Intra-night optical activity of the blazar CTA 102 during its maximum state
ATel #9776; Velimir Popov (IRIDA Observatory, Rozhen, Bulgaria), Rumen Bachev (IA-NAO, BAS, Bulgaria)
on 21 Nov 2016; 11:25 UT
Credential Certification: Rumen Bachev (email@example.com)
Subjects: Optical, Blazar, Quasar
CTA 102 is known to experience violent outbursts in the optical, the latest of which happened just recently (ATel #9756, ATel #9732). Following these reports we observed this object for four nights (17.11.2016 - 20.11.2016) in a search for intra-night variability. The instrument we used was the 30 cm reflector (Ritchey Chretien Astrograph) of IRIDA observatory, Rozhen, Bulgaria, equipped with a CCD and SLOAN g' r' i' filters. The object was monitored typically between 2 and 4.5 hours each night in 2 or 3 bands quasi-simultaneously. During each of these nights CTA 102 showed significant variations of 0.15 - 0.4 mag for the time of monitoring (with typical photometric errors of less than 0.02 mag). For the night of Nov 17, CTA 102 showed a spectacular decline of about 0.4 mag within 2 hours starting from a maximum of g'=13.6. During the next two nights rapid changes were observed between g'=14.3 and 14.5 mag. A short lasting 0.15 mag sharp peak, reaching g'=14.0 was observed in the night of Nov 20.
Clearly the object is still in a very active state and further observations are encouraged.