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ATEL # 2998; P.C. Schmidtke (Arizona State University), A.P. Cowley (Arizona State University)
on 1 Nov 2010; 21:51 UT
Password Certification: Paul Schmidtke (Paul.Schmidtke@asu.edu)
Subjects: Optical, X-ray, Binaries, Neutron Stars, Pulsars, Variables
A tentative X-ray pulsar, with a 4693 s pulse period, was found in Chandra data of the SMC by Laycock et al. (2010, ApJ, 716, 1217). They proposed the optical counterpart is emission-line star [MA93] 798 (Meyssonnier & Azzopardi 1993, A&AS, 102, 451). We have identified this star with entries smc_sc7_i_70843 in OGLE-II and 207.16259.37 in MACHO online databases. The light curves show a slow, gradual brightening, with very small scatter. Period analysis reveals no evidence for an orbital period, but weak pulsations at P=0.730 days are present in both data sets. Such periodic signatures are often seen in Be stars, including Be/X-ray pulsars.