(cba:news) ASASSN-18ey = MAXI J1820+070
jop at astro.columbia.edu
Sat May 5 15:33:19 EDT 2018
Some of you probably saw the ATEl that Michael Richmond and Stephen
Brincat sent out, reporting, among other things, a 3.4 hour period in
the light curve of this still crazy-bright X-ray (presumably black-hole)
transient. Origin unknown, but let's jump in and figure it out! All
longitudes and latitudes and lassitudes invited.
As usual, long (3+ hours) coverage will have greatest impact. But all
the data show a point-to-point scatter far greater than the error of
measurement. This means that there is considerable source variation on
timescales of just a few seconds - basically unlike CVs, which are
considerably fonder of timescales around *minutes*, not *seconds*. We
found a similar thing years ago: a 6-second QPO in our study of 1118+48,
another black-hole transient. So as long as the source is bright (now
12.5) and assuming your measurement error can tolerate it, keep the
integrations short! (Can't be any more quantitative than that, since we
don't actually know the timescale).
I certainly recommend this guy as #1 priority. Some of you are doing a
great job with AM CVn, and our many-month coverage of it will have great
impact. But old Maxie has highest priority whenever it's above 2
airmasses - certainly at non-USA longitudes, and I'd say at USA also.
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