TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3729 SUBJECT: GRB 050801, SMARTS optical/IR afterglow observations DATE: 05/08/02 02:37:50 GMT FROM: Bethany Cobb at Yale U B. E. Cobb and C. D. Bailyn (Yale), part of the larger SMARTS consortium, report: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 050801 (GCN 3725, Band et al.) with a mid-exposure time of 2005-08-02 00:01 UT, which is ~5.5 hours post-burst. Total summed exposure times amounted to 15 minutes in I and V and 12 minutes in J and K. The afterglow of GRB 050801 (GCN 3723, Rykoff et al.) is detected in our optical images. However, the afterglow is not significantly detected in our IR images. Preliminary photometry, obtained in comparison with USNO-B1.0 stars, indicates the magnitude of the afterglow at ~5.5 hours post-burst to be I = 20.2+/-0.2. The afterglow is not bright enough in the individual optical frames to significantly measure its decay over our ~40 minutes of observations. In comparison with 2MASS stars, the limiting IR magnitudes are J > 18.6+/-0.2 and K > 17.0+/-0.2.