Central Bureau for Astronomical Telegrams
IAUC 7925: 4U 1543-47; NEW TRANSITS FROM THE OGLE-III SURVEY
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 7926
.dvi or
.ps format.
Circular No. 7925
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)
4U 1543-47
R. W. Hunstead and J. Webb, University of Sydney, report the
detection of a radio counterpart of the x-ray transient 4U 1543-47
(IAUC 7920). A 12-hr integration with the Molonglo Observatory
Synthesis Telescope on June 18.50 UT (mid-exposure) yielded a
preliminary 843-MHz flux density of 11 +/- 1.5 mJy, coincident with
the optical position. No source was seen at this position in an
archival 1998 observation with a similar noise level.
NEW TRANSITS FROM THE OGLE-III SURVEY
A. Udalski, Warsaw University Observatory, on behalf of the
OGLE-III survey team, writes that photometric data collected during
the 2001 OGLE planetary/low-luminosity object transit campaign
(Udalski et al. 2002, Acta Astron. 52, 1), whereby smaller objects
are thought to be transiting across stars, have been reanalyzed
for transits with the BLS method (Kovacs et al. 2002,
http://xxx.lanl.gov/abs/astro-ph/?0206099). Thirteen additional
transit objects were detected, increasing the total number found to
59. The list of new transit objects is available from the OGLE
Internet archive (http://www.astrouw.edu.pl/~ogle;
http://bulge.princeton.edu/~ogle). The shapes of the transit light
curves indicate a few new Jupiter-sized objects (R < 1.6R_J). The
most intriguing case is OGLE-TR-56 (R.A. = 17h56m35s.51, Decl. =
-29o32'21".2, equinox 2000.0; I = 15.3, V-I = +1.3). Its transit
has a depth of only 0.013 mag and a short orbital period of 1.21192
days (based on ten individual transits). A model transit fit to
the data indicates the size of the transiting object to be 0.7R_J
if the passage were central (i = 90 deg); i.e., it may be less than
Saturn-sized. If confirmed spectroscopically to be a planet, it
would have the shortest period and would be one of the smallest
extrasolar planets (a 'hot' Saturn). Spectroscopic follow-up
observations are encouraged. Just two radial-velocity measurements
with an accuracy of about 0.5 km/s, taken at phases near 0.25 and
0.75, should place a transiting object in the planetary mass range,
if no variation is found. One of the most promising planetary
transit candidates discovered during the 2001 campaign, OGLE-TR-40,
was monitored with the 1.3-m OGLE telescope at Las Campanas
Observatory for the expected transit, and a 0.025-mag drop
in brightness (corresponding to the transit) was detected on 2002
June 15.335 UT, about 3 hr earlier than predicted from 2001 data.
Timing of the transit allows a refinement of the ephemeris, based
now on more than 100 cycles: HJD_min = 2452060.03543 + 3.43077E.
(C) Copyright 2002 CBAT
2002 June 20 (7925) Daniel W. E. Green
Read IAUC 7926
.dvi or
.ps format.
Our Web policy. Index to the CBAT/MPC/ICQ pages.
