LAST optical observations of the blazar BL Lacertae in bright optical state
ATel #16865; S. Garrappa (WIS), R. Konno (WIS), E. O. Ofek (WIS), S. Ben-Ami (WIS), D. Polishook (WIS), P. Chen (WIS), A. Gal-Yam (WIS), A. Krassilchtchikov (WIS), K. Rybicki (WIS), E. Segre (WIS), Y. M. Shani (WIS) and S. Spitzer (WIS) and on behalf of the LAST Collaboration
on 13 Oct 2024; 21:46 UT
Credential Certification: Simone Garrappa (simone.garrappa@gmail.com)
Subjects: Optical, Blazar
We report the observations of the blazar BL Lacertae at redshift z = 0.0686 (Vermeulen et al. 1995, ApJ, 452, L5) with the Large Array Survey Telescope (LAST, Ofek et al. 2023; Ben-Ami et al. 2023). The source was recently reported showing a bright outburst in the optical band (ATel#16806, ATel#16810, ATel#16830, ATel#16856), as well as in X-rays (ATel#16855), gamma-rays (ATel#16849) and VHE gamma-rays (ATel#16850,ATel#16854,ATel#16861).
We observed the source with no filter (clear) in multiple visits during the nights of 08-10-2024 and 10-10-2024. The reported magnitudes are in the LAST native AB system, calibrated relative to the GAIA-DR3 Bp band (i.e., color term was fitted and the source color was assumed to be Bp-Rp=1 mag).
From a preliminary analysis of the two nights, the brightest and faintest states for each night have been observed at:
Night: 08-10-2024
MJD = 60591.875 M = 13.74 +/- 0.02
MJD = 60591.746 M = 13.88 +/- 0.02
Night: 10-10-2024
MJD = 60593.752 M = 13.65 +/- 0.02
MJD = 60593.907 M = 13.92 +/- 0.02
The average color term for the observations is 0.96. All errors include statistical and calibration errors (of about 0.015 mag).
During these two nights, we observe significant variability of the source at time-scales of ~15 minutes. We encourage the monitoring of the source during this extended flaring activity.
LAST is a survey telescope array of the Weizmann Astrophysical Observatory (https://www.weizmann.ac.il/wao/).
