# [AstroPy] Python Functions for Horizontal to Equatorial and vice versa?

Wayne Watson sierra_mtnview@sbcglobal....
Wed Apr 21 20:19:50 CDT 2010

```I may be wrong, but it looks like there are some fairly straightforward
methods on the web for both methods.  Here are two that I've taken note
of. <http://www2.arnes.si/~gljsentvid10/sfera/chapter7.htm> and
<http://en.wikipedia.org/wiki/File:Horizontal_coordinate_system_2.png>.
Both give the details. Another,
<http://www.davincisworld.com/Satellites/OrbitalDynamics.htm>, gives the
details and performs an example  calculation. See a few pages into it,
around Figure 1.1.2.

On 4/20/2010 8:46 PM, Anne Archibald wrote:
> On 19 April 2010 15:15, Wayne Watson<sierra_mtnview@sbcglobal.net>  wrote:
>
>> I'm looking for two functions to do the coordinate transformations in
>> the Subject.  Just those two. I don't need any others.
>>
> I think you will find that you need many other functions than just
> horizontal to equatorial: the transformation depends on LST, for
> example, which you will need to convert to or from GMT, and on
> latitude/longitude; you'll probably want to convert various
> coordinates between sexagesimal and radians or degrees; you may even
> find galactic coordinates useful. Just go with something like a python
> wrapper for SLALIB.
>
> If you really want just those two functions, if it's really essential
> to keep dependencies down at the cost of debugging pain, you can write
> such a function fairly easily by converting to a 3D vector
> representation and back.
>
> Good luck,
> Anne
>
>
>>               According to a very recent article in USA Today, 47%
>>               of households and individual do not pay federal taxes.
>>               In better times, it's about 38%. It's allowed under
>>               present laws. Google USA Today "when 47% don't"
>>
> P.S. This is not a political forum. -A
>
>

--
Wayne Watson (Watson Adventures, Prop., Nevada City, CA)

(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site:  39° 15' 7" N, 121° 2' 32" W, 2700 feet

According to a very recent article in USA Today, 47%
of households and individual do not pay federal taxes.
In better times, it's about 38%. It's allowed under
present laws. Google USA Today "when 47% don't"

Web Page:<www.speckledwithstars.net/>

```