AMBER Overview

Introduction

AMBER is a near-infrared, multi-beam interferometric instrument, combining simultaneously up to 3 telescopes. 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 ofr 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), and High Resolution K band (HR-K). For central wavelengths and wavelength coverages for LR-HK, MR-K and HR-K see AMBER Instrument Description.

When using short DIT (smaller than 200ms, see next section), only a limited spectral range can be recorded. Users interested in obtaining visibility measurements at several spectral positions inside the range allowed by each configuration can add up to two additional spectral bands.

Integration times, DIT

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

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 that 70 minutes are required for one instantaneous measurement of calibrated visibilities (ie., a measurement of the science object and a measurement of an interferometric calibrator star). This applies to all spectral modes with only one band. Each additional band in the observation adds 30 minutes to the total time. A maximum of 3 bands per observation is allowed.

Further Information

Users can find more information about AMBER, including its User's Manual, under http://www.eso.org/instruments/amber/doc/.

Contacts

Please refer to the Instrument Operation Team page.