Sunday, December 17, 2017

 

Issue #551: The Simple (Suburban) Astronomical Life…


2017 wasn’t a very active year for me in astronomy. The freaking weather, if nothing else, saw to that. The Deep South Spring Scrimmage, for example, one of two star parties I still attend each year without fail, was clearly in for a rain-out and I didn’t even bother to register. That event’s fall edition, the just-finished Deep South Star Gaze, yielded only one good night out of the four I signed up for. Sigh.

But that doesn’t mean I didn’t do any telescoping. What I did do this year was mostly imaging from the backyard. That can be fun, but I have to admit the actual picture-taking part of it just ain’t that engaging. After set up is done and the mount is guiding and the camera exposing, my astrophotography consists of me sitting inside watching TV while telescope and computer do their thing on their own.

As fall segued into winter, however, the skies improved (somewhat), and I found myself in a nice clear pre-Christmas stretch. What to do? I was tired of worrying about cameras and computers for the moment. I was longing for some of that old one-on-one relationship with the cosmos that’s what got me interested in this crazy game in the first place.

To that end, what went into the backyard the other night was my consummately visual scope, Zelda, a 10-inch GSO solid tube Dobsonian reflector who came to stay with me a couple of years ago.

There are no computers involved with Miss Z. The closest things she has to electronics are her primary mirror cooling fan and her illuminated zero power aiming device, a Rigel Quick Finder. Also into the backyard went the folding aluminum camp table I use as an observing table, and my case of favored eyepieces.  Setup took all of five minutes and I was done. 

Well, I was nearly done, except for star charts. As I tell my undergraduate astronomy students, “You can’t find the stars’ homes without a map!” Did I say “no computers”? I did, but only ON the telescope. My Android tablet running Sky Safari Pro went on the observing table next to the eyepiece box. I could have used one of my print sky atlases, like Sky & Telescope’s Pocket Sky Atlas (or the new Jumbo edition, which I love). And I often do that when the yen for simple visual astronomy takes me. But you know what? In some ways, Sky Safari is simpler to use in the field than a book.

Want to find some object? No paging through an atlas, no trying to remember exactly which constellation NGC umptysquat lies in. Just click a little magnifying glass icon, type the DSO's name/designation, and the target will soon be centered on the screen under a Telrad reticle. Given my (somewhat) aging eyes, I also find SkySafari’s screen more legible than the pages of a book illuminated by a dim red LED flashlight.

On a recent cold (for me) Tuesday evening, the TV was showing nothing but reruns—when did the rascals come up with this "mid-season hiatus" nonsense? That was OK. In the backyard, the curtain was rising on the great sky show. I was excited at that prospect. Maybe more excited than I’d been about astronomy all year.

Excited, yes, but also unsure, as in being unsure exactly what to look at. While I am a big proponent of observing lists—usually if you go out to observe without one you won’t see much of anything at all—I hadn’t made one this time. Lazy? Maybe a little. Just wanting to recreate those spontaneous nights under the stars I experienced as a youngun? Perhaps that too. But I still needed some idea where to point Zelda after I’d had a nice, long look at the sinking Ring Nebula, M57.

Sky Safari sure proved its worth here. I haven’t used the program much since I bought the Pro version some months back—I’d been tied to a laptop and using Stellarium during my picture taking. However, I dimly remembered SkySafari has pre-made observing lists…

I clicked the search icon, and, sure enough, there were those lists displayed before me. Including, thank goodness, “Tonight’s best.” I began running through ‘em starting with the wonderful starball that is M15. When I applied 200x to it in the somewhat hazy (and growing hazier) sky, the Pegasus globular broke into a horde of minute suns.

And so it went till my feet began to grow cold and the haze began to devolve into clouds some time later. I had plenty of fun. But I also had some epiphanies. “Rules” if you will, for observing the deep sky under suburban backyard skies.

