==================== KNOW THIS FILE ====================


Observers using filters with passbands of less than 100 Angstroms should be aware of the following when selecting filters from these lists.


The CWLs in the lists are measured with the KPNO Lambda-9 spectrometer that works at ~f/13. When using these filters at other focal ratios, the following shifts are typical:

4m Prime Focus (f/2.8) -13 to -21 Angstroms

Burrell Schmidt (f/3.5) -9 to -13 A

f/7.5 Telescopes(2.1m and 0.9m) -2 to -3 A


There also will be a shift to the BLUE if the temperature of the observing environment is COOLER than the temperature at the vendor's lab where the filter was made. Similarly, a shift occurs due to the temperature difference between our lab and the dome. A typical shift is 1A to the BLUE for every 10 degrees Fahrenheit of COOLING (5.5 degrees C.). Thus, if we measure the filter in our 74 degree F lab, when used at 44F degrees on Kitt Peak, there will be a 3A blue shift of the filter curve.




G. Jacoby, E. and J. De Veny

Updated: 12Jan99