VLTI Matisse

Important notes and bug reports

Note: Point like telescopes are assumed. These tools are only provided for the technical assessment of the feasibility of observations. Variations of the atmospheric conditions can strongly affect the fringe visibility. Users are advised to apply caution in the interpretation of the results and are kindly requested to report any results which may appear inconsistent.

General description

The VLTI Matisse is an Exposure Time Calculator. It uses a model of the VLTI and its instruments to assess the fringe visibility, given the observed bandpass, the geometry, spectrum, and coordinates of the target and the time at which the observations are to be made. It also takes into account shadowing by telescope structures and the maximum available stroke of the delay lines for the feasibility assessment of the observations.

The tool offers an HTML/Java based interface and consists of two pages. The observation parameters page presents the entry fields and widgets for the target spectrum and geometry, time of observation, instrument configuration and results selection. A "Submit" button submits the parameters to the model executed on the ESO Web server. The results page presents the computed results. The optional graphs are displayed within Java applets allowing interactive manipulation. The results are also provided in ASCII and GIF formats for further analysis and printing. Finally, a summary of the input parameters is appended to the result page.

Instrument Properties

• Observing mode

• Spectral resolution

• Fringe Tracking settings

Target Properties

In this section, the spectrum and geometry of the target to be observed must be defined.

• Target Spectrum

  • Template Spectrum

  • Blackbody

• Target Coordinates

  • HMS

  • Degrees

  • Simbad

• Target Magnitude

  Here you specify the target magnitudes, as needed.

  • Magnitude in band of observation

    J, H, K, or N band, needed to find matching calibrator.

  • Magnitude in H band

    Only needed if FINITO is to be used (fringe tracking in H band).

  • Magnitude in V band

    Magnitude of the target itself or its Coude offset guide star in V band to check feasibility of guiding.

• Target Geometry

  • Uniform Disc

    Here you specify the uniform disk equivalent diameter of your target. This value is needed to predict visibility amplitudes of the target. A suitable calibrator would have amplitudes significantly larger than these to provide a reliable calibration.

    • Uniform disc diameter

      Given in mas.

  • Gaussian

    • Gaussian FWHM

      Given in mas.

  • Elliptical Gaussian

    • Major axis

      Given in mas.

    • Minor axis

      Given in mas.

    • Angle

      Given in deg.

  • Binary

    • Diameter, Primary

      Given in mas.

    • Diameter, Secondary

      Given in mas.

    • Separation

      Given in mas.

    • Position Angle

      Given in mas.

    • Brightness Ratio

Observation Setup

• Universal Time

  Best suited for planning visitor mode observations on a specific date. In service mode, January is best for RA of 8h, then advance RA by 2h for each month, e.g. April for RA of 14h, July for RA of 20, October for RA of 2h.

  • Date

    UT Date on which the observation shall take place

  • UT Start

    Time at which the observation shall start. Measured in Universal Time (UT).

  • UT End

    The length of time the observation shall take.

• Local Sidereal Time

  Best suited for planning service mode observations on any date.

  • LST Start

    LST at which the observation shall start.

  • LST End

    LST at which the observation shall end.

• Hour Angle

  Best suited for planning service mode observations on any date.

  • HA Start

    HA at which the observation shall start.

  • HA Duration

  • HA Step

• Baseline Configuration

  Please select the telescopes of a baseline individually.

Version Information

Send comments and questions via https://support.eso.org/