GCN Circular 31442

Amit Kumar, Rahul Gupta, Amit Ror, Ankur Ghosh, Dimple, Amar Aryan, Brajesh
Kumar, S. B. Pandey, and K. Misra (ARIES) report:

We further observed the optical afterglow of the Swift detected GRB 220101A
(Tohuvavohu et al., GCN 31347
Not found
 
 
) at z = 4.618 (Fu et al., GCN 31353
Not found
 
 
; Fynbo et
al., GCN 31359
Not found
 
 
) with the 1.3m Devsthal Fast Optical Telescope (DFOT) at
Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital
(India), from 2022-01-03 UT 12:54:68 to 2022-01-03 UT 15:04:14 (from ~55.75
to 57.91 hours after the burst). We obtained 40 frames each of 120 seconds
in Bessell R and I filters. We clearly detected the optical afterglow of
GRB 220101A in stacked frames within the Swift XRT enhanced error circle
(Tohuvavohu et al., GCN 31347
Not found
 
 
) as also reported by Kuin & Tohuvavohu, GCN
31351
Not found
 
 
; Fu et al., GCN 31353
Not found
 
 
; Hentunen et al., GCN 31356
Not found
 
 
; Perley, GCN 31357
Not found
 
 
;
de Ugarte Postigo et al., GCN 31358
Not found
 
 
; Fynbo et al., GCN 31359
Not found
 
 
; Vinko et al.,
GCN 31361
Not found
 
 
; Tomasella et al., GCN 31363
Not found
 
 
; Mao et al., GCNs 31364
Not found
 
 
, 31368
Not found
 
 
;
Noschese et al., GCN 31366
Not found
 
 
; Guelbenzu et al., GCN 31370
Not found
 
 
; Strausbaugh et
al., GCNs 31371
Not found
 
 
, 31383
Not found
 
 
, 31389
Not found
 
 
; Dimple et al., GCN 31384
Not found
 
 
; Romanov, GCN
31387
Not found
 
 
; Caballero-Garcia et al., GCN 31388
Not found
 
 
; Belkin et al., GCN 31390
Not found
 
 
; Ror et
al., GCN 31394
Not found
 
 
; Avanzo et al., GCN 31395
Not found
 
 
; Pankov et al., GCN 31398
Not found
 
 
;
Guelbenzu et al., GCN 31401
Not found
 
 
; Moskvitin et al., GCN 31420
Not found
 
 
; and Perley, GCN
31425
Not found
 
 
.

The estimated preliminary magnitudes for the R and I-band images are as
follows:

T_start-T0(hours)           Filter           Magnitude (mag)
-----------------------------------------------------------------------
55.75                              I                   19.52 +- 0.02
57.91                              R                   20.95 +- 0.04

Aperture photometry is performed, and calibration is done based on the
standard stars in the USNO-B1.0 catalogue. The quoted magnitudes are not
corrected for the Galactic extinction in the direction of GRB 220101A.

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