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X-ray detection of the old nova DK Lacertae

ATel #8610; S. F. Boardman (Commonwealth School and CfA), D. Takei (RIKEN), J. J. Drake (CfA), T. Sakamoto (AGU), A. Fruscione (CfA)
on 29 Jan 2016; 21:52 UT
Credential Certification: Jeremy J. Drake (jdrake@cfa.harvard.edu)

Subjects: X-ray, Cataclysmic Variable, Nova, Variables

We report the detection of the old nova DK Lacertae with Chandra X-Ray Observatory's ACIS-S CCD imaging spectrometer on 3 February 2015. DK Lacertae, located at (J2000) 22:49:46.970 +53:17:19.66, was discovered in 1950 at a brightness of 6 mag (Bertaud, C., 1950, IAUC, 1254, 1). Chandra detected 92.5 +/- 9.6 net counts from the source at a count rate of 0.0306 +/- 0.0032 c/s over an exposure time of 3025.6 s. No significant variability was observed during the length of the observation. With 90% statistical confidence, the size of the source indicates that it is point-like. No evidence for extended emission was found. Best-fit X-ray spectral model parameters were a temperature of kT > 91 keV and an interstellar hydrogen column density of nH = 3.5 +/- 0.52x10^21 cm^-2 for an APEC thermal plasma model and gamma = 0.92 +/- 1.3 and nH <= 3.4x10^21 cm^-2 for a power law model. The flux for the bandpass 0.5-7 keV was 4.23E-13 +/- 7.3E-14 erg/cm2/s. The hardness of the X-ray spectrum suggests the presence of non-thermal emission.