Central Bureau for Astronomical Telegrams
IAUC 2790: NEW SOFT X-RAY SOURCE; SPECTRUM OF SN IN Anon GALAXY; SHELL OF DV Aqr; A0535+26 AND HDE 245770; Obs OF COMETS
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Circular No. 2790
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Cable Address: SATELLITES, NEWYORK
Western Union: RAPID SATELLITE CAMBMASS
NEW SOFT X-RAY SOURCE
D. R. Hearn and J. A. Richardson of Massachusetts Institute of
Technology report that the SAS-3 group has discovered an intense
source of very soft X-rays in the constellation Coma Berenices. The
source, designated MX1313+29, was first observed with the SAS-3
satellite on 1975 June 12 13.33 UT, and was monitored until June 15
9.55 UT. The position of the source (90 percent confidence) is
(1950) R.A. = 198o.35 +/- 0o.25, Decl. = +29o.55 +/- 0o.25. MX1313+29 is
detected only in the energy band 0.1 to 0.28 keV, at approximately 20
percent of the total flux of the Cygnus Loop in that band. A possible
optical counterpart is HZ43, a white dwarf of mv = 12.9, with an
M dwarf companion.
J. Condon of Virginia Polytechnic Institute observed the
position of HZ43 with the National Radio Astronomy Observatory
three-element interferometer (18' beam) on June 14 0400 UT, and reports
an upper limit of 20 mJy at 2695 and 8085 MHz.
J. Liebert and H. Spinrad of the University of California at
Berkeley report that a spectrogram made of HZ43 within the past few
days shows a normal white dwarf spectrum.
SPECTRUM OF SUPERNOVA IN ANONYMOUS GALAXY
Mr. J. Liebert and Dr. H. Spinrad, University of California at
Berkeley, have obtained image-tube spectra on 1975 June 14 of the
supernova discovered by Lovas and reported on IAUC 2789. The
spectrophotometry covered 3600-7200 A. The spectra show that the
supernova has the broad spectrum features typical of a Type I supernova
at an early stage. The preliminary magnitudes obtained are
consistent with the 14.5 reported on IAUC 2789. A spectrum of the
associated galaxy, centered some 17" west of the supernova, was also
obtained. A preliminary assessment indicates a redshift of 1900
km/sec +/- 300 (corrected for galactic rotation). This redshift and
apparent magnitude of the supernova would preclude any association
of the anonymous galaxy and the supernova with M101. At the inferred
distance, some 75 percent farther than the Virgo cluster, the
supernova would be about 5 kpc from the nucleus of the associated
galaxy.
SHELL OF DV AQUARII
Wallace R. Beardsley and Merle W. King, Allegheny Observatory,
report that a spectrum obtained on May 26 using the Coude Feed at
Kitt Peak National Observatory (dispersion 17 A/mm) shows evidence
of a shell spectrum not previously observed in the 1.575551-day
eclipsing binary. The A3 spectral lines appear generally filled
in and very weak. However, very strong and sharp H and K shell-like
absorption overlays the weaker stellar components. The
effect is not present in the hydrogen lines, nor was it found in
16 spectra obtained at Allegheny Observatory (dispersion 39 A/mm)
during the interval 1971 June to 1973 Sep.; these spectra show a
normal A3 spectrum. The spectra imply that a strong shell was
recently ejected. Observations of the light curve should be made
to investigate a possible change in period.
A0535+26 AND HDE 245770
S. Rossiger, Sonneberg Observatory, reports that he and W.
Wenzel pointed out already in 1974 that the B0pe star HDE 245770, now a
possible candidate for the x-ray source A0535+26 (see IAUC 2780 and
2784), is a long-time-scale variable star (1974, Astron. Nach. 295,
47: star b). Rossiger observed this star photoelectrically between
1973 Feb. 14 and 1975 Mar. 22 on 35 nights. The mean UBV values are
as follows:
V = 8.95, B - V = +0.54, U - B = -0.51.
The observed amplitude in all three colors is smaller than 0m.15.
In contrast to these results F. Lenouvel and C. Flogere found in 1956
Mar. (1957, J. des Obs. 40, 37):
V = 9.37, B - V = +0.46, U - B = -0.53.
OBSERVATIONS OF COMETS
Mr. C. Torres, Department of Astronomy, University of Chile,
provides the following precise positions of comets Araya (1972 XII),
Cesco (1974e) and P/Forbes (1974a), obtained with the Maksutov
astrograph at the Cerro El Roble Station:
Comet 1974 UT R.A. (1950) Decl.
1972 XII Oct. 7.14434 22 02 11.62 -40 27 25.6
8.14463 22 01 25.91 -40 23 01.1
1974e Oct. 7.03045 16 12 22.08 -26 52 45.9
8.02415 16 12 38.66 -26 52 03.6
1974a Oct. 9.13590 23 12 45.18 - 9 02 42.0
10.12717 23 12 28.04 - 8 59 48.4
1975 June 17 (2790) Owen Gingerich
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