Telescopes I've Used - My Nashville Roots

A 6-inch Newtonian reflector

Looking through 6-inch reflector My first serious telescope was this 6-inch Dynascope from Criterion, which seems to have outlasted the company. I got it secondhand in 1969 from the husband of my junior-high algebra teacher (and I hereby hoist a virtual glass to the memory of Clarence and Juanita McCanless). I mowed about 40 yards that summer to pull this one off. I still use it, joined about 15 years ago by a 10" Odyssey Dobsonian and another 15 years later by a Celestron NexStar 5. As you can see from the picture, the 6-inch gets educational use these days.

Itching to be a "real astronomer", I contacted the locals at Vanderbilt University. Doug Hall got me started doing visual observations of eclipsing variables; we published a visual light curve of EG Cephei in the AAVSO Journal.

I also did lots of lunar observations (hey, the Apollo program was in full swing at the time). I'm especially fond of the photo showing Mare Orientale at unusually favorable libration. And I tried my hand at photographing the bright planets as well, just getting to the point where I could record shadow transits of Jovian moons from the old back yard. Somehow, though, going to college really cut into the time for such pursuits. Still, there were compensations - the telescopes got bigger.

Mare Orientale Albetagnius Mars through 6-inch telescope Jupiter through 6-inch telescope Saturn through 6-inch telescope

Dyer Observatory

Dyer Observatory dome The primary instrument at Dyer Observatory, which is located on the southern edge of Nashville, is the 61-cm (24") Seyfert telescope, which was named for Carl Seyfert to honor his role in the construction of both telescope and observatory. Using this telescope, I started working with Doug Hall on mass-transfer binary stars, in a way continuing the backyard studies that he had advised me on even before I got to Vanderbilt. As an example, here's a light curve of U Cephei from the photoelectric photometer on the Seyfert telescope, from the night of 3/4 October 1976. This system can change its mass transfer rate rapidly, which is often reflected in the light curve - the accretion "hot spot" can come and go, so that the eclipse can go from total to partial in form within a couple of 2.5-day orbits. It was back to total in this case, as seen from the flat bottom. The V magnitudes are differential with respect to BD +81 27. The 61-cm Seyfert telescope has an interesting convertible design, so it can be used as a classical Cassegrain or as a Baker reflector-corrector wide-field photographic telescope. As Rick Blakley at NOAO kindly pointed out, this is distinct from the better-known Baker-Schmidt design, incorporating a doublet and a corrector plate to reduce the coma inherent in the paraboloidal primary of a Newtonian or classical Cassegrain system.

Eclipse of U Cephei

Light curve of asteroid Betulia The first observations I got at Dyer were of moving targets, which taught me a lesson. Here's a light curve of the Earth-approaching asteroid 1580 Betulia, taken when it approached to about 0.13 AU from us in May 1976. The apparent motion was fast enough to limit how long it spent in the photometer's aperture, since there was no declination drive available (this, a grazing occultation of Saturn, and Comet Hyakutake are the only times I can recall actually seeing orbital motion of natural objects). This asteroid has both shape and color distributions that are complex, so it shows three maxima and minima per 6.1-hour rotation (these data were analyzed by Tedesco and Drummond in a 1978 Icarus paper). And my first Baker-Schmidt plates were also of a moving target, Comet West in the spring of 1976.

Eventually I wandered into galaxy studies, encouraged by Dan Weedman (who's stayed mum about whether this was a good idea). He started me on a photographic survey of bright galactic nuclei, the idea being to see what the systematics of nuclear properties were with galaxy type, tell whether there existed nuclei comparably bright to recognized Seyferts, and identify interesting candidates for followup (all of which were more important at the time than one would imagine 20 years later). We used the Baker-Schmidt mode of the Seyfert telescope, which gave a geometrically flat field at the same image scale as the Burrell or Curtis Schmidts at NOAO, and giving a field up to 5 degrees across. This survey ended up identifying about 1300 galaxies, aided by an early application of the digital RNGC catalog to map expected NGC objects for each plate at the right scale. From 5-minute blue-light exposures, here are a few of the most interesting nuclei from that survey (of which NGC 7714 certainly went on to considerable fame). Specifically, they are NGC 4736 (M94), NGC 4826 (M64) and the region of the Virgo cluster known as Markarian's Chain (to the northwest of M87). We identified 10 nuclei as being especially interesting for being unusually bright and small, some of which have attracted forther interest. This "top 10" list produced a few other galaxies that have proven notable. Aside from NGC 7714, NGC 4569 seems to have harbored a starburst which produced a bizarre number of A-type supergiant stars in a tiny volume, from IUE and HST data; NGC 3504 and 4385 are luminous barred starburst galaxies; and NGC 7769 has had a starburst apparently triggered by interaction with NGC 7771. (For the really curious, the ADS-scanned paper is here).

Dyer photograph of NGC 4736 Dyer photograph of NGC 4826 Markarian's chain in Virgo

61-cm Seyfert telescope Dan also got Don Hamilton and me started following the variations of Seyfert galaxies using both photoelectric and photographic techniques. The telescope is demonstrated in this picture by a famous astronomer, doing his Edwin Hubble impression at the eyepiece.

The observatory also hosts a 12-inch Cassegrain reflector built by the late John De Witt Jr. (of Project Diana fame, the first detection of radio waves reflected from the Moon in a postwar US Army Signal Corps project), originally used at his home. The optical quality was quite nice, as seen from this Jupiter snapshot which I had quite forgotten about for years.

Jupiter through 12-inch telescope
Telescope Collection

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