j2b {astroFns} | R Documentation |
J2000 to B1950 coordinate converstion
Description
Precession from J1950 to B2000
Usage
j2b(ra = "17:30:30", dec = "-28:47")
Arguments
ra |
J2000 Right ascention (string) |
dec |
J2000 Declination (string) |
Details
Enter positions as text strings with fields separated by characters d, h, m, s, a colon, or a comma, e.g. '17, 42, 28', '-28h43m03s', or '- 28 :43 : 3'. Spaces are removed in input conversion. Trailing missing values are taken as zero. The code uses an approximate formula for precession; spot checks give results accurate within a few tenths of an arcsecond.
Value
List with strings in:
ra1950 |
B1950 Right ascension |
dec1950 |
B1950 Declination |
Note
Values based on power-law expansion of more exact calculation.
Author(s)
Andrew Harris
References
Explanatory supplement to the Astronomical Almanac, Seidelmann (ed.), c.~1992, chapter 3.213
See Also
b2j
. See dms2rad
, hms2rad
for input conversions.
Examples
j2b()
j2b(ra='17h43m', dec='-28d47m30s')
tmp <- j2b(ra='17, 43', dec=' - 28, 47, 30')
str(tmp)
tmp
[Package astroFns version 4.2-1 Index]