by Dave Skitt
In early 2016, knowledge of the approaching May 9th Mercury transit and the absence of a suitable solar filter for our club’s historic, 6¼-inch Hastings-Byrne refractor, prompted me, as observatory co-chair, to look for a solution. Protruding thumbscrews on the objective cell had thwarted previous attempts to properly fit an off-the-shelf white-light solar filter. Therefore, I set about to construct a custom-made filter; one that would fit securely and complement the historic look of the scope. Using both purchased and re-purposed materials, I was able to craft a solar filter for about $50. [See “Front” and “Rear” Photographs]
The inspiration and final design were gleaned from a document entitled “Make Your Own Solar Filter” from the Kendrick Astro Instruments website (kendrickastro.com). Baader Astro Solar Safety Film was purchased from Kendrick Astro. The remainder of the materials came from my basement “supply” (it’s not junk!) pile or local hardware stores.
The finished product was completed and fully tested one week before the May 9th Mercury transit when hoards of boy scouts enjoyed a day of solar observing at our observatory. But the true test, which the filter and our legendary Hastings-Byrne refractor passed with flying colors, came at 7:14 am EST on May 9th, when the disk of Mercury could be confidently viewed against the face of the sun… what an extraordinary occasion for this historic telescope and its custom-made solar filter!
P.S. Newsflash – Use of the observatory is not restricted to nighttime viewing only! The club has white-light solar filters for not only the HB refractor, but also for the C-14 and the Explore Scientific refractor used with the Mallincam video camera. My wife, Jennifer, and I will be happy to train keyholders how to use the filters. We’d also entertain your ideas on how to possibly incorporate Hydrogen-Alpha solar observing into the observatory’s future capabilities. The August 21, 2017 Solar Eclipse is rapidly approaching…