TITLE:   GCN CIRCULAR
NUMBER:  20397
SUBJECT: Discovery Channel Telescope Imaging of ATLAS17aeu (LVCG268556)
DATE:    17/01/08 02:34:11 GMT
FROM:    Brad Cenko at NASA/GSFC  <brad.cenko@nasa.gov>

S. B. Cenko and E. Troja (NASA Goddard Space Flight Center) report on behalf of a larger collaboration:

We imaged the location of ATLAS17aeu (Tonry et al., LVC Circ. 20382) with the Large Monolithic Imager (LMI) on the 4.3 m Discovery Channel Telescope in Happy Jack, AZ. Observations were obtained in the g, r, and i filters beginning at 10:56 UT on 2017 January 7 (dt ~ 3.0 d after the GW trigger time).  The optical source is clearly detected in all three filters, with the following AB magnitudes (see also Kasliwal et al., LVC Circ. 20393)

g = 22.45 +/- 0.05
r = 22.08 +/- 0.05
i = 21.96 +/- 0.05

The resulting SED is reasonably well fit by a power-law (fnu ~ nu^-alpha) with alpha ~ 0.9.