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Optical Outbursts from SDSS J113551.09+532246.2 and SDSS J120231+450349

ATel #787; R. Quimby and P. Mondol (U. Texas)
on 31 Mar 2006; 22:51 UT
Credential Certification: Robert Quimby (quimby@astro.as.utexas.edu)

Subjects: Optical, Cataclysmic Variable, Transient

We report the discoveries of two optical transients found in unfiltered CCD images taken by the 0.45m ROTSE-IIIb telescope at the McDonald Observatory. The first object was detected on 2006 March 24.40 UT (about 15.1 mag) at RA = 11h35m51.12s, DEC = +53o22'46.1" (J2000; uncertainty +/- 0.5"). This position matches the source SDSS J113551.09+532246.2, observed in quiescence by Sloan at r= 20.71. This object was not detected by ROTSE-IIIb on Mar. 22.14 (limiting mag about 16.9), nor on a co-addition of images taken between 2005 Apr. 12 and 2006 Feb 4 (limiting mag about 18.4). The object was about 15.2 mag on Mar 25.13, and then faded to about 15.8 mag on Mar. 26.1. The object was not detected in ROTSE-IIIb images taken on Mar. 30.12 (limiting mag 16.7) nor on Mar. 31.23 (limiting mag 17.8). The object was also caught during outburst in the USNO B1.0 catalog (R2 = 15.05 mag). We tentatively classify SDSS J113551.09+532246.2 as a dwarf nova.

The second object was detected Mar. 21.15 (about 13.4 mag), and is located at RA = 12h02m30.99s, DEC = +45o03'48.7" (J2000; uncertainty +/- 0.5"). This source matches the known cataclysmic variable SDSS J120231+450349 (Szkody, P. et al. 2006, AJ, 131, 973), which is listed at r=19.92 mag. The object was not detected in ROTSE-IIIb images taken on Mar. 7.19 (limiting mag 17.5), and it has faded over the last 10 days (Mar. 25.15, 13.9 mag; Mar. 31.28, 14.8 mag).

Finding Chart for SDSS J113551.09+532246.2

Finding Chart for SDSS J120231+450349