March 30, 2020
Life - for me, for millions in the United States and around the world - has changed just a bit since I last wrote. Friends and students have fallen ill, and so many have lost their jobs. It feels crass to complain, but still: my family of four is now largely isolated in our little apartment, and my office is in a walk-in closet. It's less than ideal.
In these difficult and chaotic times, I of course have no way of traveling for work, which means that I have a surplus sitting in my research budget. Not surprisingly, that got me thinking about improving my little telescope collection.
With the Mewlon around, I decided that the C8 was expendable, after all - especially since the device I purchased to make it acclimate more rapidly (a Lymax Cat Cooler), is much bigger and heavier when accompanied with a battery than I'd anticipated. So I sold the C8 and its accessories, then used the profit to buy two new Baader diagonals: supposedly, the best on the market.
Now I had three telescopes in DC, and really four is probably the sweet spot for me. This past winter convinced me that I'm going to have my easiest observing sessions when it's cold - certainly on the rooftop, since nobody goes up there when it's even a little cool. I decided that I needed a somewhat bigger doublet refractor that would cool down very quickly, but gather a bit more light than the Takahashi FC-100DC could reveal. It couldn't be too big, however, or I wouldn't be able to easily carry or mount it. And it couldn't be prohibitively expensive (not an easy restriction, considering how refractors scale in size and cost).
After doing a lot of research - too much, considering my other obligations - I settled on a Vixen ED 115S. This is a fine doublet telescope that shows very little false color when in focus (so little that it passes as an apochromat), gathers substantially more light than a 100mm telescope, is versatile at F 7.7, and remarkably light at just over 10 pounds. For some reason, it seems to be quite rare.
The telescope is decidedly not cheap, however, though it does ship with second-rate accessories that nevertheless can only be purchased as accessories when buying from TeleVue or Takahashi. To my astonishment, I found the Vixen with a heap of top-rate add-on accessories - tube rings, greatly upgraded focuser, handle, etc. - for sale at an incredible price on Astromart, in used but like-new condition. I pulled the trigger, and the telescope arrived just a week or so later.
For more than two weeks after the telescope arrived, the clouds and rain would not relent. I suppose that's good; coronaviruses apparently do not spread as easily in humid weather. And certainly fewer people went outside. Still it was frustrating, especially as I increasingly worried about navigating my building and touching the germs on every surface. Hauling telescopes through the building increasingly seemed like a perilous prospect.
Then, last night, the sky cleared for just a few hours. I forgot about the pandemic for a moment and hurried to bring both the Vixen and my trust TV 85 to the rooftop. I mounted them on the AYO II: perhaps the finest piece of non-optical equipment that I've purchased in this hobby.
It was quickly apparent that both seeing and transparency were nothing short of atrocious. And I mean atrocious: the night probably offered a worse combination of both than anything I've experienced in the past year. On top of that, gusts of wind rolled over the rooftop, and clouds defied the forecast to move in quickly from the west.
In that context, my decision to bring the TV 85 quickly paid off. I might otherwise have been worried that the new telescope was partly to blame for the somewhat soft appearance of the Moon, for example. But the blurriness and inconstancy of the view were, if anything, even worse through the magnificent optics of the smaller telescope, despite its smaller aperture.
And despite the uncooperative atmosphere, the Vixen impressed. It took just a bit more time to cool than the TV 85, and provided useful views almost immediately. A look at Venus quickly revealed that the Vixen shows noticeably less false color than the TV 85, even in poor seeing. The TV 85 showed a fringe of blue around lunar limb in these terrible conditions; not so the Vixen. It should be noted that, to my eyes, the TV 85 normally offers almost no false color: perhaps even less than the FC-100DC (it's just amazing in that regard).
