Package coords

Purpose

This package aims to provide much of the IDL "astron" functionality that pertains to coordinate manipulations in an OO framework. Our target user is a typical astronomer who needs to analyze data, work with catalogs, prepare observing proposals, and prepare for observing runs.

Dependencies

numarray

Example

>>> import coords as C
>>> print C.__version__
0.3

>>> #Unit conversions
>>> 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.rad()
(3.2932428578545374, -0.41380108198269777)

>>> #Angular separations
>>> p1=C.Position("01:23:45.300 +65:43:31.240")
>>> p2=C.Position("01:23:45.62 +65:43:31.20")
>>> p1.angsep(p2)
0.000548 degrees

>>> delta=p1.angsep(p2)
>>> delta.arcsec()
1.973739377865491

>>> p1.within(p2,3.0,units='arcsec')
True

>>> epsilon=C.AngSep(5.0)
>>> epsilon
5.000000 arcsec

>>> delta > epsilon
False

>>> #Astronomical Date specifications
>>> d=C.AstroDate('1997.3') #Defaults to Julian year; J or B prefix also ok
>>> d.year
1997.3

>>> d.jd
2450558.8250000002

>>> d.mjd
50558.325000000186

>>> d2=C.AstroDate('MJD50658.25') #JD also ok for plain Julian Date
>>> d2.year
1997.5735797399041

>>> d2 < d
False

>>> # Coordinate conversions
>>> ob.j2000()
(188.68891666666667, -23.709055555555555)

>>> ob.b1950()
(188.03056480942405, -23.433637283819877)

>>> ob.galactic()
(298.01638938748795, 39.003358150874568)

>>> ob.ecliptic(timetag=C.AstroDate('J2000'))
(197.5848634558852, -18.293964120804738)

>>> p3=C.Position("01:23:45 -65:43:21.4",equinox='J2000')
>>> p4=C.Position("01:23:45 -65:43:21.4",equinox='B1950')
>>> p3.j2000()
(20.9375, -65.722611111111107)

>>> p4.j2000()
(21.356870704681981, -65.462921080444147)

>>> p3.angsep(p4)
0.312199 degrees

>>> p5=C.Position((0.0,0.0),system='galactic')
>>> p5.j2000()
(266.40499571858879, -28.936169261309555)

>>> #Specify position in hmsdms
>>> polaris=C.Position("02:31:49.08 +89:15:50.8")
>>> polaris.dd()
(37.954500000000003, 89.264111111111106)

>>> polaris.hmsdms()
'02:31:49.080 +89:15:50.800'

>>> print polaris.details()
System: celestial 
 Equinox: j2000

>>> #Specify position in decimal degrees
>>> ob=C.Position((52.9860209, -27.7510006))
>>> ob.hmsdms()
'03:31:56.645 -27:45:03.602'

>>> ob.dd()
(52.9860209, -27.751000600000001)

>>>
>>> #Use as calculator without saving the intermediate object
>>> C.Position("12:34:45.4 -22:21:45.4").dd()
(188.68916666666667, -22.362611111111111)

TPM Citation

Version: '0.3 (2007-2-12)'

Author: Vicki Laidler

See Also: http://www.scipy.org/AstroLibCoordsHome