{
  "bibcode": "2019GCN.25655....1B",
  "body": "Rosa L. Becerra (UNAM), Alan M. Watson (UNAM),  Nat Butler (ASU),\nDiego Gonz��lez (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM),\nMargarita Pereyra (UNAM), and Eleonora Troja (GSFC) report:\n\nWe observed the field of ZTF19abvizsw/AT2019pim (Kool et al., GCN Circ.\n25616;\n Perley et al., GCN Circ. 25643) with the COATLI 50-cm telescope and\ninterim imager\n at the Observatorio Astron��mico Nacional on the Sierra de San Pedro M��rtir\n(http://coatli.astroscu.unam.mx) from 2019-09-04 07:32 to 12:10, obtaining\na total\n of 3.04 hours of exposure in the w filter.\n\nWe detect the source at w = 21.60 +/- 0.10.\n\nOur w magnitudes are calibrated against the Pan-STARRS1 catalog, are on\nan approximate AB system, and are not corrected for Galactic extinction\nin the direction of the GRB.\n\nApplying the color transformation of Becerra et al. (2019, ApJ, 872, 118)\nto the g-r color of Perley et al., we predict r = 21.50 +/- 0.10. Thus, we\ndo\nnot see fading compared to the measurement of r = 21.62 +/- 0.09 reported by\nPerley et al. but do confirm their measurement of fading compared to the\ndiscovery magnitude of r = 19.45 +/- 0.11 reported by Kool et al.\n\nFurther observations are planned.\n\nWe thank the COATLI technical team and the staff of the Observatorio\nAstron��mico Nacional.",
  "circularId": 25655,
  "createdOn": 1567607946000,
  "email": "rbecerra@astro.unam.mx",
  "subject": "ZTF19abvizsw: COATLI Optical Observations",
  "submitter": "Rosa Leticia Becerra Godinez at Inst. de Astronoma,UNAM  <rbecerra@astro.unam.mx>",
  "eventId": "ZTF19abvizsw"
}