The telescopes tag has no wiki summary.
16
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6answers
853 views
Lenses (refractor) or mirrors (reflector) telescope?
What differentiates, in terms of practical quality, not technical implementation, a refractor from a reflector telescope?
Why would one prefer a refractor over a reflector, when reflectors come with ...
7
votes
0answers
116 views
Optimal telescope size?
Consider a diffraction-limited telescope with unobstructed aperture $D$. Such a scope is capable of yielding an angular resolution $\alpha$ that scales as $\lambda/D$, with $\lambda$ denoting the ...
2
votes
1answer
84 views
Why do focal lengths affect magnification?
For compound lenses, the image formed by first lens acts as the imaginaryobject for the second lens.
In telescopes, the objective lens projects an image on its focal point which works as the object ...
6
votes
2answers
135 views
Why does a blue sky at dusk appear nearly black through a telescope?
Earlier this evening I was looking at the Moon through my cheap toy telescope (x150 magnification) when I noticed a (rather mundane) optical effect I couldn't explain. The Sun had just dipped below ...
2
votes
1answer
144 views
Telescope size to view saturn
What is the properties (size, etc) of required lenses for minimal telescope to see the Saturn rings clearly?
8
votes
4answers
739 views
How can I stabilize an unstable telescope?
I have an 80 mm refractor telescope on a tripod, but it shakes on every touch. It's very hard to see via 6 mm (x120) ocular. Even a little wind causes the image to become too unsteady.
How ...
10
votes
4answers
2k views
Is building your own reflector telescope worth it?
I have always fancied building my own reflector telescope. I am wondering - For a certain budget, can you get better results with a home made rig? Or is this a folly, and really it would be better to ...
3
votes
3answers
409 views
How to locate the Orion Nebula?
I was trying to see Orion Nebula for few days now and I simply can't spot it. I'm using Celestron PowerSeeker 127EQ ( 5" , Newtonian , 1000m ). I'm pretty sure I have the right spot as I saw many ...
3
votes
2answers
273 views
Hartmann mask based collimation
Is there a detailed description for a Hartmann mask based collimation process?
I've been told by a friend that is possible to collimate an SCT by placing a three round holes Hartmann mask at the ...
3
votes
3answers
44 views
Quality loss when adding more components to a telescope?
I would think this would be inherently true, but I'm curious:
(Assuming the highest quality amateur instruments are used.)
Is quality lost when, say, adding a T-mount adapter, diagonal or any other ...
4
votes
1answer
36 views
Should I be concerned about spot corrosion on a telescope's primary mirror?
I am considering buying a telescope with a large primary mirror that is about seven years old - it has a small spot of corrosion on the mirror, that the owner says is stable.
Should I be concerned ...
0
votes
2answers
108 views
Do I need to focus the telescope?
I purchased a 90x refractor telescope with below configuration.
Objective: 50mm diameter with 360mm focal length
2 Eye pieces: 6mm, 20mm (10-1/ 8" scope)
1.5x erecting eye piece
It measures 13- ...
3
votes
5answers
979 views
Having difficulties finding objects with Celestron Telescope
I have a Celestron Astromaster 114 EQ, which I saw was highly recommended as a great beginner scope. But I just can't seem to find anything in the sky with it. Yes, I've removed the lens cap, yes I've ...
3
votes
2answers
97 views
The Bahtinov focusing mask
I'm looking for a webpage or a book or reference that might give me a better (and hopefully more scientific) understanding of how the Bahtinov mask works (which I understand to be the same as ...
5
votes
5answers
34 views
Which current big Earth-based telescopes are equipped with adaptive optics?
I know only that the VLT is equipped with adaptive optics (AO) to bypass atmospheric distortion. Is it the only one, or have other telescopes been build with AO in the optical and infrared spectrum?
8
votes
5answers
67 views
Exoplanet detection via space-based parasol
I remember from watching Cosmos years ago, Carl Sagan suggested an interesting hypothetical method for directly seeing exoplanets. He proposed that in the 'future' we could launch a satellite designed ...
4
votes
3answers
60 views
How long would it take to scan the visible universe for unique signals?
The article Amazing rays as star succumbs to dark side talks about a very large black hole swallowing up a star. The report goes on to say that the only reason it was discovered was because it shot ...
