{
  "bibcode": "2020GCN.28034....1R",
  "body": "A. Rossi (INAF-OAS) and P. D'Avanzo (INAF-OA Brera) report on behalf of \nthe CIBO collaboration:\n\nWe observed the field of GRB200623A (DeLaunay et al., GCN 28013) \nsimultaneously in the r' and z' bands with the LBC imager mounted on LBT \n(Mt Graham, AZ, USA). Observations started at 05:58 UT on 2020-06-25, \n50.7 hr after the GRB trigger and finished at 06:24 UT and allowed us to \nobtain 20min of exposure in each band. Observations were performed under \ngood seeing conditions (seeing ~0.9\") and reached a depth of r~26 mag.\n\nThe images covered all the three sources found by XRT (Sbarufatti et \nal., GCN 28023). No new point source is detected within their error circles.\n\nImage subtraction against TNG r-band images obtained on 2020-06-23 \n(D'Avanzo et al., GCN 28021) using HOTPANTS (v5.1.11) does not reveal \nany flux variation in the candidate found within the error circle of the \nXRT source #3. The near-by galaxy at z~0.33 noticed by D'Avanzo et al. \n(GCN 28021) is too close to saturation in LBC images, preventing us to \nmake any statement about possible flux variations within the galaxy.\n\nWe also note that a faint, extended source is present within the XRT \nerror circle of source #3, visible in both the r' and z' images, and not \nmentioned in previous reports about this event. This is also a candidate \nhost galaxy of XRT source #3 though with a higher chance association \nprobability compared to the brighter galaxy. Further Swift/XRT \nobservations will help establishing variability and possibly reducing \nthe X-ray position uncertainty.\n\nWe acknowledge the excellent support from the LBTO and LBT-INAF staff, \nparticularly B. Rothberg, F. Cusano, S. Paiano and D. Paris, in \nobtaining these observations.",
  "circularId": 28034,
  "createdOn": 1593163840000,
  "email": "andrea.rossi@inaf.it",
  "subject": "GRB 200623A: LBT optical observations",
  "submitter": "Andrea Rossi at INAF  <andrea.rossi@inaf.it>",
  "eventId": "GRB 200623A"
}