TITLE:   GCN CIRCULAR
NUMBER:  31750
SUBJECT: GRB 220310A: [KAO-Egypt] SDSS r, i observation
DATE:    22/03/13 08:17:39 GMT
FROM:    Ahmed Fouad at NRIAG  <ahmed.fouad@nriag.sci.eg>

Ahmed M. Fouad, Ali Takey, Mona Molham, Saad Ata, Ola Ali (NRIAG)
report:

We observed the optical counterpart of GRB 220310A
(H. Negoro et al., GCN 31725)
using a 1.88-m telescope at the Kottamia Astronomical Observatory (KAO),
NRIAG, Egypt.

The source was visible at the position discovered by
(V. Lipunov et al., GCN 31732)
where the SDSS galaxy (ObjID: 1237667910586532614) is located.
KAO observations started from 22:05:22 to 23:06:00 UT on 10-03-2022,
~ 21.5 hrs after the MAXI/GSC trigger.
The combined images of 10 x 150sec were created for SDSS r,i images.

We report the preliminary photometry as:
--------------------------------------------------------
Object                           / r-mag    / r-err     / i-mag     / i-err
-------------------------------/------------/-----------/------------/---------
GRB220310A by KAO  / 19.723  / 0.141   / 19.727  / 0.090
Published SDSS-gal.   / 21.94     / 0.19    / 21.62     / 0.22
-------------------------------------------------------------------------------

Aperture photometry was done based on 9 stars around the GRB in
a FoV = 8' x 8', selected from the SDSS-DR16.

The magnitude is not corrected for Galactic extinction
in the direction of the GRB.