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GCN Circular 2503

GRB031220(=H2976): TNG R-band Observation of the Chandra X-ray Sources
2003-12-29T19:55:03Z (20 years ago)
Angelo Antonelli at Obs. Astro. di Roma <>
L.A. Antonelli, V. Testa (INAF-OAR, Rome), D. Fugazza (INAF-OABr, Merate), 
M. Pedani (INAF-TNG, La Palma), L. Piro (INAF-IASF, Rome), S. Covino 
(INAF-OABr, Merate), N. Masetti, (INAF-IASF, Bologna), D. Malesani
(Sissa, Trieste) on behalf of the larger Italian GRB Collaboration 

"On 28 Dec. we imaged the field of the X-ray rich GRB031220 
(HETE trigger 2976) with the Telescopio Nazionale Galileo and
DOLORES instrument operated in imaging mode. The observation 
started at 00:54 UT and the field was imaged for a total exposure 
time of 1 hour in the R-band. Seeing varied during the observation 
from 1.1'' to 1.4''. 

At the position consistent with four of the X-ray sources observed 
by Chandra and reported by De Pasquale et al. (GCN 2502) we found 
the following optical counterparts:

  ID#     RA          DEC          Rmag   Err(mag)  

  6       4 39 46.49  7 22 19.30   20.61  0.05    
 27       4 40 03.71  7 20 55.98   19.42  0.05
 17       4 39 54.82  7 21 49.05   23.10  0.07
  7       4 39 46.13  7 22 56.26   23.48  0.11

(for errors on positions we assume a conservative value of 0.6")

For the other two sources detected by Chandra (#2 and #1 see GCN 2502) 
we did not find evidence of optical counterparts. We derived a 3 sigma 
limiting magnitude of R>24 for both sources.

Source #37 (CXOU J043857.1+072449) is out of the field of view. 

A further NIR observation of this field is planned at TNG. 

We thank the personnel of TNG for their enthusiastic effort 
to the GRB program.

This message may be cited"

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