Gaia maneuvering, could brighten briefly

From: William Keel <wckeel_at_comcast.net>
Date: Tue, 25 Feb 2014 08:14:31 -0600
This just in from the Gaia project - it could briefly brighten by  
several magnitudes during these maneuvers:

_____________________________________________________________________________________________________

Dear All,
I am writing to you since you have participated in our „Gaia in the  
Sky“ project. Your contribution was extremely helpful to assess the  
brightness of Gaia.

Now there is a very interesting opportunity to help us again:

Tomorrow, February 26, at 11:58 UTC, Gaia will change its aspect angle  
with respect to the Sun from 42 degrees to zero degrees. This maneuver  
will take eight minutes. The exact times are

Slew  SAA42 -> SAA0
starts: UTC  2014/02/26 11:58:52.815
ends: UTC  2014/02/26 12:06:43.815

We expect that Gaia will be considerably brighter than the current  
20-20.5 mag after the move to zero degrees until it will again change  
its solar aspect angle to 45 degrees  on Feb 27, 09:06 UTC. It is  
possible that Gaia will brighten by about than 5 magnitutes.

Slew SAA0 -> SAA45
starts: UTC  2014/02/27 09:06:43.478
ends: UTC  2014/02/27 09:15:11.978

The most interesting phase to take pictures and measure the brightness  
is the time of the maneuver itself because you could see the  
brightness varying on a time scale of minutes. For us data from this  
time period would be particularly useful because photometric  
measurents  could tell us how Gaia’s sunshield reflects sunlight in  
different directions.

The time of the maneuver excludes observers from Europe, because the  
change of the aspect angle takes place during daylight at our  
longitudes. Nevertheless, observations from the night between Feb 26  
and Feb 27 would also be very interesting.

Gaia’s ephemerides can be obtained at http://gaiainthesky.obspm.fr/ 
fov/ .

This information comes on very short notice but the exact times of the  
maneuver were not available earlier.

Please send observations to Martin Altmann (maltmann_at_ari.uni-heidelberg.de 
) and me (jordan_at_ari.uni-heidelberg.de).

Best regards
Stefan and Martin

PS: Please forward this information to anyone who could be interested.

Priv.-Doz. Dr. Stefan Jordan
E-mail:jordan_at_ari.uni-heidelberg.de
Astronomisches Rechen-Institut
am Zentrum fuer Astronomie Heidelberg
Moenchhofstr. 12-14
D-69120 Heidelberg, Germany
Skype name: stefanjordan2006
Tel.: +49 6221 54 1842, Fax:+49 6221 54 1888
Homepage: http://www.stefan-jordan.de
Homepage of the institute: http://www.ari.uni-heidelberg.de

_____________________________________________________________________________________________________

I'm not scheduled on a remote instrument and the weather forecast here  
is terrible, but maybe others can make use of this opportunity.

Bill Keel

--------------------------------------------------------------------------------------
William C. Keel                                        205-348-1641  
(office)
Professor, Physics and Astronomy      205-348-5051 (fax)
Box 870324                                              205-348-5050  
(dept.)
University of Alabama                             http://astronomy.ua.edu/keel
Tuscaloosa, AL 35487-0324, U.S.A.    wkeel_at_bama.ua.edu
--------------------------------------------------------------------------------------

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Received on Tue Feb 25 2014 - 14:21:40 UTC

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