Questions tagged [telescope]

Questions related to the physical instruments for astronomical observations.

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How much of M87 can i see with an amateur telescope?

I was reading about M87 and how it is possible to see it's relativistic jet with an amateur telescope. About a year ago i impulse-bought a telescope (model: Celestron CE21049 powerseeker 127EQ). I'm ...
Yeeter's user avatar
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4 votes
1 answer
166 views

Can we get a picture of Oumuamua with Hubble Space Telescope?

Can we get a picture of Oumuamua with Hubble Space Telescope? If not, what are the reasons? Answers why other telescopes might fail to get a picture of Oumuamua are welcomed as well.
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1 vote
1 answer
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Safety while using a telescope to view a total solar eclipse

I have an 8-inch reflector telescope and a solar filter that goes on the front aperture to view the Sun (most recently to view the transit of Mercury). If I were to use this telescope during a total ...
Mark H's user avatar
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3 votes
1 answer
154 views

Do telescopes exist that reflect the incoming light more than three times along their length?

Refractors only use the length of the telescope once, reflectors twice, catadioptric telescopes like those of the Schmidt-Cassegrain design three times. Have telescopes been built that reflect the ...
2080's user avatar
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2 votes
1 answer
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Do triple or more times reflecting telescopes exist?

Refractors only use the length of the telescope once, reflectors twice, catadioptric telescopes like those of the Schmidt-Cassegrain design three times. Have telescopes been built that reflect the ...
2080's user avatar
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1 answer
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How do I design a good telescope to observe nebulae and other deep sky objects [closed]

How can I make a good telescope that is powerful enough show nebulae and other deep sky objects ? (consider low budget build)
Amrith Adithya's user avatar
2 votes
1 answer
214 views

Given telescope diameter and focal length only, how can I find the size of a produced image?

I'm new to astronomy and I'm struggling to understand this concept. For example, A 20-cm diameter telescope with a focal length f = 2 meters produces an image of the moon 1.7 cm in diameter. How large ...
Stu Dant's user avatar
8 votes
3 answers
2k views

Telescope on drones to escape light pollution?

Would it be possible to mount a telescope on a high quality drone and fly above the light pollution to get better star shots (if the wind allows it of course)?
K P's user avatar
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19 votes
6 answers
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Why do small mirror imperfections matter with modern computers

Modern telescopes go to great lengths to have perfectly shaped parabolic mirrors. My question is, why go to the trouble of having a perfect mirror? Why not take a mirror roughly the right shape, and ...
DanielOfTaebl's user avatar
3 votes
1 answer
879 views

How to reduce magnification and increase FOV of a camera attached to a telescope?

I am a beginner in astronomy. I have a Maksutov telescope (90mm/1250mm). Generally I do observation with a 25mm wide angle eyepiece, but sometimes due to light pollution I can't see many stars. So I ...
Laxmikant Dange's user avatar
7 votes
1 answer
258 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 ...
franz_lyre's user avatar
9 votes
2 answers
2k views

Is it possible to observe strong gravitational lensing with amateur telescopes?

Strong gravitational lens systems like the Cosmic Horseshoe have been imaged by scientific space telescopes, but have any amateur astronomers accomplished this? Or are amateur/small ground based ...
2080's user avatar
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5 votes
2 answers
261 views

How are non-visible electromagnetic waves detected that originate from space?

How are non-visible electromagnetic waves from space detected and interpreted by the receiver? Is it in the same manner, as say radio waves produced on Earth, where the EM wave interacts with the ...
James Oconnell's user avatar
5 votes
1 answer
161 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 ...
Sidharth Ghoshal's user avatar
21 votes
4 answers
8k views

Why is Starlink polluting the night sky a big concern if we have space telescopes?

There's a lot of concern in the Astronomy community over the deployment of Starlink satellites. For a good discussion, see the related question How will Starlink affect observational astronomy? But ...
JonathanReez's user avatar
3 votes
1 answer
105 views

Hypothetically, could a civilization in a solar system near a supermassive blackhole use the blackhole as a huge gravity lens telescope?

I have heard of various proposals that use the massive gravity of stars to sort of focus light at and observe with a suitable telescope placed at such a distance, and I am assuming here that bigger ...
Hash's user avatar
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4 votes
2 answers
1k views

Plotting Equatorial coordinates to X,Y plane (simulating telescope/camera view)

I would like to simulate a telescope camera view, projecting (RA, Dec) coordinate sets to a 2D plane. So effectively the need is to convert Equatorial coordinates to (x, y) coordinates, when we can ...
AstroDuck's user avatar
1 vote
0 answers
114 views

Convert apparent magnitude in a filter to a luminosity

I have data in Johnson B & V filters and I would like to convert the observed magnitudes, m$_x$, into luminosities, L$_x$, over a passband where I already know the distance, d, to the object. x is ...
James's user avatar
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5 votes
0 answers
70 views

What to do in case of concentric circles that are not aligned with the cross after collimation (Picture inside)?

