TITLE:   GCN CIRCULAR
NUMBER:  21982
SUBJECT: LIGO/Virgo G298048: Mid-Infrared Spitzer/IRAC Observations at 3.6 and 4.5 microns
DATE:    17/10/10 13:57:54 GMT
FROM:    Mansi M. Kasliwal at Caltech  <mansi@astro.caltech.edu>

R. M. Lau (Caltech), E. O. Ofek (Weizmann) and M. M. Kasliwal (Caltech)
report on behalf of the Global Relay of Observatories Watching Transients
Happen (GROWTH) collaboration:

On 2017 Sept 29.86 UT, the Spitzer space telescope took deep mid-infrared
observations at the position of SSS17a (Coulter et al. LVC GCN 21529) with
Channel 1 (3.6 microns) and Channel 2 (4.5 microns) of the  Infrared Array
Camera (IRAC).

We conducted a preliminary analysis of the IRAC Basic Calibrated Data
(BCD), including both a median filter subtraction and ZOGY image
subtraction to remove the extended emission from the host galaxy NGC 4993.
We find possible, marginal evidence for excess emission at the position of
SSS17a at 4.5um. We are continuing monitoring with Spitzer/IRAC.

We thank the Spitzer Space Telescope team, in particular, Tom Soifer and
Nancy Silbermann, for the rapid review and scheduling of these DDT
observations (PI Kasliwal). The Spitzer Space Telescope is operated by the
Jet Propulsion Laboratory, California Institute of Technology under a
contract with NASA.