Central Bureau for Astronomical Telegrams
IAUC 3230: OPTICAL BURSTS FROM MXB1735-44; 1978a
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Read IAUC 3231
Circular No. 3230
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 Telex: 921428
Telephone: (617) 864-5758
OPTICAL BURSTS FROM MXB1735-44
J. Grindlay, Center for Astrophysics; and J. McClintock, C.
Canizares and J. van Paradijs, Massachusetts Institute of Technology,
report the detection of optical bursts from the x-ray burst
source MXB1735-44. Two optical bursts were detected on June 2 UT
with the 150-cm telescope at Cerro Tololo Interamerican Observatory
using a high-quantum-efficiency photometer (C31034), broad-band
(3100-5500 A) CuSO4 filter and 10" diaphragm centered on the optical
counterpart (McClintock et al. 1977, Nature 270, 320) of the
associated steady x-ray source 4U 1735-44. Both optical bursts were
detected as significant (5-6 sigma) ~ 50-percent increases in the source
count rate with ~ 1-2 s risetimes and decay over the next ~ 5 s.
SAS-3 data were not recorded for the first optical burst, but
simultaneous x-ray data from the SAS-3 Observatory for the second
optical burst show a coincident (within ~ 0.5 s) x-ray burst with very
similar risetime and duration. The ratio of optical to x-ray energy
flux in the burst was 2 x 10**-5, which is ~ 10 times smaller than
for the steady source. A much smaller x-ray burst without detectable
optical emission was recorded ~ 2 hr later by SAS 3.
Optical observers who can make optical observations of the
four optically identified burst sources (IAUC 2824, 3084, 3088 and
3229) are urged to contact W. Lewin (telephone 617-253-4282, telex
921473) for possible simultaneous x-ray observations with SAS 3.
COMET WEST (1978a)
Ephemeris continuation from the orbit on IAUC 3199:
1978 ET R. A. (1950) Decl. Delta r m1
June 11 13 17.87 + 8 05.3
21 13 14.68 + 8 51.3 5.776 6.107 17.2
July 1 13 12.63 + 9 27.1
11 13 11.69 + 9 54.0 6.172 6.165 17.4
21 13 11.77 +10 13.6
31 13 12.76 +10 27.3 6.556 6.225 17.5
Aug. 10 13 14.58 +10 36.6
20 13 17.12 +10 42.9 6.895 6.288 17.7
30 13 20.26 +10 47.4
Sept. 9 13 23.92 +10 51.2 7.160 6.353 17.8
m1 = 5.5 + 5 log Delta + 10 log r
1978 June 15 (3230) Brian G. Marsden
Read IAUC 3231
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