GCN Circular 21750

P. K. G. Williams (Harvard), K. D. Alexander (Harvard), and E. Berger
(Harvard) report on behalf of a larger collaboration:

We observed the position of the optical counterpart SSS17a (Coulter et al., LVC 21529) with the Atacama Large Millimeter/submillimeter Array
(ALMA) on 2017 August 19 UT and 2017 August 26 UT. Each observation
lasted 20 minutes and was performed using ALMA's Band 3, with spectral
windows of 4 GHz bandwidth centered at 91.5 and 103.5 GHz. 

We have analyzed the data using a custom CASA-based pipeline. At a mean
frequency of 97.5 GHz, we detect no emission at the location of the
optical transient to a combined 3-sigma limit of 50 microJy. We detect
a source with a preliminary flux density of ~0.2 mJy at the location:

RA = 13:09:47.696
dec = -23:23:02.31

with a positional uncertainty of ~0.04 arcsec. This is consistent with
the optical position of the host galaxy and the position of the radio
source reported by Alexander et al. (LVC 21545) and others.

We thank the ALMA staff, especially Tony Remijan, for their excellent
support.