Saturn from the Gulf of Mexico

[Jim L]

I’ve been chasing Saturn’s Cassini Division from my home northeast of San Francisco since early August; unfortunately unsuccessfully. I’d seen it quite easily multiple times over the past couple of years through a variety of small refractors in the 72 mm through 102 mm aperture range, but recent poor seeing and Saturn’s increasingly unfavorable tilt have conspired to hide the Cassini Division from me these past several months. I’m optimistic things are about to change.

My wife, Monica, and I are visiting our son’s family in Boca Chica, Texas, which is located on the Gulf of Mexico where Texas and Mexico meet along the Rio Grande river. It’s flat, humid, and this time of year breezes are light, so I’m hopeful seeing will approach the fabled excellent levels south coastal Florida is famous for. Conditions last night weren’t optimal, and Astrospheric showed average for both seeing and transparency, but this was only the first night of many to come.

We’re using my son’s Celestron Nexstar 6SE Schmidt-Cassegrain (150 mm aperture, 1500 mm focal length) telescope. We purchased it as a gift for my son in 2020, just before the Jupiter-Saturn Great Conjunction, but I’ve never looked through it and until last night I had no idea whether it was good, bad, or indifferent. Having read mixed reviews of Schmidt-Cassegrain scopes and reports that some of them can be, “soft”, I was I bit concerned that my son’s scope might be a dud.

It is not a dud, and in fact quite the opposite. My first view through it was using the Celestron 25 mm Plössl (60X) and 90° prism star diagonal (94115-A) that came with the scope. The large, unfamiliar to this refractor guy central obstruction black hole shrunk and then disappeared completely as I turned the focus knob, revealing a beautifully sharp planet and rings, multiple pinpoint moons, and a stark black background. We were off to a very promising start indeed.

Next up was the only other eyepiece my son owns: the very capable SvBony SV135 7-21 mm zoom. The change in focal length from the 25 mm Plössl to the 21 mm zoom setting was a welcome change from 60X to 71X, and concentrating a bit more on the finer details I could easily see four moons using direct vision.

Skipping the intermediate range between 21 mm and 7 mm I went directly to the 7 mm zoom setting with it’s 214X magnification. While the view remained impressively coherent, atmospheric ripples sweeping across the disk and rings showed that I was beyond what the seeing could comfortably support and so I backed down to the 15 mm to 10 mm zoom range at 100X to 150X magnification, respectively, and this is where we remained for the rest of the evening’s observing.

At lower magnification Saturn showed a pale yellow-orange pastel disk with some vertical differentiation provided by indistinct horizontal zones, and bright, crisp, rings separated from the planetary disk by black space. In the greater 100X to 150X magnification range the planetary disk zones could be further differentiated into multiple pale bands with averted vision, and the rings showed a more marked distinction between the dimmer outer “A” ring and the brighter inner “B” ring, but try as we might neither Monica nor I could pull the Cassini Division from the rings. Sometimes I thought, “almost, it’s right on the edge, I’ll glimpse it if seeing will sharpen for just a moment”, but it never happened.

What we did see were five of Saturn’s moons, in my case, and six, in Monica’s. And while the attached image was taken from SkySafari 7, it’s very much like the view at 100X magnification through the 6SE last evening. Putting labels to moons, below, of the six moons shown only visual magnitude 12.4 Enceladus eluded me, though Monica was able to pick Enceladus out using averted vision.

We’ll be here on the Gulf Coast for another couple of weeks, so I’m hopeful we’ll have some nights with better than the “average” seeing Astrospheric reported last night. If so, and if the Cassini Division reveals itself, I’ll let y’all know. Cheers!

 

[dweller25]

That’s a very accurate observation Jim 👍

Don’t mean to rub the salt in but I have just been observing the Cassini division in a 180mm reflector at x188 - albeit only at the extreme edges of the rings and I was using binoviewers which really helps.

I tried earlier but Saturn was too low and the scope was not fully cooled.

It’s always a great sight though 🙂

Edited October 13, 2023 by dweller25

[Jim L]

Hi David, I’m glad you caught a glimpse of the Cassini Division. In my case it’s the atmosphere, not the scopes, that are probably the limiting factor, though next year, and for the next couple of years after that, I’m pretty sure it will be beyond my skills and equipment to see the division, however favorable the atmosphere might be.

But still, it was a great night. The two things I’m most pleased about last night’s observing were how beautiful Saturn is if seeing is at least average, and just how well my son’s relatively compact 6” SCT performed. About that 6SE SCT, I don’t think it gave away much to my better refractors, or at least under the conditions last night it didn’t.