Central Bureau for Astronomical Telegrams
IAUC 5130: 1990 TG1, 1990 UN, 1990 UO
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Read IAUC 5131
Circular No. 5130
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
1990 TG1, 1990 UN, 1990 UO
The batch of Minor Planet Circulars being issued today contains
observations and orbital elements of two, possibly three, new Apollo
objects of V > 19, discovered during October by the University of
Arizona's Spacewatch program. This scanning search program, which is
carried out by T. Gehrels, D. Rabinowitz and J. Scotti on a 0.91-m
reflector at Kitt Peak, has recently been improved with the
installation of a 2048 x 2048 CCD, and it is likely that several faint
new earth-approaching minor planets will be discovered every month.
Information relating to them will regularly appear, of course, in the
monthly MPCs (with the orbital elements also available in the IAUC/MPC
Computer Service), but since the number of IAUC subscribers who are
both willing and able to perform follow-up astrometry or physical
observations must be extremely small, there seems little need to give
these very faint objects extensive coverage in the IAUCs. The object
1990 TG1 is currently quite far from the earth, and although the
observed arc is eight days, the orbit is quite indeterminate, and it is
not clear whether the object is an Apollo or an Amor. The orbits of
1990 UN and UO are much more secure, even from three-day arcs, and the
latter object is also some 0.5 AU from the earth. 1990 UN is closer,
and the following orbital elements are from MPC 17218; this object has
absolute magnitude H = 23.5, making it intrinsically the faintest
natural object ever observed outside the earth's atmosphere.
T = 1990 Dec. 19.727 ET Peri. = 96.999
e = 0.52737 Node = 7.765 1950.0
q = 0.80711 AU Incl. = 3.666
a = 1.70771 AU n = 0.441656 P = 2.23 years
1990 ET R.A. (1950) Decl. Delta r V
Nov. 1 23 09.39 +29 51.5 0.059 1.034 19.0
2 22 47.14 +32 05.9
3 22 19.76 +34 24.2 0.050 1.019 18.9
4 21 46.26 +36 34.6
5 21 06.22 +38 17.9 0.044 1.004 19.1
6 20 20.56 +39 10.3
7 19 32.10 +38 52.3 0.042 0.989 19.6
8 18 44.85 +37 20.6
9 18 02.31 +34 50.9 0.044 0.975 20.6
1990 November 2 (5130) Daniel W. E. Green
Read IAUC 5131
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