Dave Groski's Solar Page

Dave Groski's Solar Page
david dot m dot groski at usa dot dupont dot com
(see also http://www.spectrohelioscope.net)
DISCLAIMER : NOTE! Viewing the sun can be extremely dangerous! The information provided here is meant only as a description of what one or two people have done. The reader accepts all responsibility and liability associated with the use of any information provided here, as it is possible that important precautionary information may be left out. Neither Dave nor Matt nor anyone associated with them is responsible for damage resulting from using the information and ideas herein!
A quick note on units and usage ... Keep in mind that the promscope needs a filter with a bandwidth of 10 Angstroms or 1 nanometer. A nanometer (abbreviated "nm") is 1x10^-9 meters. An Angstrom (abbreviated "A") is 1x10^-10 meters. So an Angstrom is a 1/10th of a nanometer, i.e. quite a bit smaller. The point is that one cannot use a 10nm (100 Angstrom) filter sold by a number of suppliers. You need one with a bandwidth of 30 A (3 nm) or less to see the prominences.

Also note the difference between the 0.8 system (H-alpha) and the promscope (coronagraph). The promscope will block the disk of the Sun with an occulting disk (which allows prominences to be viewed along the limb) while the 0.8A system allows the disk of the Sun *and* the area around the Sun to be viewed. The 0.8 scope shows H-alpha surface features, like filaments, and flares, along with prominences along the limb.

Calcium-K Scope

Calcium-K scope parts list :
Hole template in Word format for filter-grommet assembly
Same layout as H-alpha above, except using a blocking filter and two calcium-k filters.
Blocking filter needs to go slightly before or after the focal point of the main objective, or between the first bino objective and the first calcium filter. Alternatively, a barlow could be used to increase the focal length to f/30-ish. In this case, the two bino objectives would not be needed, as the bandpass on the calcium filters mentioned here are much wider than that of the h-alpha filters. So a strictly parallel light beam is not needed. Note that this will also result in a shorter tube assembly.