I have been collimating my newly bought first Newtonian telescope for a few days now, but I can't get the center of the circles to align with the intersection point of the spider's reflection. I have ...
Ramy Gaw's user avatar
1 vote
1 answer
228 views

How did I flip some mirrors around in the dark at 3 AM and change the focal length of a 24 inch Boller and Chivens?

Current answer(s) to How do telescopes "zoom" and change angle of view? are "they don't", but traditional large genera-purpose observatory telescopes do sometimes (often?) have ...
uhoh's user avatar
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3 votes
1 answer
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Are X-ray telescopes with glancing angle surfaces basically "funny-looking" Cassegrain telescopes mathematically?

In this answer I included the image below of a reflective X-ray telescope. It is made from two elements; the first is concentric shells of glancing (high incidence) angle paraboloidal surfaces, and ...
uhoh's user avatar
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2 votes
0 answers
52 views

Size of crosshair

TL;DR: Does anybody know the width of a single crosshair as a fraction of the full field of view on a Skywatcher 1.25 inch 12.5mm illuminated reticle? Explanation (in case there's a different question ...
Jonny Evans's user avatar
2 votes
0 answers
62 views

What happens to the Fourier Transform of the Measured Spectrum?

What happens when you double the width of the entrance slit of a spectrograph, in turn letting in twice as much light, would there be an improvement in the Fourier transform of the measured spectral ...
Jay D's user avatar
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2 votes
1 answer
281 views

Limiting magnitudes for different telescopes

I live in an extremely light polluted place. On a new moon night, magnitude 3.5 stars are at the limit of naked eye visiblity on clear nights, and the Orion nebula is visible as a smudge through my ...
aman's user avatar
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2 votes
0 answers
25 views

Spectrograph Arrangement, Noise, and Fourier Domain [closed]

If the transform of a line profile extends out to the Nyquist frequency such that we cannot see the noise level, what could we change in our spectrograph arrangement that would allow us to see the ...
Jay D's user avatar
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5 votes
2 answers
1k 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?
nocappp's user avatar
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1 vote
0 answers
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Please Help Me With Choosing my 1st Telescope

I'm going to buy my 1st telescope. With the budget, I've shortlisted some. Tried with the YT videos, reviews and guide. Few things still bugging me. Hope somebody can give me any advice on this. There ...
Nats's user avatar
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3 votes
1 answer
130 views

Telescope showing high chromatic aberration

Hi i have made a telescope with 1100 mm focal length objective lense and 21mm plano convex as eyepiece. Both these lenses are not achromatic. But when is looked through it , the images were completely ...
sanoj's user avatar
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1 vote
0 answers
39 views

Can you attach an old Vixen model to a celestron tripod?

I would like to know if I can put an old Vixen VMC model (15 years old) onto a celestron 4se tripod. I am aware that some adaptations must be made, but I want to know if it's even possible or if it ...
Saikios's user avatar
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3 votes
1 answer
100 views

Diameter of the moon from the diameter seen in the telescope

I'm reading a chapter on convex lenses and it has this diagram: The chapter explains that triangles ABC and ADE are similar. Thus, ratio of CB to DE is equal to the ratio of BA to AD. Does this mean ...
user3349993's user avatar
9 votes
1 answer
367 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 ...
uhoh's user avatar
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2 votes
0 answers
79 views

Tradeoffs "upgrading" from a 60/900 refractor to a 150/1200 Dobsonian?

My current/previous telescope is a Skywatcher 60/900 refractor on an equatorial mount. I am now looking at a SkyWatcher 150/1200 "Classic" Dobsonian reflector. How can I compare the two in ...
vanja's user avatar
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2 votes
0 answers
59 views

Convert Object Intensity to Pixel Intensity

If I have an object of some size and spectral radiance, and it's some distance R from a camera, how would I calculate its digital count value in an image? I'm sure there's an equation out there, but I ...
user3433489's user avatar
2 votes
1 answer
102 views

Benefits to adding a 32mm Pössl to my Celestron AstroMaster 130EQ's eyepieces?

I am getting a Celestron AstroMaster 130EQ soon. I have heard that its eyepieces aren't the best, so I am considering a 32mm Pössl. For such a choice, what would be the arguments for and against? How ...
Jacob Kurzawa's user avatar
3 votes
1 answer
140 views

Maritime telescopes: Stabilisation requirements for optical vs. radio telescopes?

