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Alopeke & Zorro

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Overview of Capabilities

'Alopeke and Zorro (Hawaiian and Spanish for "fox") are identical fast, low-noise, dual-channel, and dual-plate-scale imagers based on the Differential Speckle Survey Instrument (DSSI, Horch et al.2009, 2012). 'Alopeke was built in 2017 and is permanently mounted on the calibration port at Gemini North. Zorro has been mounted on the calibration port at Gemini South on May 2019. In speckle mode they provide simultaneous two-color diffraction-limited optical imaging (FWHM~0.02" at 650nm) of targets as faint as V~17 over a 6.7" field of view. Wide-field mode provides simultaneous two-color imaging in standard SDSS filters over a 60" field of view.

'Alopeke and Zorro each have two identical Andor iXon Ultra 888 EMCCD cameras. These 1024x1024 detectors have 13 μm pixels and are capable of 26 fps readout of the full chip, and faster readouts are possible for subarrays. The detectors have an EX coating with > 80% quantum efficiency from 420 to 780 nm and > 90% QE between 550 and 720 nm.

A fixed dichroic splits the input telescope beam at 674 nm, with blue light reflected to the blue filter wheel and red transmitted to the red filter wheel. The plate scale is 0.0096"/pix in speckle mode and 0.0725"/pix in wide-field mode. The cameras underfill the detectors yielding circular fields of view of 6.7" in speckle mode and 60" in wide-field mode.

The standard procedure for speckle imaging at Gemini is to operate the EMCCDs using 60 msec exposures, and gather images in sets of 1000 frames.

The visiting instrument team will take all observations and will provide their standard pipeline-reduced speckle data products to PIs. There is no requirement to collaborate with the instrument PI for this level of service. If you need more than this, then the PI would appreciate an offer to collaborate. All raw and reduced data will be made available via the Gemini Observatory Archive.

Papers containing 'Alopeke and/or Zorro data should acknowledge Gemini and the 'Alopeke / Zorro team.

The PI for the Gemini Speckle program is Steve Howell (NASA Ames Research Center).

The 'Alopeke Instrument Scientist is Andrew Stephens.

The Zorro Instrument Scientist is Ricardo Salinas.


Please see the Status and Availability pages for more information.

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Gemini Observatory Participants