Central Bureau for Astronomical Telegrams
IAUC 4097: CPD -58 2721; Occn BY PLUTO ON 1985 Aug. 19; EXO 041604-5504.9
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Read IAUC 4098
Circular No. 4097
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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).
OCCULTATION BY PLUTO ON 1985 AUGUST 19
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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