You asked for it, so here it is… the third part of my interview with Rod Mollise, author of Choosing and Using a New CAT: Getting the Most from Your Schmidt Cassegrain or Any Catadioptric Telescope. In this installment, Rod tells you about the best deep-sky objects to see from the city, his favorite sights in the night sky after 40 years of observing, and the secret of how he saw a supernova in a distant galaxy from the bright, hazy skies of Mobile, Alabama.
If you observe under light-polluted skies, these articles will help you get the best possible views of the heavens under the most unfavorable conditions.
One-Minute Astronomer (OMA): You mentioned non-magnifying finders like the Telrad or the red-dots. A lot of telescopes come with those these days. Are they of much use in the city?
Rod Mollise (RM): A Telrad or a red-dot sight is not of much use in the city. For the same reason star-hopping’s hard. If you can’t see many stars with the naked eye, you won’t see many stars in your Telrad or zero-power finder. They don’t gather any more like than what your eye gathers with its tiny lens.
In those cases, you want a minimum of a 50 mm optical finder. In the city, that, as I said, can still be very limiting in certain places if the light pollution is so bad you still can’t see many stars even with a 50 mm finder. That’s true in many locations. But one is a darned sight better than a Telrad in those conditions.
“Uncle Rod” Mollise, author of “The Urban Astronomer’s Guide“
OMA: So when you plan an observing run, each night, do you use a software package to plan urban observing, or just a star map?
RM: There are three programs I use. I couldn’t recommend one over the other. Deep Sky, Sky Tools, and Astro Planner. All three of those are basically the same thing. They’re very huge databases with charting features as well and a lot of other stuff. Their value is that you can tell them, “Make me a list of all the galaxies in Virgo with magnitude 10 and higher than 30-degrees in the sky at 9 p.m. on April 1”, and it will spit a list right out. That is really the only way to fly. Like I said, most of these programs will do fairly good charts or, if you’re lazy like I am, you’ll just take your laptop into the backyard, plug it into the telescope, bring up your observing list, click on the first item in your observing list and send the telescope there.
But the bottom line is, you need an observing list and the easy way to do it is with one of those programs Deep Sky, Sky Tools, or Astro Planner. They’re all very inexpensive and they can do more to keep you interested than many other things. Any one of those programs will have a database of 100,000+ objects. You’ll never run out of things to see and it makes it so easy to find things to look at that will be in a good spot and bright enough for you to see in the city.
OMA: All right. Now when you’re out with your telescope, one thing that I’ve found when I’ve got my list in hand, I’ve got my high-power eyepiece, I’ve got my telescope… I find something that drives me crazy is that’s it’s hard to get away from streetlights or a neighbor’s floodlights in the backyard. Have you got any tips to help keep those lights out of your eyes?
RM: Well, you know, you have to be creative. In some cases, it may be like I said, when you’re observing a certain part of the sky, all you have to do is get in the lee of a shed and lots of light is blocked out.
As I alluded to earlier, the biggest hindrance to seeing things in the city is not skyglow. I hear people say, “Well in my city, the dimmest star I can see is magnitude 2.” Yada, yada, yada. That’s a bunch of bull hockey, usually. Usually what’s happened is there’s nearby ambient light sources. Light in the immediate area that are shining right into your face that keep your pupils constricted, that keep you from achieving any dark adaptation. You can see a lot in the city sky even with skyglow if you can obtain a modicum of dark adaptation.
Now there are various ways to do that. You can go from the simple, like a dark hood, or an eye patch, things that keep the light out of your observing eye except when your eye is at the eyepiece. Or you can get fancier. If you have a detached house with a nice secure backyard, you might consider an observatory. As I say in the book, a lot of my country friends think it’s fun that you’d want to have an observatory in an urban backyard. But actually, one of the main benefits of an observatory is more of a benefit in the city. It keeps you blocked from light, wind, and things like that.
But you know, anything will work. A tarp hung up on a clothes line or something like that. Or a ladder with a piece of poster stapled to the top of it. Just anything you can devise to put you in a shadow.
But again, the important thing again is to block urban ambient light sources. Because ambient light sources do more than anything else to keep you from seeing “stuff”.
OMA: If you’re looking at a light, it’s going to constrict your pupils, and you’re out of luck.
RM: That’s right. You will never get dark adaptation. And I think you’d be surprised even from the worst light-polluted city what you can see if you’re eyes are dark adapted and you’re only just dealing with the urban skyglow.
OMA: O.K. Well let’s talk about some of the things you can see from the city. Now of course many beginners want to tackle the moon and the planets, Jupiter and Saturn especially, and they make good targets from the city. But what kind of deep sky objects look good? You mentioned you can see the whole Messier list.
RM: Indeed you can, but before we leave the subject of moon and planets, what many people don’t know is not only can you see the moon and planets from the city by also they look better from the city.
OMA: Why is that?
RM: Often the air above a city, for a variety of reasons… heat signature and other things… is more stable than it is out in the country.
But yes, you can see the entire Messier. Now when I say you can see the entire Messier, I don’t mean you don’t have to work at it! If you’re going after something like the “Ghost Galaxy”, M74, you are going to wait until your skies are the very best, until a cold front has passed through. Wait until M74 is as high in the sky as it will get, that is, when it’s at culmination. Etc. etc. It may take you weeks to see M74, and when you see M74 all you may see is the core. But you will at least have the satisfaction of saying, “I did it!” And by struggling to see M74, you have improved your observing skills so much that you will see a lot more in M74 when you get to dark skies than you otherwise would have.
