Unprecedented Optical Flare Continues in Blazar 1308+326, Reaching Historic Maximum Brightness
ATel #15474; Madeline L. Hulburt, Ha-Eun H. Choi, Norah Du, Thomas J. Balonek, Riley M. Corcoran, John J. Slater, Warner S. Neal, Chloe R. Malinowski, Matthew J. Sampson, Victor K. Unnone, James F. Heatherton, Jordan L. Tockstein (Colgate Univ., Hamilton, NY USA)
on 26 Jun 2022; 10:18 UT
Credential Certification: Thomas J. Balonek (tbalonek@colgate.edu)
Subjects: Optical, Blazar, Quasar
The blazar 1308+326 (B2 1308+326, OP +313, AU CVn) (z=0.996) has reached an historic maximum brightness of R ~13.2 on 2022 June 26 UT (JD 2459756) during the ongoing unprecedented optical flare (see ATel #15441, #15447, #15459). This current two-week-long, two magnitude flare is one of many several-week to month-long flares that have occurred during an extended optical outburst which began in 2018. Several flares in 2019 and 2020 during this outburst peaked around R ~15.0, with the most recent previous flare peaking at R ~14.6 on 2022 April 30.
We have done an extensive literature and web search for all optical measurements of this object, and to our knowledge the 2022 June 26 measurement is the brightest ever reported for 1308+326. Several optical flares in the late 1970s and early 1980s were observed primarily in B, but also in V and R. Their corresponding peak brightness in R is dependent on estimates of the B-R and V-R color indices, comparison stars used, and flux density to magnitude conversions. We estimate that the peak brightness of several flares in the 1976-1983 interval peaked between R ~13.5 and ~14.5.
The current outburst of 1308+326 began on 2022 June 14 (JD 2,459,744) when it was R ~ 15.2 (ATel #15441). The object has steadily brightened each night by an average of one-sixth of a magnitudes per day, corresponding to nearly two magnitudes in twelve days.
Our preliminary photometry of 1308+326 subsequent to our compilation presented in ATel #15441, using comparison star C (R = 13.28) of Smith et al (1985, AJ, 90, 1184), are presented below. We report only our first and last observations for each night. The average brightness is calculated from typically one dozen two-minute images taken in a sequence lasting about half-an-hour.
2022-06-20.10 UT (JD 2,459,750.60) R = 14.45 ± 0.02
2022-06-20.24 UT (JD 2,459,750.74) R = 14.42 ± 0.03
2022-06-21.09 UT (JD 2,459,751.59) R = 14.17 ± 0.02
2022-06-21.26 UT (JD 2,459,751.76) R = 14.12 ± 0.02
2022-06-22.10 UT (JD 2,459,752.60) R = 14.10 ± 0.02
2022-06-22.27 UT (JD 2,459,752.77) R = 14.07 ± 0.04
2022-06-24.11 UT (JD 2,459,754.61) R = 13.52 ± 0.02
2022-06-25.10 UT (JD 2,459,755.60) R = 13.44 ± 0.02
2022-06-25.24 UT (JD 2,459,755.74) R = 13.40 ± 0.03
2022-06-26.10 UT (JD 2,459,756.60) R = 13.26 ± 0.02
2022-06-26.24 UT (JD 2,459,756.74) R = 13.28 ± 0.03
We are aware that other observers use R = 13.20 for comparison star C (in which case our measurement on 2022 June 26.10 would correspond to R = 13.18). We continue to report our measurements using the comparison star C magnitude R = 13.28 to be on the same scale as our previously reported ATel observations.
Observations were obtained with the Colgate University Foggy Bottom Observatory (Hamilton, NY USA) 0.4-m Ferson telescope equipped with an FLI PL1001 CCD camera. Student research participation at Colgate University has been supported by the NASA / New York Space Grant, the Justus '43 and Jayne Schlicting Student Research Fund, and the Colgate University Division of Natural Science and Mathematics.
We encourage multi-wavelength observations of these outbursts.
