Throughput
The relative throughput of
Small Fibres is plotted as a function of the fibre number. Most fibres lie
in the region within 15% from the median throughput; the few ones with lower
throughput are under examination and a higher sensitivity might be restored
for the forthcoming runs.
On October 2004, some first measurements of the absolute throughput
of the Small Fibres and Wyffos Long Camera were obtained under variable seeing
conditions of 1-1.3 arcsec. The following Table reports the magnitude
of a star giving 1 electron/sec/Angstrom when observed at zenith (1 airmass).
Numbers are scaled to the "median" fibre (i.e. to the median relative throughput).
|
Lambda (Å) |
3700 |
4000 |
4500 |
5000 |
5500 |
6000 |
6500 |
7000 |
7500 |
8000 |
8500 |
9000 |
| R600B |
mag (1 e-/sec/Å) |
13.1 |
15.3 |
16.3 |
16.6 |
16.5 |
16.3 |
16.0 |
|
|
|
|
|
| R600R |
mag (1 e-/sec/Å) |
|
|
|
|
|
|
16.6 |
16.6 |
16.5 |
16.5 |
16.5 |
16.2 |
Estimates for other gratings can be obtained by scaling the above figures
according to the relative efficiency of the
ISIS gratings.
No direct throughput measurements are available yet for the WYFFOS
echelle mode with the Small Fibres, but they are expected to be similar to
the figures ( PDF format
) measured in the past for the Large Fibres.
