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IAUC 5407: 1991f1; LB 1800; 1991n

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                                                  Circular No. 5407
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


PERIODIC COMET KOWAL 2 (1991f1)
     Ephemeris from the orbital elements on IAUC 5406:

     1991 ET      R.A. (1950) Decl.     Delta      r       m1
     Dec. 10     8 31.62    + 0 39.2    0.756    1.546    14.3
          15     8 32.92    - 1 27.5
          20     8 33.07    - 3 26.2    0.739    1.574    14.3
          25     8 32.13    - 5 14.8
          30     8 30.20    - 6 51.4    0.736    1.608    14.4


LB 1800
     R. Baptista, Instituto Astronomico e Geofisico, Sao Paulo; and
D. Cieslinski, Instituto Nacional de Pesquisas Espaciais/SECT, San
Jose dos Campos, communicate:  "We have discovered that the ephemeris
of Buckley et al. (1990, Ap.J. 355, 617) for the timings of minimum
light in the eclipsing cataclysmic variable LB 1800 has accumulated
an error which now amounts to +0.26 cycles.  We used the
FOTRAP photometer at the 0.6-m telescope at CNPq/Laboratorio Nacional
de Astrofisica, Brazil, to obtain high speed (10-s) UBVRI photometry
of this object.  The data comprise three observed eclipses,
on 1991 Jan. 13, Dec. 4, and Dec. 5.  We determined the times of
minimum by adjusting a parabola and a cubic function to the points
during eclipse and calculating their minimum, and by employing
bisected chords to find the average of the mean point from a group of
chords at different depth levels.  We list below the measured
timings, the corresponding cycle, and O--C values with respect to the
new ephemeris (the uncertainties quoted in parentheses are the
errors of the mean of the determinations from the methods employed):
HJD 2448269.63136(15), 6177, +0.0024; HJD 2448595.73325(11), 7583,
+0.0015; HJD 2448596.66022(09), 7587, -0.0018.  Together with the
original 9 timings of Buckley et al., this gives the new ephemeris
Tmin = HJD 2446836.96176(25) + 0.231936060(35)E, with a
corresponding dispersion of 0.00636 cycles for the 12 timings used."


PERIODIC COMET FAYE (1991n)
     Total visual magnitude estimates (cf. IAUC 5382) by A. Hale,
Las Cruces, NM (B = 10x50 binoculars; L = 0.41-m reflector):  Nov.
27.21 UT, 9.7 (B); Dec. 4.27, 9.9 (L); 13.29, 10.3 (L).


1991 December 17               (5407)             Daniel W. E. Green

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