Time assignment information
Australia Telescope Compact Array upgrades
During 2002, an interim system will be available for observations at 12 and 3-mm wavelengths using three antennas with dual polarisation capability. System calibration is achieved at 12-mm with noise diodes, and at 3-mm with a room temperature paddle which provides a hot-cold load. The millimetre systems will remain largely unchanged during 2002, with the next major change being in early 2003 when the final systems start being delivered. The 12 and 3-mm bands remain divided into two sub-bands (16.1-18.9 and 20.1-22.5 GHz at 12-mm, and 84.9-87.3 and 88.5-91.3 GHz at 3-mm). A physical swap of hardware in the antenna vertex rooms is needed to switch between the sub-bands. The web pages on the millimetre systems are being regularly updated and are available at
http://www.atnf.csiro.au/observers/docs/3mm
and
http://www.atnf.csiro.au/projects/mnrf1996/12mm_details.html .
While the millimetre systems are being developed, proposals to use the 12 and 3-mm systems must include an ATNF collaborator.
Array configurations and shuffling
Two new configurations are being offered at the Compact array for the first time in the 2002 May observing term. The H75 configuration is a hybrid array with antennas on both the east-west and north-south tracks. This array will provide reasonably good u-v coverage with a very compact array, in four hours observing time. The EW214 configuration provides a compact east-west array that is efficient at mosaicing large areas of sky.
For millimetre observations, to optimise the Fourier coverage with a 3-antenna system, antennas will be shuffled in some configurations to optimise the baseline spacings. .
Flexible scheduling
We will use a form of flexible scheduling during May 2002 term. The aim of the flexible scheduling is to make best use of all observing conditions including weather best suited to millimetre observing. In doing this, we have to recognise that we do not have telescope operators and full service observing is not possible. Undoubtedly, the mode of flexible scheduling will evolve as we gain experience.
The mode of flexible scheduling will work by designating some centimetre projects as "swap" projects. It is expected that these will predominantly use the compact configurations. Swap projects will be paired with a "mm" project in the same array configuration to be observed earlier in the schedule. If the mm project meets with poor weather, the swap project will be observed instead, and the mm project moved into the slot vacated by the swap project. Otherwise, the swap project will observed as originally scheduled. In some cases more than one swap project may be paired with a mm project or vice versa.
The Time Assignment Committee will initially determine which projects have swap status (respecting the wishes of the proposers where possible). The PIs on cm projects designated as "swap" projects will be contacted by the scheduler after the Time Assignment meeting in early March, to discuss scheduling issues.
Bob Sault
Officer-in-Charge
Australia Telescope Compact Array
(Bob.Sault@csiro.au)