Questions tagged [telescope]

Questions related to the physical instruments for astronomical observations.

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5answers
23k views

Can an astronomical telescope view objects on Earth?

I am new to telescopes and I'm planning to buy an astronomical telescope like the "Celestron AstroMaster 114 EQ Reflector". Just curious to know whether it can be used to view objects on Earth (e.g. ...
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316 views

Why was the (small) Hubble better able to find KBO targets for New Horizons than large adaptive optics ground telescopes?

When initial searches for a Kuiper Belt object for New Horizons to fly to after passing Pluto did not find good targets, the Hubble telescope was used, and it resulted in the current targeted flyby ...
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1answer
839 views

How can I observe Sgr A* with itelescope.net

I've been experimenting with itelescope.net and tried to observe Sgr A*. I was wondering if there are any suggestions how I can best observe the surrounding stars.
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3answers
756 views

When did "resilvering" large telescope mirrors actually refer to aluminization, and why was it necessary?

This answer nicely summarizes the general picture of historical use of silver for mid to large size telescope mirrors, and the shift to aluminum once good quality vacuum pumps and chambers suitable ...
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4answers
577 views

Where exactly is the modification that first corrected the spherical aberration in Hubble's primary mirror?

The April 2015 CBS News article How NASA fixed Hubble's flawed vision - and reputation describes the modification taken to the Hubble Space Telescopes by the Space Shuttle that was used to correct for ...
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1answer
740 views

Plot of best available resolution vs wavelength - radio through gamma rays?

What I'm looking for is a graphic that shows in a general way the best available telescope resolution vs wavelength throughout the entire wavelength spectrum. So for example, there might be two very ...
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2answers
2k views

What kind of things I could "see" with an amateur radio telescope?

There are apparently not many reasonably priced radio telescopes available for the amateur users. I only could find a SPIDER 230C 2.3 meter diameter compact radio telescope, which costs ~10 k€. ...
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1answer
177 views

Why telescope mirror glass shipped as randomly broken chunks of a constant size in cardboard boxes?

The video MIRROR LAB: Preparing for Casting GMT's Mirror 6 shows the unpacking several hundred boxes full of broken glass from OHARA, packed in styrofoam. The glass chunks are a fairly uniform size of ...
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2k views

Selecting a Telescope for Viewing Planets

I hope to observe planets like Jupiter and Saturn, and moons. I am a novice when it comes to telescopes and I know images in magazines are not taken with at least 12-inch telescope in a middle of ...
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1answer
303 views

How are the world's biggest telescopes cleaned?

How are the world's biggest telescopes, (such as the Very Large Telescope for example) cleaned? My research includes what I have read about CO2 cleaning here. Are there any other ways to cleaning the ...
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2answers
485 views

Why aren't secondary mirrors offset to get rid of diffraction spikes due to the support vanes?

Some kind of ellipsoidal shape mirror could reflect to a secondary mirror which is not in the way of the infalling light. Two advantages are immediately obvious. The primary mirror would not be partly ...
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1answer
897 views

Which type of telescope should I make?

I am not very much interested in observational physics but I just like to look at the night sky. It gives me a lot of inspiration. So, i was thinking about making a telescope for basic observations. I ...
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Can we see the color of nebulae?

Someone asked me this question: To see the color of the Great Nebula in Orion, how large the aperture of the telescope should be. I don’t even know whether this is possible. I understand that the ...
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1answer
337 views

Is there a cosmic, rather than technological, upper limit to what a telescope can resolve?

Space radio interferometers could have a baseline of millions of kilometers, but is there a point where a larger baseline doesn't improve the resolution anymore because the photons observed are ...
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3answers
565 views

Can we visually perceive exoplanet transits with amateur telescopes?

Is it possible for an amateur astronomer to visually perceive an exoplanet transit by the change of brightness of the star via observations spaced over time, or is the variation of the brightness too ...
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2answers
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Jupiter with a mobile phone and Celestron Astro FI 102mm Maksutov

My name is John, I am new here and now that I am retired I decided to get myself my first ever telescope, why I never got one before I have no idea...probably too busy. So I thought I would try and ...
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2answers
263 views

Ninth planet - what else could it be?

