Urban Observer’s Survival Guide, Part I
Posted by Brian Ventrudo
A special treat for you today… the first of three segments of my interview with Rod Mollise, author of The Urban Observer’s Guide and his just-published book Choosing and Using a New CAT: Getting the Most from Your Schmidt Cassegrain or Any Catadioptric Telescope. Rod’s a renowned astronomy author and educator, and he graciously spent some time explaining the why’s and how’s of urban astronomy for amateurs. Here’s the first part of our interview.
(NB: This is issue is quite a bit longer than usual, but if you have to fight light pollution or you know fellow astronomers who do, this series of articles is well worth reading…)
Brian Ventrudo, Editor (OMA): Many city-based amateur astronomers believe you need to dark country skies to see faint deep-sky objects like galaxies and nebulae.
But if you live in a decent-sized city it takes time and energy (and more than a few dollars) to truck your telescope out an hour or so outside of the city.
And the harder you make it for yourself to observe with your telescope, the more likely it is that you won’t do much observing at all. And you might eventually lose interest in this wonderful pastime of amateur astronomy.
But you can see many beautiful celestial objects, even in bright city skies… if you know where and how to look and if you know a few tricks of the trade.
So to help you out, I’ve got on the line today Mr. Rod Mollise, also known as “Uncle Rod”. Rod is the author of The Urban Astronomer’s Guide, which is part of Patrick Moore’s “Practical Astronomy” series, published by Springer-Verlag. And he has recently published his new book Choosing and Using a New CAT: Getting the Most from Your Schmidt Cassegrain or Any Catadioptric Telescope.
Rod’s been an amateur astronomer, well, for maybe for more years than he cares to admit. But he knows a thing or two about tackling light-polluted city skies and getting the most out of a small telescope in the city.
Rod Mollise (RM): Hello, Brian, and thanks very much for having me on, buddy.
OMA: Thanks for joining me. So, tell us a bit about your background in astronomy. How did you get into this captivating pastime? And why astronomy instead of say, bird watching or coin collecting?
RM: Well Brian, that’s one question I probably can’t answer. As far back as I can remember, at least since I was four or five years old, I had always been interested in what I called “the great out there”. I guess kids… interests come and go… but astronomy, science, math, those were things that must have taken hold at a very early age for me and never let up. I can’t tell you the first time I wondered about the night sky. I can go back to the first astronomy book I ever got, but I honestly can’t tell you a time I was not interested in astronomy.
OMA: Now a lot of well-known amateur astronomers—and I would certainly consider you to be well-known, being a published author and speaker. But a lot of well-know amateurs like David Levy or Jack Newton have set themselves up in places that have extremely dark sky. But you live around Mobile, Alabama, correct?
RM: That’s right, Brian.
OMA: What’s the sky like there?
RM: It’s pretty putrid, actually. But like many amateur astronomers, I’m also tied to my workplace and so is my wife. And for a lot of us, that means we make the best of the skies we have whether they are good or bad. And that’s the bottom line for everybody: make the best of what you’ve got.
OMA: That’s a good point we’d like to explore more here. A lot of people think you need dark sky to see anything. As the author of the “Urban Astronomer’s Guide”, I’m assuming you don’t agree with that?
RM: Well I do and I don’t Brian. Let me preface this all by saying that I certainly don’t recommend nothing but urban astronomy. I am a firm believer in getting out to dark sights and joining in the battle against light pollution maybe by joining the International Dark Sky Association—the IDA. Certainly there’s nothing that stimulates or helps continue your interest in astronomy than getting out where it’s really dark, even if that’s a club sight an hour from home. But the other side of that is that you can’t remain interested in astronomy when you only get out once a month. And how many club observing sessions are ruined by weather, and that means maybe you don’t get out every month. Maybe you get out every few months, and you just can’t keep going that way.
If you’re going to remain interested in amateur astronomy, you’re going to have to get out more often and have to get out into the back yard and make the best of what you’ve got there.
OMA: Fair enough. I’m from an observing site also… I’m in suburban Ottawa, Canada, so it’s not much fun here. But you can see a few things. Now from your locale, for example, what can you expect to see from in town with a modest telescope? What kind of objects?
RM: Canada? Ain’t that north of the Mason-Dixon line, boy?
OMA: It is!
RM: That’s what I’ve heard. Anyway, seriously, what can you see from the average light-polluted sky, and by that we’re saying maybe magnitude 4 or 5 limit, somewhere in there. What you can see is the entire Messier list, the entire list of Charles Messier’s deep-sky objects, you can see many other clusters, nebulae, and galaxies besides.
OMA: So that’s 100+ objects.
RM: One-hundred-plus objects, and once you work beyond the Messier, there are plenty of NGC objects… that’s the next list up for most amateur astronomers… to see as well. You couldn’t see everything from your backyard in a year or five years or ten years. Even if you really worked at it. There’s plenty to be seen. It’s just a matter of getting out there and seeing it.
OMA: So more than just the moon and planets… the bright stuff.
RM: Far, far more than just the moon and planets. I live exactly two miles from the downtown of a city of 250,000, and I have seen the entire Messier list from my backyard including the supposedly hard ones like M101 and M74. And many of those with a 4” telescope…
OMA: With a 4” telescope!
RM: There is no lack of things to see.
OMA: So if you’ve got a site and you can’t wait to get out there… let’s talk about telescopes. Does light pollution affect the kind of telescope you should use for city observing? Do you need a special “city telescope”?
RM: In a way, you do. And not in the way that most people think. One thing I’d like to do right here before we go any further is debunk what I call the “urban aperture myth”. You may have heard people say that if you live in the city or in the heavily-light-polluted suburbs you should not buy a large telescope. It will just collect extra light and you won’t see as much in a large telescope as you would see in a smaller one.
And the answer, being polite, is the word: rubbish!
If you want to… I could go on and on about this silly story… but if you want to prove or disprove it for yourself, get a 4-inch telescope, get a 12-inch telescope, set them up in your city observing location and point them at M13. Use eyepieces that give similar magnification and take a look. In the 4-inch you’re going to see a bright smudge and in the 12-inch you’re going to see a ball of stars. I won’t belabor the point but in the city in particular, aperture always wins, all other things being equal.
In dark locations, small aperture telescopes can perform incredibly well and keep up very well with larger telescopes. Such is not the case in the city. In the city, all things being equal, always choose the largest telescope.
Well things aren’t always equal, so let me amend that to say: choose the largest telescope you can handle. Obviously if you live on a 5th-floor walk-up you can’t have a 16-inch solid-tube Dobsonian. If you’re going to observe in the city, get the largest-aperture telescope you can handle, that you can store, and that you can move around. That is very, very important.
OMA: For someone with a backyard and a decent view can you make a couple of recommendations for a good telescope. In general terms.
RM: The telescopes I used for my book range from a 3-inch short-tube to a 12-inch Meade Dobsonian and everything in between. I guess if I had to say anything I’d go back to the urban aperture deal. Choose a telescope that is a minimum of 8-inches in aperture.
The other thing I’d say is that in the city, we tend to not to be able to use low-power and wide-field scopes. At low-power in the city you do get a bright sky background. So do not go out of your way to get a short-focal-length wide-field telescope. One is O.K. One can be used. But one offers no advantage to the city observer. For a city observer, something like an 8-inch F/10 SCT (Schmidt-Cassegrain telescope) for an f/6 Newtonian or an f/8 or f/10 refractor is just fine.
(In the next part of this interview… the best kind of mount for urban observing, and the truth about go-to telescopes …)