Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Power Law Decays in the Optical Counterparts of GRB 970228 and GRB970508   We report on R_c and K band observations of the optical counterpart to GRB
970508 with the Fred Lawrence Whipple Observatory (FLWO) 1.2m telescope. Eleven
R_c-band observations were obtained on 1997 May 12, and three on May14. The
counterpart clearly faded between the two nights. On May 12 there was no
evidence for variability (<9%) on 10-70 minute time scales based on 11 R_c-band
observations. On May 19 a one hour observation set a limit on the K magnitude
of K>18.2. Comparison of these data points with those obtained by other authors
shows that the decay of the optical counterpart can be well fitted by a power
law of the form f ~ t**-alpha where alpha = 1.22 +/- 0.03 with occasional
fluctuations superposed. We note that the decay of the optical counterpart to
another burst, GRB 970228, can also be well fitted with a power law with
exponent alpha = 1.0/+0.2/-0.5 with occasional fluctuations superposed. These
two decay light curves are remarkably similar in form to that predicted by
cosmic-fireball models.

37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