TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4837 SUBJECT: GRB 060218/SN 2006aj, SMARTS optical/IR observations DATE: 06/02/26 18:43:22 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 position of GRB 060218/SN 2006aj (GCN 4775, Cusumano et al.) over 5 nights. Total summed exposure time on each night amounted to 36 minutes in I and 30 minutes in J. The object shows continued brightening over our images. The preliminary I magnitude of the object on 2006-02-22 is calculated based on contemporaneous observations of Landolt RU149. The preliminary J magnitude on the same day is calculated in comparison to 2MASS stars in the field. Mid-Exposure UT Date and Time 2006-02-22 00:35 I = 17.58 +/- 0.05 J = 17.31 +/- 0.05 I mag relative to 1st epoch J mag relative to 1st epoch 2006-02-23 00:27 -0.18 +/- 0.02 -0.11 +/- 0.05 2006-02-24 00:20 -0.29 +/- 0.02 -0.24 +/- 0.05 2006-02-25 00:16 -0.39 +/- 0.02 -0.28 +/- 0.05 2006-02-26 00:18 -0.46 +/- 0.02 -0.38 +/- 0.05