JRA3%20-%20High-speed%20astronomy

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JRA3 - High-speed astronomy
With bigger telescopes, one can study fainter and
more distant objects, but bigger telescopes also
open new opportunities to study objects that vary
rapidly in time, sometimes in milliseconds or
less. Current detectors are far too slow to study
these flickering objects. JRA3 is a technology
development programme for detectors with time
resolutions down to a microsecond which will
sensitive enough to be useful for astronomy.
Three different detector technologies are being
pursued in parallel at 5 technology centres
across Europe. In a complementary effort the
corresponding high-speed controllers and
data-reduction software are being developed.
Technology Development Three different
technologies are being developed in this
activity Electron-multiplier CCDs. These
are commercially available, but require
additional development for astronomical
use. Avalance photodiodes (APD). These
deliver the fastest time resolution but must
be configured into arrays of individual cells.
pn-sensors. Specially developed
electron-multiplied CCDs in deep-depletion
technology with extended near-infrared
sensitivity.
Flashing objects in the sky Most stars vary
little and slowly, and can be observed adequately
with existing astronomical hardware. However,
some of the more interesting objects, vary
extremely rapidly. White dwarfs which receive
mass from a companion star (accretion) vary on
time scales of a second and less, while accreting
black holes and neutron stars vary on millisecond
time scales. Some of the fastest variability is
observed in the enigmatic gamma-ray bursts, where
variations in less than a millisecond have been
seen in X-rays. Though the bursts produce
visible light as well as gamma rays, the
technology to observe them at very short time
scales in the visible is still to be developed.
Other rapidly varying astronomical objects
include flare stars and microquasars.
Artists impression of a black hole accreting
from a companion star, producing X-rays, visible
light and a jet. Processes close to the hole
cause it to vary on time scales of milliseconds.
Participants The collaborating organisations
are Max Planck Institute for
Extraterrestrial Physics Max Planck Institute
for Astrophysics Landessternwarte Heidelberg
UK Astronomy Technology Centre University of
Cambridge National University of Ireland
Nordic Optical Telescope Scientific
Association European Southern Observatory
Wavelength response of pn-sensor
Photon
Structure of an avalanche photodiode
OPTICON is funded by the European Commission
under Contract RII3-CT-2004-001566