data, observed_source_name, equivalent_focal_length=28 * u.m
	):
	"""
	Extract source position from data
	Parameters
	----------
	pandas.DataFrame data: input data
	str observed_source_name: Name of the observed source
	astropy.units.m equivalent_focal_length: Equivalent focal length of a telescope
	Returns
	-------
	2D array of coordinates of the source in form [(x),(y)] in astropy.units.m
	"""
	observed_source = SkyCoord.from_name(observed_source_name)
	obstime = pd.to_datetime(data["dragon_time"], unit="s")
	pointing_alt = u.Quantity(data["alt_tel"], u.rad, copy=False)
	pointing_az = u.Quantity(data["az_tel"], u.rad, copy=False)
	source_pos_camera = radec_to_camera(
	observed_source,
	obstime,
	pointing_alt,
	pointing_az,
	focal=equivalent_focal_length,
	)
	source_position = [source_pos_camera.x, source_pos_camera.y]
	return source_position

For cases in which the name solver of astropy does not work (e.g. GRBs, GW, neutrino alerts) one needs to pass the coordinates directly to make this function work. Used in the explore DL2 notebook (theta2 distribution calculation)