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Posts Made By: Enrique Barrio

May 28, 2007 07:45 PM Forum: Telescope Making

A dumb question re binocular viewers and refractor

Posted By Enrique Barrio

I search these forums and didn't find anything; but, I was wondering if anyone has tried to use the principles of a binocular viewer in reverse; to connect two telescopes to a single eyepiece. The thought comes to mind, when I consider that connecting two 6" refractors yields 56.5 square inches of light gathering appeture; the equivalent of an 8.5" refractor. If the tubes can be properly matched, collaminated, and mounted, would it be possible to achieve the performance of a larger scope, while reducing the technical challenge of producing an ever larger, heavier, and more difficult objective lense?

June 11, 2007 11:09 AM Forum: Beginning Astronomy?

Identifying man made objects

Posted By Enrique Barrio

Last night, as I was casually scanning the skies with binoculars, I noticed an object moving due North at a high and constant rate of speed. It seemed neither an aircraft, nor meteorite, and was most likely one of the many man made items currently in orbit. It sparked my curiosity; and, I wonder if anyone know of a tool which would help us to identify and track satillites and space junk?


August 8, 2007 02:50 AM Forum: Beginning Astronomy?

I am on a quest for that rarest of all beasts; a actual brick and mortar astronomy store

Posted By Enrique Barrio

As much as we like to put down department store scopes; I rarely see anything better for sale anywhere other then the internet. I googled my state state this afternoon, and except for a few camera stores with a beginner scope or two; there was nothing.

Are there any real store anywhere that actually carry equipment that would be worth a visit. Is our hobby really that arcane? Has science in general drifted that far from popular appeal?

I love the internet as much as most; but, every so often it is nice to be able to kick the tires and buy something on the spot.


October 8, 2007 09:10 PM Forum: Solar System Observing

Re: MARS 10/07/07

Posted By Enrique Barrio

That is a terrific shot of Mars. It resolved very clearly even with fairly high magnification.

October 21, 2007 02:46 PM Forum: Beginning Astronomy?

A bone to pick on the subject of scale

Posted By Enrique Barrio

We know the derision that most of us feel when we see a tiny department store scope packed in a box proclaming some absurd amount of power and decorated with Hubble quality images. But, there is alot more of that sort of thing happening all throughtout the hobby of astronomy. We need only google a Messier object, or enjoy one of "Pictures of the Day" on our home page, to be awed by brilliantly detailed photos of strikingly beautifull objects. Unfortunately, almost all of those images are completely alien to what we can expect to see by simply turning our scopes skyward and taking a peek.

What seems to be missing is an element of scale; the lengend on our mental map of the sky which proclaims a measure equivalent to so many miles to the inch. But, not only along the one dimension, since so many other factors determine what can actually be seen and how it should be expected to appear.

Let's look at some of the major points of confusion:

1) The apparent size of the target: It is perfectly natural to want to illustrate each subject with the best available image. But, in doing so we usually add to the confusion by readilly mixing up the apparent size of objects. The same textbook, or article will contain a vast array of scales with no attempt to juxposition the one against the other. The moon may generously fill your field of view at 100x; but, what about the other planets, or beyond them some of the endless other objects? Should we be looking for an elephant that generously fills FOV, perhaps a tiny version of the same, or merely a trunk, a tail, a leg, or an ear?

2) Just what are we looking for: There is a vast difference between imaging and visual astronomy. Just becuase we can capture vast amount of detail on an image does not mean that the details are useful to visual astronomers. Sometimes the excess details merely obscures the relevant landmarks. I was looking at an old series of plates reproduced in David Bergamini's The Universe (Time Life, 1962, pg 57) which shows four photos of a star cluster taken through the 100 inch at mt. Wilson. The images show the same object after a 6 minute exposure, a 15 minute exposure, a 37 minute exposure, and a 94 minute exposure. The appearance of the object changes so drastically as to be barely recognizable. Just how is an image processed through hundreds of stacked plates, and representing many hours of exposure, helpful in identifying an object when merely viewed visually?

