History:

• June 2005: Installed new IJ and JH grisms in UIST; problem with Focus and wierd arcs (see previous page).
• December 2005: UIST warm – install 4pix and 2pix slits with 3mm spacers to try and bring IJ and JH spectra into focus.
• July 2006: UIST warm over summer. Use smaller spacers to improve focus. Also update OT so new slits available (to be released later in the year). 4pix slit+spacers now give ~4-5 pix resolution.

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Jul 2005 – Normal/old slits (no spacers); new IJ and JH grisms

DAYTIME TESTING –

Arc Line width versus internal (array) focus:

Width of BB spectrum thru the 2 pix pinhole versus internal (array) focus:

The above tests “suggest” that the array needs to be focused beyond its current “high” limit of 5mm. Possible solution – move slits away from array!

Feb 2006 – New slits plus 3.5mm spacers; new IJ and JH grisms

DAYTIME TESTING –

Arc Line width versus internal (array) focus:

On arc spectra, now see sharpest lines at a focus of around zero – i.e. at the other end of array travel! Below – comparison plots from the above data.

Comparison of old/no-spacer and new/3.5mm-spacer 4-pixel slits