def test_coord_trans2():
""" Test finding ci,eta and cos 45, ra 45 """
crval1 = 45.0
crval2 = 45.0
diff_ra = 5.0 # in arc seconds
diff_dec = 5.0 # in arc seconds
ra = crval1 + diff_ra / 3600.0
dec = crval2 + diff_dec / 3600.0
# both crval1 and crval2 = 45, gives h in equation = 1
# and an eta close to diff_dec
xi, eta = coord.radec2std(crval1, crval2, ra, dec)
assert math.isclose(xi, -3.535, abs_tol=0.001)
assert math.isclose(eta, diff_ra, abs_tol=0.001)
def test_coord_trans1():
""" Test finding xi,eta and cos 90, ra 45 """
crval1 = 45.0
crval2 = 90.0
diff_ra = 3.0 # in arc seconds
diff_dec = 3.0 # in arc seconds
ra = crval1 + diff_ra / 3600.0
dec = crval2 + diff_dec / 3600.0
# declination near 90 yields xi values close to 0
# and an eta close to diff_dec
xi, eta = coord.radec2std(crval1, crval2, ra, dec)
assert math.isclose(xi, 0.0, abs_tol=0.001)
assert math.isclose(eta, diff_ra, abs_tol=0.001)
def test_coord_trans3():
""" Test going from ra,dec -> xi,eta -> ra,dec """
crval1 = 27.89
crval2 = 56.08
diff_ra = 5.0 # in arc seconds
diff_dec = 5.0 # in arc seconds
ra = crval1 + diff_ra / 3600.0
dec = crval2 + diff_dec / 3600.0
# both crval1 and crval2 = 45, gives h in equation = 1
# and an eta close to diff_dec
xi, eta = coord.radec2std(crval1, crval2, ra, dec)
ra_test, dec_test = coord.std2radec(crval1, crval2, xi, eta)
assert math.isclose(ra, ra_test, abs_tol=0.00001)
assert math.isclose(dec, dec_test, abs_tol=0.00001)