Central Bureau for Astronomical Telegrams
IAUC 3247: V861 Sco; SMC X-2; PKS 1954-388; X-RAY EMISSION FROM TWO SN REMNANTS; COMET AND FMO; 1977g
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Circular No. 3247
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 617-864-5758
V861 SCORPII
P. Massey and P. S. Conti, Joint Institute for Laboratory
Astrophysics, University of Colorado, communicate: "We have obtained
nine coude dispersion red spectrograms of V861 Sco = HD 152667,
identified as an eclipsing x-ray source on IAUC 3234. The plates
were obtained at Kitt Peak National Observatory on eight consecutive
nights beginning June 30 UT and cover one orbit. Two well-separated
emission features are observed at H-alpha and behave as follows:
(1) The weaker emission peak is displaced blueward by a constant
velocity of -300 km/s; it changes drastically in strength
with phase, virtually disappearing when the B0 supergiant is behind
the x-ray source (note that this occurs half a cycle later
than reported on IAUC 3234). The variability of this feature is
gradual and cannot be due to an eclipse of the purported accretion
disk. (2) The radial velocity of the stronger peak is displaced
redward by 200 km/s with respect to the absorption lines but varies
in phase with the B star. This feature also changes in strength
but less dramatically than does the blue component. Our observations
are consistent with the existence of two emission peaks, but
not with a single emission feature and a central absorption."
SMC X-2
D. C. Morton and P. Murdin, Anglo-Australian Observatory; and
R. Thomas, University of Tasmania, suggest that the more likely
optical candidate for SMC X-2 is the fainter star 2" south of the
previously suggested magnitude 15 object (IAUC 3127, 3134, 3143).
It is the new candidate (spectral type B1e) that shows the reported
H-alpha and H-beta emission; the brighter component of the double star
appears to be a normal O7 star.
PKS 1954-388
G. Gilmore, Department of Physics, University of Canterbury,
writes: "The quasar PKS 1954-388 (R.A. = 19h54m39s.01, Decl. = -38o53'l2".6,
equinox 1950.0; z = 0.630; Shimmins et al. 1971, Astrophys. Lett. 8,
139) has brightened by approximately two magnitudes over 24 days.
Observations with an unfiltered Varo single-stage S2OR image intensifier
show it to be similar in brightness to the star 15" east and
35" south of the quasar on May 8 and 9 and June 11 and 12 UT. On
July 6.55 UT it was similar in brightness to the star ~ 30" west."
X-RAY EMISSION FROM TWO SUPERNOVA REMNANTS
I. Tuohy, F. Cordova, G. Garmire and J. Nugent, California
Institute of Technology; and P. Charles, S. Bowyer and F. Walter,
University of California at Berkeley, report the discovery of soft
x-ray emission from two southern supernova remnants:
Energy range Flux kT NH Identif.
Name (keV) (erg cm**-2 s**-1) (keV) (cm**-2)
H1207-52 0.25-1.0 2.0 x 10**-10 0.1 3 x 10**21 PKS 1209-52
H1616-51 0.6 -2.0 2.1 x 10**-10 0.2 9 x 10**21 RCW 103
The observations were made using the HEAO-A2 low-energy detectors.
The values of kT and NH refer to a simple thermal model with
absorption, and it is stressed that these preliminary spectral
parameters may be uncertain by up to a factor of 2. The error box
containing RCW 103 also includes MSH 16-51, but the latter remnant is
considered a less likely candidate in view of its greater distance
(Clark and Caswell 1976, Monthly Notices Roy. Astron. Soc. 174, 267).
COMET AND FAST-MOVING OBJECT
R. D. Eberst, Royal Observatory, Edinburgh, writes that he has
recently found images of a comet and a fast-moving asteroidal object
on plates taken on consecutive nights a year ago with the U.K.
122-cm Schmidt telescope at Siding Spring. The comet has a tail
3' long; the object, designated 1977 OA, was near the edge of each
plate, particularly the first one. The following positions of the
ends of each trail are probably accurate to +/- 2":
1977 UT R. A. (1950) Decl. Mag.
Comet July 18.57526 20 52 54.20 -34 03 10.7 ~18
18.62387 20 52 52.25 -34 03 10.3
19.61292 20 52 06.84 -34 02 51.6
19.68848 20 52 04.48 -34 02 51.2
1977 OA July 18.57526 21 01 50.47 -37 59 26.9 ~17
18.62387 21 01 35.43 -37 58 55.1
19.61292 20 56 40.87 -37 46 31.5
19.66848 20 56 24.26 -37 45 48.8
PERIODIC COMET ASHBROOK-JACKSON (1977g)
J. Bortle, Brooks Observatory, provides the following total
visual magnitude estimates, obtained using a 32-cm reflector: July
12.30 UT, 12.8; 13.30, 12.9.
1978 July 25 (3247) Brian G. Marsden
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