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Auburn Astronomical Society E-Newsletter April, 2007 In this Issue
This month’s meeting will be on Friday, April 6, at 8:00PM in room 215 of the Aerospace Engineering Building. Riders from the Montgomery area are welcome to meet at the home of Russell Whigham, 518 Seminole Dr., and carpool over to Auburn. Plan to be ready to leave for Auburn at 7:00PM. AAS Vice president and program chair, Allen Screws, writes: Our April program will be the John Dobson tape “A Sidewalk Astronomer”. It's about 80 minutes long so I guess we could do it in one meeting or stretch it over two. It's subtitled: A film about astronomy, cosmology, and John Dobson. I guess it's about his life, telescopes, and activities plus. Our dark-sky star party this month will be on
Saturday, April 14, at Cliff
Hill’s farm, clouds permitting of course.
April 6, April meeting Mark your calendars for Saturday, April 21. The Auburn Astronomical Society in partnership with the W. A. Gayle Planetarium, will celebrate National Astronomy Day, at the planetarium in Oak Park in Montgomery. This is traditionally our best attended event of the year. We extend a special invitation to those of you who live too far away to attend most of our events, to come and spend the afternoon and evening with us. If you plan to attend, please let me know. If you’re bringing telescopes, let us know what type(s) and size(s). Planetarium director, Rick Evans, needs a list of names for the name tags and a head count for refreshments. If you don’t have a telescope, we always need people to help at the AAS information table and someone to help keep an eye on the clock to point out satellite passages to our guests. If you are considering the purchase of a telescope, this is a good place to look and ask questions. If you have a telescope or accessories for sale, this will be the best place in town your yard sale. Rick is still firming up details with a speaker,
but the day’s agenda will be like those of recent years:
3:00PM: AAS members and friends begin setting up telescopes. Early bird visitors will be able to view the four-day-old Moon, Venus near its greatest elongation, and the Sun in the light of hydrogen-alpha with the AAS PST scope, and members filtered white-light images.For those who have never attended one of our Astronomy Day events, you can get a feel for what goes on by going to the “Field Trips” link from the AAS menu, then to “W.A. Gayle Planetarium Events”. Remember to wear your AAS Shirt if you have one. It’s time for another group photo. March Star Party
Ray Kunert’s Observatory
Observing report from Conecuh National Forest
I made my ninth trip down to the Conecuh National Forest on Friday March 16, because the forecast for Saturday looked iffy. The Gegenshein seemed a lot less visible than it was back in November, and there seemed a bit more haze in the air, but the conditions were still decent. I did a bunch of galaxy observing, scoring seven more Hickson galaxy groups, as well as hopping around the Virgo Cluster. Other highlights of the night included splitting the gravitationally lensed Twin Quasar in Ursa Major, picking out M87’s jet at 410X. It was very subtle, but at high power I kept detecting a second condensation of light near M87's core. I was able to determine the position angle of the glow relative to the core, and sketched it relative to the background stars. The angle I sketched the jet coming out of the core exactly matched an image I found. Finally I was able detect the planetary nebula Abell 40 in Ophiuchus. Jupiter was also very striking hovering just over the Pipe Nebula just before sunrise. It actually wasn't a banner night for me. The observing list is long because I spent 9 hours at it, and you can get quite a bit of observing done in that time period. I wore out at 3:30 AM due to waking up early the previous morning, and took an hour nap as the Milky Way climbed high enough for me to do some observing of it. [Editor’s note: Since this report, John has received a replacement for his original 18-inch mirror used for the above observations. John continues:] The new mirror is really excellent BTW.
Stars really snap to a focus now. Saturn was extremely crisp, and
I do believe the view I got of it was better than through Greg Glasscock's
12.5" StarMaster. I'm very happy, and will likely end up keeping
this scope, unless I get a really nice figure on my 25". With the
new mirror, I was also able to split Sirius and resolve Sirius B as a tiny
dot hiding deep in Sirius' glare.
David King This news release may be of interest to your readers.
David T. King, Jr.
