February 14, 2015 – The Great Red Spot is Mine!

Last week I went out to once again hunt my elusive quarry, my very own personal white whale, Jupiter’s Great Red Spot. Unfortunately, because of my own ineptitude, I misread Sky & Telescope’s GRS transit calculator and thought I’d be able to see the transit that was to occur a bit after midnight, Eastern Time. Of course, I forgot that the listing of “00:32” on the same date I was observing meant that that the transit happened the night before.  Whoops!

But no matter! I forged on into the night!  Well, not so much night, because of the practically full moon glaring down on me. But there was the King himself, at opposition, as big as he gets. I spent the better part of an hour just looking, and looking, and looking.

I started off with my 10mm Orion Sirius Plossl at 154x. Nice. I moved up to my beloved 8mm TeleVue Plossl, my goto planetary EP, at 193x. Nicer. But the seeing was sooo good that I thought, what the hey, let me try out the 6mm Meade Modified Achromatic that I had gotten (along with the 10mm Orion) as an extra with a used ST-80 I bought. And wouldn’t ya know it, that also looked nice – even at 257x. No degradation of the view.  Stunning.

With each eyepiece, I was able to get into sharp, crisp focus easier than I ever had in the few months I’ve been observing. Jupiter’s limb was sharp. Instead of moments of great seeing between minutes of lousy seeing, it was completely the opposite way around. The main two equatorial belts stood out, like they always do, with some detail in them as well. I was also getting a third belt on one side, and hints of a fourth on the other.

There was a slight haze of clouds high up, there was very little wind, there was a nice thick crust of ice and snow between me and the ground, and the telescope had been cooling outside for two hours.  All of this, but most importantly the slight haze, combined to make the seeing absolutely tremendous.

But I thought that on nights where the seeing is superb like this, that this is where you could easily see the differences between quality eyepieces and not-so-quality ones. My cheapo little Modified Achromat was hanging right in there with my vaunted TeleVue. How come?  How could a lowly Kellner show me everything the top-of-the-heap TeleVue was showing me, and bigger, besides?  I wish I knew, but it’s making the extra money I had spent on the ST-80 look better and better all the time.  I had thought about selling off both the 10mm Sirius Plossl, because it’s only “multi-coated” and not “fully multi-coated”, as well as selling off the 6mm MA.  Not anymore.  They’ve earned the right to stay in the eyepiece case.

Flash forward a week to last night, the first clear night since my tremendous seeing adventure.  The GRS predictor had a transit occurring at 9:08pm – and yes, this time I double-checked it to make sure I was reading it right.  It looked like the seeing would be just about as good as it had been a week before – there had been a haze of clouds passing by when I put the scope out to cool, the crust of snow was still there, the scope would have almost as much cooling time.

I had planned for an open cluster survey night, starting out in Cassiopeia, and making my way all the way down to Canis Major.   Unfortunately, the temperature was in the teens, and although I was fully bundled, it was just too cold to get in the mood for a full four-hour observing marathon.  My hand was quickly freezing every time I took my gloves off to change an eyepiece or work the focus.  Brrrrr.  The survey would have to wait.

The seeing turned out to be just good; not great. The sky was remarkably clear otherwise, though.  It must have been pretty dark when I started out at 8:20, because the Trapezium’s four stars were easy to see with direct vision – which is a small accomplishment with my scope in Manhattan, especially before 10 or 11pm when the lights start to go out.

After a little fooling around with a couple of the open clusters, I got right down to business at 8:30.  The Sky & Telescope transit page said I should be able to see the Spot at least 50 minutes before and after the 9:08 transit, and I was well within that window.  So, again, I started staring, and staring, and staring.

I was observing with my trusty 8mm TeleVue Plossl at 194x. The really steady periods were less than a quarter of the time, so although the seeing wasn’t great, it wasn’t too bad either. Three moons lined up on the right. I switched to my Meade 9.7mm Plossl, on which I have a variable polarized moon filter, to see if that would help by cutting back on some of the glare. It didn’t. I put the TeleVue back in, and around 8:45pm, I thought I saw something. It seemed like the equatorial band on the bottom didn’t go all the way to the limb, almost as if there were a hole in the band. Could that be it?

The thing is, in the last 20 or so years, the GRS has faded quite a bit.  It ain’t so red any more.  Astronomers don’t really know why.  Since the seeing wasn’t quite as good as I had been hoping for, I decided to back off the power, giving the 10mm Orion Sirius Plossl a shot at it at 154x.  You do this because when you overmagnify on a less-than-stellar seeing night, you do actually lose some detail as the larger image roils and boils more.

At first I wasn’t sure. But as 9:00 approached, the atmosphere calmed down, and, and . . .

THAR SHE BLOWS! There was no mistaking it. It was oval, it was just below the equatorial belt, it was there!  Now, as is the case with certain other astronomical objects [cough – Andromeda Galaxy – cough], it wasn’t that the actual object was impressive in and of itself, but the fact of actually seeing it that is intense.  With the GRS, it’s pretty neat that that storm could swallow up three earths whole.

Well, that’s another object off of my list.  I had never seen it as a teenager, even though I had been observing with much bigger instruments (a 6-inch and an 8-inch), and I had significantly less light pollution 30 years ago and 30 miles away from Manhattan.  Unfortunately, they didn’t have the GRS transit calculator back then, so there would be no way to know when to look.  And since, apparently, you can only see it within a half hour of the transit, and not 50 minutes or an hour either way, and given that Jupiter’s day is about 9 hours 50 minutes long, that means that you’d only have about a 10% chance of seeing it randomly.  I never did.  Now I finally have.
Next time:  Light pollution filters
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