TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  975
SUBJECT: GRB 010222, Decay Slope Confirmed
DATE:    01/02/23 07:16:07 GMT
FROM:    Javier Gorosabel at LAEFF-INTA, Madrid  <jgu@laeff.esa.es>

J. P. U. Fynbo (ESO, Garching), J. Gorosabel (DSRI, Copenhagen),
B. L. Jensen, H. Pedersen, J. Hjorth (U. of Copenhagen),
M. I. Andersen (University of Oulu),  
A. A. Kaas, T. Abbott, T. H. Dall and R. Oestensen (NOT), report
 
 "Using the ALFOSC on the 2.5m Nordic Optical Telescope, we have
  obtained R-band imaging of the optical counterpart of GRB 010222 
  (GCN #961, GCN #963). We have derived the following preliminary 
  magnitudes;
 
  Date, Feb 2001(UT)      R         Texp(s)
  =========================================
    23.008--23.012   19.56+-0.03     300
    23.015--23.019   19.53+-0.03     300
    23.020--23.023   19.56+-0.03     300
    23.083--23.086   19.65+-0.03     300
    23.087--23.091   19.68+-0.03     300
    23.145--23.148   19.76+-0.03     300
    23.165--23.167   19.79+-0.05     100
 
  Our zero-point is based on the the reference star 'A' of McDowell
  et al. (GCN #963). We have fitted a power-law light curve to the
  magnitudes reported by  Stanek et al. (GCN #970) and to the ones 
  displayed above. We obtain a value for the slope of 0.86+-0.01
  (chi^2/dof= 12.7/8=1.6), which is consistent with the one reported
  by Price et al. (GCN #973)"