's tiling capabilities are aimed at quickly localizing astrophysical transients, such as GRBs and other transients, with positional error circles that cannot be covered by a single XRT 23.6′ diameter field of view.
Targets of Opportunity (ToOs) that make use of the tiling capabilities are limited to a single series of observations to cover all of the tiles until the requested exposure time is reached. Any follow-up observations should be requested with additional ToOs after the source has been localized within the tiles. Since tiling observations require quick response from the Observatory Duty Scientist, may require significant observing time, and override previously scheduled targets, you will be asked to justify your need of tiling in your request.
The default tiling configurations consist of four and seven tile patterns, in a fixed pattern. The configuration of these tiles are shown below, with estimates of the complete and maximum coverage radii. These should be compared to the approximately 11.8′ radius of the XRT field of view. It is not possible to alter any parameters of the tiling other than the choice of 4- or 7-tile pattern, and the choice of center of the tiling pattern, as these tiling patterns are executed automatically on-board Swift
This means that these tiling patterns offer the quickest way for Swift
to observe targets with larger error circles. More complex tiling observations may be available through manual planning, but will have a much higher overhead and will take longer to be observed.
Four Tile Pattern
Seven Tile Pattern