Scott Thompson
When I first met Greg and Mary Beth Dimijian, we were on an astronomical tour in Arizona. We share many interests and fascinations as well as concerns about the beautiful nature that surrounds us each day. I have a great respect for Greg’s works and his views. His photography from around the world inspires as well as teaches its viewers of the diverse habitats that are diminishing before our eyes. I urge you to visit his web site at http://www.dimijianimages.com/. When Greg sent me a few of his star trails from around the planet I couldn’t resist asking him to spin off a few words for an article. He obliged with the following that I hope you will enjoy. Even if you are not inclined as a photographer to take photos, perhaps you will learn something about how the stars rotate around our fragile planet. Greg begins: Photographers who haven’t taken photos of star trails have missed out on a lot of fun. You never know quite what you will get, and the results may surprise you every time. Look at the 3 examples in this article and make a guess why they all look so different. From: Larry Owsley
From Ben Hammond: Hi Tech Star Gazing Stuff
on CNN web site
From: Larry Owsley
Subject: Uncle Rod's Rebel Reviews
Michael Schwartz is new to AAS. For you foodies out there, Michael is the Executive Chef at the Capital City Club, here in Montgomery. He was at our March star party, hungry for information on our hobby. The following are e-mail exchanges between us. Michael asked such good questions, that I thought many others considering the purchase of a telescope could profit from his posers: Hello Michael,
...
Here are few questions that I hope you'll be able to answer.
Superior materials, design, craftsmanship, a dash of snob appeal, some supply & demand issues, and yes. Having said that, I wouldn't recommend it for you right away unless you just can't tolerate anything less than perfect pinpoint star images from edge to edge of your eyepieces. Most folks are willing to sacrifice a little optical perfection for a little more light gathering capability (aperture). 2. What are the advantages of an observatory ? Permanent scope alignment, local light shielding, zero set-up/take-down time, protection from wind, protection from dew, ready access to computers, cameras, charts, and notes always ready to go. 3. What's the biggest scope you've ever looked through? The largest was a 25-inch Dobsonian. The central star in "The Ring" nebula was barely visible. I've also looked through several 24's, 20's and 18's. The best view is any of the above with a O-III filter sweeping around the "Veil" nebula. !!! 4. I saw an advert for a 14 " SCT. Are the images really that much different through one of these vs. maybe an 11" Comparing an 11-inch to a 14-inch, would be about
like comparing an 8-inch to the 11-inch -- that much difference.
As telescopes go up in size, they also go up in weight, cost, resolution
and light-gathering ability at an exponential rate. My C-11 is the
maximum size and weight I would want to try to manage. The optical
tube assembly weights 65 lbs. The C-14 OTA is about 110 lbs. [http://www.company7.com/celestron/]
5. Could you introduce me to Cliff Hill sometime in the near future? I may not get to the Saturday night parties. But I may be able to make it out on Sunday or Monday night following the party. ( I don’t want to intrude or seem to take advantage ) Just give him a call and mention the Auburn Astronomical
Society:
6. Where are the darkest skies within our area ( 1 to 2 hours ) Do you have Goggle Earth? Try this overlay: Montgomery Light Pollution1.kmz If you don't have Google Earth, let me know and I'll send a screen shot of the map. Hope this helps, Russell
Are there any club members who have Takahashi's or larger Dobsonians ? Ray Kunert (he was the guy you were set up next to, and was visiting with, when I arrived at the star party) has a Takahashi Sky 90. Dobsonians in decreasing aperture:
You may also like to know that Tom McGowan makes the MidnighTelescopes and mentioned last month that he has the mirrors and materials for 3, 20-inchers. He lives in Deatsville. I'm hoping that they'll all be at Astronomy Day on April 21. I know you said you had to work that night, but maybe you could stop by for a few minutes around mid-afternoon, to have a look. When I read the advert for that 14 ", they mentioned the weight was 48 lbs and I thought to myself I could manage that. But you say it's really 110. That’s a lot to schlep out to the field each month. I wonder how crisp the images are on that scope ? It's a Celestron SCT, Starbright coatings and Starfast computerized locating. Pretty expensive too. I got those numbers from a Google hit on Company 7's page. Could be, that the C-14 weight was for the OTA and mount. As to how crisp, it's all in the collimation: http://legault.club.fr/collim.html I will likely seek to purchase a larger scope one day. But I really would like to see significant differences in the " Seeing of Stuff " ( to put it plainly ). For me, I was using a 6" Newt for a good while. I did a bunch of reading on the SCT's and thought that was the right way to go. So I saved up and bought the C-8. I am happy with the clarity and ease of use. But there isn't that much difference with the size of the images ( Saturn or Jupiter for instance ) over the 6 " Newt. The focal length on your SCT is 2 meters. I would have guessed that for a 6 inch Newt, it would be about 4 feet. I'm surprised you didn't see more difference. Did you do a side-by-side test? What do you would you suggest? Thanks ahead of time. Hope I'm not taking too much of your time. I'm enjoying your questions. The only way to know for sure what's best for you is to try everything. We have a pretty good sampling within the club, but a regional star party would be your best bet:
Russell
Here's
a few more Q's
Like: More good stuff like you're asking about in your question #3, below. Dislikes:
2. There's a minor problem call the "Dobsonian Hole". When the scope is pointed straight up, you lose the mechanical advantage of the leverage of the overall length of the scope, making for tedious adjustments in altitude and azimuth. The good news is that all of the stuff that's overhead, will be easily reachable in an hour or so. 3. If tracking/guiding is an issue, you'll need the GoTo option. This isn't a big deal if it's just you and you're only interested in visual observation. A clock drive is an asset at public events, and essential for imaging. 2. Can you help me better understand focal lengths & Low & High power settings. ( In particular, how they relate to my C-8 ) Here's the basic arithmetic: Magnification=Telescope focal length divided by eyepiece focal length. Your C-8 has a focal length of 2000 mm. If you're using a 20mm eyepiece, 2000/20=100X. Focal Ratio= Telescope focal length (2000mm), divided by telescope aperture (200mm). In your case f/10. Exit pupil = Eyepiece focal length
divided by telescope f/#. In your case 20/10=2
3.