But continuing on the subject of what you can see… not everything is hard. Open star clusters in particular aren’t hurt very much at all by city light pollution. Or at least they are not harmed as much as a nebula or a galaxy.
Double stars are always easy.
Globular clusters are fairly easy, especially the bright showpieces. A 12-inch telescope will show up an M13, or an M15, or an M2, for just what it is… a big ball of stars. You won’t find it looking as good, naturally, as you would in the dark country, but still it will look darned good.
OMA: Now what kind of object, conversely, is too hard to see from the city, or is very challenging?
RM: The challenge objects from the city are the “challenge nebulae”. Even with a light pollution filter, as I said… something like the Horsehead… don’t waste your time.
However, brighter nebulae, like of course, the Orion Nebula, the Trifid Nebula, nebula in that class are easy. We’re speaking of diffuse nebulae.
Now conversely, many planetary nebulae except the largest ones, are very easy in the city. M57, the Ring Nebula; the Blue Snowball that’s obvious in Andromeda are hardly hurt at all by light pollution, and also respond very very well to light pollution filters.
So galaxies… how about galaxies? Galaxies are easily visible. You can see scads of galaxies. The drawback is that you’re not going to see the delicate spiral arms that you’re going to see from the country. Even a fairly bright galaxy like M51, the Whirlpool, you’re just going to see two cores instead of M51 and its companion. But on the other hand as I said you can say you saw it, and on some really good nights maybe you can see some detail. And again, you will be a better observer.
Plus don’t count anything out. Many times I have trotted out into the backyard here with a 12-inch telescope and wound up seeing a supernova near the core of a dim NGC galaxy because someone called up and wondered if I could see it with my horrible skies, and I took on the challenge. I guess that’s the number-one thing in urban astronomy, and the number-one thing in astronomy altogether… there’s no sure way of being proven wrong than to say some observation is “impossible”. You never know until you try.
OMA: So two miles from downtown Mobile you saw a supernova in another galaxy?
RM: Oh, heck yeah!
RM: But, I turned off the TV, got off my butt, and went out back with my telescope. That’s the main factor there. You have to not just observe. You have to make observing a habit.
I think William Herschel, arguably the greatest amateur astronomer of all time, had it best. I don’t have the exact quote, but he likened observing to playing music…
OMA: Yes, yes…
RM: How good a musician would you be if you one a month? Not very good! How good an amateur astronomer, or professional astronomer, would you be… or telescope operator, or anyone else who has to observe the night sky… if you only did that one time a month?
RM: If you get out in your backyard every night and try to see the “Black Eye” in M64 and finally see a trace of it, you’re going to be, again, a heck of a better observer when you do get out to where the skies are really good. If you get out in your backyard all the time and keep in practice, there’s less chance you’re going to be completely clueless when you do get out to the Texas Star Party or somewhere really good.
OMA: Right, right. You’ll know how to find things and how to look for things.
RM: And how to look for things, and how to look at things.
OMA: Exactly, exactly. So if you were told tomorrow night is your last night on Earth and you could go out with your chosen telescope. From your backyard, what would be your favorite one or two or three objects you’d like to look at?
RM: That would be like saying, “What are your one or two favorite members of your family”? I’ve been observing the night sky seriously since 1965 and the stars and the planets and the moon and the deep-sky objects are my friends. I mean my wife just finds it amusing that I’ll be talking about some distant galaxy as if it’s a little buddy of mine, a little playmate, positively chuckling over it.
But if I just say, what things would I want to look at before I leave this plane, I keep coming back to the Moon. The Moon has been a source of enduring interest for me. Jupiter. Jupiter has been a source of enduring interest for me. And then the Messier objects, and especially… I don’t have to name them… they trip off every amateur astronomer’s tongue: M42, and M13, and M7, and M8, and M15 and M2, and M31. I think those 110 objects… those 110 friends of mine… plus our Sun’s little family… I would do my damndest to see as many of that bunch as I could before I left.
I guess at this time of the year (editor’s note: November 2008), if you were to pin me down, what would be the one thing I would look at, it would be the Great Orion Nebula, M42.
OMA: It’s a beauty!
RM: I spent last night from a truly dark sight observing it with a 13 mm and 8 mm Ethos eyepiece. Looking at it, looking at the countless tiny stars embedded in these tendrils of gas. Looking at the space of dark nebula between M42 and M43 and I’ve got my iPod on and all of a sudden on the iPod comes Enya with her song “To Paint the Sky With Stars”. And I almost fell off my observing ladder, bud!
OMA: Fantastic! That is fantastic.
RM: Well, it ought to tell you something that I can still retain that enthusiasm after 40 years. And the only secret to maintaining your enthusiasm is to get out there and do it!
OMA: Rod, thanks very much for doing this. There aren’t many who specialize in “urban observing” so it’s great to hear all these tips and tricks, especially from someone who wrote the “bible” of urban observing. It was great speaking with you. I really enjoyed it.
RM: Ah, anytime, and best wishes and good observing to you and your many subscribers, Brian. Thanks a lot.
OMA: Thanks very much.