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GCN Circular 20485

LIGO/Virgo G268556: RATIR Observation of iPTF Candidates
2017-01-20T05:10:34Z (7 years ago)
V. Zachary Golkhou at ASU/SESE--RATIR <>
Zach Golkhou (ASU), Nat Butler (ASU), Neil Gehrels (GSFC), Alexander
Kutyrev (GSFC), William H. Lee (UNAM), Eleonora Troja (GSFC), and Alan M.
Watson (UNAM) report:

We observed a number of iPTF candidates (Kasliwal et al. LVC GCN#20398)
with the Reionization and Transients Infrared Camera (RATIR;
on the 1.5m Harold Johnson Telescope at the Observatorio Astron��mico
Nacional on Sierra San Pedro M��rtir from 2017/01 11.28--11.30 UTC (6.85
days since the GW trigger; Shawhan et al. LVC GCN #20364) and again from
2017/01 12.44--12.46 UTC.

At positions consistent with each iPTF source position, we report riZY
photometry for the probable host galaxy from the first epoch. In comparison
with the SDSS DR9 and 2MASS catalogs, we obtain:

# Source   r                   (dt_r)  i                     (dt_i)   Z
             (dt_Z)   Y                (dt_Y)
iPTF17ce 19.84+/-0.04 (0.36) 18.92+/-0.02 (0.36) 18.37+/-0.02 (0.07)
18.35+/-0.03 (0.07)
iPTF17ck 18.17+/-0.01 (0.71) 17.59+/-0.01 (0.71) 17.63+/-0.01 (0.15)
17.33+/-0.01 (0.15)
iPTF17dz   ...                          19.09+/-0.01 (0.51) 19.30+/-0.03
(0.22) 19.23+/-0.04 (0.22)
iPTF17ef 19.18+/-0.02 (1.07) 18.92+/-0.02 (1.07) 18.86+/-0.03 (0.22)
18.59+/-0.02 (0.22)
iPTF17ei 16.77+/-0.01 (1.38) 16.37+/-0.01 (1.38) 16.17+/-0.01 (0.29)
15.97+/-0.01 (0.29)

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the source direction. Exposure times (dt) are reported in

We find no evidence for variation in flux at >2-sigma confidence from an
image subtraction analysis between our two epochs.

We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
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