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IAUC 4097: CPD -58 2721; Occn BY PLUTO ON 1985 Aug. 19; EXO 041604-5504.9

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                                                  Circular No. 4097
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM    Telephone 617-495-7244/7440/7444

CPD -58 2721
     P. W. Hill, C. S. Jeffery and K. Morrison, St. Andrews
University, report that the extreme-He star CPD -58 2721 (IAUC 4086)
shows semi-regular light and color variations with amplitudes 0.07
mag in V and 0.07 mag in (Stromgren) u-b with cycle-time ~ 17 days.
This result is based on observations made with the South African
Astronomical Observatory's 0.5-m telescope in May-June and implies
further similarity between CPD -58 2721 and the H-deficient binary
KS Per (Osawa et al. 1963, P.A.S.J. 15, 313).

     N. Brosch and H. Mendelson, Wise Observatory, telex that
their photoelectric observations on Aug. 19 indicate that Pluto
occulted a 12.8-mag star as predicted by Mink and Klemola (1985,
A.J., in press).  The mid-time of the occultation was 17h59m21s +/-
2s UT.  Although the entire event lasted at least 80 s, the starlight
disappeared completely only for ~ 14 s, indicating that this
was an almost-grazing occultation.  This may be the first
detection of an atmosphere around Pluto or possibly 1978 P1.

EXO 041604-5504.9
     D. Alloin and D. Pelat, Meudon Observatory; and S. D'Odorico,
European Southern Observatory, write: "A new, soft x-ray source at
high galactic latitude (R.A. = 4h16m03s5 +/- 1s5, Decl. = -55deg04'55" +/-
20", equinox 1950.0) has been discovered from EXOSAT low-energy
observations. The x-ray flux in the range 0.04-2 keV is variable and
changes by 70 percent on a timescale of 1 month.  We find channel-
multiplier array (+ thin Lexan) count rates between 0.5-0.85 x 10**2
cts/s, corresponding to ~ 0.14-0.23 mCrab.  The source is detected
at a 6-sigma level.  An optical counterpart can be found on the ESO B
Survey as a star of B ~ 16.  Quick image-dissector-scanner and CCD
spectra of this object were obtained on May 1 and 14 at ESO with a
spectral resolution ~ 1.3 nm; they show strong Balmer absorption
features and a weak Ca-II K line, suggesting an A5-type star.
From an echelle spectrum taken on Apr. 3 the H-beta line-center
provides a heliocentric velocity of 20 +/- 8 km/s."

1985 August 26                 (4097)              Brian G. Marsden

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