TITLE:   GCN CIRCULAR
NUMBER:  22472
SUBJECT: MAXI J1820+070: Swift/UVOT counterpart correction 
DATE:    18/03/12 02:55:49 GMT
FROM:    Jamie A. Kennea at PSU/Swift-XRT  <kennea@swift.psu.edu>

J. A. Kennea and M. H. Siegel (PSU) report on behalf of the Neil Gehrels
Swift Observatory

In GCN #22471 the UVOT counterpart reported was incorrect, and was in fact
an unrelated star near the XRT position. In the UVOT prompt white image we
detect a bright source, which has considerable brightening over archival
images of the field, at the following coordinates, RA/Dec(J2000) = 75.09138,
7.1853, which is equivalent to:

RA(J2000) =  18h 20m 21.93s,
Dec(J2000) = +07d 11m 07.1s

This source lies 0.36 arc-seconds from the source ASASSN-18ey (ATEL #11400),
and is therefore the same source.

We note that the XRT position is 10.5 arc-seconds from the UVOT/ASASSN
position, however, given the brightness of the XRT source, we believe it is
the same object as MAXI J1820-070 and the associated ASASSN-18ey.

We apologize any confusion.

[GCN OPS NOTE(13mar18):  Per author's request, the "ASASSN-18el" was changed
to "ASASSN-18ey".]