[AstroPy] Proper Motions in astropy.coordinates

[Russell Owen]

It is not a hard computation, but I suggest working in spherical coordinates or using spherical trig for best results.

If you want a ready made solution, I wrote two that might be of interest:

- RO.Astro performs astronomical coordinate conversions, and handles proper motion, parallax and radial velocity. It is part of the RO package, which is pure python <https://pypi.python.org/pypi/RO>. pip install works.

- CoordConv is much faster  (C++ with Python wrappers), but has many dependencies, including slalib, so it takes more work to install. <https://github.com/r-owen/coordConv>. I wrote this package for the Apache Point Observatory telescope control system.

Both packages also include a spherical trig solver and convenient conversion between spherical and cartesian coordinates.

-- Russell

On May 11, 2015, at 8:49 PM, gonghang.naoc <ghang.naoc at gmail.com> wrote:

> I have a similar question. Is there any other package about PM calculation?
> Thank you.
> Hang
> 
> On Sun, May 10, 2015 at 5:24 PM, Josh Walawender <jmwalawender at gmail.com> wrote:
> Hi all,
> 
> Is there a method do calculations of proper motions in astropy.coordinates?  It looks to me as if the SkyCoord has obstime and equinox properties but how would I transform from a coordinate defined for a particular obstime and equinox to another obstime (e.g. for the same equinox)?
> 
> I just did this calculation in a brute force way (multiplying the proper motion in mas/yr by number of years and adding that angle to the ra and dec independently), but it felt like there should be a better way.
> 
> thanks!
> Josh
> 
> 
> _______________________________________________
> AstroPy mailing list
> AstroPy at scipy.org
> http://mail.scipy.org/mailman/listinfo/astropy
> 
> 
> _______________________________________________
> AstroPy mailing list
> AstroPy at scipy.org
> http://mail.scipy.org/mailman/listinfo/astropy

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/astropy/attachments/20150512/66ba0c3a/attachment.html>