We have detected the GRB 971214 near-IR counterpart 3.5 hours and 5 hours after the gamma-ray event which enables to conclude that:
i) a magnitude difference is derived from our measurements, whereas would be expected assuming a power-law decay with index (similar to the one observed at optical wavelengths). This implies a deviation of . If the assumed power-law index were 1.4, then the rejection level would be . Thus, our measurements suggest a rising or a flat light curve segment with a duration hours (between 3.5 and 10.2 hours after the burst). This conclusion must be taken with care since the above-mentioned rejection levels are not stringent enough to assure the result with total confidence;
ii) the power-law decline in the near-IR should be steeper than the one given by ;
iii) for the observations carried out on Dec 15.44-15.51, there is a change in the slope of the measured energy distribution at some wavelength between the J and bands (possibly around H).
© European Southern Observatory (ESO) 1998
Online publication: June 12, 1998