1.2m CCD Filters

  • Observers are not allowed to change CCD filters. Please ask the staff during daytime or by email before you arrive if you need to change filters. Plan to arrive the day before your run, especially if you will be bringing filters.

  • We have two sets of 4" UBVRI filters used in the top box for the CCD.

  • The set currently in use, called the Harris Set, was delivered in the fall of 1998. These filters are thinner than the SAO set, and are MgF coated. As well, the U filter has a liquid CuS04 cell for red blocking, and thus is far superior to the all-glass U filter of the SAO set. Click here for transmission curves or for a listing There is no curve for the U + CuSO4 filter yet, but here is the U1 glass itself (assume that the red leak is taken care of by the CuSO4), and here is the transmission curve of a similar filter owned by KPNO. The interference I filter was delivered in April of 1999. It has a better-defined transmission curve than the SAO I, which is a long pass filter, thus even though the improvement is small (10%), the transformation to standard Kron-Cousins I should be better than for data taken with the SAO I filter.


    • The Harris BVRI filters are parfocal, but for U, the focus is about 80 (old) units higher.

    The SAO set, dating from 1992, is all glass, and is coated with Sol Gel; thus it cannot be cleaned. This set also includes a Z filter with strong astigmatism. Click here for transmission curves or here for a listing. 

    Count rate improvement of Harris set over the SAO set:
U       0.54mag (60%)
B       0.23mag (23%)
V       0.34mag (37%)
R       0.40mag (44%)
I       0.10mag (10%)
  • We also have a set of SDSS filters , u', g', r', i', and z'.
    • Here are the transmission curves and listings.  The curve for the g' filter is incomplete. The previous i' filter was badly cracked; it has been replaced with an Omega 767.2wb153.5 i'.


  • Here are the 4" narrow band filters that we have available:

    • [OII]3727 curve and listing*
    [Ne III]3869 curve and listing*
    [OIII]4363 curve and listing*
    He II 4686 curve and listing
    [OIII]5007 curve and listing*
    G continuum curve (5260) and listing
    H_alpha_6563 (5nm FWHM) curve and listing
    H_alpha_6563 (1nm FWHM) curve and listing*
    SII 6725 (5nm FWHM) curve and listing
    R Continuum (7130) curve and listing

    Note: asterisks indicate filters that currently require mounting in holders; request these well in advance of your run.

  • Note that the 2" filters vignette at the edges of the 4shooter CCD field, in an ugly way that yields astigmatic star images. If you have a very special reason to use these filters, you should contact the staff well in advance of your run.
    • Click here for a listing of 2" filters.

    Last update 07/12/04 by EF