Telescope: OK, so you wanna do some casual backyard visual observing, do you? Which scope? If you only have one, naturally that’s it. If you have a stable like some of us do, however, which one to use?

There is something to be said for a small telescope, especially a refractor, for casual backyard use. Especially for spur of the moment observing. I can have my 3-inch f/11 achromat or even my 4-inch f/10 achromat in the backyard and ready to rock in minutes. Since there is basically no cooldown required, I can have a quick look at M13 and be back inside for more Gotham after the commercial ends.

Casual observing, looking at the showpieces in an off-the-cuff sort of way, is great. But what if you want more? I, for example, have been thinking about running through the 600 objects in Orion’s (great) Deepmap 600 list. Some of these objects—in fact a of lot them—are  a challenge for a small suburban refractor. At this point it's time to kick the aperture up a couple of notches.

What is the optimum aperture in the backyard for me for deeper deep sky observing? I’ve found that to be 10-inches. The horsepower gain over a three or four inch (or even an 8-inch) is considerable—don’t believe the old urban legend that says that more aperture doesn’t help in a light polluted suburban sky. A 10-inch solid tube (especially) Dobsonian is also very portable, if not in grab ‘n go fashion.

Equatorial or alt-azimuth mount? Either is fine with me, but my backyard observing does tend to be of a more casual nature than what I do at dark sites, and I usually don’t want to spend a lot of time fooling with a goto GEM. With a decent Dobsonian I don't miss tracking motors. Even my humble GSO “tracks” fine by hand at 300x. Its motions are smooth and easy, and even novices will soon get the hang of following objects with a scope like Zelda.

Yes, even a 10-inch Dobsonian can be a handful for some of us, especially as we grow older. If you’re observing in your backyard, however, you can minimize the amount of setting up and tearing down you have to do. If you have a reasonably secure yard, why not leave the telescope set up through stretches of clear weather? That’s what you'd do at a star party, so why not at home? A good cover like a Telegizmos one will keep your beloved telescope snug and safe from unexpected weather. Doing this is like having an observatory without the expense and hassle of actually putting up a dome or roll-off.

Eyepieces:  Even if you’ve only been in our avocation for a short time, you’ve probably already begun to accumulate a box full of oculars. Which are good ones for the backyard?

As I've said many a time before, don’t scrimp on eyepieces. Buy the best you can afford. You'll be able to use them for the rest of your observing career. Good coatings and light transmission characteristics and build quality (a decent eye-cup is important if you have considerable ambient light to deal with in the backyard) are frankly even more important under the suburban sky than at a dark site.

Getting a good eyepiece does not mean you have to spend a mint. I love my TeleVue Ethos eyepieces, which I bought not long after they were released. But if I had to do it over again, I would likley not spend the money they command. As you know, I'm cheap and to my eyes the considerably less expensive Explore Scientific 100-degree eyepieces are every bit as good. And the even less expensive Meade 100s pleased me a lot when I reviewed them for Sky & Telescope not long ago.

Ethoses and other 80 - 100-degree jobs, are what your old Uncle favors? Yep. Especially if I'm using a Dobsonian without automated tracking. With a non-motorized telescope, keeping an object in view is much easier with a wide apparent field eyepiece. If you've got a wide field eyepiece, it's also sometimes possible to star hop using that eyepiece rather than a finder. That is particularly nice in areas like Virgo where there are few guide-stars visible in a 50mm finder. I can "eyepiece-hop" to those multitudinous galaxies.

A top of the line eyepiece may be wonderful, but that doesn’t mean it’s wonderful all the time, including in compromised suburban skies. I’ve had a 27mm TeleVue Panoptic for years and will never part with it. It’s a classic from a master of eyepiece design. However, in the backyard, I find a much humbler ocular, a 2-inch Bresser 25mm I won at a star party last year, trumps it. Slightly more apparent field, slightly darker field. Would I trade the 27 for one? No way. But the more expensive eyepiece isn’t always better.

