Detection and Photometry of the Optical Afterglow of the Gamma-Ray Burst GRB180914B
ATel #12053; J. Vinko, K. Sarneczky and R. Szakats (Konkoly Observatory)
on 20 Sep 2018; 18:17 UT
Credential Certification: Jozsef Vinko (vinko@astro.as.utexas.edu)
Subjects: Optical, Gamma-Ray Burst, Transient
The optical afterglow of the recently discovered bright Gamma-Ray Burst GRB180914B (GCN 23226, 23231, 23232, 23234) was detected on stacked 3 x 300 sec CCD frames taken with the 0.6/0.9m Schmidt telescope through BVRI filters on 2018-09-18.94 UT (4.18 days after the initial burst in the observer frame).
The source is clearly present on multiple frames at R.A.=22:09:25.55, Decl.=+25:03:43.90
(Zheng & Filippenko, GCN 23236). Aperture photometry, tied to nearby PS1 stars, gives the following AB-magnitudes for the afterglow:
B = 21.29 +/- 0.28, V = 20.78 +/- 0.19, R = 21.01 +/- 0.15, I = 20.30 +/- 0.18
Compared to earlier optical detections (GCN 23236, 23237, 23238, 23239, 23240, 23241, 23243, 23244, 23245, 23246, 23249, 23250, 23251, 23252, 23253, 23255, 23256) the source is fading rapidly, in accord with the recent analysis by Kahn et al. (GCN 23256).