With its remarkably wide view of view, the TV 85 did provide superior views of the Pleiades. The Vixen dazzled too, but there was just something about the TV 85 view that stood out. Maybe the fault lay in the eyepieces: while I used a TeleVue Plossl in the TV 85, I used a Baader Hyperion Zoom in the Vixen. In my experience, there's no substitute for TeleVue eyepieces.
A look at Orion, however, exposed the advantage of larger aperture. Despite the abysmal seeing, the Trapezium was absolutely crystal clear, with an impressive amount of space between its components. Switching to a 2", 55 mm TeleVue eyepiece revealed all of Orion's belt at around 16x, glittering and glorious despite hazy atmosphere and light pollution.
In short, the new telescope is wonderful: optically on par with the Takahashi and TeleVue, nearly as portable as the Takahashi (though it requires a heavier mount and tripod), almost as quick to cool down, and aesthetically really nice to boot. It is also just a joy to use. There's no fussing with anything, and it works beautifully on the AYO II mount. My only complaint comes by way of comparison: while the upgraded Moonlite focuser is rugged and fluid, the stock TeleVue focuser is just a bit smoother.
Who knows what the world looks like when I next write. In the meantime, it's nice to be reminded - with the aid of two fine telescopes - that the universe will remain more or less the same.
March 8, 2020
The sky was clear the past two nights, as if to compensate for the arrival of COVID-19 in our city. Temperatures are rising, too, although they were plenty cool during that first night (March 7th). Since our baby still wakes up all the time - including every 1-2 hours at night - I once again walked up to our roof. Someday, I hope to be able to visit nearby parks again.
On both nights, I stepped out with my Takahashi FC-100DC. The telescope is absolutely stable on my next AYO II mount - a significant difference over the AYO Traveller mount, especially in windy weather (and it's been a bit breezy here on the rooftop). Although ClearDarkSky forecast average seeing on both nights, I've learned to take that with a couple grains of salt, and indeed once again there seemed to be pockets of decent and poor seeing in the night sky. On the 7th, the nearly-full Moon appeared reasonably steady through my eyepiece; on the 8th, a high-altitude haze and turbulent air worsened the view considerably. Still, there's always something satisfying about seeing the apparently full Moon in the night sky, and then discovering a terminator with a telescope.
I can only step out at around 8:30 most nights - after my daughter goes to bed - and at that point Venus, which is now near opposition, is sinking quickly towards the horizon. Not only does it then shine through a lot of atmosphere, but it's also just above a bank of currents boiling up from some pipes on our rooftop. And when I turn my telescope to have a look, it's usually right after I set up, when the tube still hasn't fully cooled down. Venus is, in other words, usually a shimmering mess of false color.
Yet on the eighth, for maybe five glorious minutes, I did get a nice view early in the evening, at around 82x with my Nagler Type 6, 9mm eyepiece (it's a favorite). Any more magnification, and the view softened in a hurry. At 82x, however, I thought I might just be able to make out some darker details in the disk; in fact I was quite sure of it, but of course unlikely visual phenomena that are just at the edge of perception should always be taken with a healthy dose of skepticism. Minutes later, the view broke down and Venus was out for the night.
On both nights, with Orion very high in the sky, I easily split Rigel A and B. Turning to the Orion Nebula, I think I was able to make out five - perhaps even six! - stars in the Trapezium on the 7th. At 123x, the whole view seemed full of delicate nebulosity (faint, however, because I'm surrounded by lights on our rooftop and my eyes don't fully dark adapt). On the 7th, a small crowd came out to our rooftop and one young man wandered over. He asked me what I was looking at; I mentioned the Orion Nebula. "What's a nebula?" he asked. Vinny - that was his name - now you know!
