Name

---

    CO_ABERRATION

Purpose

---

    Calculate changes to Ra and Dec due to "the effect of aberration",

Explanation

---

      as described in Meeus, Chap 23.

Calling Sequence

---

      co_aberration, jd, ra, dec, d_ra, d_dec, [EPS = ]

Inputs

---

      jd : Julian Date [scalar or vector]
      ra, dec : Arrays (or scalars) of the ra and dec's in degrees
  Note: if jd is a vector, ra and dec MUST be vectors of the same length.

Outputs

---

      d_ra, d_dec: the corrections to ra and dec due to aberration (must then
                    be added to ra and dec to get corrected values).

Optional Input Keyword

---

      eps : set this to the true obliquity of the ecliptic (in radians), or
        it will be set for you if you don't know it (in that case, set it to
                an empty variable).

Example

---

  Compute the change in RA and Dec of Theta Persei (RA = 2h46m,11.331s, Dec =
  49d20',54.54" on 2028 Nov 13.19 TD
      IDL> jdcnv,2028,11,13,.19*24,jd ;Get Julian date
      IDL> co_aberration,jd,ten(2,46,11.331)*15,ten(49,20,54.54),d_ra,d_dec
      ==> d_ra = 30.045" d_dec = 6.697"

Notes

---

  These formula are from Meeus, Chapters 23. Accuracy is much better than 1
  arcsecond.

Revision History

---

  Written, June 2002, Chris O'Dell, U. of Wisconsin
  Fix error with vector input W. Landsman June 2009