[vsnet-outburst 23405] SDSS J080710.33+485259.6 (ATEL)

[Taichi Kato]

The Astronomer's Telegram                   http://www.astronomerstelegram.org

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ATEL #12558                                                          ATEL #12558

Title:  Detection of a photometric period during outburst in the AMCVn
                binary SDSS J080710.33+485259.6
Author: Thomas Kupfer (University of California, Santa Barbara), Elme
                Breedt (University of Cambridge), Gavin Ramsay (Armagh Observato
ry),
                Simon Hodgkin (University of Cambridge), Tom Marsh (University o
f
                Warwick)
Queries:        tkupfer at ucsb.edu
Posted: 7 Mar 2019; 23:04 UT
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.