Questions tagged [telescope]

Questions related to the physical instruments for astronomical observations.

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6
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2answers
205 views

How accurately could late 50s - early 60s humans have mapped the solar system?

What if early SETI investigations had focused on our own solar system, rather than distant stars? Given the technology that existed around the 1950s, how much surveillance would humanity be able to do?...
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2answers
2k views

How to align equatorial mount in the Southern Hemisphere?

I'm new to astronomy and recently got myself a telescope with an equatorial mount. I've found lots of resources online showing how to align the telescope but they all operate on the assumption that ...
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1answer
160 views

Can ground based telescopes use a starshade in space?

1) Could a starshade in orbit be used by ground based telescopes? If so, what kind of orbit should it have? 2) Could the same starshade be used by two different space telescopes, or does the ...
6
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1answer
225 views

How does the black hole at the center of M87 look like in the visible spectrum?

I learned here that the picture of the black hole we saw all over the news was a false color image, based on the radio spectrum emissions. How would the black hole at the center of M87 look like when ...
6
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1answer
317 views

Angular diameter of the Sun's reflection from the ocean, seen from Sun-Earth L1?

I'm trying to understand how smooth the reflecting ocean surface would need to be to produce such a small bright spot as seen from the DSCOVR satellite at Sun-Earth L1. It appears to be only about 8E-...
6
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1answer
622 views

Do primary mirrors in large observatories undergo regular removal and re-coating of the aluminum? Why?

Performance of astronomical mirrors that are exposed to the environment for long periods of time can experience a slow degradation of performance. They usually need to receive some kind of regular ...
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2answers
1k views

What should I look for in an astronomy tripod?

I have a Celstron SkyMaster 20x80 binoculars, and a tripod — Vanguard 263AT with a SBH-100 head. The binoculars weighs 2.2kg, while the head is rated to a loading capacity of 10kg, and the legs to a ...
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1answer
1k views

Build a high quality telescope from scratch [closed]

I am interested in building a high quality portable telescope from scratch in an attempt to better understand how telescopes work. What kind of materials do I need? How would I go about putting the ...
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1answer
6k views

Most important feature of a telescope

I was taking an astronomy test, the following question came up: The most important function of the astronomical telescope is: Resolving power Light gathering power magnifying power ...
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1answer
929 views

Telescope collimation issue

Recently, I purchased a Chinese 8 inch reflector telescope from local store. When I observing stars and planets I've been having trouble getting really sharp image from this telescope. I observe Venus ...
6
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1answer
731 views

What's a good step up from 7x50 binoculars?

I own a Nikon OceanPro 7x50 pair of binoculars, but I find that when I look at the moon, I would like more magnification. My requirements are: costs less than $400 weighs less than 10kg the length ...
6
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1answer
372 views

Basic DIY Telescope

I am looking for a design of a cheap and easy telescope to build with my 9yo daughter with the only basic requirement being that I'd love to be able to see detail on the moon. Looking around, there ...
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2answers
536 views

What range of exit pupils work for observing the full moon?

I'm observing the full moon, from a major city, with heavy light pollution and dust. The objective size is fixed, for this comparison, something between 4 and 6 inches. The question is about the ...
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0answers
90 views

How long would it take to first detect a new object in the night sky given its apparent magnitude?

If an object as bright as the star Polaris (Apparent Magnitude +1.8) showed up in the night sky, it would be detected almost instantly by stargazers. If an object as bright as Pluto (Apparent ...
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0answers
104 views

SpaceX's Starlink Megaconstellation and its Effect on Earth-Based Astronomy [duplicate]

SpaceX's Starlink project is already greatly impeding scientists ability to make good Earth-based observations. With the planned launch of 12,000 satellites total, the future is uncertain. Is there ...
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6answers
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Would a telescope that uses Fresnel lenses be more practical than using regular lenses?

If we were to make telescopes with Fresnel lenses instead of regular lenses, would it be more practical? Would this also allow for much bigger telescopes to be made? Here is an example of the type ...
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3answers
406 views

What is it about the layout of the three gratings in a Bahtinov mask that makes its indicate focus in this way?

