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IAUC 5148: 1990ag; X-RAY TRANSIENTS NEAR MX 0836-42; 1990i

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                                                  Circular No. 5148
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

     A. V. Filippenko, University of California at Berkeley (UCB),
reports:  "M. Dickinson (UCB) obtained a CCD spectrum (range 400-800
nm, resolution 2 nm) of SN 1990ag (cf. IAUC 5141) on Dec. 14 UT with
the Shane 3-m reflector at Lick Observatory.  The object is probably
a peculiar type-II supernova, with strong, very narrow H-alpha
emission and weaker H-beta emission on an otherwise nearly featureless
continuum.  A CCD spectrum (range 610-690 nm, resolution 0.3 nm)
obtained by Filippenko with the Shane reflector on Dec. 17 reveals a
double-peaked H-alpha profile, with FWHM = 600-700 km/s and a separation
of about 300 km/s between the peaks.  The redshift of the host
galaxy is roughly 0.054."

     F. Makino and the Ginga Team, Institute of Space and Astronautical
Science, telex:  "Two transient x-ray sources near MX 0836-42
(IAUC 5139, 5142) were observed individually with the Large Area
Proportional Counters (LAC) aboard Ginga by off-axis pointing.  The
observations of GS 0836-429 and GS 0834-430 were conducted during
Dec. 13.5-14.5 and 14.5-16.3 UT, respectively.  A typical type-1 x-
ray burst, similar to those observed on Nov. 27 and 28, was detected
on Dec. 14.106 from GS 0836-429, possibly identical to MX 0836-42
and the ROSAT northern source; but no pulsation was observed from
this source.  The pulsation at apparent heliocentric period of
12.3278 +/- 0.0003 s (at Dec. 14.929) was observed from the sky
region including GS 0834-430, the ROSAT southern source, and GRS
0831-429.  The full amplitude of the pulse was about 13 percent of
non-pulse component.  The x-ray flux of both sources were roughly 30
mCrab and both spectra were of hard power-law type.  Our previous
conclusion (IAUC 5139) was confirmed."

     Total visual magnitude estimates (cf. IAUC 5134):  Nov. 22.77
UT, 7.0 (M. Ohkuma, Shirahama, Japan, 7x50 binoculars); 24.49, 7.4
(C. S. Morris, Pine Mountain Club, CA, 20x80 binoculars); 27.51, 7.6
(A. Hale, Las Cruces, NM, 10x50 binoculars); Dec. 10.33, 8.3 (Hale);
17.81, 8.7 (A. Pearce, Scarborough, W.A., 20x80 binoculars).

1990 December 18               (5148)             Daniel W. E. Green

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