Central Bureau for Astronomical Telegrams
IAUC 5051: 1989c1; BZ UMa; TIME ADJUSTMENT ON 1990 Dec. 31
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Circular No. 5051
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
COMET AUSTIN (1989c1)
J. R. Ducati and C. M. Bevilaqua, Instituto de Fisica, Universidade
Federal do Rio Grande do Sul, Porto Alegre, report: "We obtained
photoelectric photometry of comet Austin on eight nights
(May 16, 20; June 1, 11, 15, 16, 17, 18) with molecular-band filters
and diaphragms of 30", 50", 100", 150", 200", and 250" on the
0.50-m Cassegrain reflector of Morro Santana Observatory. Ratios
of intensity, I, of molecular bands to neighboring continua, A =
484 nm and B = 684 nm, are I(C2 514 nm)/IA = 7.18 +/- 0.83 for May
16 and 20, and 1.99 +/- 0.36 for June 1-18 in the nuclear region,
increasing by 50 percent outwards; I(C3 406 nm)/IA = 1.24 +/- 0.43
with non-systematic variations, decreasing slightly outwards; I(CO+
426 nm)/IA = 1.49 +/- 0.07 for the first four nights, 0.42 +/- 0.08
for the last four, constant over the comet; I(CN 419 nm)/IA = 0.59
+/- 0.19 constant over time and object; I(H2O+ 700 nm)/IB = 2.66
+/- 0.48 overall, increasing slightly outwards; IA/IB = 1.57 +/-
0.41 overall."
Total visual magnitude estimates (cf. IAUC 5033): June 17.31
UT, 7.4 (C. S. Morris, Lockwood Valley, CA, 20x80 binoculars; tail
length about 1 deg); 19.93, 7.8 (V. F. de Assis Neto, Sao Francisco
de Oliveira, Brazil, 10x70 binoculars); 21.14, 9.7 (G. Kronk, Troy,
IL, 0.33-m reflector); 23.27, 9.4 (A. Hale, Las Cruces, NM, 0.41-m
reflector); 24.27, 9.1 (Morris); 26.56, 10.5 (A. Pearce, Scarborough,
W.A., 0.20-m reflector).
BZ URSAE MAJORIS
P. Schmeer, Bischmisheim, West Germany, reports that this
cataclysmic variable is undergoing another outburst (cf. IAUC 4691).
Visual magnitude estimates: July 9.94 UT, 12.2: (Schmeer); 10.96,
12.4 (G. Poyner, Birmingham, England); 11.90, 12.8: (Schmeer). W.
Wenzel (IBVS 2256) suggests that this star might be an intermediate
object connecting the U Gem and WZ Sge classes.
TIME ADJUSTMENT ON 1990 DECEMBER 31
Bulletin C2 of the International Earth Rotation Service announces
that a positive leap second will be introduced such that the
sequence of UTC second markers will be: 1990 Dec. 31d23h59m59s,
31d23h59m60s, 1991 Jan. 1d00h00m00s. From 1990 Jan. 1 to 1990 Dec.
31, the difference UTC-TAI = -25s; beginning 1991 Jan. 1, UTC-TAI =
-26s.
1990 July 13 (5051) Daniel W. E. Green
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