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MACHO Observations: Sharing 0.9-m Telescope Time (1Dec94)
(from CTIO, NOAO Newsletter No. 40, 1 December 1994)

As of 1 September, the MACHO project started nightly observations on the
0.9-m telescope. MACHO stands for Massive Compact Halo Object; the
MACHO team is searching for gravitational lensing events that might reveal
baryonic dark matter in the galactic halo.

The MACHO agreement, between the Center for Particle Astrophysics at the
University of California, Berkeley, and CTIO/NOAO, runs for two years,
five months, subject to yearly renewals. They have been allocated 13% of
the 0.9-m time throughout the year, with an additional week of dedicated
observing per year, to result in a total of 15% of the available time.

As part of the agreement, CTIO has agreed to obtain MACHO observations
every usable night on relevant target fields in the Galactic bulge and the
Magellanic Clouds. The MACHO team have shipped a Sun workstation,
disk, and Exabyte drive here, which have been integrated into our network.
When the telescope is turned over for the MACHO time (currently about 70
minutes/night) the CCD acquisition and data storage runs from their
machine. The "normal" 0.9-m observers stay logged into their own console
and can continue to process and inspect data, etc. A timer is started in the
MACHO Sun, which begins a countdown. Observations are being taken by
CTIO Observer support personnel, and calibrations are being taken in the
mornings by observer support.

In return for these services, the MACHO project is providing CTIO with
some funds dedicated to improving the performance of our small telescopes.
With these funds, we intend to make additional hires to assist in the data
taking and to carry out a telescope improvement plan. Currently on our
improvement list for the 0.9-m are installation of fans in the (closed)
telescope tube, a temperature monitoring system, a corrector/field flattener,
guiding and focus upgrades, and primary mirror support improvements.

The 0.9-m observers were notified of this program by a memo from J. Elias
in their telescope assignment letters. They have been allocated additional
nights over the TAC recommendation to compensate for the 13% loss to the
MACHO observations. We have been e-mailing the observers to notify them
about the actual time during each night that the MACHO observations are
scheduled, approximately one week in advance of the scheduled runs.

As always, sharing nights and telescope time is a delicate business. The
MACHO team are aware of these issues, and have been very reasonable and
flexible. Cordial relations and considerate discussions among all involved
will help make this a successful scientific program, and should benefit all
the users of our telescopes, and the observatory in general.

Bob Schommer

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