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Imaging

The properties of NIRI in imaging mode are summarized in the following sections. Three selectable fields of view and pixel scales are available. With adaptive optics NIRI is available at f/32 for J-L' imaging (but see caveats for L'), and at f/14 for imaging out to 2.5 microns due to the increased thermal background. Imaging at L' is impossible at f/6 and only sometimes possible at f/14. The narrow band L filters (e.g., the PAH filter, Br alpha) can be observed at f/32, f/14, and f/6. M' imaging is only possible at f/32.

NIRI

Overview of NIRI's Capabilities

Gemini's Near InfraRed Imager and Spectrometer, NIRI, was built by the University of Hawaii's Institute for Astronomy. It provides a range of imaging and spectroscopy options in the 1-5 micron wavelength region.

NIRI's detector is a 1024x1024 ALADDIN InSb array. The instrument has three cameras: f/32, f/14, and f/6. In imaging mode they provide plate scales of 0.022, 0.050, and 0.117 arcsec pixels, respectively and fields of view of 22x22, 51x51, and 120x120 arcseconds squared, respectively.

Observing with Gemini

How to observe with Gemini. Is this better as an expanded menu with a lot of items, as it is now (broken up by headings for Phase I and Phase II), or with just 3 expandable subheadings beneath it, or broken into two categories (phases 1 and 2) at the top level?

Imaging

Basic characteristics of Michelle's imaging mode

  • Several medium and narrow-band 10 um and 20 um filters (chop and nod)
  • Image FWHM at or approaching the diffraction limit (FWHM ~ 1.22 lambda/D ~ 0.31" at 10 microns, ~0.63" at 20 microns)
  • Pixel dimension = 0.1005" (imaging only)
  • Field of view = 32"x24" in imaging mode (but note that current maximum chop throw is 15")
  • Imaging usually not available using the broad band N and Q filters, due to detector saturation

Michelle

Overview of Michelle's Capabilities

Michelle is a mid-infrared (7-26 micron) imager and spectrometer, formerly in use at UKIRT but now on long-term loan at Gemini. Michelle is available for imaging and spectroscopy with all of its gratings and its echelle. Imaging polarimetry is now also supported.

Long-slit Spectroscopy

Long slit spectroscopy can be obtained in either normal or Nod-and-Shuffle modes using GMOS standard slits or custom slits.

Imaging

GMOS can perform broad band imaging (using the SDSS filter system) or narrow-band imaging using select filters. The field of view is 5.5 arcmin x 5.5 arcmin (and does not cover the entire CCD package), with two ~ 2.8 arcsec (39 pixel) gaps between the detector chips, as shown below (GMOS-S, GMOS-N original EEV CCDs and upgraded e2v DD devices). To cover the gaps it is recommended to use dither steps of at least 5 arcsec in the X-direction.