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