[vsnet-grb-info 22236] LIGO/Virgo S190425z: RATIR non-detection of the Swift/UVOT source

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24335
SUBJECT: LIGO/Virgo S190425z: RATIR non-detection of the Swift/UVOT source
DATE:    19/04/28 22:39:18 GMT
FROM:    Eleonora Troja at NASA/GSFC/UMD  <eleonora at umd.edu>

Eleonora Troja (GSFC/UMD), Alan M. Watson (UNAM), Rosa L. Becerra (UNAM),
Nat Butler (ASU), Diego Gonzalez (UNAM), Alexander Kutyrev (GSFC/UMD),
William H. Lee (UNAM), Margarita Pereyra (UNAM), and
Tanner Wolfram (ASU) report:

We observed the location of the Swift/UVOT transient (Breeveld et al.,
GCN Circ. 24296) with the Reionization and Transients Infrared Camera
(RATIR;
www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio
Astronómico Nacional on Sierra San Pedro Martir from 2019/04 28.28 to
2019/04 28.49 UTC (approximately 3 d after the GW trigger), obtaining
a total of 1.92 hours exposure in the r and i bands and 1.21 hours
exposure in the Z, Y, J, and H bands.

For a source within the UVOT error circle, in comparison with the
USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma):

  g > 23.5
  r > 23.4
  i > 23.3
  Z > 22.2
  Y > 22.2
  J > 21.8
  H > 21.4

The nearby objected reported by Palmese et al. (GCN Circ. 24312) is
detected in our images at H~20.1 mag.

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio Astronomico Nacional in San Pedro
Martir