What aperture scope will help me to really see detail while viewing Galaxies
and Nebulae
Yes, it makes sense, but I can't really answer your question. You can definitely see spiral structure in "The Whirlpool" galaxy, even in my 11-inch. A 20-inch will begin to approach photos you've seen (if you're not expecting much color), and larger is better, but still may not rival the best images you've seen. 4. Do you know anyone who owns a C-14 ( that I may see first hand through it ) Charles Floyd (Phenix City) is the only AAS member who has a C-14. He also has a Meade 12-inch LX200. His interest lies in imaging. Auburn University has one that the use in their astronomy course lab. I had the pleasure of looking through it back in the early eighties. Even from the light polluted site in front of Parker Hall it was very impressive. It also took two of us to lift the OTA into the forks. 5. Lastly , do the guy's who own those larger Dobs bring them out to the star parties often? Semi-often. As you might expect, these guys are looking for really dark skies -- much darker than at Cliff Hill's farm. John Tatarchuk, has made several trips to the Conecuh National Forest, where he has reported 7th magnitude naked-eye stars. When they do bring them out, it a purely unselfish act, because they're mainly doing it for our enjoyment. In my C-8 , Saturn appears about the size of a pencil eraser. The addition of 2x Barlow makes it a bit bigger, but not much to brag about. Can you help educate me in the areas of low , med , and high power settings? Maybe these are effecting my views ? Maybe I’m just limited because of 8" aperture.- Chef If your collimation is precise, I suspect it's the effects of poor seeing or that your C-8 hasn't cooled down to ambient temperature. The best view I've ever seen of Saturn was a medium power view through a 12.5-inch Dob. Second best was a 3-inch Questar. Can you see the Cassini division? Keep 'em coming, Russell ==============================
Michael, On this one, I'm deferring to the experts. I'm forwarding this to: John Tatarchuk, William Baugh, Eddie Kirkland, and Tom McGowan. Guys, how about making the case for Michael's Big Dob and help him with his choices. Ok
My Friend,
1. 6K is well beyond my budget for a C-14 and although I think the views might justify the expense, my wife would probably disagree. So, my question is , Is a larger Dob the way to go to get more aperture for less $$ & what are the trade offs? 2.
There are any number of Dobs out there to buy. From new to used, in all
price ranges.
3.
Discovery makes a 15 " size for about 2999.00 w/ No cooling fan + Shipping
costs are extra.
