Return to directory of Todd's CASA extensions

Converts a direction from J2000 to ICRS using the CASA measures tool and computes the angular separation. See also ICRSToJ2000. As discussed in CAS-7885, the optically-defined FK5 frame differs from ICRS by a maximum of 31.57 mas, while the J2000 frame differs from ICRS by 23.15 mas. Note that J2000 is also used as a name to label the epoch that corresponds to 2000-Jan-01 at 12h UT.


au.J2000ToICRS(radec, date='', verbose=True)
  • radec: sexagesimal string format
  • date: optional -- CASA shows no date dependence in this calculation! Any of these formats is valid (The time portion is optional):
    • 2011/10/15 05:00:00
    • 2011/10/15-05:00:00
    • 2011-10-15 05:00:00
    • 2011-10-15T05:00:00
    • 2011-Oct-15T05:00:00


CASA <9>: au.J2000ToICRS('18:37:24.5088 -33:19:08.760')
Separation: radian = 2.33282e-08, degrees = 0.000001, arcsec = 0.004812
  Out[9]: '18:37:24.50859, -033:19:08.764028'
-- ToddHunter - 2015-09-24
Topic revision: r2 - 2016-03-07, ToddHunter
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding NRAO Public Wiki? Send feedback