General astronomy discussion

Re: What's the trick? M71

DonDon — Sun, 29 Jun 2008 15:18:56 GMT

That's exactly were I've been looking, I may need a higher power lens. But I still think one of the bright stars is missing, I believe there all yellow stars. Thank's. As a mater of fact, that is the exact same map I use also.

Re: What's the trick? M71

DaveMitsky — Sun, 29 Jun 2008 15:07:37 GMT

I believe that you may be looking in the wrong part of Sagitta. M71 lies near the center of the constellation, to the east of the tail of the arrow.

http://www.atmob.org/library/member/skymaps/MAP8.PDF

http://www.pbase.com/bobstarzynski/image/86461050/original

Dave MItsky

Re: What's the trick? M71

DonDon — Sat, 28 Jun 2008 21:55:25 GMT

Thank's for the links, Dave. Very interesting. I know I was right there, but like I said, I couldnt find that one star. I'll try it again, but if anybody gets the chance to check it out, see if you can find that star at the bottom of the feather..

I think sombody my have bought it, and moved it,

Re: What's the trick? M71

DaveMitsky — Sat, 28 Jun 2008 21:17:19 GMT

M71 is a rather unusual globular cluster. It is much less concentrated and more difficult to discern than most. At one time, it was considered to a rich open cluster by some astronomers.

http://www.seds.org/messier/m/m071.html (information)

http://education.gsu.edu/spehar/FOCUS/Astronomy/star-hop/Monthly/msh09-1.htm#8 (star-hop)

http://www.visualdeepsky.org/cgi-bin/search.cgi?catalogs=Messier&ids=71 (observations)

Dave Mitsky

Re: What's the trick?

DonDon — Sat, 28 Jun 2008 19:41:39 GMT

I think sagitta has lost a star. According to my reasearch M-71 is located below and between two bright stars, I cant find the star at the bottom of where the two lines from the feathers come together. I have found every other object in that area, including the dumbell last night. What's the trick??

Re: What's the trick?

WannaB — Mon, 23 Jun 2008 19:33:28 GMT

zachsdad,

THANK YOU!!!

Re: What's the trick?

zachsdad — Mon, 23 Jun 2008 19:28:21 GMT

I use the Celestrom Ultima 2X barlow (it's exactly the same as the Orion Shorty), and have encountered no problems with any of my plossl eyepieces (ranging from 6mm to 32mm). I also have seen no vignetting in any of my eyepieces -- plossls, Orion Expanse, Orion Stratus, and Baader Hyperion. The Ultima works great in both my scopes -- f4.7 dob and f5 refractor. I think you will be fine with the Orion plossls combined with a good quality Orion barlow. I'd stick with the Shorty, or one of the 3 element full length units. But, that's just my opinion.

Good luck.

Re: What's the trick?

WannaB — Mon, 23 Jun 2008 19:08:37 GMT

O.K., Thanks for the explanation. That presents a problem for me then. I was going to buy a Barlow from Orion and use it with the Plossl's that were provided with the scope I bought. May have a problem, huh?

Anyone have an opinion on how the quality is with the Orion Plossl's and how an Orion Barlow works with them?

Re: What's the trick?

DaveMitsky — Mon, 23 Jun 2008 17:53:01 GMT

"Barlows usually have some effect on the characteristics of the eyepiece with which they are used. For example, the eye relief of the eyepiece may be altered. And in rare instances, users reported that they are not able to reach focus using a Barlow with certain eyepieces (the Plossl design seems to be the most problematical). The effects vary with the quality and/or design of the Barlow and the eyepiece. Another effect is a change in the image quality, specifically in the sharpness of the image. Lesser quality Barlows may also cause vignetting, which is a falloff in brightness at the edge of the field of view. Unfortunately, inferior quality Barlows are commonly included with scopes sold in department stores in order to increase magnification to impossible levels."

http://www.bpccs.com/lcas/Articles/barlow_vs_eyepiece.htm

There's more on Barlow lenses at http://www.televue.com/engine/page.asp?ID=42

You may find a search engine useful for answering additional queries.

Dave Mitsky

Re: What's the trick?