As for viewing the Cassini division. Yes. But the object ( Saturn ) was still tiny. How big does it appear in your C-11 ? If you can see Cassini, it counts. I've only seen the elusive Enke division once with the C-11 -- under abnormally good seeing. That's
it for now. I'll talk to you soon- Michael
Michael,
First of all, ALL truss tube designs require collimation every time they are set up. Tube dobs can hold their collimation (most of the time), but you had better well check it every time before you observe. However, collimation is extremely easy with the right tools, such as a laser collimator, Cheshire sight, or combination of the two (there are all sorts of collimation tools). I personally prefer just a simple laser and Mark 1 eyeball. All you have to do is adjust the secondary mirror so that the laser hits the center of the primary, then adjust the primary till the laser hits the hole it comes out of. Then I give it a one over through the focuser to make sure everything looks right and the laser is hitting the center of the secondary. It usually takes all of 2 minutes. Sometimes the process gets a bit more convoluted than that, but 95% of the time that's all I have to do. However, don't let collimation scare you, it truly is easy. Heck, it was easy the first time I had to do it- as I mentioned these big dobs must be collimated every time they are used, so they are designed to make the job easy. About telescopes though... I have heard lots of good things about the Meade Lightbridge scopes. Personally, I wouldn't buy one simply because it's Meade- they're mass-produced in China, and every time you buy one you are contributing money to a nation that has nothing better to do than to blow up old weather satellites and spread massive quantities of dangerous material in earth orbit (not to mention everything else crooked the commies do). I'd rather buy products from the USA or Canada, and you'll get much better quality products that way too. Furthermore, Meade's suit against Celestron a few years back [vexed] me off, and several years back I bought some expensive Meade accessories that turned out to be nothing other than trash glued together with optical cement. However, all that said, these telescopes have been garnering some fairly good reviews. Some things on them must be modified- such as painting the inside of mirror box black. The general consensus seems to be that they are good values for the price you pay. I personally like Discovery. They have built up a reputation for quality optics, and I haven't read anything about them ever churning out a bad mirror, which must mean that it is a rare occasion indeed. The Discovery scopes I have looked through have all been excellent, and the owners never have anything bad to say. Sky and Telescope gave a very positive review to the 12.5 Premium Discovery model a few years back. On some of the tube-dob Discovery models- I don't know which- you can break the tube down into two pieces for easy transport and storage. It's called a split-tube design. If I had to purchase a moderate sized dob and couldn't afford a premium brand like Obsession or StarMaster, I would probably buy a Discovery. Furthermore, Discovery scopes are made in the USA and not mass produced by some Chinese worker making five cents an hour. It drives the price up a bit, but Discovery does represent in my mind a step in quality in-between Meade and the big-name truss dob makers. There is a third option. Tom McGowan, a member of the club here, makes his own truss dobs by the name of Midnightelescopes. He made Eddie Kirkland's scope, and I was impressed enough by his craftsmanship to take up his offer of building my 25" for me. Eddie's scope looks and handles just as nice as any Obsession or StarMaster, and Tom adds his own touches such as the upper cage nesting into the mirror box for compact storage and a built-in filter slide. He uses the same optics that the big-name dob makers use. I know that Tom was planning on building some 12.5" scope(s). If you are interested in his scopes, you ought to get a hold of him. I was actually considering selling my 18" Obsession once I get my 25" (I've been waiting on the dang mirror for two years now). I'm not so sure I want to sell it now- James Mulherin sent me a brand new mirror to replace my old sub-par one and the optics on it are just exquisite. I guess I'll decide after I get my 25" and see how I like its performance on the planets. Anyway, before you decide, you really should try out one of these scopes. I'd be willing to meet you out at the club star party site sometime, maybe even a weekday if it doesn't conflict with classes. I don't want to go on a truly good new moon weekend night since those are so rare that I've got to spend them down at a darker site. Good luck with your decision.
I am not really any closer to a decision just yet. After speaking to John, I'm inclined to try out different eyepieces and see if that may help my quest for better views. Although, having a larger Dob in addition to my C-8 might be the direction I take. This sounds like a good way to go, to me. I do have some questions regarding eyepieces. Maybe you can help . It looks like today's topic is "Eyepieces". Have you been here? http://www.televue.com/engine/page.asp?cat=2. Lots of good info. 1. What is considered a high power eyepiece ? From "Choosing Eyepieces" from the above link: HIGH-POWER VIEWINGOf course, there are exceptions. I increased the magnification up to 700x (using a 4mm orthoscopic eyepiece) with the C-11 on the planetary nebula, NGC3242, aka " Ghost of Jupiter "and " CBS Nebula" before the full detail of the CBS logo was realized. 