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IAUC 5804: 1993i; HD 98800; 1993 KA

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IAUC number

                                                  Circular No. 5804
Central Bureau for Astronomical Telegrams
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

     S. Nakano, Sumoto, Japan, reports the recovery of this comet
by T. Seki at Geisei, the positions being very close to the prediction
on MPC 16379 (ephemeris on MPC 21958).  The comet is diffuse
with little central condensation, coma diameter 20".

     1993 UT             R.A. (2000) Decl.        m1
     May  24.77222    1 12 09.20   +17 34 18.7    18
          25.77639    1 13 59.40   +17 51 18.8    18

HD 98800
     F. C. Fekel, Marshall Space Flight Center, NASA; and B. W.
Bopp, University of Toledo, write:  "High-resolution CCD spectra of
the dusty K5 V star HD 98800 (Zuckerman and Becklin 1993, Ap.J. 406,
L33; Gregorio-Hetem et al. 1992, A.J. 103, 549) have been obtained
at Kitt Peak National Observatory.  The spectra confirm the dwarf
spectral type and show rotationally-broadened photospheric lines,
H-alpha emission, and a very strong Li I absorption line.  The overall
spectrum of HD 98800 closely resembles that of the young,
chromospherically active, single BY-Dra star HD 82558 (Fekel et al.
1986, A.J. 92, 1150).  The measured Li I equivalent width of 0.04
nm implies an abundance log n(Li) = 2.2 and an age of 20-30 Myr.
An upper limit on the rotation period, based on our measured v sin
i = 11 +/- 1 km/s, is 3.7 days.  HD 98800 should be photometrically
variable, and potentially a strong x-ray and radio source."

1993 KA
     E. S. Howell and M. C. Nolan, Lunar and Planetary Laboratory,
communicate:  "We obtained CCD photometry of 1993 KA using the
1.54-m Catalina telescope.  We measure V = 16.916 +/- 0.014 and V-R
= +0.434 +/- 0.018, averaged over the interval May 18.2125-18.2800
UT.  In this time interval, the brightness variation in both Harris
V and Cousins R filters was < 0.10 mag, which is within 1.5 sigma
of the mean value.  However, the Harris B filter photometry shows
significant variation in this same interval; B-V ranges from +0.482
+/- 0.046 to +0.747 +/- 0.030 in about 30 min.  We did not obtain
data over a full rotation period, and we can only estimate that the
period is longer than 3 hr.  CCD spectra were obtained on May 19
and 20, which may help in understanding these color variations."

1993 May 26                    (5804)            Daniel W. E. Green

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