[AstroPy] Heliocentric Velocity Correction

Erik Tollerud erik.tollerud@gmail....
Wed Mar 21 19:46:08 CDT 2012


FYI this is definitely something that is quite high on the priority
list for the upcoming astropy.coords package, as it has a quite
natural connection to the solar system models that are necessary for
some of the coordinate transforms.

On Wed, Mar 21, 2012 at 6:49 AM, Kelle Cruz <kellecruz@gmail.com> wrote:
> Thanks so much for the responses to Vivienne's (my student) question about
> heliocentric velocity.
>
> However, none of these packages were very user friendly and we ended up just
> going with IRAF's
> rvcorrect: http://stsdas.stsci.edu/cgi-bin/gethelp.cgi?rvcorrect
>
> I hope the eventual astropy has something more straightforward, or at least
> better documented with examples.
>
> kelle
>
> On Tue, Mar 13, 2012 at 4:16 PM, David Berry <d.berry@jach.hawaii.edu>
> wrote:
>>
>> Pyast (http://dsberry.github.com/starlink/pyast.html) provides a wide
>> range of facilities for handling spectral, celestial and time axes.
>> This includes heliocentric velocity correction (amongst other things)
>> for spectral axes. In particularly, see the "SpecFrame" class
>> (http://www.starlink.ac.uk/docs/sun211.htx/node680.html#SpecFrame). If
>> you create two SpecFrames with different properties (i.e. different
>> standards of rest, units, geocentic observatory positions, etc), then
>> the astConvert method
>> (http://www.starlink.ac.uk/docs/sun211.htx/node245.html#xref_astConvert)
>> can be used to get the transformation between them.
>>
>> David
>>
>>
>> On 13 March 2012 19:58, Scott Ransom <sransom@nrao.edu> wrote:
>> > Hi Vivienne,
>> >
>> > There are heliocentric velocity routines which have many of the major
>> > observatories in pyslalib (which wraps the GPL'd version of SLALIB).
>> > See the sla_earth routine for a description (and for a way of getting
>> > even more accurate values).
>> >
>> > https://github.com/scottransom/pyslalib
>> >
>> > Scott
>> >
>> > PS:  There is a _lot_ of other high-quality functionality in SLALIB
>> > (which is all wrapped by pyslalib) as well...
>> >
>> > On 03/13/2012 03:24 PM, Vivienne Baldassare wrote:
>> >> Is there a python function for calculating the heliocentric velocity
>> >> correction?  I found one called helcorr.py in the Astrolibpy library
>> >> but
>> >> am curious if there is another one worth considering.  In particular, I
>> >> noticed that the major observatories aren't in by default.  If this is
>> >> the only one, is it worth me improving this one?
>> >>
>> >> Best,
>> >> Vivienne Baldassare
>> >>
>> >>
>> >> _______________________________________________
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>> >
>> > --
>> > Scott M. Ransom            Address:  NRAO
>> > Phone:  (434) 296-0320               520 Edgemont Rd.
>> > email:  sransom@nrao.edu             Charlottesville, VA 22903 USA
>> > GPG Fingerprint: 06A9 9553 78BE 16DB 407B  FFCA 9BFA B6FF FFD3 2989
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>
>
>
>
> --
> Kelle Cruz, PhD — http://kellecruz.com/
> 917.725.1334 — Hunter ext: 16486 — AMNH ext: 3404
>
>
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-- 
Erik Tollerud


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