Finding Objects:  If you’re gonna see objects, you gotta find ‘em. The question is how to do that. Especially in the backyard where object finding is harder than anywhere else thanks to the bright skies and lack of stars to use as guideposts.

Certainly you can use goto. I’ve been a big proponent of automatic object locating since I realized goto was practical, affordable, and reliable over twenty years ago. Goto makes finding things in star poor suburban skies simple. One big benefit? If you know your goto mount places objects in the field without fail, you may be able to spy a very marginal DSO by scanning that field intensely. Not sure if the object is in the field or not? You’re tempted to move on after a little looking.

However, if, like me, a big part of backyard observing is “simple,” you may want to eschew batteries and cables and computers as I do with Zelda. What is effective for object locating in brighter skies? Not a zero power sight like Zelda’s Rigel Quick Finder, at least not by itself. There are not enough guide stars to allow you to pin an object down precisely without optical aid. That’s why I always use a 50mm finder in concert with the Rigel. I roughly position Zelda with the zero power sight, and then home in with the the  finder scope and SkySafari.

What sort of 50mm finder? I prefer a right angle-correct image ("RACI") finder like the one Zelda came equipped with. The finder has a star diagonal which means I only have to shift my eye a short distance from the main scope eyepiece to view through the finder—very convenient and comfortable. The finder’s special built in star diagonal presents an image that is both right side up and mirror correct.

So, then you star hop. You look at your charts and draw imaginary lines and shapes to find your object: “M57 is halfway along a line between those two stars”…"M15 makes a shallow triangle with those bright stars" and so on and so  forth. One tip? I find that if I can’t locate an object after several tries, it means I’m not just slightly off from its position in the sky, but way off. I further note it’s pretty easy to get out of practice with star hopping. If I haven’t done any in some months, it may take an evening or two to get back in the swim of things. Knowing that, I don’t get frustrated (“Why can’t I even find M37? I’m going back inside!”). I keep going and it all eventually comes flowing back.

Finally, don’t discount star hopping as fun in and of itself. Especially in suburban skies were the objects themselves don’t always look that great. The hunt is its own reward and sometimes that is enough.

Observing. You know all those observing tricks you’ve learned over the years? Or, if you’re a novice, the ones you’re reading about online or hearing from the old-timers at the club? They are very important for maximizing your viewing under compromised skies…

Averted vision:  The light receptors toward the edge of the retina, the rods, are more sensitive than those near the center, the cones. So, if you’re observing an even marginally dim DSO, look “away” from it rather than directly at it to see the dimmest details.

Which eye? If you’re right handed, your right eye is likely the "dominant" one. If you’re left handed, vice-versa. Usually the dominant eye is better for deep sky observing, but experiment with the opposite eye as well.

Shake it! The eye-brain combo has an easier time registering moving objects, so sometimes a tap on the telescope tube will cause a challengingly dim DSO to appear as if by magic.

You can see a lot more if your eyes are as dark adapted as they can be. In the suburbs, what usually prevents that is not so much the general light pollution, but ambient light. Turn off nearby lights and shield your scope and yourself from those you can’t turn off.

Most amateur astronomers tend to use too little magnification on objects rather than too much. In the suburbs, more power darkens the background sky and increases contrast between it and the object of your desire.

Growing older. Alas, it happens to the best of us, even me. Being aware of the changes you’re experiencing or will experience will help you deal with them.

Your eyes’ corneas are probably beginning to yellow for starters. That can be good and bad. Bluer objects won’t be as bright, but if you, like me, are a fan of achromatic refractors, you’ll find the color purple has been much reduced. Your eyes now have built-in yellow filters and it’s as if your fast achromat has suddenly become an APO. Eventually, if you progress to cataracts, your eye doctor will say it’s time for the big fix, surgery. That will both return the stars to their accustomed brightness and turn your "APO" back into an achromat.

