AAO Newsletter July 1996 - Page 3
than do the other 4m-class telescopes (even after allowing for the half
share factor). The oft-cited leanness of the AAO operation is at least
in part simply due to under-nourishment. We are also concerned that the
current plans to 'privatise' the Royal Observatories could lead to a decline
in support for the Plate Library in Edinburgh, the fast measuring machines
and related facilities upon which the effectiveness of the Schmidt Telescope
operation, and hence 2dF, depends. The decision of the Australian Government
not to join ESO earlier this year means that the AAT will remain Australia's
primary optical telescope for rather longer than expected, and as such
it must be kept fully equipped with state-of-the-art instruments if Australian
astronomy is to maintain its internationally competitive position.
So the future of the AAO is rosy from the point of view of demand for
the telescopes and the number of exciting new instruments that are being
proposed, but only marginally healthy in budget terms. A relatively small
injection of cash would make a big difference and enable the expertise
and enthusiasm of the staff to be fully utilised for the benefit of astronomy.
I am pleased to be able to hand over the Observatory in a good state, confident
that it will continue to thrive under Brian Boyle's leadership, and grateful
to have had the opportunity to work with such a good team and to contribute
to so many exciting enterprises over the last decade.
2dF Commissioning
Significant progress has been made, on both positioner and spectrograph
fronts, since my last newsletter article.
While the May commissioning
was heavily compromised by poor weather, we were able to make significant
progress with 2dF positioning and auto-guiding. In particular, simultaneous
auto-guiding on all 4 guide fibres was achieved using stars beyond our
expected practical, good seeing limit of V ~ 15. Furthermore we were able
to demonstrate that the auto-guide signal was imperceptibly perturbed by
movement of the fibre positioner gantry thus validating the design goal
which requires us to observe while re-configuring.
The June on-telescope
commissioning saw an incomplete but nevertheless impressive system, with
about 250 fibres mounted, 190 of which fed our No. 1 spectrograph. While
the positioner itself was routinely displaying fibre positioning accuracy's
in the order of 0.3" rms we had not, at this stage, the ability to
study radial trends in the data. More work clearly needed to be done to
fully characterise the positioner's astrometric performance, however the
signs were that the system was working close to the specified accuracy.
Configuration speed, however, was still relatively slow and we await the
new amplifiers (probably not until October) before attempting a significant
increase in gantry speed.
After much effort, spectrograph focus was achieved approximately uniformly
over the full surface of the chip to a ~ 2.3 pixel (FWHM) level, quite
good enough for science observations but with still some way to go before
getting to the sub 2-pixel, expected performance. Of some significance,
however, was the fact that system throughput (telescope; fibres; spectrograph)
approximated to expected performance levels. Only crude estimates were
made and we await a careful photometric campaign before giving definitive
numbers, however there is little doubt now that the 2dF will come
