[SciPy-user] Problem with AstroLib - coords-0.2

humufr at yahoo.fr humufr at yahoo.fr
Wed Aug 2 07:31:12 CDT 2006

```Hi,

I look a little bit on this problem and I saw that the answer is not true but
not false... It's true modulo 360 degree but it's false because (for what I
know) right ascension is always positive. That can be a big problem if you
want to transform it in hms (the answer is different):

In [1]: import coords as C

In [2]: ob=C.Position('12:34:45.34 -23:42:32.6')

In [3]: ob.dd()
Out[3]: (188.68891666666667, -23.709055555555555)

In [4]: ob.j2000()
Out[4]: (188.68891666666667, -23.709055555555555)

In [5]: ob1=C.Position((188.68891666666667, -23.709055555555555))

In [6]: ob1.hmsdms()
Out[6]: '12:34:45.340 -23:42:32.600'

In [7]: ob1=C.Position((-171.31108333333333, -23.709055555555555))

In [8]: ob1.hmsdms()
Out[8]: '11:25:14.660 -23:42:32.600'

So like I did in the ticket:

http://projects.scipy.org/astropy/astrolib/ticket/8

I suggest to change a little bit the function j2000 in position.py (and all
function with the same problem) but perhaps I'm wrong, I don't think so ot in
other hand that means that the hmsdms must be change to take care of this
problem because it's j2000 who are false or hmsdms.

I hope that help a little bit.

N.

Le mercredi 12 juillet 2006 21:25, Tara Murphy a écrit :
> Hi,
> I've just started playing around with coords-0.2 and am having a problem
> reproducing the example shown on the wiki:
>
> http://www.scipy.org/AstroLibCoordsSnapshot
>
> I am using Python2.4 and I've pasted my session below. When I try ob.dd()
>
> and ob.j2000() the answers are not the same:
> >>> import coords as C
> >>> ob=C.Position('12:34:45.34 -23:42:32.6')
> >>> ob.hmsdms()
>
> '12:34:45.340 -23:42:32.600'
>
> >>> ob.dd()
>
> (188.68891666666667, -23.709055555555555)
>
> >>> ob.j2000()
>
> (-171.31108333333333, -23.709055555555555)
>
>
> Is this something I'm misinterpreting, or is it a bug?
>
> thanks,
> Tara
>
> -----
> Dr. Tara Murphy
> ARC Postdoctoral Fellow
>
> School of IT             |    School of Physics
> Room 448                 |    Room 565
> University of Sydney     |    University of Sydney
> P: +61 2 9351 4723       |    P: +61 2 9351 3041
> E: tm at it.usyd.edu.au     |    E: tara at physics.usyd.edu.au
>
> http://www.it.usyd.edu.au/~info1903
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```