Detection of a photometric period during outburst in the AMCVn binary SDSS J080710.33+485259.6
ATel #12558; Thomas Kupfer (University of California, Santa Barbara), Elme Breedt (University of Cambridge), Gavin Ramsay (Armagh Observatory), Simon Hodgkin (University of Cambridge), Tom Marsh (University of Warwick)
on 7 Mar 2019; 23:04 UT
Credential Certification: Thomas Kupfer (tkupfer@caltech.edu)
Subjects: Optical, Cataclysmic Variable, Transient
We report the detection of a photometric modulation of 53.3+/-0.3mins in the known AMCVn binary SDSS J080710.33+485259.6, discovered by Kong et al. 2018 (PASP, 130, 4203). At this long period for AMCVn dwarf novae, SDSS J080710.33+485259.6 is the longest period outbursting AMCVn known. Observations were made with the LCO 2m telescope on Haleakala on March 1 07:17 - 8:40 UT and 10:11 - 11:34 UT. A total of 280 exposures with an exposure time of 20sec were taken in g'. The object was ~19 mag at the time of observations, about 1.5 mag above quiescence (g'= 20.39 mag).
The outburst was first detected by Gaia Alerts on Feb 26 2019 when the object reached a brightness of G=18.51. It was given the alert identifier Gaia19atk. It was however detected at about 1 magnitude above its quiescent brightness on Nov 24 2018 as well, at G=19.78. Earlier observations by the Catalina Real-time Transient Survey show similar variability, with occasional detections at around 1 magnitude above quiescence. No large amplitude outbursts have been observed.
On March 6 at 9:40 UT we observed the object again in g' and r' using again the LCO 2m telescope on Haleakala with an exposure time of 60 sec. Conditions were poor but SDSS J080710.33+485259.6 was detected in the r band image indicating it was still brighter than in its quiescent state. Further monitoring is encouraged to see if the object brightens again.
This work makes use of observations from the Las Cumbres Observatory (LCO) network.
