As a follow up to my previous post about the Baader Moon & Skyglow filter, I did finally get to take the scope out to check out a 5-day, 9-day, and 10-day old moon, and in doing so, I figured out what the M&SG is actually doing. At first I thought it might be doing something similar to what those blueblocker sunglasses do; you know the ones you used to see advertised on late night TV – blocking out some slice of the spectrum so as to allow your eyes to focus better on the slice that’s remaining. Filters that they use on achromatic refractors do this; they eliminate the violet portion of the spectrum – that part that isn’t coming to a focus anyway and is instead causing a purple haze around bright objects. The parts that remain are in sharper focus as a result.
But that wasn’t it. What the filter really does is to somehow reduce the glare. You would think that that’s what a polarizing filter should be doing – which is exactly what my Orion Variable Polarizing filter should be doing. But the M&SG does it differently somehow. Yes, the object (whether it’s the moon or Jupiter) is very slightly darker – but not nearly as dark as the Polarizing filter makes it. The object also takes on the slightest blue tint, which you forget about five seconds after you notice it. What I’ve decided that the M&SG does is that it just reduces that annoying glare so that the really bright spots aren’t quite so bright and aren’t washing out the darker areas. This is similar to how you can’t see the Galilean satellites because Jupiter’s so bright, or how you can almost never see stars in the same field of view as Jupiter because Jupiter overwhelms them.
Now, the M&SG won’t eliminate that kind of glare. But it does reduce the glare from the very bright lunar and planetary surface so that the contrast features can really pop. So, for example, with the 9-day-old moon, I was taking a really good look at Copernicus, and the rilles and tiny little craters in the highlands all around the crater were stunning. I also saw the Straight Wall, a feature which I had never seen before – although, admittedly, I didn’t know it existed before, either. The seeing was so good, I used my 6mm Modified Achromat at 257x for some really closeup views of the terraced walls of Copernicus. Jupiter looked great as well, with some nice detail coming out of the equatorial bands.
But on a down note, there’s seems to be something going on on the roof of my building, where I observe. My building is 17 stories tall, and running from the ground floor all the way to the roof are vents from every kitchen and bathroom in the building – which are all located in the interior, not by windows, which is why they need venting. At the top of each vent is a giant fan, sucking air through the system. Usually, at least some of these fans are off, and some on. However, the last couple of times I’ve been up on the roof, it seems as if all two dozen vent fans have been running at full tilt.
Incredibly, this is causing the whole roof to vibrate. Oh, nothing a human could see or feel. But the telescope sure can. It seemed like the moon was vibrating in the scope. The Trapezium has been looking like the Octagon this past week. I’m hoping this is just some kind of spring cleaning phenomenon, and not some permanent aspect of observing life on the roof from now on. We’ll see.
Last night I took a walk on over to a local park, Carl Schurz park, to see what the observing conditions were like there. I never realized how good I had it on my roof until I took that walk. It would be about a half mile walk to an observing spot where I could see at least some of the southern sky; any closer to home and the south becomes increasingly blocked out by tall buildings. I suppose I could sling the scope over my shoulder and make that walk. However, that’s not even the worst of it. The worst of it is that the conditions are awful. As you might expect, the park is well-lit. Everywhere you go, there’s bright sodium lights shining right in your face.
Well, almost everywhere. For some reason, the lights on the playground that my daughter used to play on were not on. However, although the playground area was relatively dark, or at least a lot darker than all the lit-up walkways, the playground’s sky was mostly blocked by trees. Lots of trees. And even though the calendar says it’s been spring for over a week now, the trees aren’t anywhere near beginning to bloom. When they do in a couple of weeks – if this winter ever ends – there’ll only be a sliver of sky left between all those leaves. That’s no good.
I understand that the Great Lawn in Central Park has some great southern views with not too much ground light pollution from the walkway lights, which you can get away from a bit by moving south on the lawn. But that’s quite a haul – almost a mile and a half’s walk each way, lugging a 20 pound telescope over one shoulder, and my accessory bag over the other. And no place to sit. Not very inviting. Not at all. Not unless I get some kind of case for the scope and a dolly to carry it on.
Strangely, though, the roof vibration thing might have been more psychological, than anything else. I decided the last two times I went out to forget about astrophotography because of it. But tonight I decided, what the hey, I may as well give it a chance, to see if the vibrations were really effecting the view or not. I came up with this:
Not bad! I discovered the burst function on the camera that takes three shots in a row. I think that’s a big help in terms of keeping the camera steadier while the pics are taken, at least until I get a camera mount.
Obviously, I’m thrilled that those ventilation fans weren’t as bad as I thought. Thinking back, it was actually pretty windy the last couple of times I was out. Not tonight, though, and it seems like the vibrations decreased a lot. Phew!