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Possible Swift-UVOT optical counterpart for IGR J17098-3628

ATel #479; A. J. Blustin (MSSL-UCL), A. K. H. Kong (MIT), K. Wu, C. Brocksopp, K. McGowan (MSSL-UCL), J. A. Kennea, P. Roming, J. A. Nousek (PSU), K. O. Mason (MSSL-UCL), N. Gehrels (GSFC) on behalf of the Swift-UVOT team
on 3 May 2005; 21:45 UT
Credential Certification: Alexander J. Blustin (ajb@mssl.ucl.ac.uk)

Subjects: Infra-Red, Optical, X-ray, Binary, Black Hole, Neutron Star, Transient

Referred to by ATel #: 490

The X-ray transient IGR J17098-3628, discovered by INTEGRAL (ATEL #444), was observed by Swift on May 1st from 16:23 UTC until 18:19 UTC. It was detected in soft X-rays by the Swift-XRT (ATEL #476), and possible optical/IR counterparts, associated with 2MASS J17094612-3627573, have been identified from the 2MASS All-Sky Catalogue, SuperCOSMOS Sky Survey (ATEL #477) and new observations with the Magellan-Baade telescope (ATEL #478).

During the May 1st Swift observation, the UV/Optical telescope (UVOT) obtained a total of 2443 s exposure time through the V filter. In an image generated from all of these data coadded, we detect a 19.3 +/- 0.1 magnitude source within the 5 arcsecond XRT error circle at R.A.=17h09m46.161s, Decl.=-36d27m58.05s, apparently identical with the possible SuperCOSMOS optical candidate at R.A.=17h9m46.166s and Decl.=-36d27m57.50s.

An image of the Swift-UVOT source is available at http://www.mssl.ucl.ac.uk/twiki/bin/view/SwiftBA/IGRJ17098-3628 .

As reported in the SuperCOSMOS Sky Survey, the B and R magnitudes of this source (or group of sources combined, as reported in ATEL #478) are 21.16 and 19.43 respectively. The observed UVOT V magnitude of 19.3 may imply that the optical transient has brightened; further observations are recommended to establish whether this is the case.

The Swift-UVOT magnitude is based on a preliminary zero-point, measured in orbit, and will require refinement with further calibration.