Thursday, August 28, 1997 Oregon Star Party

To my pleasure the mostly cloudy skies through the day and into the evening cleared after sunset.  To my astonishment, not only did they clear but they became the most transparent and perfectly steady skies that I’ve ever observed under.

I saw dramatic detail in the Milky Way everywhere I looked to the limit of my eyes.

Extreme observing kicked in with Judy Dethloff mentioning that she could see the central star of the Ring Nebula in her 16 inch [41cm] f/4 Dob. Sure enough, it was there, and steady too.

I walked back to my 20.5 inch [52cm] f/5 computerized altazimuth telescope wondering what it might reveal.  My 9mm Nagler with a barlow gave a beautiful view at 750x. I could see the second star inside the ring. Word was getting out that seeing was perfect and people were pulling barlows out of their eyepiece cases, so scoring an additional barlow wasn’t easy from a nearby observer.  This put me at about 2000x or about 100x per inch of aperture, considered the extreme upper limit of useful magnification.

The Ring Nebula completely filled the wide field of view with the central star appearing as a tiny speck of light without need of averted vision. The scope’s computerized tracking with motorized motions including focusing made this possible. Howard Banich was observing at 1200-1800x with his 20 inch on an equatorial platform.

After we traded views, curiosity got the better of me and I got ahold of a third barlow. Triple stacking the barlows I had great difficulty focusing the image since only a portion of the annulus filled the field. I reckoned that I was observing at 6000x or a bit less. The field had an eerie unsettling feeling. I returned the third barlow, remarking to bystanders that I was going back down to low power, 2000x. My words were repeated back to me for a very long time afterwards.

After hours of observing deep sky objects like never before, we enjoyed remarkable views of Saturn at the highest magnifications we could muster with our telescopes.

Every scope I looked through, whether high end custom or simply decent, whether big or small, no matter the type, performed wonderfully. That night more than any other taught me that transparent skies and steady seeing matter most.

For us in the Pacific Northwest part of the USA, we get our best seeing when the jet stream is far north of us. There are a number of nights a year where I employ 750x.

PS: William Herschel famously said that he observed at 6000x. See http://adsabs.harvard.edu/full/1924MNRAS..84..607S. Quite a few others have observed at extreme magnifications also.

Mel Bartels