8
votes
1answer
32 views
How do I use this 'Horizon Observatory'?
Just around the corner, we have one of these:
It's at the Halde Hoheward (article in the German wikipedia), and it's called a 'Horizon Observatory' by the people who built it.
How does it work ...
2
votes
0answers
123 views
Future space-based telescope array
Radio-telescopes (e.g. the Very Large Array (VLA)) can simulate one gigantic dish by using separate smaller dishes.
Q: Could such an array of optical telescopes potentially see an exoplanet at say 20 ...
10
votes
2answers
104 views
How do air Cherenkov telescopes work?
The very highest energy photons, gamma-rays, are too energetic to be detected by standard optical methods. In fact they rarely actually make it to the surface of the Earth at all but interact with ...
8
votes
1answer
291 views
Why is the Ritchey–Chrétien telescope preferred in professional astronomy?
Hubble, as well as numerous other professional telescopes, use the Ritchey–Chrétien design. What optical and instrumental advantages does this kind of telescope have for professional astronomy?
10
votes
2answers
396 views
Observing Jupiter's non-Galilean moons
What strength of telescope is required to observe some of the non-Galilean moons of Jupiter?
My current telescope at 50 magnification resolves the Galilean moons well, but I'm guessing it's far ...
7
votes
1answer
30 views
What size aperature would I need to find and see the supernova in M51?
On June 2, 2011, a new supernova was identified by an amateur French astronomer in M51.
What size telescope aperture would one need to have any chance of seeing this? Given the right sized scope, ...
7
votes
6answers
443 views
Can any telescope be used for solar observing?
Can any telescope, such as a 8" reflector, that is normally used at night to look at planets be used or adapted for solar observing?
What kind of adapters or filters are required or is it better to ...
20
votes
4answers
287 views
How to determine what size telescope to buy
A couple of years ago my son showed an interest in astronomy and we bought a 6" reflector telescope. We use it pretty regularly and have enjoyed it immensely. Lately we've both been wishing we had ...
26
votes
4answers
217 views
Telescopes to avoid as a beginner? [closed]
I've heard people talk about "department store scopes" or "trash scopes". How do I know what to avoid in a beginner scope? How can I know that I'm not getting something we will be more frustrated with ...
8
votes
1answer
81 views
Where can I find information for how to create amateur radio telescope?
Where can I find good source of information for how to create amateur radio telescope.
Particularly interested in creating Fresnel Zone Plate Antennas (aka flat dish).
design, diagrams, ...
-1
votes
2answers
2k views
Celestron NexStar 6 SE vs. Orion XT8 [closed]
I'm interested in purchasing a new telescope and have narrowed it down to the NexStar 6 SE vs. the Orion XT8.
I'd like to be able to get into astrophotography and read that having the Go-To ...
6
votes
3answers
39 views
How to get started in Astronomy (UK based) [closed]
I have always been interested in space and astronomy (in my youth - I wanted to be an astronaut).
However for various reasons, I never quite got started. I now want to get started - small but ...
3
votes
2answers
38 views
Particular targets of high angular resolution infrared telescopes
I work in the field of infrared interferometry, specifically instrumentation.
As such, I need to be aware of the science goals of such an instrument. Is there a quick list of important and ...
1
vote
0answers
24 views
What equipment is needed for equatorial drift scanning/TDI with a Dobsonian?
It should be possible to do a "parked scan" along the celestial equator ("stripe 82" and "stripe 10") with a Dobsonian telescope, as no tracking is required. I can foresee two issues, though: first, ...
6
votes
2answers
85 views
If you focus in on one image, is combining two telescopes really equivalent to a larger mirror?
Have a look at this example:
In addition, the Keck I and Keck II telescopes can work together as the Keck Interferometer. The 85-metre (279 ft) separation between the two telescopes gives them the ...
3
votes
1answer
120 views
Error analysis of flux from telescope-CCD setup (photometric calibration)
I am doing photometric calibration of a telescope and am trying to work out the errors on the flux that I measure. I have attempted to work out the errors due to the process of removing bias, dark ...
6
votes
1answer
123 views
What sort of equipment would I need to take a photo like this?
I'm interested in doing some astrophotography and I'm looking into the equipment needed to get a photo like this: http://www.flickr.com/photos/cscunha1984/6619321531/in/faves-heyvian/
I'm not looking ...
