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ATEL # 1878; Marina Orio (INAF-Padova & U Wisconsin), F. Di Mille, A. Bianchini & S. Ciroi (U Padova)
on 17 Dec 2008; 4:24 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Marina Orio (email@example.com)
The WZ Sge-type optical transient M31N2008-11b (K. Itagaki, CBET# 1588) was observed with the Swift X-ray telescope for a total exposure time of 2872 seconds on December 12, 2008 and it was not detected, with a 3 signa upper limit to the Swift XRT PC count rate of 0.0007 cts s(-1), and an upper limit of the unabsorbed flux approximately 3x10(-14) erg/cm^2/s. If the object had the same optical to X-ray luminosity ratio in outburst as WZ Sge, it should have been detected with an approximate Swift XRT PC count rate of 0.11 cts/s. It is therefore more than a factor of 100 intrinsically less X-ray bright in outburst than WZ Sge at the same post-outburst epoch, although it has many other characteristics in common with WZ Sge.