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Swift Observations of NGC 1313

ATEL # 1530; K. J. Perry, J. M. Miller (University of Michigan)
on 16 May 2008; 15:31 UT
Password Certification: Jon Miller (

Subjects: X-ray, Binaries, Black Holes

We report on three X-ray sources within the spiral galaxy NGC 1313, namely X-1, X-2, and SN 1978K. The sources X-1 and X-2 are well-known ultra-luminous X-ray sources (ULXs). Two separate observations were taken containing all three objects, occurring on 2006 June 21 and 2007 November 23. XSPEC version 11 was used to fit each of the sources using a phabs*power-law model along the 0.5-10.0 keV band. X-1 was found to have power-law indices of 1.8(1) and 1.9(4), and luminosities of 7.5(9) E+39 erg/s and 3.3(1) E+39 erg/sec. X-2 was found to have power-law indices of 2.6(7) and 2.0(8), and luminosities of 1.1(5) E+39 erg/s and 2(1) E+39 erg/sec. SN 1978k was found to have a power- law index of 2(1) and a luminosity of 8(4) E+38 erg/s. The distance to all three was assumed to be 3.7 Mpc, and 90 percent confidence errors are quoted. Thus, these short Swift monitoring observations have revealed statistically significant variability in X-1, but were not sensitive enough to detect significant variability in X-2.

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