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DSSI Speckle Camera (North)
Overview of Capabilities
DSSI (Differential Speckle Survey Instrument, Elliott Horch, Southern Conn. St. Univ.) provides simultaneous diffraction-limited optical imaging (FWHM~0.02" at 650nm) of targets as faint as V~16-17, in 2 channels over a ~2.8 - 5.6 arcsecond field-of-view.
DSSI was built in 2008 and more recently upgraded with two new Andor Ixon Electron-Multiplying CCDs (EMCCDs). The EMCCDs are 512x512 pixels each with plate scales of 0.011 arcsec/pixel at Gemini. DSSI collimates the input beam and splits it, using a dichroic, into blue and red components which are passed through filters and then focused onto the two EMCCDs.
The standard procedure at Gemini is to operate the EMCCDs using 60 msec exposures, and gather images in sets of 1000 frames (yielding total exposure times of integer minutes). This readout rate is made possible by windowing the readouts for each camera to a 256x256 pixel region (ie. a 2.8"x2.8" field, which is the largest practical field to match an isoplanatic patch of atmosphere). The photon-multiplying properties of the EMCCDs produce effectively very low read-noise data, enabling speckle imaging of much fainter targets than has been historically possible. The diffraction-limited resolution possible at Gemini (0.016" FWHM at 500nm or 0.025" at 800nm) offers proposers unique capabilities.
The PI for the Gemini-North Speckle program is Steve Howell (NASA Ames Research Center).
The camera is expected to be offered to the Gemini community in 2013B for a period of up to three weeks from late July to late Auguest. Therefore targets with RAs between 15h and 3h (wrapped around 0h) may be proposed for, subject to actual scheduling and required total exposure time.
Please see the Status and Availability pages for more information.
DSSI Science Highlights
How to Use These Pages
The DSSI pages are organized as follows:
- Status and Availability: Modes available in upcoming semesters; links to news items.
- Imaging: Components used in imaging mode and guidance on how best to use the instrument in this mode.
- Sensitivity: Sensitivity estimates.
- Overheads: Details of the observing overheads.
- Guiding Options: Guiding considerations, and wavefront sensors available for use with the camera.
- Calibration: How to calibrate the observations.
- Observation Preparation: How to configure the instrument.
- Data Format and Reduction: Description of data reduction resources.
- Documents: Design documents and references.