You may develop increased sensitivity to cold. I was pretty OK in this regard all through my 40s and well into my 50s. In my 60s, I find I get colder more quickly and can’t ignore that as easily as I once could. When my feet get cold, I know it’s time to quit. There is a big plus for backyard observing in this regard:  When my feetsies get cold I can take a break inside and go back for more when I warm up.

Feeling creaky. Except for my (self-imposed) back problems, I’m pretty good here. The time will come for all of us, however, when it’s harder to contort the old bod to do things like look through straight-through finders. Luckily, there are work-arounds like the above-mentioned RACI finder. Did you know you can even get a right-angle adapter for a Telrad sight?

Weight can become a problem as we age. Make that will become a problem. That’s no reason to stop observing, however. Even if you have to drop down a couple of aperture notches, some telescope is better than no telescope. Also, modern designs like ultralight Dobs mean many of us are going to be able to carry on with at least as much horsepower as we used in middle age. The backyard is a big win here, since you can do things like wheel the scope out of and into a garage on a set of "wheely bars," etc., instead of having to carry the instrument to and from a vehicle.

Some of the older observers I know are beginning to go inactive due to a fear of falling in the dark. If you are in your 70s or 80s, there’s no doubt falls can be dangerous. In the backyard, however, you can do things like position small red lights on the ground to show the way, mark the scope  and observing table with more red lights, and turn on white light when needed. In the backyard, you’re at least very familiar with your surroundings, too.

So, I've given up dark site observing? No. Not quite. I’ll go to a dark site when I’m chasing the dimmest of the dim, or want the best astrophotos I can get. But otherwise, it’s the friendly and comfortable back 40 for me these days.

Comments:
This post should be required reading for every astronomer. I am going to go with an Alt/AZ (probably the Orion as it is a few bucks cheaper)for my quick peek for my ES102.

With my new found 8 second high ISO capability I've found that my C90 on the SLT is pretty cool for EAA, so as long as I've left my C90 out to cool very nice quick look.

But to keep me active I now really have three tools:

My 10 x 50's on a monopod with fluid feed and a 127 mini fluid head. For the first time ever I was able to see M33 from my yard with the 10 x 50's. Portable and quick to find with.

Next up is a pair of cheap 20 x 80 Starmasters on a CF tripod that is very all on a large ball head (put a red dot on these with velcro for finding stuff way up. Lots of clouds here in the NW and with the 20 x 80 was able to see m42 for five minutes in a small sucker hole.

And finally, an Alt/Az mount for the es102 for quicker peeks a star clusters and brighter M's from the yard. This will also be my primary EAA/stacking scope reserving the C8 for high power planet videos and small deep fuzzies.

I've realized that by using my binocs, SLT/C90 (I could replace this with an 80 ED, but it is my first scope and the optics are very good), and hopeful my 102 on an Alt/az I can increase the number of times I "under stars".

I used to just print out a viewing list and goto and spend time viewing the "prettiness" , now I am revisiting the M's and taking sometime to see what new research is going on on my "quick peek" lists. Still peek at the Urban Astronomer every now and then:)and Steve's M objects.

I've never been a "scope collector" and I never really let aperture fever take hold and having a lot of large scopes including a 14i in the club lending library never needed to. I am very happy with my current setup and thinking finally adding a Refractor completed , for me, the perfect setup.

Yes, my scopes are small but at 68 I can still easily mount and carry them.
 
Nicely written and couldn't agree more--the peace of searching for objects with a simple dob is a an anchor for observing and never loses its appeal.
 
Uncle Rod,

Fewer posts this last year or not, I'm years late to the game on your posts. I've had plenty to catch up on over the past year or so I've been reading them as "light" reading. Thus far you've convinced me to buy an AVX, go wireless, and that the problem with my planetary images is not just seeing. These posts could quite literally be a book. Even the older ones are still quite relevant, largely up-to-date. Thank you!
 
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