INFRARED PHOTOMETRY OF THE BLACK-HOLE CANDIDATE SAGITTARIUS A-ASTERISK

An infrared source has been imaged within 0.2'' +/- 0.3'' of the unique Galactic center radio source Sgr A*. High angular resolution ('FWHM' similar to 0.55'') was achieved by rapid (similar to 50 Hz) real-time image motion compensation. The source's near-infrared magnitudes (K = 12.1 +/- 0.3, H = 13.7 +/- 0.3, and J = 16.6 +/- 0.4) are consistent with a hot object reddened by the local extinction (A(v) similar to 27). At the 3 sigma level of confidence, a time series of 80 images limits the source variability to less than 50% on timescales from 3 to 30 minutes. The photometry is consistent with the emission from a simple accretion disk model for a similar to 1x10(6) M. black hole. However, the fluxes are also consistent with a hot luminous (L similar to 10(3.5-4.6) L.) central cluster star positionally coincident with Sgr A*.