We present BV { R _ { C } } J H { K _ { s } } photometry of the optical afterglow of the gamma-ray burst ( catalog GRB~021211 ) taken at the Magellan , MMT , and WIYN observatories between 0.7 and 50 days after the burst .
We find an intrinsic spectral slope at optical and near-infrared wavelengths of 0.69 \pm 0.14 at 0.87 days .
The optical decay during the first day is almost identical to that of ( catalog GRB~990123 ) except that ( catalog GRB~021211 ) ’ s optical afterglow was intrinsically approximately 38 times fainter and the transition from the reverse shock to the forward shock may have occurred earlier than it did for ( catalog GRB~990123 ) .
We find no evidence for a jet break or the cooling break passing through optical frequencies during the first day after the burst .
There is weak evidence for a break in the J -band decay between 0.89 and 1.87 days which may be due to a jet .
The optical and infrared data are consistent with a relativistic fireball where the shocked electrons are in the slow cooling regime and the electron index is 2.3 \pm 0.1 .
The forward shock appears to have been expanding in a homogeneous ambient medium during the first day after the burst .
Our analysis suggests that the jet of ( catalog GRB~021211 ) may have a small opening angle and that the total gamma-ray energy is likely to be much less than the canonical value of 1.33 \times 10 ^ { 51 } erg .
If this is the case then it is possible that most of the energy of the burst is in another form such as a frozen magnetic field , supernova ejecta , or a second jet component .
The host galaxy of ( catalog GRB~021211 ) is subluminous and has a star formation rate of at least 1 \mathcal { M } _ { \sun } yr ^ { -1 } .