2. What EP would you recommend w/ wide FOV and high power ? While it's more in the mid-power category, but I really like the 13mm Type 6 Nagler, but I'm having a hard time justifying the cost for the few minutes each year I'd be using it. For now, I'll just keep setting up at star parties next to my unselfish friends who already have them. ;-) 3. What is so different about the Nagler EP's that they have a category all unto themselves. It must be the 82 degree apparent field of view. 4. Pricing is all over the planet on Brands of EP's. I know you get what you pay for. What are some excellent performing Brands @ moderate prices? F/10 and slower scopes are much more forgiving than say, an f/4.5, so you can get away with using mid-priced eyepieces without compromising much on the quality of your view. For the same reason, Kellner eyepieces work just fine in f/15 scopes. I have several University Optics eyepieces that are my "most used", though I could really tell a difference when looking at Uranus when I borrowed a 13 Nagler! I haven't tried one, but I've read that the Williams Optics UWAN series, particularly the 28mm (2-inch), are an excellent buys. <http://www.telescopes.com/series/william-optics-uwan-series-eyepieces-5788.html>. But, if I had it to do all over again, I think I would opt for fewer and better eyepieces in the mid-power range. I'm quite happy with my UO 40mm MK-70 for wide fields. I've tried the 31 Nagler, but at over 2 pounds, it becomes a real balancing issue, and I didn't think the difference was worth the cost. In a big Dob, it's a entirely different matter. 5 Who are the other club members who have a variety of EP's that I may test drive a few in order to make a good purchasing decision ? John, Eddie, Tom, and Don Cluck all have excellent eyepiece collections. I'm not as familiar with William's eyepieces, and Ray has a collection similar to mine -- I think. 6. If you could only choose 3 Ep's, which ones would they be ? ( I know, that's not fair ) But I ask in light of choosing 3 to put in the budget. I don't think I can improve on Uncle Al's recommendations at: <http://www.televue.com/engine/page.asp?ID=222> I know I'm treading on thin ice to take issue with Uncle Al, but the consensus on the Yahoo! SCT users group, seems to be that the 1.25-inch opening at the rear of the 8-inch scope, makes a 2-inch diagonal and 2-inch eyepieces overkill. The 10-inch and larger SCT's have a larger opening at the visual back, making the 2-inch optics the way to go for wide field SCT observing. I've always heard that for 1.25-inch optics, that a 32mm was the lower limit. Again, I'm copying this to the more experienced observers for their input. Good questions, Russell
Well, if you're looking at a big dob still, you'll probably want to splurge still on eyepieces. A good scope is only a good scope if it is using good eyepieces, and a good scope can give bad views with cruddy eyepieces. Really, I am not much of an eyepiece expert, and am pretty far behind times on the "economy" lines of eyepieces. You see, I never really had any interest in getting any of them. However, I do still know a bit about eyepieces in general. Basically, what makes the Naglers, Panoptics, and Pentax XW's so expensive is that they offer wide fields of views with MINIMAL DISTORTION around edges of the fields of view, even in fast telescopes. Naglers are also known for their excellent planetary performance. My dob is a f/4.5, I don't use a coma corrector, and stars in my Panoptics, Naglers, and my Pentax are pinpoints from the center of the field all the way to the edge. The Pentax XWs offer an apparent field of view of 65 degrees, Panoptics have an AFOV of 68 degrees, and Naglers have an AFOV of 82 degrees. What you will find in the economy lines of wide field eyepieces is that they will perform fine in scopes all the way down to like f/6 of f/7, but faster than that and the stars at the edge of the FOV start to become distorted. Let me tell you a little story about Meade. Once, when I was younger and more gullible, I bought a Meade 24.5mm Super Wide eyepiece, with a AFOV of 68 degrees of so. I pay like $250 for this thing, which according to Meade, is one of the “finest eyepieces in the world”. Well, I get it, pop it in my 8” f/6 dob, and the distortion around the edge of the field of view was terrible! All the stars were deformed into little arcs! Needless to say, I have never used it since. About a year and a half later, I purchased a 19mm Tele Vue Panoptic, and the stars were pinpoints all the way to the edge of the FOV. I still use the Panoptic to this day, it’s a fine eyepiece. This is one of the many reasons I hate Meade, but to get on with the story, I was in junior high at the time and loaned out the 24.5mm one of the science teachers who owned a 10” SCT. He didn’t find a thing wrong with it! Apparently, the eyepiece shows little or no edge of the field aberrations through an f/10 scope. Well, anyway, if you really can’t afford splurging on eyepieces, you might try getting a set of, I donno, Plossls maybe. Tele Vue makes decent Plossls. The two big drawbacks of Plossls is their short eye relief at short focal lengths and small apparent field of view of 50 or 52 degrees. However, they don’t really induce any distortions to the image. Maybe someone who is more familiar with cheaper eyepieces could provide a better suggestion. Hope this helps. If you would like to try
out some Naglers, Panoptics or my Pentax, or see a big dob, I should still
be free to observe from Cliff Hill’s farm on perhaps April 6 or 7.
Hoping to see everyone at the meeting and star party, Russell
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