WIYN Observatory


The One Degree Imager (ODI) is the newest instrument at WIYN. ODI utilizes both WIYN's one degree field of view and excellent image quality. The focal plane of the optical imager is sampled with 0.11" pixels, or up to 1 Gigapixels in total. The sharpness of images can be actively improved by correcting images for tip/tilt image motion during the integration. Corrections can be done over the entire field of view, using a novel detector technology called Orthogonal Transfer Array CCD, making ODI a unique and competitive instrument in the era of wide-field imaging. ODI is funded by the WIYN partners and the National Science Foundation.

ODI is currently in operation at WIYN. Thirty out of a total possible sixty four OTAs comprise the central observing area, subtending an area of approximately 48 x 40 arcminutes on a side.

ODI Overview


Telescope   WIYN 3.5m
Telescope Port   Permanently mounted at f/6.3 Nasmyth port


Field of View   1° x 1° square; 1° diameter circle unvignetted; useful science FOV for partially filled = 48' x 40'
Pixel Scale   0.11 arsec/pixel
Detectors   (partial focal plane) 30 Orthogonal Transfer Array CCDs. Each OTA CCD comprises 64 480x496 pixel cells; pixels are 12μ square
Readout Noise   7 - 11e-
Gaps between detector cells   3" in x direction
1.2" in y direction
Filling factor of each OTA   93%
Filling factor of focal plane   84% (for full focal plane with all operating cells)
QE curve of the OTA CCDs


Initial Filter Set   g',r',i',z', (u' is on order) (full size)
Filters from NOAO CCD Mosaic Imagers (in adapter)
Filters size   42cm, 42cm
Number of filter slots   9


Readout Time   30 seconds


File Size   up to 2GB, about 1GB in the current 30 detector configuration
File Format   Each focal plane readout produces a directory in which data from each OTA is contained in a 64-extension MEF file.


Active image quality improvement   On-chip image motion correction (experimental)
Atmospheric dispersion compensator
Guide Modes   Static Imaging - no OT shifting; detectors are operated like CCDs
Coherent Guiding - Identical OT shifting of all cells


All ODI data will be transferred to the ODI PPA system at Indiana University. It will be pipeline processed to remove instrumental signature, and archived. Raw and reduced data may be downloaded from the archive by PI's and Co-I's during the proprietary period and by anyone after the period ends.
Proprietary period   18 months (default)

Last modified: 23-Sep-2015 14:25:05 MST