Questions tagged [telescope]

Questions related to the physical instruments for astronomical observations.

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2
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0answers
36 views

How to pick a telescope?

I am trying to find a started telescope for my high school sister and my goals are to have awesome pictures and to let her explore her interest in the stars! They live in a clear night sky area so Im ...
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Methods for testing a refracting telescope lens

I have an old (nearly 50 years old)alt-azimuth three-inch (7.6cm) refracting telescope that someone else made. They ground the lens, created the cylindrical body and added a rack and pinion style ...
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52 views

How can I determine if a typical low-end telescope is a refractor or reflector?

Is there a way to distinguish (with no manual, product info etc)?
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41 views

Number of actuators in adaptive optics

It is well known that diffraction resolution of a telescope depends on the exterior radius of aperture: One can, for instance, use just a narrow outer ring of a parabolic mirror and the resolution ...
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1answer
70 views

What are the benefits of a large refracting telescope?

Currently, refractor telescopes are limited in aperture because gravity will deform the main lens over time. According to Wikipedia the largest practical refracting telescope is 1m. If we were to ...
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40 views

Is it possible to build a ground-based telescope that can directly image Earth-like planets orbiting in the habitable zone of sunlike stars?

In the following discussion I will refer to Earth-like exoplanets planets orbiting in the habitable zone of sunlike stars simply as “Earth-like exoplanets." NASA is currently developing or ...
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19 views

How to determine Az-El pointing of a telescope spiral scan?

I am writing a simulation of an automated telescope observation program. One part of this is to run a spiral scan pattern on and around objects of interest. I would like to tile this scan pattern so ...
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1answer
92 views

If we've only observed Oumuamua as a single pixel, how can we know its shape?

On a separate Oumuamua question (Oumuamua alien space junk?), I was confused how shape could be inferred from a single pixel, per another user's (@Uwe) comment. It was suggested I ask this question ...
3
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1answer
50 views

Beneficial astronomical uses of satellite constellations like Starlink?

Has any thought been given to software that would use predictable occultations by Earth-orbiting satellites to improve (rather than degrade) astronomical observations? Potential challenges I could ...
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1answer
95 views

Would a 1000 km telescope be able to resolve microscopic detail?

I have calculated that a 100m telescope can resolve 16m on the moon. Does that mean a 1000km telescope is 10000x better and can resolve 1.6 mm objects on the moon and even smaller closer? Or is there ...
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4answers
207 views

Why are telescope mirrors made of glass?

Optical telescope mirrors are typically made from endlessly polished glass surfaces that have been aluminised to provide a very smooth surface of reflective aluminium. But why the need for glass at ...
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1answer
64 views

What are criteria to compare and evaluate different 12 inch truss Dobsonian telescopes?

What are criteria to compare and evaluate different 12 inch truss Dobsonian telescopes? I'm primarily interested in comparing mirror quality and weight (price I can do myself of course). Two examples ...
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3answers
1k 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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a budgeted telescope around $150

I live in Mississauga (a large city in Ontario, Canada), I am looking for a budgeted telescope around $150. Which one or what type should I go for to explore the night sky planets?
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Does it make more sense to upgrade our existing telescope or to buy a new one?

We're at a bit of a crossroads here, since we're faced with what appears to be a tough choice. We've got a Celestron 11" SCT tube with a Losmandy G11 equatorial mount, all bought in 1996. The mount ...
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1answer
271 views

Split telescope into two eyes

I am looking for an appendage to attach to the end of a telescope which splits the image into two eyes instead of one. Does such an appendage exist?
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1answer
74 views

Questions about amateur astrophotographer Nik Szymanek's telescope

The 2011 Sixty Symbols video Spy Satellites (from Deep Sky Videos) shows amateur astrophotographer Nik Szymanek and his telescope. Question: Can someone identify the model and design of this ...
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153 views

Minimum Telescope Needed to See Saturn's Rings

I am a total novice. My daughter, likes Saturn. Since Saturn is so close I thought it was a good time to view it with her. What are the minimum needed telescope specs? GC Update: Can answer ...
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1answer
257 views

Is there any site with telescopes data?

Is the data gathered from telescopes "open source"? If so, is there any website that group it all?
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38 views

Use of an Equatorial Mount [duplicate]

What is Equatorial Mount in simple terms? What is polar alignment? What will happen if we use an Equatorial Mount without polar alignment? And if we polar align how can we point at other stars?
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2answers
191 views

What kind of telescope should I get my husband?

I'm very much an amateur when it comes to telescopes. My husband wants one for his birthday. I'm willing to spend up to $900 on one. Can any of you gurus give me advise as to which one I should buy? ...
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1answer
172 views

Why is this telescope so short? How hard is it to make such a fast primary?

The recently discovered object C/2019 Q4 (Borisov) is in the news because it might have an eccentricity greater than one, which means it might be from outside the solar system, though not necessarily. ...
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2answers
113 views

How can I obtain raw observation data of stars surrounding Sgr A*?

Are there any publicly available telescope that offers the sensitivity to observe the stars surrounding Sgr A*? If not, is there any raw data available that I could download?
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1answer
791 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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1answer
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What's the origin of Clyde Tombaugh's 9-inch Newtonian telescope?

Astronomer Clyde Tombaugh is shown in a now-famous photograph at the age of 24 with his "homemade" 9-inch Newtonian telescope in this image also shown in Elva R. O'Hara's Clyde W. Tombaugh: Farm Boy ...
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3answers
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Meade ETX-90 with computerized mount slews too far during auto-alignment

I've been trying to get my new ETX-90 to properly align itself these past few nights, but without success. I've mostly been using the Easy align functionality, which has been choosing Arcturus and ...
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1answer
59 views

Difference between first (focal length (fl.) 500 mm, ocular (o.) 10 mm) and second telescope (fl. 1000 mm, o. 20 mm)? (both 50 x)

Magnification is defined as $f_{objectiv}/f_{ocular}$. If I had the first telescope with the focal length of 500 mm, ocular 10 mm and second telescope with the focal length of 1000 mm, ocular 20 mm, ...
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1answer
72 views

Does anybody recognize this kind of prism?