The question Lucky imaging with Celestron 14 - is this result reasonable? includes a beautiful example of a focus test using a Bahtinov mask and the image below from Deep Sky Watch's Home Made ...
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3answers
3k views

Dish antenna as parabolic mirror for OPTICAL telescope?

Can I use a chrome painted dish TV antenna as a parabolic reflector for my optical telescope? Given that glass mirrors are quite expensive, I am thinking of using a Dish TV antenna and coating its ...
5
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1answer
440 views

Is Sahara desert a good place to build radio/optical telescopes?

At least Atacama Desert of northern Chile is a good place to build telescopes. VLT and ALMA locate there. What about Sahara desert? http://en.wikipedia.org/wiki/Atacama_Large_Millimeter_Array http:...
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4answers
1k views

Is there a website that shows equivalent views through different telescopes?

I'm trying to buy a beginners telescope. I have a Celestron TravelScope, but would like something better. When I look at other models, many users have posted images from their viewfinders. Is there a ...
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3answers
1k views

Claim that 30-m class telescopes will have resolution far superior to Hubble: true?

This article makes the claim that the Giant Magellan Telescope (GMT, number 4 in the list) will have resolution 10 times better than that of Hubble, while the Thirty Meter Telescope (TMT, number 3 in ...
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2answers
762 views

What can I see with different apertures?

I'm looking to buy a telescope, and every mainstream website says that aperture is the most important factor, and buy the largest telescope your budget can afford. However, a website I found offering ...
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4answers
232 views

How can Mercury's sodium tail be imaged?

I recently learned that Mercury has a sodium tail. Can this sodium tail be imaged with a ground based telescope? Is so, what is the minimum setup required to be able to take a picture of it? Do you ...
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2answers
215 views

Telescopes for beginner astrophotography

I'm a fairly experienced photographer and have enjoyed taking lots of photos of the night sky with my existing gear - wide angle starscapes over pretty hills, mostly. I'd like to move on, having ...
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1answer
171 views

Which space telescope is the most distant?

From the earth, and from the sun. Only interested in active, operational ones.
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1answer
522 views

Colossus telescope, trying to outsmart aliens?

I was listening to Jeff Kuhn's talk on SETI's Colossus telescope project. Background: He explains his theory that a civilization living somewhere the galaxy would want to hide, and thus would ...
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1answer
717 views

Why when we look through a telescope in space, do the billions of stars not block our view from seeing further?

I know that we are able to "see back into time" by looking very far away through telescopes such as the Hubble telescope, but my question is, wouldn't you run into at least a couple of stars that were ...
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2answers
13k views

How many celestial bodies can I see with a 90x telescope?

I am a 9th class student so I'm a beginner at using a telescope, hence please help me. How many bodies can I see using a 90x telescope? How will I know when and where I should point a telescope to ...
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2answers
642 views

A smudge near Jupiter

I was looking at the Jupiter for the first time today and I have noticed a smudge near it. Could someone explain what it is, please? I was looking online but did not find anything. So I thought that ...
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1answer
499 views

Is it possible to steer the sight of a Liquid Mirror Telescope using a plain mirror scheme? If yes, why hasn't it been done?

I have read about Liquid Mirror Telescopes in a number of places, and according to these sources, a major disadvantage of these telescopes is that they can only "see" straight up. In a nutshell, the ...
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2answers
443 views

Upgrade tripod on a cheap telescope

I got a cheap refractor as a present - my intro to astronomy. I think it’s not great, but I’m having plenty of fun looking at the moon and planets, and who knows, maybe some other objects soon. The ...
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3answers
1k views

Question about Telescopes , observations and explanations of the observations

Though I am active on Physics, I am new to Astronomy. I am an amateur astronomer, actually even worse than amateur. I have just started it. I have a 60 mm objective 700mm focal length refractor which ...
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1answer
496 views

Was the use of silver on 'optical' telescope mirrors more common in the past? Why?

In the past, weren't many astronomical telescope mirrors periodically removed and 'resilvered', and wasn't this actually done using silver? I'm guessing that this is much less common now - new ...
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1answer
537 views

What determines which frequency range a radio telescope has?