2
votes
2answers
177 views
How to correct flares and sharply focus on my telescope when viewing planets.
A month or two ago I purchased a “Skywatcher Explorer 130P Newtonian Reflector” telescope - which so far is brilliant when looking at the Moon, esp. using a neutral density filter. However, when ...
6
votes
1answer
110 views
Why is the Hubble Space telescope able to see farthest in the universe?
What determines how far a telescope can see in the universe? How does recording data for a very long time (~10 years) help? If we could build a telescope which work at microwave region, will it be a ...
4
votes
2answers
129 views
How to adjust feather touch focuser for collimation?
I have a Starlight Instruments feather touch focuser for my Dobsonian telescope.
While trying to collimate the secondary mirror with the focus all the way in, I noticed that my Howie Glatter laser ...
8
votes
3answers
258 views
Why is this radio telescope's reflector spherical and not parabolic?
This is the Arecibo Observatory in Arecibo, Puerto Rico. Its reflector is spherical, measuring 1,001 ft. in diameter. It is considered the most sensitive radio telescope on Earth, but the fact that ...
4
votes
4answers
355 views
Are telescopes with a concave lens useful for astronomy?
Are telescopes with a concave lens (instead of convex ones) ever useful for astronomy?
And if so, where are they used? Do they ever affect resolving power?
13
votes
4answers
139 views
Why don't we have a better telescope than the Hubble Space Telescope?
The Hubble Space Telescope (HST) was launched in 1990, more than 20 years ago, but I know that it was supposed to be launched in 1986, 24 years ago. Since it only took 66 years from the fist plane to ...
2
votes
3answers
271 views
How could I translate a field of view value into a magnification value?
When I zoom in with Stellarium, it indicates a field of view (FOV) value in degrees, but most binoculars and telescopes are advertised with value like "nX magnification power."
How could I translate ...
0
votes
1answer
63 views
Telescopes Meade Etx90ec [closed]
Hi I am looking to purchase a second hand Meade ETX90ec
Meade Telescope ETx 90 EC comes with deluxe tripod ,3 super plossol eyepieces 9mm, 15mm, 26, also barlow lens. Has anyone had any experience ...
6
votes
4answers
54 views
Does the current light pollution set a fundamental limit for the range of Earth-based telescopes?
As far as I know, all deep-sky pictures are captured with the Hubble Space Telescope.
If there would be no atmospheric distortion, could we make deeper pictures in the optical spectrum with ...
0
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0answers
43 views
Observing through a 90 degrees positioned telescope on a flat surface
Assuming I'm standing in the middle of the ocean with a large telescope, positioned such that it's angle is 90 degrees (i.e, it's parallel to the sea) and assume that there are no light interferences ...
4
votes
3answers
443 views
Sky-Watcher Skyhawk 1145P SynScan AZ GOTO
What is the experience using the Sky-Watcher Skyhawk 1145P SynScan AZ GOTO telescope and can it be recommended for a new astronomer? Is it any good?
5
votes
1answer
273 views
What telescope would I need to observe Mars's polar caps?
What telescope refractor aperture size would I need to observe Mars's polar caps?
I have a Levenuhk Strike NG 80mm, and I can see red disk of planet but cannot see any details on the surface.
6
votes
3answers
153 views
Is it possible to make a hydrogen-alpha solar scope?
Is the construction of an etalon / Fabry-Pérot interferometer within the reach of amateur telescope makers? Are there any resources pointing to such projects?
4
votes
1answer
19 views
What demonstrations for a five-hour optical and radio astronomy workshop? [closed]
I volunteer at a group that has restored the oldest German radio telescope. We are now at a point where we want to invite interested amateur astronomers and school children to workshops. I'm currently ...
3
votes
2answers
26 views
Are our telescopes capable of taking actual images of brown dwarfs?
http://www.sciencedaily.com/releases/2011/08/110824102135.htm
And could we achieve a high enough resolution to actually be able to study the dynamics of brown dwarf atmospheres in the near-future?
...
4
votes
4answers
217 views
Can the Hubble telescope bring any star into focus?
Lets say I am talking about a view like this supernova - 13 billions light year away. In short can Hubble bring any star into focus in the entire universe? And if so, to what definition?
I also ...
