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.

Solar Prominence 'Scope

Prominence scope parts list :
Text from "spectrohelioscope.net" :

Here are the basic plans for the promscope(coronagraph) that I designed. Twenty of these units were built in a weekend when the Delmarva Star Gazers (www.delmarvastargrazers.org) hosted a telescope making weekend in Spring. The telescope provides excellent views of prominences. Most of the parts can be obtained at the local home Improvement store. The optics and metal telescope tube came from Apogee. The 10 Angstrom 656 H-alpha filter came from Maier Photonics that was used for the class. The original prototype used a filter from Andover Corp. The telescope can be built for under $300 and only requires hand tools.

The "cones" picture shows the brass 1/4" diameter ferrules that were used for the occulting disks. They came out of 1/4" Swagelok plumbing tee used with 1/4" copper tubing. The ferrules at attached to 1" long 1/4" diameter "stand-off" The stand-off has a thread hole down it's center and the ferrule is held on to it with a 8-32 bolt and washer. The stand-off is commonly used to mount circuit boards. It is epoxied to the center of the field lens The image also show a 24" mm OD adjustable iris that is placed between the relay and field lens and used to adjust the contrast of the image.

All the optics, iris and filter are mounted inside 1" standard copper tubing. The parts are held in place with 4-40 set screws. The lens and filter have masking tape applied to the edges for a better fit and also so the set screws or not pushing against bare glass. The inside of the copper tube is lined with black flocked paper to reduce stray light.

The copper tube is placed inside a chromed 12" x 1- 1/4" sink trap extension. The flaired end of the sink trap is 1- 1/4" ID so it fits standard eyepieces. The outside ends of the copper tube are wrapped in a few turns of 1/2" wide masking tape to makes up the difference in diameter between the outside diameter of the copper tube and inside diameter of the sink trap. The sink trap with the optics becomes the focusing tubing for the telescope and fits nicely into a 1- 1/2" PVC to 1- 1./4" The end of tube is stabilised by three nylon tipped set screws, placed about 1-1/2" behind the PVC sink trap adapter and at 120 degree centers. The sink trap slides easily into and out of the adapter so one can focus the image, then can be locked by tightening the plastic nut on the sink trap adapter.