Central Bureau for Astronomical Telegrams
IAUC 6184: GRO J1629-49; EXO 053109-6609.2
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Circular No. 6184
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
Phone 617-495-7244/7440/7444 (for emergency use only)
GRO J1629-49
D. J. McKay, M. H. Wieringa, and N. P. F. McKay, The Australia
Telescope (AT) National Facility, CSIRO, report the results of AT
Compact Array observations of the area of the gamma-ray outburst
reported on IAUC 6182: "Observations on July 6.2, 6.6, and 7.2 UT
at frequencies 1380, 2378, 4800, and 8640 MHz indicate that there
is no new bright radio source in the field. We have remeasured the
source PMN J1628-4936 (nominated in IAUC 6182 as a possible radio
counterpart): flux-density = 1.2 +/- 0.1 Jy at all but 8640 MHz,
where it is strongly resolved; R.A. = 16h28m57s.8 +/- 0s.2, Decl. =
-49o36'26".4 +/- 1".0 (equinox 2000.0); angular size 15". This
source is also identified with a source catalogued in 1979 as an H
II region (G334.714) and with IRAS 16251-4929. On the basis of
this information, we believe that the PMN object is an H II region
not identified with the gamma-ray object. We detect no radio
source at the optical position reported by McNaught (IAUC 6183) to
a limit of 10 mJy at 2378 MHz on July 6.2 and 6.6."
R. H. McNaught now retracts his note on IAUC 6183, saying that
his optical candidate for GRO J1629-49 is present on the SERC I
survey (but not the ESO R). G. Garradd further reports that
inspection of a UKST film taken on July 7 UT by K. S. Russell shows
nothing new that is obvious down to mag about 15, using the I
survey photograph as a comparison; he looked a further 0.5 deg
outward from McNaught's original search area.
EXO 053109-6609.2
K. Dennerl, F. Haberl, and W. Pietsch, Max-Planck-Institut fur
Extraterrestrische Physik, Garching, communicate: "We report the
discovery of coherent 13.7-s pulsations from EXO 053109-6609.2, a
Be transient in the Large Magellanic Cloud, with the ROSAT Position
Sensitive Proportional Counter (PSPC). The pulsations are present
in several observations covering intrinsic source luminosities from
1 x 10E35 to 3 x 10E36 erg sE-1 (E = 0.1-2.4 keV). We determined a
barycentric pulse period of 13.67133 +/- 0.00005 s at 1991 Oct.
31.158 UT and a rate of period change of (+1.5 +/- 0.1) x 10E-8
during 3.3 days, which exceeds the long-term trend by at least one
order of magnitude. Under the assumption that the observed period
change is predominantly caused by orbital Doppler shifts, the
orbital period can be constrained to the range from 4 to 40 days,
with 25.4 days as the most probable value."
1995 July 7 (6184) Daniel W. E. Green
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