My simple understanding is that a parabolic dish focuses radio waves to a receiver. It is obvious that any parabola focuses visible light and heat, so I assume that it focuses all radio wavelengths ...
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2answers
822 views

How do or could radio telescopes contribute to exoplanet studies?

Current and upcoming telescopes which find exoplanets and take spectra of their atmospheres seem to be optical or infrared. What about radio telescopes applied to exoplanets? They are larger and more ...
5
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1answer
240 views

What can a lunar-based telescope do?

What can a lunar-based telescope do? If the band is ultraviolet and it can do high time sampling exposure, maybe it can be used to get distance for a star with stable pulses. However, the star should ...
5
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1answer
53 views

Infrared Region Telescopes

Why do we need to build telescopes that can view in the infrared? What exactly do we need to see in the infrared region? I know this seems like a really broad question but I'm just curious about it.
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2answers
109 views

Can the transit of satellite in front of Sun be visible in 10-inch telescope?

I have 10 inch Sky-Watcher telescope and I would like to know if a satellite passing in front of Sun can be visible. Suppose that satellite's angular diameter is 1˝. Yes, I know the formula $\theta=\...
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1answer
108 views

Is Cosmic Ray Astronomy a thing?

Historically astronomy has been the regime of visible light, looking at distant objects in the visible spectrum and later taking photographs in the visible spectrum. In the past century radio ...
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1answer
1k views

How does a Bahtinov mask work?

For focusing the image of a telescope, one can use a Bahtinov mask. How does this mask work, and how did Mr Bahtinov get the idea to cut such a peculiar shape? Is it possible for me to design my own ...
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1answer
60 views

Advice for next steps with astrophotography

Over the last year, I have started to take up the hobby of astrophotography. At the moment I have been focused on planetary astrophotography. Up until now I have been using a Celestron 5SE telescope (...
5
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1answer
86 views

If the visibility function is the Fourier transform of the sky brightness distribution, why do you need the dirty beam and dirty image to find it?

In radio astronomy, the dirty image is equal to the inverse Fourier transform of the uv-plane coverage times the sampled visibilities. The dirty image is also equal to the convolution of the "...
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2answers
305 views

What is the gain of a telescope?

What is the gain of a telescope? How would I go about calculating the gain from a flatfield image?
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1answer
415 views

Surface brightness of deep-sky objects and telescope specs

I'm new to amateur astronomy, and I recently acquired my first small telescope. I've just learned a bit about surface brightness after an unsuccessful night of trying to locate a few nebulae that were ...
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2answers
172 views

Names of specific galaxies in Hubble's XDF

I'm working on a little side project that traces and identifies galaxies in Hubble's XDF using OpenCV. This is my current progress with tracing the more prominent galaxies: I was wondering if there ...
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2answers
28k views

What can we expect to see with a telescope with a 70mm aperture and a 10mm eyepiece?

We purchased my young daughter a beginner telescope for Christmas and she's super excited to look at the large planets. Our telescope has a 70mm aperture and two eye pieces (10mm and 20mm) How much, ...
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2answers
302 views

Bad seeing on a clear night?

I want to say first off, I am a complete beginner, starting out my interest in astronomy (so go easy!). I have been able to see some nice sights on some nights, however, I had a strange experience ...
5
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1answer
184 views

Diameter of Astronomical Object Using Magnification

I took a picture of Jupiter through my telescope, using an iPhone. I know the magnification of the telescope lens I used, and can Google to get the magnification of the iPhone lens (the magnification ...
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1answer
61 views

How to compare a Catadioptrics light asorbtion with a reflector?

I used to have a 6" Dobsonian reflector, and the next telescope I buy, I want it to have the equivlant of about a 11/12" dobsonian reflector. I'm looking at this Nexstar VX 9.25 , it says 235mm ...
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3answers
2k views

Telescope buying guide for a beginner in India

I am located in the southern part of India and am looking forward to buy a telescope to gaze up to look ay farther planets, moons in our solar system and take pictures. How should I go about getting a ...

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