Author: Behrouz Safari
License: MIT

numeph

Convert JPL SPK ephemeris to numpy array

Installation

Install the latest version of numeph from PyPI:

pip install numeph

Requirements are numpy and jplephem

Save some segments of 'de440s.bsp' from 2020 to 2030:

from datetime import datetime
from numeph import SPK

t1 = datetime(2020, 1, 1)
t2 = datetime(2030, 1, 1)

spk = SPK(fname='de440s.bsp', t1=t1, t2=t2,
          segs_tup=[(0,10), (0,3), (3,399), (3,301)])

# save as txt file
spk.to_txt('de440s_2020_2030.txt')

# save as pickle
spk.to_pickle('de440s_2020_2030.pickle')

Load .txt or .pickle files:

You can load the above saved files using load_txt and load_pickle functions. The will return a dictionary of Segment objects.

from numeph import load_txt

dc = load_txt('de440s_2020_2030.txt')

To access each segment, pass the (center, target) tuple as dictionary key.

seg = dc[(3,301)]

get position of an object from a segment:

t = datetime.utcnow()
pos = seg.get_pos(t)

See more at astrodatascience.net