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Integration Time Calculators

Available integration time calculators:

Gemini North Gemini South
GMOS North (optical imaging and long-slit spectroscopy)   GMOS South (optical imaging and long-slit spectroscopy)
NIRI (near-IR imager. For AO imaging at L' see here)   GSAOI (near-IR AO imager for GeMS)
NIFS (near-IR integral field spectrograph) Flamingos-2 (near-iR imaging and long-slit spectroscopy)
Michelle (mid-IR imager and spectrometer)   T-ReCS (mid-IR imager and spectrometer)
GNIRS (near-IR spectroscopy)   Acquisition Camera (optical imaging, instrument retired)

The Gemini Integration Time Calculator (ITC) consists of a web form in which the user defines the principal aspects of the observation and a Java servlet, resident on a Gemini Observatory computer, performs the calculation and generates the results.

The web form is divided into four sections: (1) the spatial profile, spectral shape and brightness of the astronomical source, (2) the instrument and telescope configuration, (3) the observing conditions and (4) methods of how the observation will be carried out and the results analysed. There are additional help pages in each section that provide further information (e.g. see the more info links within the form).

Within the form, the desired characteristics are defined by selecting radio buttons (e.g. to choose between point or extended source), pull-down menus (e.g. to select the units for source brightness) and text boxes to enter numerical values (e.g. for source brightness). Clicking on the calculate button will post the user-defined values to the servlet and create an output web page containing the results. Unavailable features are indicated by red crosses.

The ITC is built around re-usable modules (e.g. for definition of the astronomical source) and specific elements for individual instruments. There is a separate web form for each instrument. Only the facility instruments listed above are supported; sensitivity tables are available for visiting instruments on the relevant web pages.

caution Caution: the ITCs make some assumptions about telescope and instrument performance and approximations for computational simplicity. Estimated accuracies will be posted as they become available. The calculated integration times do not take overheads into account.

ITC performance: imaging calculations typically take 2-3s, spectroscopic calculations take 4-5s, and calculations with multiple IFU elements take slightly longer.

Please report any problems with the ITCs via the Gemini HelpDesk. Please e-mail Bryan Miller ( with suggestions (but use the HelpDesk for questions!).