GCN Circular 6331

P. D'Avanzo, L.A. Antonelli, L. Calzoletti, S. Campana, G.  
Chincarini, M.L. Conciatore, S. Covino, S. Cutini, P. D'Avanzo, V.  
D'Elia, F. Dalessio, F.  Fiore, D. Fugazza, P. Goldoni, D. Guetta, C.  
Guidorzi, G.L. Israel,  D. Malesani, N. Masetti, A. Melandri, E.  
Meurs, L. Nicastro, E. Palazzi, E. Pian, S. Piranomonte, D. Rizzuto,  
L.  Stella, G. Stratta, G. Tagliaferri, G. Tosti, V. Testa, S.D.  
Vergani,  F. Vitali report on behalf of the REM team:


We observed the field of the GRB 070420 (Stamatikos et al. GCN 6330
Not found
 
 
)  
with the robotic 60-cm REM telescope located at La Silla (Chile). A   
set of observations was performed automatically in the optical and  
near infrared filters (V, R, I and J, H, K, z) starting on 2007 April  
20 at 06:19:32 UT, 42s after the Swift trigger and 79s after the GRB  
time.

Although the observations were performed under thin clouds and at  
very high airmass (~ 7.5) we clearly detect the NIR and optical  
afterglow at the coordinates reported by UVOT (GCN 6330
Not found
 
 
).

Preliminary analysis gives an approximate magnitude about 5 minutes  
after the burst time was H  = 13.1 +/- 0.2.

Observations were then soon interrupted due to excessive airmass.

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