GMOS-N Fringing in the red

The GMOS-N red EEV CCDs have significant fringing in the red. This page shows examples of fringe frames in imaging mode in the i'-filter and the z'-filter as well as science data before and after correction for the fringing.

The data shown on this page were obtained the night of August 19-20, 2001, during the commissioning of GMOS-N. This was close to new moon, and the sky was photometric. The fringe strength in the z'-filter is typically +-2.5% of the background, while in the i'-filter the fringing is +-0.7% of the background. The fringe frames are also available as FITS images (117Mb gzipped tar-file).

z'-filter fringe frame.	i'-filter fringe frame. The images was median filtered with a box 17pixels by 17 pixels in order to increase the signal-to-noise. Because this fringe frame was constructed from only 6 science exposures, artifacts are seen from insufficient cleaning of signal from objects. The signal in the artifacts is typically less than 1% of the background level.

Relative strength of the fringes in the z'- and the i'-filter.

z'-filter science frame before and after fringe subtraction.

i'-filter science frame before and after fringe subtraction.

Last update June 27, 2002; Inger Jørgensen