Transcript Folie 1 - univie.ac.at

www.brite-constellation.at
BRITE-Constellation currently consists of two
satellites, UniBRITE and BRITE-AUSTRIA
(TUGSAT-1) and two satellites to be funded by the
Canadian Space Agency (CSA). Each will fly a
CCD camera to perform high-precision two-color
photometry continuously for two years or more,
primarily of stars brighter than 4th magnitude (V),
and with reduced accuracy also of fainter stars.
Nanosatellites for
Astrophysics
BRITE-Constellation will photometrically measure
low-level
oscillations
and
temperature
variations in stars brighter than visual
magnitude 4.0 (and with less accuracy also down
to a visual magnitude of 7.0).
There are 534 stars brighter than V = 4.0 mag in
the sky and observable at the proposed precision
level with BRITE-Constellation. Considering the
typical time scales for their variability ranging from
an hour to several weeks and aiming for a
frequency resolution sufficient for asteroseismology, BRITE-Constellation expects to
observe on average 20 stars simultaneously.
The primary science goals are studies of
massive stars in our Galactic neighbourhood,
representing objects which dominate the ecology
of our Universe, and also highly evolved giant
stars of lower mass to probe the future development of our Sun. The operation policy will be to
observe a few fields over a long time span and
possibly some short runs in between, which will
assure optimum use of near polar low-earth orbits.
The figure below shows the location of the 534
stars with V ≤ 4 mag in the Hertzsprung-Russell
Diagram color-coded with the object types taken
from the VISAT database.
BRITE-Constellation is made possible by
innovative technology currently developed in
collaboration between Canada and Austria. A
launch of UniBRITE and BRITE-AUSTRIA in late
2010 is envisioned.
The first Announcement of Opportunity for
submission of observing proposals from the
community has been released (Sep. 2008) at
www.brite-constellation.at by the BRITE Executive
Science Team.
Each of the 7kg BRITE satellites is equipped with
a small dioptric telescope. A “constellation” of
satellites provides improved time coverage and
two- color information: one satellite carries a blue
and the other a red filter.
The 20cm cube structure houses three orthogonal
reaction wheels and three magnetorquer coils for
three-axis attitude control and momentum
dumping. Attitude determination is provided by a
magnetometer, six sun sensors and a star tracker.
This equipment will enable attitude determination
to 1 arcminute or better, attitude control accuracy
to better than a degree, and attitude stability down
to one arcminute rms.
Instrument
The science payload of the satellite consists of a
five-lens telescope with an aperture of 30mm
and an interline CCD detector KAI 11002-M from
Kodak with 11M pixels, along with a baffle to
reduce stray light. The instrument has a resolution
of 26.52 arcseconds per pixel and a field-of-view
of 24 degrees.
Figure: BRITE telescope and CCD
Contact: Werner Weiss (UniBRITE, U. Vienna),
BRITE Filters
Figure: The HRD of the 534 brightest (V ≤ 4 mag) targets
The effective wavelength range of the UniBRITE
instrument will be defined by a blue filter covering
390-460nm and the BRITE-AUSTRIA instrument
by a red filter constrained to 550-700nm.
Ground stations
Up to 400 data sets will be obtained from a target
field per day and transmitted via ground stations
located in Graz, Vienna and Toronto.
Figure: Field of view centered on Orion
Otto Koudelka (BRITE-AUSTRIA, TU Graz),
Engineering Team
Anthony Moffat (Canadian BRITEs, U. Montréal),
Science Team
Funding Agencies
Figure: BRITE ground station located in Graz
Robert Zee (Canadian Program Manager, U. Toronto)