This Echo is READ ONLY !   NO Un-Authorized Messages Please!
 ~~~~~~~~~~~~~~~~~~~~~~~~   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Global Network of Astronomical Telescopes (GNAT)
Tucson, Arizona

Contacts:
Dr. Eric R. Craine, 520-325-4505, craine{at}gnat.org

Embargoed until 27 May 2003, 12:30 p.m. CDT

AUTOMATED TELESCOPE ARRAY DISCOVERIES MOUNT

Astronomers are announcing today early results of a prototype, 
three-telescope array of automated astronomical imagers. These have
been used to discover new Solar System objects, as well as to
discover and monitor the time variable brightness of stars,
especially those potentially harboring extrasolar planets. The report
is being presented today by Dr. Eric R. Craine of the Global Network
of Astronomical Telescopes (GNAT), Tucson, Arizona to the American
Astronomical Society meeting in Nashville, Tennessee. The system is
of special interest because of its very low cost, extremely high data
output and application to myriad astronomical observations.

This array is named the Moving Object and Transient Event Search
System (MOTESS). It was designed by Roy A. Tucker of Goodricke-Pigott
Observatory (GPO), Tucson, Arizona. It was originally implemented for 
discovery and astrometric measurement of asteroids, but it is also
used as a large-scale, cost-effective photometric monitoring
instrument with large volume data handling techniques developed under
direction of Dr. Eric R. Craine and Mark S. Giampapa of the National
Solar Observatory (NSO), Tucson, Arizona. The prototype automated
MOTESS observatory, located in Tucson, is a proof-of-principle system
for a 48-telescope, globally distributed network planned by GNAT.
During its first two years of automatic operation, MOTESS has yielded
valuable observations of asteroids as well as stellar variability.

The MOTESS system is both cost-effective and productive. Costs for
the telescope hardware are minimized through "scan-mode" operation,
whereby each telescope in the array is pointed at a specific position
in the sky with respect to the Earth. The view of the sky seen by
each telescope changes by virtue of the rotation of the Earth,
thereby scanning the sky across the field of view of each instrument.
With no moving parts in the hardware system, costs of the prototype
system were held at under $20,000, a fraction of the cost of more
traditional, comparable telescopes. The telescopes make their
observations automatically and continuously throughout the night, and
hence remain unattended by human operators during that time. Since
the cameras make one long, uninterrupted exposure throughout the
night, there is no deadtime for moving the telescopes to new
positions or inactivating camera recording while individual images
are read out. Each image has a width nearly twice the full Moons
diameter, and about 10-12 hours of time long, thus typically covering
about 200 square degrees on the sky per night, per telescope in the
array. During the course of a year, the system typically makes
several observations per night of approximately 1.5 million stars, as
well as hundreds of asteroids and transient events. 

Asteroid searches with the MOTESS system involve acquisition of
triplets of images of select regions of the sky, each telescope
contributing one of the images of the triplet each night. These
images are aligned with respect to one another and they are
alternately displayed in software such that moving objects are
visually distinguished from the fixed background stars. Detection of
asteroids as faint as 20-21 magnitude is possible with this system.
During the first year of observation, 290 newly discovered asteroids
were measured. Naming rights for over 180 new asteroids have accrued
to the program. Experience with this system is leading to data
handling software which is expected to provide automated detection of
such asteroids. 

The MOTESS system is presently accumulating a catalog of three 
brightness observations per night of the 1.5 million stars in its 
current observing list. These observations are repeated nightly 
throughout the year, enabling the creation of long-term light curves
for each of these stars. In the region of the sky along the celestial
equator presently monitored, there are 179 known variable stars, all
of which have been observed. In addition, examination of the light
curves in this database indicate that there are approximately 55,000
newly discovered variable star candidates. These include stars that
vary periodically, either due to eclipses by companion stars or by
intrinsic internal pulsations, as well as stars which vary
irregularly over long periods of time.

The MOTESS system is a pioneering complement to other planned major 
survey instruments, and it is a valuable test-bed for developing 
techniques of handling large volumes of specialized astronomical
images. Combined discovery rates of asteroids as well as varyiable
stars of many different types provides analysis opportunities which
could occupy hundreds of students and researchers for many years to
come. The flow of MOTESS data will triple by Spring of 2004 with the
implementation of six more telescopes in the emerging network of
scan-mode systems. GNAT is actively seeking collaborators interested
in studying and analyzing these interesting new objects.

For more information, see:
http://www.gnat.org/~ida/gnat/index.html

 - END OF FILE -
==========

@Message posted automagically by IMTHINGS POST 1.30
---