AAOmega - multiple-object
mode characteristics.
AAOmega will use the refurbished
2dF fibre positioner
to provide multiple-object spectroscopy of 350-392 objects (exact
number not yet determined) over a 2 degree
field of view. The refurbishment includes a number of enhancements
to the 2dF fibre positioner to improve performance and reliability, including:
new (flatter) field plates, a redesigned gripper z-drive, and
new fibre retractors. The number of guide/fiducial fibre bundles
will increase from 4 to 8, improving both the chances of allocating guide
stars and the autoguiding efficiency.
The existing 8m-long 2dF
fibres will be replaced with 35m long STU fibres that allow the new
AAOmega spectrograph to be
located in the Coude room. This will provide a very mechanically
and temperature stable environment, and consequently much reduced
systematics, important for observations at high spectral resolution.
A summary of the predicted performance of AAOmega in
multiple-object mode is given in the table below.
| AAOmega
- multiple-object mode |
|
| Field of view |
2 degrees |
| Number of fibres |
350-392 |
| Angular size of fibre |
2.0" |
| Wavelength range |
0.37 - 0.95 microns |
| Dispersion |
0.2 - 0.5 Å/pixel |
Spectral resolution ( / ) |
1300 - 8000 |
| Spectral resolution (FWHM) |
3.5 Å |
| Peak system throughput (Blue/Red arm) |
0.17/0.201 |
| Limiting magnitude |
B = 22.02 |
1 End-to-end throughput, from top of atmosphere to CCD,
including fibre seeing losses.
2 Calculated for a galaxy in 1" seeing, exposure time
of 4 hours, with a S/N=10/Angstrom
Last modified: 3 July 2003, Terry Bridges.