So recently it was announced that there might be a ninth planet out there. Some people (from NASA) say the odds are 50% that it is a real planet, since it hasn't been discovered by telescopes yet. ...
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889 views

Eyepiece diameter for small focal length planetary viewing on a large dobsonian?

I have a 12" dobsonian with a 1500mm focal length and want to do some higher magnification planetary viewing. Currently my highest magnification is ~80x via my 19mm eyepiece (calculated here), but I ...
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539 views

Why do we use FITS format for scientific images especially in astronomy? How is it different from formats such as JPEG, PNG etc?

I am new to astronomy and I found that the telescopic dataset can be stored in the FITS format instead of JPEG. Why do we have a special image format just for scientific images?
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2answers
24k views

I'm having trouble achieving sharp telescope focus

I've been having trouble getting really sharp focus on my telescope. Using Saturn as a reference, with a 20mm eye piece it is very sharp. But when I go to 10mm or 6mm, it gets bigger and blurrier. I ...
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268 views

Why not us interferometry to take a picture of Pluto?

Interferometry is among the best ways (if not, the best way!) to have an image of a very distant object. Recently a picture of the black hole at the center of M87 was released. It is the result of ...
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470 views

My local night sky is so bright that I can only see the Moon, so would a low-cost telescope be any use?

Light pollution is so bad near our home that we can't see anything other the Moon in the night sky. For instance there is a street light on all night right in our lane and there are many other housing ...
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2answers
128 views

Is it possible to use Photolithography for telescope image sensor?

The current largest digital CCD camera is the Vera C. Rubin Observatory, which has a whopping 3.2 gigapixels with a pixel size of 10 micrometers. In contrast, Agfa 10E56 holographic film has a ...
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1answer
7k views

Has THC been detected in space?

I was wondering if and how astronomers have/had detected the molecule Tetrahydrocannabinol (THC), commonly known for it's effects in marijuana, in space. I had previously seen a hoax regarding the ...
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1answer
317 views

How much competition there is for jobs in astronomy compared to other fields of science?

I will soon finish a master's degree in computer science. I have been interested in astronomy for some time, which has included playing around with a Newtonian reflector telescope and reading about ...
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1answer
5k views

Are Barlow lenses stackable for bright objects?

I'm back to the refractor that I own, and I want to maximize the zoom capacity. I realized today that I own more than one barlow lens, and I was wondering if I could stack them together for looking at ...
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1answer
118 views

Where can I find Arecibo's data archive?

Does anyone know where I can find Arecibo's historical data? After much searching, I can find neither hide nor hair of it. It doesn't help that the search results are completely dominated by the news ...
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1answer
128 views

What is the size of the image sensor in the largest optical telescopes?

What image sensors (imaging electronics) are used in telescopes? Like CCD, is that the best option? What is the typical physical size and resolution of the photo-sensitive surface of the currently ...
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1answer
646 views

What kind of telescope do I need to see most of the Jupiter's moons?

I have a simple Newtonian reflector telescope. Using it, I am able to see the Galilean moons of Jupiter. However, Jupiter has much more moons than that (Wikipedia says 67 have been discovered this far)...
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3answers
13k views

Is it safe to view moon at daytime through telescope

I have a little 76mm Newtonian Reflector. I want to see the moon at daytime. Is it safe to look at sky at daytime when sun is shinning or there is any risk of sun.
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246 views

What makes small interferometers useful? Like NIRISS on JWST

NIRISS is an instrument on the James Webb Space Telescope. It has a "non-redundant aperture mask" which obviously covers most of the area of the sensor. It seems to be advantageous for high contrast ...
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1answer
88 views

Occultations of Triton

I've been listening to an episode of the "NASA in Silicon Valley" podcast about the SOFIA mission. One of the techniques they use at SOFIA is stellar occultations to study different objects. My ...
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1answer
245 views

Lucky imaging with Celestron 14 - is this result reasonable?

