Central Bureau for Astronomical Telegrams
IAUC 5165: N Mus 1991 (X-RAY TRANSIENT IN MUSCA); 1991b
The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).
Read IAUC 5166
Circular No. 5165
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
NOVA MUSCAE 1991 (X-RAY TRANSIENT IN MUSCA)
R. M. West, European Southern Observatory, reports: "M. Della
Valle and B. Jarvis (ESO, La Silla) have found the probable optical
counterpart of GRS 1121-68 (IAUC 5161) at mag about 17-18, near the
edge of the Ginga error box, on a 90-min IIIa-J + GG385 plate taken
by G. Pizarro on Jan. 13.25 UT with the 1-m Schmidt telescope. The
new object is also visible on a Schmidt plate (45-min exposure) taken
Jan. 12.3. On a CCD frame obtained with the 2.2-m telescope on
Jan. 15.1, the star was estimated as somewhat brighter, at V about
14.5. Calibrated CCD frames, obtained by Della Valle and Jarvis
with the ESO 3.5-m New Technology Telescope and EMMI on Jan. 15.3
(0".94 seeing), indicate a possible further brightening: V = 13.40
+/- 0.03, B-V = +0.25; V-R = -1.04. Two 3-min EMMI spectral exposures
(resolution about 0.8 nm, S/N about 110) show a quasi-featureless
continuum, particularly strong below 600 nm; there is possibly
a narrow H-alpha emission. On one of the NTT frames (5 s in R),
transmitted this morning to ESO-Garching, I measured the following
position of the starlike object (transfer by 14 secondary PPM-standards
from a 2-hr ESO Schmidt plate; estimated accuracy +/- 0".2 in
both coordinates): R.A. = 11h24m18s.49; Decl. = -68 24'01".7 (equinox
1950.0). Inspection of the best ESO (R) Schmidt plates (epochs
1984 Jan. 29 and Feb. 22) shows the probable progenitor near the
plate limit (R about 21.5); this star is somewhat better visible at
the SRC (J) plate (1976 Apr. 3) at J about 21 and barely visible on
the ESO (B) plate (1976 Feb. 2) at about the same magnitude; it was
therefore blue. The position, measured on the SRC (J) plate, is R.A.
= 11h24m18s.51; Decl. = -68 24'01".9; the offsets are 0".14 and
0".19, respectively. It is concluded that the object is likely to
be a galactic nova, which has so far brightened by about 7.5 mag and
may still be rising. Ground- and space-based observations,
especially spectroscopic, are urged."
COMET ARAI (1991b)
Total visual magnitude estimates (cf. IAUC 5158): Jan. 9.67 UT,
9.8 (M. Okhuma, Doudaira, Saitama, Japan, 0.16-m reflector); 10.56,
9.8 (T. Yusa, Yoneyama-cho, Miyagi, Japan, 0.15-m reflector); 13.27,
10.0 (C. S. Morris, Pine Mountain Club, CA, 0.26-m reflector).
1991 January 15 (5165) Daniel W. E. Green
Read IAUC 5166
Our Web policy. Index to the CBAT/MPC/ICQ pages.