On both nights, I did a little equipment testing. First, I've been tempted by the new Takahashi FC-100DZ. Its color correction is a bit better than that of my 100DC, especially at red wavelengths. With Mars reaching opposition later this year, it might be an upgrade worth making. On the other hand, the slight improvement in color correction comes at the cost of a longer focal ratio (F8 VS F7.4) and a substantially heavier (33% more!) tube. That may mean that I can't mount the DZ on my lightest-weight tripod and mount. And I wonder whether the DZ would complement my Mewlon as nicely as my DC can - at least in theory, since I rarely have a chance to use the Mewlon. The false color around Venus and even the Moon on the 8th (in poor seeing) did make me think, but for now I definitely lean towards keeping the DC.
I also tested a new pair of binoculars on the eighth. For a while, I've been looking for binoculars that aren't too expensive - I don't use binoculars enough to justify a high price - but also are more than toys. The big Celestron 15x70 binoculars that I've mentioned earlier in this space quickly fell out of collimation and are now completely useless. I bought a small (8x42) pair of well-reviewed Oberwerk binoculars last year, but they were surprisingly heavy, and they too lost collimation in a hurry. I returned them and replaced them with Nikon 10x50 Action Extreme binoculars.
Right off the bat, the feel and size of the binoculars felt right. They were actually easier to hold steady than the smaller Oberwerk binoculars. Turning to the Moon, the view impressed: a bit of false color no doubt magnified by that high-altitude haze, but wonderfully sharp nonetheless. I think this pair is a keeper, and at $150 I don't have to feel that it represents a blown investment if I don't use it much.
March 1, 2020
It's been a remarkably cloudy month. I even travelled briefly to Arizona, and even there, in the desert: rain. I could scarcely believe it. But at last, tonight the clouds parted over Washington, DC, and although the sky was just a bit hazy and I didn't have much time, I figured I'd take the TV 85 to the rooftop anyway.
I'm so happy I did. When I stepped out, the Moon was high in the sky - just passing the Pleiades, actually - Venus was still well above the horizon, and Orion was glorious overhead. I just picked up an AYO II mount - a much sturdier upgrade over my VAMO Traveller that took about four months to manufacture and ship - and was eager to see how it would perform.
It's odd: seeing for me can vary enormously from one part of the sky to the other. Part of the reason no doubt has to do with how often I observe from a rooftop. Warm air rising from my building naturally obscures anything too near the horizon. But after observing from enough parks, I'm convinced that DC must have some unusually turbulent - or at least complex - skies. In any case, Venus was a bit of a mess for me tonight, though of course I could clearly make out its phase. And I was impressed to see very little false color around its disk - none when the seeing briefly stabilized.
The Moon, by contrast, was just stunning. I know I've sung its praises repeatedly in these pages, but wow: the TV 85 is a miraculous telescope. Maybe I just have a perfect sample? Once again, I saw absolutely no false color on the Moon. Once again, the view was absolutely razor-sharp, with that beautiful cold, white hardness that the Moon can have when it's high in the sky. And the mount clearly made a difference in stabilizing the telescope. It's a hair less smooth than the Traveller, but much sturdier and nearly as compact.
This time, I enjoyed picking out the subtlest shadows I could spot at nearly 200x. It's always striking to me that those shadows can give the impression of towering peaks on the Moon - the impression of the lunar landscape that prevailed until the Space Age - whereas of course the Moon's surface is quite flat compared to Earth's. It's amazing, the optical illusions oblique light and a lot of distance can inspire.
TeleVue, it seems, does not get a lot of love compared to its competitors: Takahashi, for example, or AstroPhysics. Apparently TeleVues show just a bit too much false color, and their cost is just a bit too high. But when it comes to optical quality, my TV 85 is easily a match for my FC-100DC. False color is absent; stars are absolutely pinpoint. The TeleVue also seems to focus just ever so slightly more perfectly than the Takahashi - although that may be a result of its smooth, two-speed focuser - and it cools down more quickly.
The Takahashi, of course, is all but flawless in its own right. And it draws in more light, which does make it better for some purposes. All the same, I've never been disappointed after observing with the TeleVue; I've never felt that I really should have brought out a bigger telescope. It's an incredible little instrument.