Previous Article
Next Article
Table of Contents

A New TAC Process (1Mar96)
(from KPNO, NOAO Newsletter No. 45, March 1996)

Several years ago the demand for dark time was largely composed of
proposals for observations of faint extragalactic objects, while the
bright time was primarily used for galactic objects and stellar
evolution programs. Since a separation by lunar phase also separated
the overall scientific areas of interest, KPNO convened two committees,
the "Bright" TAC and the "Dark" TAC with different areas of scientific
expertise to reflect this difference in demand.

The development of infrared arrays changed all this. We are now seeing
many proposals in bright time that require expertise in extragalactic
astronomy for proper evaluation. Similarly, the advent of wide field
CCD detectors gave rise to programs in dark time that addressed
problems in stellar populations in our own and nearby galaxies. The
composition of the two committees rapidly changed to reflect this new
demand, and both committees now have expertise in galactic and
extragalactic astronomy. However, the two committees still retain the
"Bright" and "Dark" names, and for the larger aperture telescopes the
proposals seen by each committee are still sorted by lunar phase. This
can cause some problems, particularly when a given program asks for
dark time on one telescope and bright time on another. Moreover, having
both galactic and extragalactic expertise on both committees means that
this expertise must be spread rather thinly if each committee is to be
an optimal size.

We have been aware of these problems caused by the evolution of the TAC
process and have been exploring options for addressing them. An
additional complication arises from the need to consider future demands
on the TAC process, such as inclusion of Gemini programs and review of
programs that may involve time at private observatories. Discussions on
this complex topic have been held at a special AURA workshop last
spring, with the combined KPNO/CTIO Users Committees during their fall
1995 meeting, and with each of the standing KPNO TACs. Options
discussed ranged from maintaining the status quo to establishing many
narrowly focused discipline-specific panels.

The general outcome of these discussions is one of evolutionary change
with an eye to future demands. Thus for the fall 1996 semester there
will again be two KPNO TACs, but they will be named "Galactic" and
"Extragalactic," with expertise concentrated in the appropriate areas.
The division between "Galactic" and "Extragalactic" is not always
clear. In general "Galactic" will include objects in our galaxy and the
Local Group. However, the Galactic committee will have general
expertise in stellar evolution and stellar populations, so proposals
that explore the evolution of stellar populations in distant galaxies,
if done spectroscopically, could go to the "Galactic" TAC. However,
stellar population studies at very high redshift that use wideband
photometry with multiple bandpasses would probably go to the
"Extragalactic" TAC. In order to assist us in sorting the proposals,
the proposal form will be revised to allow you to pick the category in
which you wish your proposal to reside. This change will not only
allow for a better match of expertise to programs for each TAC, it
will also allow one TAC to evaluate completely complex programs that
require several telescopes at different lunar phases.

After the TAC review, the telescopes will be scheduled as before. We
anticipate that the extragalactic programs will still demand most of
the dark time, and that this lunar phase will, for most telescopes, be
more heavily oversubscribed than bright time. Proposals with the
highest TAC grade will be given preference in terms of lunar phase.

We hope this change in the TAC procedure will produce an improved
review process. Please send us your comments on any aspect of our
proposal review program. We will continue to monitor its performance
and will make further changes in response to your comments and to
changes in our users' needs.

David De Young

Previous Article
Next Article
Table of Contents