Questions tagged [telescope]

Questions related to the physical instruments for astronomical observations.

58 questions with no upvoted or accepted answers
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What is the highest resolution image of the moon taken from Earth's surface?

According to this article: https://www.theguardian.com/science/2018/jul/26/star-spotted-speeding-near-milky-way-black-hole-for-first-time the Very Large Telescope is "powerful enough to see a tennis ...
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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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1answer
254 views

Why did the Event Horizon Telescope take so long to take a photo of a black hole?

The Event Horizon Telescope is in the news now because they are about to release the first ever picture of a black hole. They have been working on this since 2006. Why did it take 13 years to produce ...
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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 ...
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78 views

Deciding optical factors between a refractive and reflective space telescope optics as a function of aperture? (visible light)

Reading Yale News' Lighting a path to Planet Nine: To detect objects that are otherwise undetectable, Rice and Laughlin employ a method called “shifting and stacking.” They “shift” images from a ...
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How was astronomical data meant to be handled on HST precursors?

The first drafts for a large space telescope such as Hubble were made in the 60's, and the idea of a space observatory originated long before that. From Wikipedia: In 1968, NASA developed firm ...
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49 views

Things to be aware of when designing a custom equatorial fork mount

I'm still relatively new to amateur astronomy, and I would like to get into astrophotography. I've looked at different equatorial mounts, and I think I like the benefits of fork mounts. I'd like to ...
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51 views

Meade LX200GPS electronic RA movement very slow

I use a Meade 200 LX GPS. Last night between viewings it was placed in Sleep mode. On return the scope was making noises as if the motor was running. The scope was stationary, but had moved to what ...
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54 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 ...
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How did Michelson measure the diameters of jupiter's moons using optical interferometry?

In Betelgeuse: How its Diameter was measured (Chant, C. A., Journal of the Royal Astronomical Society of Canada, Vol. 15, p.133, Bibliographic Code: 1921JRASC..15..133C) the author says: The paper in ...
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184 views

Angular magnification of three lenses telescope?

What is the magnification of a three-lens telescope? As a child I built a "telescope": objective lens $$f_1 = 20 cm$$ middle lens $$f_2=5cm$$ and eye lens also $$f_3=5cm$$ My drawing of my ...
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49 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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98 views

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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52 views

Is it possible to model a solar thermal concentrator using Zernike polynomials?

This question might seem a bit off-topic, but I guess there are a lot of people here that know about optics, telescopes, etc. I would like to simulate solar thermal systems that focus solar ...
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57 views

Is there a Free repository of pictures taken everyday of the night sky?

I'd like to know if there's a repository out there of pictures taken everyday of the night sky. Not looking forward to anything fancy. Maybe a group of people out there have set up something out of ...
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518 views

Radiometer Equation for Flux Density

In Duncan and Lorimer's Handbook of Pulsar Astronomy, the equation for the flux density using a radio telescope is given as (for a top-hat function): $$S=\frac{\beta\,\mathrm{SNR}\, T_{sys}}{G\sqrt{...
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131 views

need data-point: actual counts per second with APD (avalanche photodiode) detector

I'm designing a sensor system to perform specialized [astronomy and space-sciences] experiments, and need a "reality check" to support or adjust my theoretical calculations. What I need is the "...
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40 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 ...
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Custom INDI client & Telescope control

I have started building my own INDI client library in dotnet standard C# to remotely control my Celestron NexStar 5SE telescope. If you want to see my client code it can be found here on github. My ...
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63 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 ...
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28 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 ...
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43 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 ...
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160 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 ...
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36 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 ...
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49 views

Is there a more permanent way to set up an Artificial Horizon?

For the last few months we have been constantly setting up an Artificial Horizon (Davis Instruments) using motor oil as the liquid. We discovered that it is very hard to take a reading off of it ...
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43 views

Can telescopes determine whether Hygiea is in hydrostatic equilibrium?

10 Hygiea is a spherical body in the main asteroid belt. With future telescopes like the Vera Rubin LSST or the James Webb Space Telescope, can we determine whether Hygiea is actually in hydrostatic ...
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Telescope focal length, reducer and/or Barlow

Say I have a scope with a given diameter $D$, a given focal length $f$, and a given exit barrel diameter $B$. It has a maximum true FoV of $B/f$ (supposing $B<<f$). Would adding a 0.5x focal ...
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325 views

Which Barlow lens should I choose, 2x or 3x?

I recently bought a 6-inch reflector, 750 mm focal length and I want to get a Barlow lens to get better observations. I have 2 eyepieces, one 9mm and one 25mm. My question is: Should I go for a ...
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82 views

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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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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Within a given image of a multiple-image producing gravitational lens, does Fermat's principle apply?

The question Does gravitational lensing provide time evolution information? is excellent! When we see multiple images of the same object because of the phenomenon of gravitational lensing, do all the ...
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Webcam set up small circle tunnel vision type view

I've just adapted a webcam for my telescope. I'm new to astronomy so I'm not sure if the view I get is right. When I attached the webcam to my Barlow lens, the view on my laptop becomes a tiny ...
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49 views

Finding individual band magnitudes: Why and how is the integration of individual flux values for each wavelength used?

What differentiates the distance modulus equation to find the difference between two apparent magnitudes? For example, $$ m_1 = -2.5\cdot log_{10}\left(\frac{F_1}{F_2}\right) + m_2$$ leads to the ...
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51 views

Any method to apply inverse TPoint model?

I have an automated telescope that I have written some software for. I am currently using TPoint to compensate for some of the irregularities of my system. However with TPoint you apply an offset (...
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61 views

Visible Light Ground-Based Solar Observatory Data Archives?

I'm mainly searching for the best(or good/significant/important) solar data archives via ground-based telescopes. If I'm not being very straightforward... Say if I wanted high quality/resolution ...
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98 views

Help With Transit Radio Telescope Data Analysis

My high school teacher and I recently built a 10 ft. mesh dish transit radio telescope. In order to compete this year at Nationals for our science fair, we came up with the idea of using a bluetooth ...
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118 views

Given a collection of pixels, how to deduce the flux from them?

I've obtained the coordinates of brightest pixels from different images (.fits files) using Python. I want to get the flux of each pixel. How do I go about finding out the flux?
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50 views

Telescope optical tolerance from central axis

I sometimes encounter telescopes/binoculars with a decent objective diameter but are very difficult to use because they only work when the eye is looking down the central axis (i.e. in the centre of ...
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What is the cost and benefit of building two identical telescopes?

I suppose that (especially space) telescope costs is dominated by design and development, not by material and manufacturing. So once a telescope has been developed and designed, how much extra would ...
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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 ...
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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 ...
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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 ...
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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 ...
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Question about telescope eyepieces

I have a Celestron 60LCM refractor telescope. It has a 60mm aperture and a 700mm focal length. It came with two eyepieces. One is 25mm and the other is 9mm. They are marked only with their focal ...
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What are Native coordinates in the World Coordinate System?

i am writing my first paper about our solar telescope, and i need to explain the optical transformations in terms of World Coordinate Systems. I am not sure if i got the following right, and would be ...
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Is there a good replacement finder scope for the Celestron 127EQ?

I've had a Celestron 127EQ for a couple years now and have only used it a couple times. One of the reasons I haven't gotten much use out of it is that when I do use it I spend all of my time aligning ...
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81 views

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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31 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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120 views

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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48 views

Combining lenses to make a telescope

Hi I have two Galileo 700mm x 60mm Astro/Terrestrial Refractor Telescopes. Can I take the lenses out and make one powerful telescope?