ESO Faint Object Spectrograph and Camera
CCD#40 Flexture with Pointing

Spectral line shifts were determined for a number of telescope pointings relative to the line position at zenith. The set-up comprised Grism #8 with 0.7" slit and unbinned pixels. Three exposures of helium arc lamp spectra were taken at each position except at zenith where 4 sets of 3 exposures each were taken.  The results are plotted below.
NOTE : It has recently been noticed that strong fringes in the red part of the spectrum are not eliminated competely using dome flats. They did disappear when internal flats taken at the same position were used. We are carrying out tests to see if this can be reproduced  and if it is related to flexure.

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Last modified: Tue Jan 15 20:11:04 CLST 2002 

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