3UCAC 064456146 (11m6) by (50000) Quaoar on 2012 April 17 for
Europe, Near East
and Africa as well as the Atlantic Ocean
Based on astrometry
from the RIO group for Europe and updated by other astrometry an
occultation of a 11m6 star can be observed in the morning of the
17th of April 2012 at approx. 2h 19min UTC.
The occultation is
very well in reach of many video and digital camera systems
attached to telescopes as small as 8 inch. We urgently ask
everybody, to take part in the international campaign for
The goal is to
determine the diameter of Quaoar and find out, if the TNO has an
atmosphere. Therefore, not only the determination of the exact
time point of dis- and reappearance is necessary, but also the
exact determination of the lightcurve during dis- and reappearance
of the star behind the disk of Quaoar.
On this site, more
infos will be posted, to give you informations about how to
observe. The RIO astrometry group, leaded by Marcelo Assafin, as
well as many other observers have made astrometric observations
with large telescopes, to define the position of the star as well
as possible in the milliarcsecond range.
informations about final updates of the astrometry can be found on
Felipe Braga-Ribas (LESIA) Website
about this and other actual events.
astrometric situation is very poor despite the brightness of the
star. The weather conditions in the last days for astrometry were
very poor, therefore its not known at the moment, if better
prediction can be get. In any case, you will either be informed on
this page or on Felipe's page.
The occultation track
Best and worst
with repect to Europe....
The best occultation
situation after calculations by Jean Lecacheux is the following,
he used the UCAC2 positions of the stars and the Quaoar position
corrected with an offset from the last observed occultations. It
is as follows:
The worst calculation
with respect to Europe is shown here:
this calculation the star was observed for several night with
TRAPPIST telescope. Julio Camargo measured the images with respect
to UCAC2 catalog.
The star position is very good and
consistent with WFI position.
writes on the webpage about the Quaoar occultation (6th
of April 2012)
are expecting to have new astrometric measurements of Quaoar in
the next days. Experience shows that the path can still change as
Quaoar approachs the star, and the relative positions (i.e.
ephemeris) gets better and better. So keep checking for new
updates. And if its "costless" for you to observe,
observe it whatever are the predictions.
an eye on the Website of