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Circular No. 7867 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) XTE J1751-305 C. B. Markwardt, University of Maryland and Goddard Space Flight Center (GSFC); and J. H. Swank, GSFC, report that RXTE PCA monitoring observations of the galactic-center region on Apr. 3.6 UT revealed a new millisecond pulsar, designated XTE J1751-305. The best fitting source position is R.A. = 17h51m.5, Decl. = -30o30' (equinox 2000.0), with an estimated position uncertainty of about 5', due to nearby confusing sources (see item by in 't Zand et al., below). In the first 200 s of a pointed RXTE PCA observation on Apr. 4.65, x-ray pulsations were detected (with 10-sigma significance) at a barycentered frequency of 435.313 Hz +/- 0.005 Hz. The r.m.s. pulsed amplitude in the band 2-10 keV was 2.5 percent. The approximate 2-10-keV x-ray fluxes on Apr. 3.6 and 4.6 were 55 +/- 1 and 60 +/- 2 mCrab, respectively. More observations by RXTE are scheduled. This is only the second accretion-powered millisecond pulsar. Further observations at other wavelengths are encouraged. J. J. M. in 't Zand, Astronomical Institute, Utrecht University, and Space Research Organization Netherlands (SRON); P. Lowes, SRON and BeppoSAX Science Operation Center, Rome; J. Heise, SRON; and A. Bazzano and P. Ubertini, Istituto di Astrofisica Spaziale e Fisica Cosmica, Rome, report that XTE J1751-305 was detected in a BeppoSAX Wide Field Camera observation during Apr. 4.3-4.6 UT at a flux of 52 +/- 3 mCrab (2-28 keV) and localized at R.A. = 17h51m16s, Decl. = -30o37'.5 (equinox 2000.0; uncertainty 1'.2, 99-percent confidence). No systematic flux trends were observed at more than the 10-percent sensitivity, and no x-ray bursts were detected. SUPERNOVA 2002br IN MCG +03-27-61 T. Matheson, S. Jha, P. Challis, and R. Kirshner, Harvard- Smithsonian Center for Astrophysics, report that a spectrum (range 370-750 nm) of SN 2002br (cf. IAUC 7853), obtained by M. Calkins on Mar. 15.25 UT with the F. L. Whipple Observatory 1.5-m telescope (+ FAST spectrograph), shows it to be a normal type-Ia supernova about a week after maximum. Adopting the NASA/IPAC Extragalactic Database recession velocity of 10 248 km/s for the host galaxy, the supernova expansion velocity is about 10 200 km/s for Si II (rest 635.5 nm) and 13 200 km/s for Ca II (rest 395.1 nm). (C) Copyright 2002 CBAT 2002 April 4 (7867) Daniel W. E. Green
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