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GRACES Integration Time Calculator

IMPORTANT: Please, make sure to stay on the safe side when you estimate the required integration time for your targets. The current version of the ITC is based on theoretical predictions of GRACES phase I performances. They give results that are close to what was observed during phase I commissioning. It will be improved after we get the first verification data of GRACES phase II.


How to use the GRACES ITC  

  1. Astronomical source definition: Enter the brightness (in mag) in the selected filter, and give a temperature for the model black body. It is currently not possible to use actual spectra of stars, galaxies or QSO. The GRACES ITC assumes photometric conditions. To correct for worse conditions, please refer to Gemini observing constraints for cloud cover and modify the brigthness accordingly. For instance, for CC70%, you must add 0.3 mag.
  2. Instrument (ESPaDOnS) configuration: Select the Olapa 1 amp option and choose the other options at your own taste. These option are the central wavelength (the wavelength at which the wavefront sensor will optimise guiding), the spectroscopic mode (star only or star+sky, see more here) and the readout mode. To choose a CCD readout speed, please refer to the Detector characteristics page.
  3. Details of observation: Enter either the aimed signal-to-noise ratio or the desired exposure time. Make sure you select between "calculate S/N only" and "calculate exposure time" accordingly.
  4. Observing condition constraints: Please refer to the Gemini observing constraints for image quality to determine the value to use under Image Quality. The three choices of Moon phases can be considered as equivalent to sky backgrounds of 20%, 50/80% (depending on the distance to the moon you choose) and Any.
  5. Click on the Calculate button.  

When preparing a proposal using GRACES, PIs have to include Overheads in their estimation of the total requested time per target.




Astronomical source definition

Point source with spatially integrated brightness mag in filter
Model black body spectrum with temperature K

Instrument (ESPaDOnS) configuration

CCD chip
Spectrum central wavelength: nm
Observing Mode:
CCD Readout Mode:

Details of observation

Total integration time to achieve a S/N ratio of (not yet implemented)
Total S/N ratio resulting from an exposure time of secs

Observing condition constraints

Image Quality: arcsec
Moon phase:
Angular distance from the Moon: deg
Zenith distance: deg


Based on the ESPaDOnS' exposure time calculator (EETC).

																														Last update February 10, 2015 by GRACES team