Questions tagged [telescope]

Questions related to the physical instruments for astronomical observations.

35 questions with no upvoted or accepted answers
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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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40 views

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

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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83 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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0answers
45 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 ...
3
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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 ...
3
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56 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 ...
3
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411 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{...
3
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125 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 "...
2
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38 views

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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53 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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44 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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77 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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109 views

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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47 views

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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885 views

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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66 views

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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42 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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48 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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97 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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105 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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49 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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63 views

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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49 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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1answer
84 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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27 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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83 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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41 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?
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135 views

Celestron NexStar 130 SLT Computerized Telescope GoTo Not Accurate

I am trying to use a Celestron NexStar 130 SLT Computerized Telescope, but I am not able to use the GoTo function. I do the three start alignment, it confirms matches, I make sure the level is ...
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74 views

Retrofitting a Dobsonian Reflecting Telescope for smart phones?

Just received an old Orion Deep Space Explorer 6" Dobsonian Reflecting Telescope. I'm hoping to gift it to my kids, but I want to add a twist... We have a microscope with an adapter for an iPhone ...
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29 views

StarNavigator 90 motorized battery

I was given a StarNavigator 90 (DS-2090) with a motorized mount (Single-arm, motorized Alt-Az) which works with 8 AA batteries. Only issue is that it eats the batteries so I was wondering what kind of ...
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58 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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36 views

Travel telescope: attaching a Lunt 80mm ed on a Dolica tripod

I'm assembling a compact and light travel telescope. I'm going for the small Lunt 80mm ed refractor telescope mounted on a light Dolica tripod. For those with this --or similar-- assembly, I would ...
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362 views

Planets not visible

I have recently purchased an Orion AstroView 90mm Equatorial Refractor telescope, also this is my first time having a telescope. The telescope came with a 25mm and a 10mm eyepiece, I also bought a ...
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1answer
98 views

Where can I still find solar film?

I, like many others, am excited to see the eclipse. I want to view the eclipse through my telescope, however, I don't have any solar safety equipment for solar viewing and I cannot find any online ...