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Optical counterpart and a probable pulse period in IGR J01054-7253

ATEL # 2088; Coe M.J. (Southampton University), Bird A.J (Southampton), McBride V.A. (Southampton), Townsend L.J. (Southampton), Corbet R.H.D. (NASA/GSFC), Udalski A. (Warsaw University)
on 18 Jun 2009; 9:29 UT
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Password Certification: Malcolm Coe (

Subjects: Optical, X-ray, Binaries, Neutron Stars, Pulsars

The new Integral source, IGR J01054-7253, in the SMC (see ATEL 2079) has been observed by the Swift Observatory on 17 June 2009. These observations reveal an accurate position for this source of RA 01:04:41.41 Dec -72:54:04.6 (2000) with a 3.6 arcsec error circle. This position lies within 3.5 arcsec of the V=14.8 star [M2002] SMC 59977. Furthermore, OGLE III data of this object reveal a very variable object in the I band, showing outbursts of ~0.8 mag lasting about 1 year, typical of Be stars in the SMC. No periodicity is apparent in the optical data. The Swift data were taken in four segments of ~1ks each and three of the four segments show evidence for a periodicity at 17.49s, particularly the last one. Combining these three segments supports such a period at the 99.7% confidence level and the folded lightcurve reveals a single-peaked sinusoidal pulse profile. Follow-up observations by RXTE are scheduled to verify this result. Thus we propose that IGR J01054-7253 is a new High Mass X-ray Binary in the SMC. We are grateful to the prompt response of Swift in helping us identify this new source.

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