Yale/WIYN One Degree Imager Survey Observational Strategy

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To maximize our competitive advantage in image quality, we intend to use the best imaging conditions for observations in a single bandpass. Barring unforeseen problems with fringing, we expect that bandpass to be the i-band. We expect to be able to achieve deep co-added images with FWHM <= 0.5", superior to any other existing or planned imaging survey of more than a few degrees prior to the launch of a JDEM mission. Much of our science is geared to exploit this unique capability. In "medium" seeing, we will obtain data in other bandpasses such that the total depth in the summed images is comparable (although the image quality will necessarily be poorer), and also a few i-band images for time-series purposes. In "poor" seeing we will execute projects specifically designed for such conditions that are not necessarily part of the main survey. Thus the available observing time might be divided into four categories:

We expect that each visit to a given survey field will include a number of dithered images, each of which will have an exposure time of a few minutes. The depth per visit will thus be comparable to the depth per visit planned for the LSST. The specific exposure time per image will be greatly dependent on the readnoise of the array, since we hope to achieve sky-limited imaging. Given the small size of our pixels, this is likely to impose a significant constraint. We expect there will be at least 20 visits per field, thus obtaining the desired total depth, and providing enough separate visits to determine periods for periodic variables. Visits will be scheduled to provide logarithmic time sampling from minutes to years. The combination of logarithmic time sampling and sufficient repeat visits to determine periods will also be a unique feature of our survey.

In 150 nights, with typical weather conditions,we expect to cover between 30 and 100 fields, depending on the depth and number of visits desired for each field - discussions continue on the exact tradeoff between depth and coverage. The fields are likely to be grouped into three contiguous regions, as follows:

Note that other fields can be observed as part of add-on or extension programs