SOFIA stands for Stratospheric Observatory for Infrared Astronomy. She says: My telescope stays stable with a spherical bearing, shock absorbers, and gyroscopes. I suppose a similar system would ...
B--rian's user avatar
  • 5,616
2 votes
0 answers
196 views

Celestron uncommon DC long barrel connector

I have tried to connect a 12v DC adaptor and also a battery pack to my telescope unsuccessfully. Sadly it seems Celestron DC jack needs to be around 2mm longer than common 5525 DC ports. I was ...
Real Dreams's user avatar
2 votes
0 answers
56 views

What are recent discoveries with Earth-based radar telescopes?

The Wikipedia article on radar astronomy lists a few important discoveries using radar technology in general, i.e. also using space-crafts: The following is a list of planetary bodies that have been ...
B--rian's user avatar
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2 votes
1 answer
505 views

Can I see Jupiter, Saturn, Mars and Venus with the Spectra Optics Telescope 600x50? [duplicate]

Is it possible to see Jupiter, Saturn, Mars and Venus with the Spectra Optics Telescope 600x50? And even the moon? This is the description of the telescope: User-friendly and easy to install with ...
John's user avatar
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1 vote
2 answers
1k views

Can I see Jupiter, Mars and Saturn through the National Geographic 76/350 Dobsonian Telescope?

Is it possible to see Mars, Jupiter and Saturn through the National Geographic 76/350 Dobsonian Telescope? It's the most affordable telescope I can get at the moment. Also, what about the moon? Will ...
John's user avatar
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3 votes
1 answer
52 views

Is sky-glow affected by height?

I'm an architecture student and my graduation project will consist of building a research center for outer space, my question is whether or not height would affect sky-glow or not ? Thanks in advance, ...
Shadi Amr's user avatar
4 votes
1 answer
272 views

How to connect my phone to a motorized telescope via a cable?

Some motorized telescopes (e.g. Celestron NexStar Series) have no WiFi by default. Can I connect my phone to them to be used as a hand control via a cable? The telescopes have AUX port and phones USB ...
Real Dreams's user avatar
10 votes
4 answers
4k views

Why can't we build a huge stationary optical telescope inside a depression similar to the FAST radio telescope?

So first we'll have to find a natural depression or we should create one. I understand you can only see a single portion of the sky since it can't be moved, so my money is on creating an artificial ...
AKR's user avatar
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3 votes
0 answers
82 views

Can the "haze" of a mirror telescope be quantified?

When reading Why was StDr56 discovered only now? and its answers and comments, I realized that refractor telescopes, and in particular the Dragonfly Telephoto Array are a great tool to find nebula and ...
B--rian's user avatar
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1 vote
1 answer
1k views

What eyepiece to use for moon?

I'm using a 95mm f/8.4 telescope. What's the best eyepiece that I can buy for a very close look at the moon or even planets? I'm a beginner in this field so please help me. Thank you.
Hasith Magage's user avatar
8 votes
3 answers
697 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 ...
Vitor Z.'s user avatar
  • 153
2 votes
1 answer
258 views

Fresnel lenses for a makeshift Galilei telescope?

For a kindergarden (pirate) party, friends of me want to build together with the 4 year old kids a functional pirate's telescope for each of the kids. On the web I found full constuction sets, e.g. ...
B--rian's user avatar
  • 5,616
3 votes
1 answer
85 views

How do we differentiate between a star or planet and noise introduced due to equipment?

I understand that differentiating between celestial bodies and noise due to equipment is a fundamental problem in astronomy. I also understand that we solve this problem by looking at something called ...
user14812745's user avatar
2 votes
2 answers
247 views

Using a refractor telescope 5" aperture, 900mm focal length for terrestrial viewing

Can I use a refractor telescope 5" aperture, 900mm focal length on an equatorial mount for terrestrial viewing.
JACQUES MERRAN's user avatar
3 votes
2 answers
116 views

Understanding energy loss in a telescope aperture due to atmospheric dispersion

I'm trying to understand energy losses due to atmospheric dispersion, given the plot below from the Keck telescope. For a typical seeing I'm told that there's 80% encircled energy in 1". The ...
theWrongAlice's user avatar
2 votes
1 answer
90 views

Telescope lens problem when cold

We are having a problem with our scopes on cold nights. (-10F is about average here.) One poorly aimed breath means that the eyepiece lens fogs. We have to remove the lens and keep it under our arms ...
Bookaholic's user avatar
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