Current Performance of Existing Astronomical Interferometers
Interferometer and observing mode |
Waveband |
Limiting magnitude |
Minimum baseline (m)
(un-projected) |
Maximum baseline (m) |
Approx. no. visibility measurements per year
(measurements per night x nights used per year) |
Max ratio of no. phase / no. amplitude measurements
(measure of imaging performance, 0 = none) |
Accuracy of amplitude2 measurements |
Accuracy of phase measurements
(milli-radians) |
Number of spectral channels
(max in use simultaneously) |
Comments |
CHARA Array[1] |
V, R, I, J, H, K |
8 |
34 |
330 |
7500 |
0.7 |
1% |
10 |
30000 |
Yes... 30000 in the visible band; maxiumum baseline 330-m |
COAST visible |
R, I |
7 |
4 |
60 |
2000 |
0.5 |
4% |
10 |
4? |
300 cloudy nights per year, maximum baseline 100-m |
COAST infrared |
J, H |
3 |
4 |
60 |
100 |
0.5 |
20% |
10 |
1 |
300 cloudy nights per year, maximum baseline 100-m |
GI2T visible |
R, I |
5 |
10 |
65 |
2000 |
0 |
10% |
- |
400? |
CLOSED in 2006 |
IOTA |
J, H, K |
7 |
6 |
30 |
10000 |
0.3 |
2% |
10 |
1? |
Integrated optics beam combiner. CLOSED. |
ISI |
N |
0 |
10 |
50 |
5000 |
0.3 |
1% |
1 |
1000 |
Maximum baseline 70-m |
Keck Interferometer |
H, K, L, N |
10.3 |
85 |
85 |
1000 |
0 |
4% |
1 |
330 |
Nulling Key Science Underway - No imaging on a single baseline instrument; maximum baseline 11-m. CLOSED. |
Keck Aperture Masking |
J, H, K, L |
2 |
0.5 |
9 |
20000 |
0.9 |
20% |
10 |
1 |
CLOSED. |
MIRA 1.2 |
R, I |
3 |
30 |
30 |
500 |
0 |
10% |
- |
1 |
Mid-Infrared |
Navy Precision Optical Interferometer(NPOI) visible |
V, R, I |
5 |
5 |
300 |
50000 |
0.7 |
4% |
10 |
16 |
at NOFS; siderstats operational 4 x 1.8m added apertures in FY13. World's largest optical baseline-437m, 6-phased |
Palomar Testbed Interferometer[2] |
J,H,K |
7 |
86 |
110 |
50000 |
0 |
2% |
0.1 |
5,10 |
"dual-star" capable , No imaging on a single baseline instrument. CLOSED 2009. |
SUSI |
B, V, R, I |
5 |
5 |
640 |
5000 |
0 |
4% |
10 |
21 |
No imaging on a single baseline instrument; Maximum baseline 160m |
VLTI
+UTs AMBER |
J, H, K simultaneously |
7 |
46 |
130 |
400 |
0.3 |
1% |
10 |
2000 |
Used for a few weeks per year. Longest overall VLTI Baseline 130m |
VLTI
+ATs AMBER |
J, H, K simultaneously |
4 |
46 |
130 |
400 |
0.3 |
1% |
10 |
2000 |
Longest overall VLTI Baseline 130m |
VLTI
+UTs VINCI |
K |
11 |
46 |
130 |
400 |
0 |
>1% |
- |
1 |
Integrated optics beam combiner. Longest overall VLTI Baseline 130m |
VLTI
+ATs VINCI |
K |
Never checked |
12 |
200 |
400 |
0 |
>1% |
- |
1 |
Longest overall VLTI Baseline 130m |
VLTI
+UTs MIDI |
N |
4.5 |
46 |
130 |
200 |
0 |
10% |
- |
250 |
Used for a few weeks per year. Longest overall VLTI Baseline 130m |
VLTI
+ATs MIDI |
N |
4.5 |
? |
200 |
200 |
0 |
10% |
- |
250 |
VLTI inldes World's largest unfilled apertures (siderostats, 1.8-m, 8-m). Longest overall VLTI Baseline 130m |