Integration Time Calculator Help

Gemini North		Gemini South
NIRI (near-IR imager with grism spectroscopy) - v4.2		Acquisition Camera (optical imaging) - v4.0
GMOS North (optical imaging and long-slit spectroscopy) - v4.0		GMOS South (optical imaging and long-slit spectroscopy) - v4.0
Michelle (mid-IR imager and spectrometer) - v4.1		T-ReCS (mid-IR imager and spectrometer) - v4.0
NIFS (near-IR itegral field spectrograph) - v4.2		GNIRS (near-IR spectroscopy) - v4.0
		bHROS (high-res optical spectroscopy) - not yet available
		Phoenix (high-res near-IR spectroscopy) - time calculator at NOAO

Recent updates: 24may2007 Added LGS support for NIRI. Merged NIRI and NIRI+Altair. Added support for NIFS + P2. Minor form changes. 15Sep2006 Added filter profiles for NIRI(v4.1). Removed sky background constraint for Michelle(v4.2). 24may2006 Fixed bug with minimum emission line width that affected all the instruments. Also added HK notch filter for NIRI. 28feb2006 NIFS added to the list of available ITC's. Added support for Michelle Polarimetry in the imaging mode. 23jun2005 New near-IR and mid-IR background files and updated throughputs provide improved match to observed performance. Background and atmospheric transmissions models are high resolution for Michelle echelle. Michelle spectroscopy re-enabled. 23jun2005 All v4.0 ITC running on new server for improved calculation speed.		Recent updates: 24may2007 Minor form changes. 24may2006 Fixed bug with minimum emission line width that affected all the instruments. 28feb2006 New filters added for GMOS South. 23jun2005 New near-IR and mid-IR background files and updated throughputs provide improved match to observed performance. Background and atmospheric transmissions models are high resolution for GNIRS R=18000. T-ReCS re-enabled. 23jun2005 All v4.0 ITC running on new server for improved calculation speed.

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, which 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. Changes, enhancements and bugs within the ITC are listed chronologically.

Caution: the ITCs make some as yet unverified 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 4s, spectroscopic calculations take 10-20s, longer for large IFU calculations. (The calculation is the same in the spectroscopic case as for imaging but generating the graphics consumes 10-15s).

We are collecting a wishlist of modifications and improvements for possible inclusion in future releases. Please e-mail Bryan Miller (bmiller@gemini.edu) with suggestions (but use the HelpDesk for questions!).

Introduction to the Integration Time Calculator