The extreme, red afterglow of GRB 060923A: Distance or dust?
  Gamma-ray bursts are powerful probes of the early universe, but locating and identifying very distant GRBs remains challenging. We report here the discovery of the K-band afterglow of Swift GRB 060923A, imaged within the first hour post-burst, and the faintest so far found. It was not detected in any bluer bands to deep limits, making it a candidate very high redshift burst (z>11). However, our later-time optical imaging and spectroscopy reveal a faint galaxy coincident with the GRB position which, if it is the host, implies a more moderate redshift (most likely z<2.8) and therefore that dust is the likely cause of the very red afterglow colour. This being the case, it is one of the few instances so far found of a GRB afterglow with high dust extinction. 
N. R. Tanvir, A. J. Levan, E. Rol, R. L. C. Starling, J. Gorosabel, R.   S. Priddey, D. Malesani, P. Jakobsson, P. T. O'Brie...