WannaB — Mon, 23 Jun 2008 17:25:39 GMT

FYI, "shorty" Barlows tend to vignette with longer focal length eyepieces. This may or may not bother you.

O.K. What does vignette mean? And how will that affect my longer focal length EP's? So, would it be better to go with the normal Barlow?

Sorry for being so ignorant and needy!!

Re: What's the trick?

DonDon — Mon, 23 Jun 2008 16:56:29 GMT

Thank's Dave, some very helpfull advice, and links. Next time i'll try to dig a little deeper, through the 192 pages before I post a question that has already been asked, sorry.. Don. Thank's for the info on the book also, i'll put it on my list.

Also I printed out the list of objects you gave, I will defenitly give them a try..

Re: What's the trick?

DaveMitsky — Mon, 23 Jun 2008 16:07:44 GMT

You're probably thinking of the Orion SkyGlow filter, which is a broadband LPR filter. Most people, including me, do not find them to be terribly useful for visual use. I happen to own a 2" Orion UltraBlock, along with a number of other filters, and employ it regularly. It's great for widefield views of the North America (not American) Nebula and the Cygnus Loop (Veil Nebula complex), as well as for enhancing plantetary nebulae such as NGC 1514.

FYI, "shorty" Barlows tend to vignette with longer focal length eyepieces. This may or may not bother you.

You may want to pick up a copy of Phil Harrington's great book on astronomy gear entitled Star Ware or borrow a copy from a local library.

Dave Mitsky

Re: What's the trick?

WannaB — Mon, 23 Jun 2008 15:45:07 GMT

Dave Mitsky,

So that Orion Ultrablock is a good filter to buy? I thought I had read somewhere that it really wasn't worth the money? Don't ask where I read that. I've read so much stuff the last month or so I can't keep it all straight. In all seriousness, I think I need to slow down and concentrate on one thing, get that resoved and then move on. My problem with that is I can't figure out what my priority should be. I think it goes like this...(1)get a shorty barlow 3-element, (2)get a 17mm or 20mm wide field eyepiece, (3)????????.

Re: What's the trick?

DaveMitsky — Mon, 23 Jun 2008 14:50:53 GMT

DonDon:

Thank's, I have NightWatch on the way, but I dont know if it has charts in it or not?

Edit

And would the narrowband filter help with all the other colorfull objects?

Edit

If so, then I ask for recomdations on witch type to get.. Thank's everybody!!!!

Nightwatch is generally acknowledged as the single best book for novices. It does contain a series of charts for finding some of the showpiece DSOs but there are certainly better observing guides as such on the market, the best by far being The Night Sky Observer's Guide.

As has already been mentioned, nebula filters do not enhance color. However, they do improve the views of a great many emission and planetary nebulae and make it possible to detect some nebulae - the Horsehead Nebula, the California Nebula, the Veil Nebula complex, and the Helix Nebula, for example - which would be difficult or impossible to see otherwise.

Generally speaking, a narrowband filter such as the DGM Optics NPB, the Lumicon UHC, and the Orion UltraBlock is the single best filter to purchase.

See the following sites for more on nebula filters:

http://www.prairieastronomyclub.org/filters.htm

http://pages.sbcglobal.net/raycash/filters.htm

http://sciastro.net/portia/advice/filters.htm (Disregard what is said about the H-beta filter being useful on only two objects, since it has been found to enhance over a dozen dim nebulae.)

http://www.novac.com/resources/filters/

http://www.knoxvilleobservers.org/dsonline/tips/lprfilters.html

Dave Mitsky

Re: What's the trick?

DaveMitsky — Mon, 23 Jun 2008 03:42:03 GMT

The subject of seeing color in certain DSOs has been discussed here before a number of times as well as many other astronomy fora. In short, color can indeed be perceived in some nebulae, M42 and planetary nebulae such as IC 418, NGC 3242, NGC 6210, NGC 6543, NGC 6572, NGC 7009, and NGC 7662 being prime examples.

Browse http://cs.astronomy.com/asycs/forums/p/26926/348548.aspx#348548 for a more detailed explanation.

Dave Mitsky