GRB 210218A: MITSuME Akeno optical upper limits
Abstract
We observed the field of GRB 210218A (Sbarufatti et al. GCN #29529, Zhu et al. GCN #29530, Xin et al. GCN #29531) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation with a series of 10 sec exposures started at 2021-02-18 13:36:05 UT(46 seconds after the Swift BAT trigger). We stacked the images with good conditions. We did not find any new point sources within the Swift BAT circle (Sbarufatti et al. GCN #29529) in all three bands. We obtained the 5-sigma limits of the stacked images as follows. T0+[sec] MID-UT T-EXP[sec] 5-sigma limits ------------------------------------------------------------------------------------------------ 46 14:03:01 1220 g'>17.3, Rc>17.5, Ic>16.7 ------------------------------------------------------------------------------------------------ T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used the UCAC4 catalog for flux calibration. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
- Publication:
-
GRB Coordinates Network
- Pub Date:
- February 2021
- Bibcode:
- 2021GCN.29532....1O