Calcium-K optical solar filter and what radio wavelength ? Hi Tom, The Calcium II K spectral line is radiated by electrons moving between different energy levels in a singly ionized Calcium atom. The electron stays bound to the ion. The line is seen at relatively low levels of the Solar atmosphere. Solar radio waves are generated by electrons that are not bound to an atom or ion (moving in helical motion along magnetic field lines), and by plasma waves excited by electron beams and mass ejections. The sources are frequently very far from the photosphere. To better understand the great complexity of Solar Physics, I do not limit myself to particular radio frequencies or spectral lines. I take advantage of the broad range of optical and radio observations recorded by Terrestrial and Space Observatories, such as the Radio JOVE Observatories, Culgoora, Hinode, Nancay, SOHO, STEREO, TRACE, WIND, and others. Much of the data is public and available to all Radio JOVE participants. I use it all the time. I believe that assembling a Radio JOVE Kit, or any other type of radio or optical telescope, and observing with it, is a great Science Education Project. I believe that analyzing a variety of other public data is a great Science Education Project, and enriches our observations with Radio JOVE Kits. You had a very good idea, enjoy your K line filter and your classic refractor. I look forward to your reports in the Radio JOVE Lists. Victor Herrero Submitted to the NASA GSFC List 100316 0331 UT ------------------------------------- Thomas Ashcraft <ashcraft@xxxxxxxxxxxxx> Mon, Mar 15, 2010 at 3:51 PM To: Radio_JOVE@xxxxxxxxxxxxxxx Maybe someone could answer this question here or direct me elsewhere. I am thinking about getting a Calcium-K line solar visual filter for my old optical refractor telescope and I wonder if there is an optimum radio frequency for receiving phenomena at the Calcium-K line? For example : I think ( but am not sure ) that the 20 MHz radio jove frequency is observing emissions that occur at a certain height in the solar corona. I pasted some info on Calcium-K at the end of this message. I hope my question is clear enough and thanks in advance for any help on this matter. If I can clarify further I will try. Tom / New Mexico "Calcium K (Ca-K) Telescopes and Filters are used to study the wavelength of 393.4nm. This emission line is one of 2 that are produced by Calcium just at the edge of the visible spectrum in a layer that is slightly lower and cooler than the layer viewed in Hydrogen-alpha. The emission line displays areas of Super Granulation Cells that are brightest and strongest in areas of high magnetic fields such as sunspot activity and active regions. Having the ability to study the Calcium K and the Hydrogen-alpha line provides important insights into the structure, strength, and depth of these active regions."