{
  "bibcode": "2004GCN..2576....1R",
  "body": "E. Rykoff reports on behalf of the ROTSE collaboration:\n\nThe ROTSE-IIIb robotic telescope at McDonald Observatory, Texas, \nresponded automatically to INTEGRAL Trigger #1756 (GRB040422) within 8 s \nof the receipt of the first alert, and 22.1 s after the beginning of the \nGRB.  Our response sequence consists of 10 5 s exposures, 10 20 s \nexposures and 200 60 s exposures, all unfiltered.\n\nAs the burst was behind the galactic plane, we expect significant \nextinction in our optical passband.  Applying the formula from \nFinkbeiner, Schlegel and Davis (1998), we expect 4.4 magnitudes of \nextinction in the R-band, although they give a caveat that their \ncalculations \"should not be trusted\" at galactic latitudes of |b|<5.\n\nOur first 5-s exposure started at 06:58:27.21 UT.  We visually compared \nour images to the DSS using the revised error circle as reported by \nMereghetti et. al (GCN 2572).  We find no objects absent from the DSS to \na limiting magnitude of R ~ 16.5, although field crowding creates \nsignificant source confusion.  Coadding our first 10 images, with an \neffective exposure time of 110 s, also does not reveal any new objects \nto a limiting magnitude of R ~ 17.5.\n\nFurthermore, no objects in the error box varied significantly over the \ncourse of our 3.7 hours of observation.",
  "circularId": 2576,
  "createdOn": 1082692943000,
  "email": "erykoff@umich.edu",
  "subject": "GRB 040422: ROTSE-IIIb Prompt Optical Limits",
  "submitter": "Eli Rykoff at Univ. of Michigan/ROTSE  <erykoff@umich.edu>",
  "eventId": "GRB 040422"
}