{
  "bibcode": "2020GCN.29029....1A",
  "body": "Tomas Ahumada (UMD), Harsh Kumar (IITB), Christoffer Fremling (Caltech),\nLeo Singer (NASA GSFC) report on behalf of the ZTF and GROWTH\ncollaborations:\n\nReanalysing the data used in Ahumada et al. GCN 28727, we provide a revised\nmagnitude of the source detected in the Gemini Multi-Object Spectrograph\n(GMOS-N) i-band image of ZTF20abwysqy/AT2020scz (Ahumada et al. GCN 28295).\n\nWe imaged the region of GRB 200826A (GCN 28284) with GMOS-N, mounted on the\nGemini-North 8-meter telescope on Mauna Kea, on three nights: 2020-09-23\n(2459115.9675 mjd), 2020-10-10 (2459133.8039 mjd) and 2020-11-08\n(2459167.9342 mjd). Each epoch consisted of 14 r- and i- band 200s\nexposures. We reduced and co-added the images from each epoch using\nDRAGONS, a Python-based data reduction platform provided by the Gemini\nObservatory. We subtracted the coadded images using HOTPANTS and PyZOGY\nindependently. We now present the revised magnitudes using a zero-point\ncalculated using 23 stars in the field from the SDSS catalog. We apologize\nfor any possible confusion caused by the erroneously reported photometry in\nGCN 28727.\n\nIn the 2020-09-23 images, a source is detected at the position of the\nafterglow with i = 25.49 +- 0.15 mag, but not in r-band up to r > 25.6 AB\nmag. In the 2020-10-10 images, we do not detect a transient in either\nfilter up to a 5-sigma limit of i > 25.4 mag and r > 25.5 mag.\n\nAt the host galaxy's redshift of z = 0.7481 (GCN 28319) and assuming Planck\n2015 cosmological parameters, the absolute magnitude of the GMOS-N\ndetection is M_i = -17.9 AB mag.\n\nWe thank the Gemini Observatory Director for awarding this observing time\nand the Gemini staff for help with planning and executing the observations.\n\n-- \nTomas Ahumada (he/him)\nPh.D. Student\nDepartment of Astronomy\nUniversity of Maryland, College Park\nNASA <tomas.f.ahumdamena@nasa.gov> Goddard Space Flight Center, Code 661\nB.Sc. Astronomy, Pontificia Universidad Cat��lica de Chile",
  "circularId": 29029,
  "createdOn": 1607727981000,
  "email": "tahumada@astro.umd.edu",
  "subject": "GRB 200826A: GMOS-N detected source magnitude (Correction)",
  "submitter": "Tomas Ahumada at U. of Maryland  <tahumada@astro.umd.edu>",
  "eventId": "GRB 200826A"
}