3) What about aperture: Aperture is king, the bigger our scopes the more light that they can collect, and the more likely that our eyes will be able to resolve the finer details of the object. But just how should an object appear in a six inch scope, and how would that image appear differently in a 20 inch, or a mere two inch? Similar to exposure length, we can expect the object to look vastly different; what may seem little more then a dim fuzzy can resolve itself into something sharp, colorful, and awe inspiring. Once again we are often led astray, our popular image does not align with what we can expect to see through the eyepiece.

4) Which way is up?: There may be no up or down in space; but, there certainly is an up or down to the Earth bound observer. How many times have we seen images rotated out of true, with no indication as to which side of the image should be aligned with the celestial pole?

Perhaps what we lack is a common language. We know that what we will each see when we look up at the sky will vary depending on many factors, certainly not the least of which is ourselves. But, we seem to lack the means to communicate; how do we describe a landscape where the landmarks change in apparent size and shape? Do we have a program out there where you can define your equipment,eyepiece, location, seeing, and exposure and have it return a photo-realistic recreation of how the sky should appear through your eyepiece? Experience and computer aided navigation can cure much of this; they can point our scopes in the desired direction. But, there is still a gap between what we can actually see and how we describe it.


November 1, 2007 04:37 AM Forum: Solar System Observing

What is the best way to keep track of comets

Posted By Enrique Barrio

I was presently surprised by Comet Holmes. But, it has left me wondering about other know comets and when and where they may be paying a vist to the inner solar system. Can someone recommend good resource for tracking these objects?

November 18, 2007 09:00 AM Forum: Solar System Observing

Did NASA accidentilly nuke Jupiter?

Posted By Enrique Barrio

In September of 2003 NASA sent their Galileo space probe on a terminal decent into Jupiter's atmosphere. About a month later, on October 19th, this photo was proportedly taken. It show an odd dark surface feature which might be the result of a nuclear detonation.



Full Story here:
http://www.enterprisemission.com/NukingJupiter.html

Lets say that have a healthy sense of skeptism about this image. Can any of you provide any evidence to collaborate this report?

March 16, 2008 01:04 AM Forum: Solar System Observing

The moons of Jupiter and Saturn

Posted By Enrique Barrio

Mars can be a frustrating planet to observe. It is small and distant, and the local dust storms can mask most of the surface features, leaving only a subtile hint of detail in most small scopes. But, even so, you can begin to see the disk of the planet with even a pair of astronomical binoculars; which is to say at 20-30x.

Understandably, the Jovian system is about 3 times as far from us, and even its largest moons are but 2/3 the size of Mars. But, 30x300%x3/2=135x, and even on a calm clear day when I can crank my 8 and 10 inch scopes up to around 500x the moons resolve to mere star-like points of light. Is it possible to resolve the moons around these systems a bit more clearly; and, if so, what does it actually take to get to resolve to at least a nice round disk for these objects?

October 17, 2008 12:53 PM Forum: Equipment Talk

Celestron C-150HD reflector

Posted By Enrique Barrio

I own a Celestron C-150HD reflector, the discontinued 6 inch short tube with a spherical mirror and a built in Jones-Bird corrector on the secondary. I purchased this one as a challenge, and knew ahead of time that it is hard to get good performance out of these; but, it has been fun trying. This one still has issues on brighter targets, and it has trouble resolving images at magnifications higher then 100-150x. In short it's performance is worse then I would expect from an uncorrected 150mmx500mm short tube.

What I wanted to share with you is a odd effect that I have been noticing at the eyepiece. Even when collimated and properly focused, the scope tends to distort brighter targets like Jupiter, or Saturn; however, by moving further away from the plossl eyepiece (say 25-50mm - well beyond normal eye relief) the image seems to improve. Does anyone have experience with this, and can some explain why this seems to occur? I am wondering whether spherical mirrors favor one eyepiece design over another.

n2s

October 31, 2008 03:12 AM Forum: Beginning Astronomy?

What are the advantages/disadvantages of a fast fo

Posted By Enrique Barrio

I have used a variety of telescopes for years, but I have yet to get into astro-photography, and I am not sure that I fully appreciate the advantages of a fast vs. longer focal length scope. Granted, the same eyepiece will yield a wider field of view with a shorter length scope, and an a 20-inch obsession at f15 would require a 20+ foot high platform for the observer. But, short of the purely mechanical issues,and the assumed qualitative advantages of very long focal length scopes; What are the arguments for and against a fast scope?