I attempted to do some lucky imaging of Jupiter using a permanent installation (Celestron $14$" SCT + Paramount ME II) and Nikon D5600 attached directly to a Baader Hyperion 8-24mm eyepiece (...
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2k views

Chromatic aberration in lens

Is there a way to prevent chromatic aberration without using an achromatic lens in refracting telescopes or in any other instruments...?
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4answers
12k views

What's the difference between a Newtonian telescope and a regular telescope

So, recently I was shopping for telescopes and I decided on the following telescope: https://www.amazon.com/Celestron-21049-127EQ-PowerSeeker-Telescope/dp/B0007UQNKY/ I had exactly $180 to spend, ...
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2answers
24k views

What are the advantages and disadvantages of a 2-inch eyepiece versus a 1.25-inch eyepiece?

I'm considering picking up some new eyepieces for my telescope and am interested in comparing 2-inch and 1.25-inch eyepieces. Are there any disadvantages to 2-inch eyepieces? Are 2-inch eyepieces only ...
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4answers
599 views

Why not use only one support vane for the secondary mirror, to avoid multiple diffraction spikes?

Each vane holding the secondary mirror in front of the primary causes a diffraction spike. Couldn't the secondary mirror be held with only one vane? If stability is the issue, couldn't it be ...
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1answer
686 views

Will JWST be as durable as the hubble telescope?

JW Space Telescope is designed for a 5-10 year mission duration. Seeing as Hubble and other space missions have paved the way for JWST for reliability issues, It even has zero friction gyro's with 100+...
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2answers
17k views

Which planets, nebula, and other objects can be seen using Celestron Astromaster 130EQ

I have got a Celestron Astromaster 130EQ telescope, which lens should I use to see the various planets and nebula? When I tried to see Mars it was only a small red dot on scope. As per the ...
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3answers
1k views

How would a Fast Fourier Transform Telescope work without a mirror, dish or lenses?

I recently came across a short article mentioning the idea for a telescope built without mirrors or lenses that instead uses an array of antennas and massive computing power to resolve an image. Such ...
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3answers
2k views

Astronomical telescope making

I am thinking about making a telescope. I have a 100cm focal length lens which I can use as objective lens in my telescope. So which is the best focal length I can use as eyepiece in my astronomical ...
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1answer
2k views

How do telescopes "zoom" and change angle of view?

Images from the Hubble Space Telescope have widely different angles of view. Is this only the result of composing multiple images, or can the telescope itself change its "zooming" optically, ...
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2answers
251 views

Would alcohol wiping damage multi-coated eyepiece coating? How else can I take COVID precautions on the eyepiece?

My small group of friends will be wearing masks. But could COVID-19 be spread by eyes/eyelashes touching the eyepiece? If so, what precautions should I take? I have a small Starblast scope with an ...
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1answer
310 views

If we had the right technology could we see a distant star in detail?

If, for instance, Hubble's camera was a $10^{300}$ times better, could it see a distant star in details, or is there a limit to the amount of light that reaches the Earth's orbit or perhaps does the ...
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2answers
205 views

Do we know at which angle the Event Horizon Telescope will look at the accretion disk of Sagittarius A*?

Do we know at which angle the Event Horizon Telescope will look at the accretion disk of Sagittarius A*? Additionally, would it matter if we are exactly in the plane with the accretion disk, i.e. ...
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1answer
881 views

What is the meaning of "bright unresolved sources"

In many articles talking about telescopes, they talk often of "bright, unresolved sources". "bright" usually mean that the magnitude should be less than a certain threshold, (or that the signal to ...
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2answers
1k views

What should I expect to see with my telescope with what EP's?

Recently got a Celestron 130 SLT (first "real" scope) and have a question. I have the following: 130mm F/5 newtonian, 650mm focal length scope 9 and 25mm factory EP's (more on that later) Svbony 2x ...
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1answer
1k views

Periodic error correction in automatic telescopes

I am starting a study on automatic telescopes and the correction of their periodic error. I found two ways of correcting it : with a CCD camera and manually by recording the error. I was wondering if ...
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1answer
203 views

Planned telescope to detect alien waste-heat

I remember watching a talk by someone who designed a telescope to view a single star at a time. The purpose of the telescope was to detect waste-heat which would presumably be emitted by any ...
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2answers
202 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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