Central Bureau for Astronomical Telegrams
IAUC 2922: X-RAY BURSTS; 1975j
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 2923
Circular No. 2922
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
X-RAY BURSTS
The following coninunications are from the SAS-3 Group,
Massachusetts Institute of Technology:
W. H. G. Lewin reports the discovery of a rapid, repetitive x-ray
burst source, designated MXB1730-335, at the position: R.A. =
17h30m25s +/- 30s, Decl. = -33o29'+/- 12' (equinox 1950.0; l = 354o.78, b =
-0o.29). The bursts were observed between Mar. 1.9 and 4.6 UT.
They typically have risetimes of less than 1s, and they last for a
few seconds (small bursts) to ~ 50s (giant bursts). The time from
one burst to the next is approximately linearly proportional to the
energy in the first burst. The smallest bursts are separated by
15s. Giant bursts are separated by ~ 5-10 min. Between the
appearance of two giant bursts there are in general 5 to 20 smaller
bursts. The bursts are detected from 1 to 18 keV. The peak intensity
of the giant bursts is comparable to the x-ray intensity of
the Crab Nebula. The source behaved differently near Mar. 2.6 UT,
when the bursts were weaker, their risetimes were much longer (~
10s), and the repetition rate was down to one burst per 1-5 min.
This region of the sky was also observed by SAS-3 during Feb. 1.7-4.8
UT; no burst trains were observed at that time.
G. Clark reports: "We have found evidence of regularities in
the occurrence times of 25 brief intense x-ray bursts detected between
Jan. 26 and Feb. 10 during intermittent observations of the
region around the galactic center. The region includes the two new
burst sources recently reported (IAUC 2918) and now designated
MXB1743-293 and MXB1742-297. Twelve bursts that may have come from
MXB1742-297 have an apparent period of 0d.55 with a phase jitter of
3.2 percent. Of the remaining bursts, eight that may have come
from MXB1743-293 have an apparent period of 1d.46 with a phase jitter
of 6.2 percent. Seven of the 25 bursts show a distinctive
double-peak structure. Six of these are among the eight with the
1d.46 period."
W. H. G. Lewin reports the discovery of another source, MXB
1728-34, near R.A. = 17h28m, Decl. = -33o.9 (l = 354o.1, b = -0o.1). The
radius of the error circle is 0o.3, and the region includes the x-ray
source 3U 1727-33. Four bursts were observed, near Mar.
2d20h17m, 3d01h30m, 3d10h56m and 4d01h09m UT. Taking earth occultation
into account, the data are consistent with an average time
separation of ~ 4h.8 between bursts. All bursts have risetimes of
less than 1s and decay times of ~ 10s. None of them shows a double
peak. The bursts are observed in the energy range 1-18 keV, and
the intensity at burst maximum is comparable to that of the Crab.
J. Doty reports: "A strong x-ray burst was observed on Mar.
1d10h34m30s UT from near R.A. = 7h.6, Decl. = -50o (l = 263o, b = -14o)
The radius of the error circle is 13o. There is no known globular
cluster in this area. The burst had a risetime of less than a few
seconds and lasted for ~ 15s."
COMET MORI-SATO-FUJIKAWA (1975j)
The following precise positions have been reported:
1975/76 UT R. A. (1950) Decl. m1 Observer
Oct. 29.14618 8 36 11.73 -14 30 32.9 Ferreri
29.17587 8 36 12.54 -14 32 12.5 "
Dec. 4.30209 8 25 08.39 -57 55 24.6 Torres
5.33438 8 23 03.12 -59 13 25.8 "
5.34306 8 23 02.69 -59 14 17.2 "
6.15877 8 21 15.03 -60 15 16.1 8.3 Debehogne
6.17782 8 21 12.43 -60 16 42.4 "
6.31910 8 20 52.37 -60 27 13.6 Torres
7.19205 8 18 45.01 -61 31 48.5 8.3 Debehogne
7.27931 8 18 31.38 -61 38 13.0 "
8.15193 8 16 11.78 -62 41 53.8 8.5 "
8.22603 8 15 59.01 -62 47 16.4 "
10.25381 8 09 40.36 -65 11 49.1 8.5 "
10.26074 8 09 38.86 -65 12 17.7 "
Feb. 4.83750 23 44 38.35 -67 56 28.0 Hers
8.79583 23 41 27.24 -66 37 27.8 "
18.76111 23 37 08.38 -63 48 07.0 "
W. Ferreri (Pino Torinese Observatory).
C. Torres (University of Chile, Cerro El Roble Station). 60' tail
northwestward on Dec. 4, 10' on Dec. 5 and 6.
H. Debehogne and R. R. de Freitas Mourao (National Observatory, Rio
de Janeiro). 25-cm astrograph. Measurer: Debehogne.
J. Hers (Randburg, near Johannesburg). 20-cm reflector.
Further total visual magnitude estimates: 1975 Dec. 9.48 UT, 8
(T. B. Tregaskis, Mount Eliza, Victoria, 15-cm reflector); 26.44,
8.7 (B. Nikolau, Palmerston North, New Zealand, 20-cm reflector);
27.42, 8.5 (A. F. Jones, Nelson, New Zealand, 4.5-cm finder; suspected
10' tail in p.a. 20o, 32-cm reflector); 1976 Jan. 2.42, 10
(S. McMillan, Brisbane, Queensland, 30-cm reflector); 5.41, 8.5
(Jones); 6.43, 9.0 (McMillan); 31.51, 8.9 (R. R. D. Austin, Mount
John Observatory, 15-cm reflector; 5' tail in p.a. 140o).
1976 March 5 (2922) Brian G. Marsden
Read IAUC 2923
Our Web policy. Index to the CBAT/MPC/ICQ pages.
