Current Performance of Ground-Based Interferometers
Here is a list of currently existing astronomical interferometers, and some parameters describing their performance.
Columns 2-5 determine the range of targets that can be observed and the range of science which can be done. Higher limiting magnitude means that the array can observe fainter sources (and the most interesting sources are often very faint). The limiting magnitude is determined by the atmospheric seeing, the diameters of the telescopes and the light lost in the system. A larger range of baselines means that a wider variety of science can be done and on a wider range of sources.
Columns 6-10 indicate the approximate quality and total amount of science data the array is expected to obtain. This is per year, to account for the average number of cloud-free nights on which each array is operated.
Current Performance of Existing Astronomical Interferometers
Interferometer
and observing
mode | Waveband | Limiting
magnitude | Minimum
baseline
(m) | Maximum
baseline
(m) | Approx. no.
visibility
measurements
per year | Max ratio of
no. phase /
no. amplitude
measurements | Accuracy of
amplitude2
measurements | Accuracy of
phase
measurements | Number of
spectral
channels | Comments |
| | | | (un-projected
baseline) | | (measurements
per night x
nights used
per year) | Measure of
imaging
performance
0 = none | | (milli-radians) | (max in use
simultaneously) | |
COAST
visible | R, I | 6 | 4 | 60 | 2000 | 0.5 | 4% | 10 | 4? | 300 cloudy
nights per
year |
COAST
infrared | J, H | 3 | 4 | 60 | 100 | 0.5 | 20% | 10 | 1 | 300 cloudy
nights per
year |
GI2T
visible | R, I | 5 | 65 | 65 | 2000 | 0 | 10% | - | 400? | |
| IOTA | J, H, K | 7 | 6 | 30 | 10000 | 0.3 | 2% | 10 | 1? | |
| ISI | N | 0 | 10 | 50 | 5000 | 0.3 | 1% | 1 | 1000 | |
Keck
Interferometer | K | 10 | 85 | 85 | 1000 | 1 | 4% | 1 | 1 | |
Keck Aperture
Masking | J, H, K, L | 2 | 0.5 | 9 | 20000 | 0.9 | 20% | 10 | 1 | |
| MIRA 1.2 | R, I | 3 | 30 | 30 | 500 | 0 | 10% | - | 1 | |
NPOI
visible | V, R, I | 5 | 5 | 300 | 50000 | 0.7 | 4% | 10 | 16 | |
| PTI | K | 6 | 110 | 110 | 10000 | 1 | 4% | 0.1 | 1 | |
| SUSI | B, V, R, I | 5 | 5 | 640 | 5000 | 0 | 4% | 10 | ? | |
VLTI
near infrared
See below for
future performance | J, H, K | 12 | 46 | 130 | 400 | 0.3 | 1% | 10 | 4000? | Used for
interferometry
a few weeks
per year |
VLTI
mid infrared | N | 4 | 46 | 130 | 200 | 0 | 10% | - | 250 | Used for
interferometry
a few weeks
per year |
New Interferometers and Improvements to Existing Interferometers
Expected Future Performance of Astronomical Interferometers
Interferometer
and observing
mode | Waveband | Limiting
magnitude | Minimum
baseline
(m) | Maximum
baseline
(m) | Approx. no.
visibility
measurements
per year | Max ratio of
no. phase /
no. amplitude
measurements | Accuracy of
amplitude2
measurements | Accuracy of
best phase
measurements | Number of
spectral
channels | Comments |
| | | | (un-projected
baseline) | | (measurements
per night x
nights used
per year) | Measure of
imaging
performance
0 = none | | (milli-radians) | (max in use
simultaneously) | |
| CHARA | J, H, K | 12 | 70 | 400 | 100000 | 0.7 | 1% | 10 | 100? | 2005? |
LBTI near
infrared | J, H, K | >20 | 8 | 22 | 10000000 | 1 | 30% | 100 | 100? | 2006? |
| MRO | R, I, J, H, K | 14 | 7 | 400 | 100000 | 0.6 | 1% | 10 | 1000? | 2008? |
VLTI
near infrared
using 4 ATs
and PRIMA | J, H, K | 13 | 8 | 200 | 10000 | 1 | 1% | 0.1 | 4000? | Operating
every night
2008? |
VLTI
near infrared
using 3 UTs
and PRIMA | J, H, K | 16 | 46 | 130 | 500 | 1 | 1% | 0.3 | 4000? | 2008? |
