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Library Fringe Frames

For each WFS run on the INT a series of library fringe frames are being constructed for any R (see note at bottom of page), I, i', or Z-band data taken. As expected filters blueward of R show no measurable fringe patterns. WFS runs using the SDSS r' filter show no measurable sky fringes, highlighting the pitfalls caused by the extended the red tail of the conventional "Harris" R-band filter.

Using the red filters results in the following fringing levels - for reference rms dark sky photon noise is approximately 1% of sky for a 600s exposure.

After optimally removing the zeroth order fringes the residual fringe pattern is generally < 1/10th of the original level. In particular the results so far indicate that:

Zeroth order fringe removal has been done for all R, I, i' and Z-band data taken and processed throught the WFS pipeline (from more details click here ).

The master zeroth order fringe frames (or sky super flats if you prefer that term) were constructed using imcombine within IRAF to produce a nightly stacked image for each passband. Each of the nights was them imcombined to produce the "average" or zeroth order fringe frame for each separate observing run. Examples of these are accessible below.

The simplest way to access a file is to select the appropriate month/year, click on the link to obtain a listing of available files, and then right click to download the file.

WFS fringe maps are now available on   flatsnbiases page

For examples of other fringe frames contact