Bug in calc_frame_pos_angle function

[pragyachawla]

While reading a measurement set using the from_file function, I get the following error message:

File /opt/conda/lib/python3.11/site-packages/pyuvdata/utils/phasing.py:1669, in calc_frame_pos_angle(time_array, app_ra, app_dec, telescope_loc, ref_frame, ref_epoch, telescope_frame, ellipsoid, offset_pos)
   1664 up_ra[up_dec > (np.pi / 2.0)] = np.mod(
   1665     up_ra[up_dec > (np.pi / 2.0)] + np.pi, 2.0 * np.pi
   1666 )
   1667 up_dec[up_dec > (np.pi / 2.0)] = np.pi - up_dec[up_dec > (np.pi / 2.0)]
-> 1669 dn_ra[-dn_dec > (np.pi / 2.0)] = np.mod(
   1670     dn_ra[dn_dec > (np.pi / 2.0)] + np.pi, 2.0 * np.pi
   1671 )
   1672 dn_dec[-dn_dec > (np.pi / 2.0)] = np.pi - dn_dec[-dn_dec > (np.pi / 2.0)]
ValueError: NumPy boolean array indexing assignment cannot assign 0 input values to the 705 output values where the mask is true

The from_file function is calling the calc_frame_pos_angle function in utils/phasing.py. Line 1670 in utils/phasing.py seems to have a bug in that the minus sign before dn_dec is missing. As far as I understand it, lines 1669 and 1670 should instead be:

dn_ra[-dn_dec > (np.pi / 2.0)] = np.mod(
    dn_ra[-dn_dec > (np.pi / 2.0)] + np.pi, 2.0 * np.pi)