AMBER Overview


AMBER is a near-infrared, multi-beam interferometric instrument, combining simultaneously up to 3telescopes. AMBER can be used in Period 82 and following with UTs or ATs (see below for current performance specifications). All possible triplets of UTs are available,and a number of selected AT combinations. For the telescope positions and baseline lengths of the different AT and UT baselines, please refer to URL: VLTI Configuration page

Because of the scarce availability of UTs for AMBER, it is recommended that any scientific program of the UTs is designed so that scientifically meaningful results can be achieved in a single night.

Spectral Modes and Coverage

The following spectral modes are offered: the Low Resolution K band (LR-HK), Medium Resolution K band (MR-K),Medium Resolution H band (MR-H), and High Resolution K band (HR-K). For central wavelengths and wavelength coverages for LR-HK, MR-K, MR-H and HR-K see AMBER Instrument Description.

the choice of the DIT impacts the spectral range that can be recorded. see next section.

Integration times, DIT

If no fringe tracker is used (i.e. for faint and/or extended objects, or airmass too high), the DIT has to be short to minimise atmospheric turbulence. For LR-HK and MR-K, DITs are fixed to 25 ms on the UTs and 25ms or 50mson the ATs if absolute visibility measurements are the goal. In HR-K it is assumed a DIT of 50 ms for absolute visibilities. For closure-phase anddifferential-mode the maximum allowed DIT is twice the DIT allowed in absolute mode. DITs longer than this can onlybe done in Visitor Mode (under exceptional weather condition).

External fringe tracking with FINITO is available on both the UTs and the ATs. FINITO is used by default in MR and HR, since then longer DITs are possible, allowing AMBER to readout the full chosen spectral band.

Please refer to the instrument description page for limiting magnitudes.

Execution times

The user should assume between 60 to90 minutes are required for one instantaneous measurement of calibrated visibilities (ie., a measurement of the science object and a measurement of one or two interferometric calibrator star). Please refere to the AMBER User Manual for more information.

Further Information

Users can find more information about AMBER, including its User's Manual, under


Please refer to the Instrument Operation Team page.