Coverage for bilby/core/utils/conversion.py: 67%

1import numpy as np 

2 

3 

4def ra_dec_to_theta_phi(ra, dec, gmst): 

5 """ Convert from RA and DEC to polar coordinates on celestial sphere 

6 

7 Parameters 

8 ========== 

9 ra: float 

10 right ascension in radians 

11 dec: float 

12 declination in radians 

13 gmst: float 

14 Greenwich mean sidereal time of arrival of the signal in radians 

15 

16 Returns 

17 ======= 

18 float: zenith angle in radians 

19 float: azimuthal angle in radians 

20 

21 """ 

22 phi = ra - gmst 

23 theta = np.pi / 2 - dec 

24 return theta, phi 

25 

26 

27def theta_phi_to_ra_dec(theta, phi, gmst): 

28 ra = phi + gmst 

29 dec = np.pi / 2 - theta 

30 return ra, dec