Circular No. 5409
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505
MARSDEN or GREEN@CFA.BITNET    MARSDEN or GREEN@CFAPS2.SPAN
 
 
EDITORIAL NOTICE
     Following the recommendation of IAU Commission 20 and the
announcement on IAUC 5278, we shall henceforth be using on these
Circulars the 2000.0 equinox (more specifically, the mean equator and
equinox of the FK5/J2000.0 system) for positional observations,
orbital elements and ephemerides of comets and minor planets.
The independent variable for the elements and ephemerides will in the
future be denoted by TT (terrestrial time, or more specifically
terrestrial dyamical time), which is essentially identical with ET
(ephemeris time), a term that is now considered obsolete.  At the
present time TT-UT is approximately +58 seconds.  Following numerous
requests, we shall also include in the ephemerides columns giving
the solar elongation and the phase angle, and all the information
will be given for each ephemeris line.  We repeat the earlier advice to
the effect that positions of novae, supernovae, etc., will continue to
be given in the 1950.0 (FK4/B1950.0) system.  The 2000.0 system and
numerous "user-friendly" improvements are also being introduced in the
Computer Service.
 
 
1991 VH
     The following precise positions have been obtained by R. H.
McNaught and D. I. Steel at Siding Spring:
 
     1991 UT             R.A. (2000) Decl.
     Nov. 25.50433    1 00 24.50   -56 34 36.3
          25.54699    1 00 34.54   -56 32 34.8
          27.51292    1 08 31.49   -54 59 27.0
          27.52360    1 08 33.76   -54 58 55.6
     Dec. 20.55921    2 16 10.63   -34 31 32.1
          20.56671    2 16 11.65   -34 31 06.0
          21.58118    2 18 35.35   -33 33 39.9
          21.59549    2 18 37.29   -33 32 49.7
 
     Orbital elements from 15 observations Nov. 9-Dec. 21:
 
     T = 1991 Sept. 22.5580 TT        Peri. = 206.9816
     e = 0.144068                     Node  = 139.5040  2000.0
     q = 0.973019 AU                  Incl. =  13.9269
       a =  1.136795 AU    n = 0.8131688    P =   1.212 years
 
 
1991 December 24                                   Brian G. Marsden