Supplemental to this answer to Did Edmund Scientific 4¼ inch Newtonians have 90° prisms as secondary mirrors in the 1970's? I was poking around a bit further and ran across this "1960's Edmund ...
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2answers
54 views

Did Edmund Scientific 4¼ inch Newtonians have 90° prisms as secondary mirrors in the 1970's?

I mentioned my old telescope's secondary mirror in this answer (stiffness) but I'm not certain I am remembering correctly. My first telescope was a Edmund Scientific 4¼ inch Newtonian reflector. This ...
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1answer
29 views

Telescope focal point and inversion

When looking at a diagram of the optical path through a newtonian reflector, the lines always cross before the eyepiece. I understand that the eyepiece is used to focus this diverging light cone so ...
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1answer
24 views

Comparing info for WISE and GALEX

I'm trying to compile a table showing the wavelengths and flux at m=0 for WISE, Spitzer and GALEX, but I can't find the right data for GALEX. Here's what I have so far: ...
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2answers
134 views

Why does this Lowell Observatory telescope have so many knobs? What do they all do?

The Fox News article Arizona city played critical role in moon exploration history covers several interesting activities that took place in Arizona in preparation for the Apollo Moon landings. It ...
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2answers
59 views

Which Lowell Observatory telescope is this? (used to draw Moon maps for the Apollo program)

The Fox News article Arizona city played critical role in moon exploration history covers several interesting activities that took place in Arizona in preparation for the Apollo Moon landings. It ...
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1answer
74 views

Old Telescopes versus New

I am having trouble finding the quality of old telescopes. My question is how does a decent modern telescope that cost about a couple hundred USD compare to the top-notch telescopes in the nineteenth ...
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3answers
2k views

Why different specifications for telescopes and binoculars?

Sorry for the noob question but I don't seem to be able to find the answer on the internet. I've been looking through some telescopes and binoculars and noticed that shops typically give different ...
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1answer
292 views

Unable to locate Big Dipper through Polar Axis Finder

I have recently purchased a CG-4 Polar Axis Finder for my CG-4 mount. This PAF has markings on the lens for aligning with Big Dipper or Cassiopeia, which looks like this: I have aligned the PAF to ...
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Telescope was working and now it's not

We have a Celestron 70AZ 70mm f/10 refractor that has been working perfectly. Our children knocked it over the other day, and now when we try to view the moon, it ...
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1answer
133 views

How to find the source of the light? [closed]

There are millions of galaxies out there in the entire universe. When a telescope is set to a direction to to identify the stellar objects, it can capture all lights from all the objects. How do we ...
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1answer
863 views

Recording Spectral Lines at Home

I was wondering if it would be possible to record the emission/absorption spectra of stars without expensive spectroscopy equipment. Would it be possible to somehow utilize diffraction grating? I own ...
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1answer
86 views

Custom telescope

I am currently trying to make a Keplerian telescope from "scratch" with plano-convex lenses bought online. I have found my objective and eyepiece lenses. I'm just not sure if they will suffice to ...
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2answers
148 views

How to locate nebulas visible through AstroMaster 114 telescope without device assistance?

I will be going to the desert this month and it's my understanding that the night sky will be very dark there. I've got some practice locating the planets but I'd really like to get a look at a nebula ...
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0answers
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Why look at an infrared telescopes's mirror with ultraviolet light? (Herschel Space Observatory)

While link-clicking for Where did Herschel Space Telescope go in 2013? I ran across the 2009 Time Magazine article Two Telescopes to Measure the Big Bang which shows the file photo below with the ...
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1answer
66 views

Long tube for eyepiece

I have two short telescopes. The tubes that the eyepieces fit in are different; one is short and one is long, such as the tubes on the Celestron first scope and the Jason Comet chaser. Why is this so ...
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How was the astrometry of the famous 1919 solar eclipse confirmation of General Relativity calibrated and verified?

The new New York Times article The Eclipse That Made Einstein Famous describes several events and discussions on the hundred year anniversary of the the 1919 solar eclipse and verification of the ...
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2answers
143 views

Second Telescope: Maksutov Cassegrain vs Refractor

I bought my first telescope, a 3-inch refractor a few weeks ago. It has been a wonderful experience seeing the Moon, Jupiter, Saturn magnified and Andromeda, M33, M81 and much more for the first time. ...
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3answers
365 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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1answer
60 views

How to check what telescopes were looking at a certain portion of sky at a particular time?

I have some data that I collected from observations at a specific RA, DEC and I am trying to figure out what telescope surveys were looking at that portion of the sky at that particular time? I am ...
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2answers
5k views

What detail can Hubble see on Mars?

I'm researching a scene for a sci-fi novel in which the near-future protagonists observe earth through a station-mounted telescope in Mars orbit. My goal is to understand how much detail they ...
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2answers
257 views

What is the maximum distance measurable with parallax?

What is the furthest star or celestial object whose distance has been calculated with parallax and how does it compare to the theoretical limit using today's telescopes? And how exactly does telescope ...
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1answer
40 views

What determines the surface material of the ALMA and Spitzer telescope?

The transition between metal dish and mirror happens around hundreds of microns. For example, the shortest wavelength the ALMA(metal dish) can detect is about 0.3mm, while the longest wavelength the ...