TITLE:   GCN CIRCULAR
NUMBER:  20879
SUBJECT: LIGO/Virgo G277583: ATLAS17cck is likely a minor planet
DATE:    17/03/16 04:20:07 GMT
FROM:    Peter Garnavich at Notre Dame  <pgarnavi@nd.edu>

C. Littlefield and P. Garnavich (Notre Dame) report:

We obtained images of the field around
the optical transient ATLAS17cck (GCN 20877) which
is within the localization region of LIGO/Virgo G277583.
Unfiltered CCD images were taken using the 0.8-m
Krizmanich telescope under poor conditions.

We detect a bright (r=16.5 mag) source at
07:44:53.33 +24:45:52.9 (J2000) which is
not visible in the SDSS DR12 images. This source
is 41 arcsec east of the position reported
for ATLAS17cck. Using MPChecker to
search for minor planets we find that
(1056) Azalea (V=16.3) was within 6 arcsec of
the position of ATLAS17cck at 2017 March 15.43 UT,
the time of the first ATLAS detection.

It is likely that minor planet Azalea is ATLAS17cck and
we suggest that fixed position photometry of this
moving source could mimic a fading transient.