Questions tagged [telescope]

Questions related to the physical instruments for astronomical observations.

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4
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3answers
441 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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4answers
1k views

Mars looks like a blur

I took my telescope out tonight (I am new, just got the telescope a few days ago, it's my first one) and I was observing Mars, however all I see is just an bright orange circle, with no surface detail,...
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1answer
65 views

lousy mirror corrected by software

Would it be possible to get a terribly shaped mirror, like a large sheet of something reflective, give it a general shape like a telescope mirror, but not anywhere near as precisely shaped as in a ...
3
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2answers
118 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?
3
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2answers
1k views

Is the angular resolution of a telescope irrespective of used eye-piece?

Suppose a telescope has aperture $D = 20$ cm. The angular resolution of such telescope, according to the Rayleigh criterion (if I have understood it correctly), is given by $$\theta = 1.22\cdot\frac{...
3
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1answer
468 views

What determines which frequency range a radio telescope has?

My simple understanding is that a parabolic dish focuses radio waves to a receiver. It is obvious that any parabola focuses visible light and heat, so I assume that it focuses all radio wavelengths ...
3
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2answers
85 views

Can we measure comets in a similar way to exoplanets?

A 2km comet at 40AU's can dim a sun sized star at 100 light years by 3%, and a 10km comet can cause an eclipse (is that right?) So would 2,3,10 km objects be easy to measure via star dimming if we had ...
3
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1answer
487 views

Celestron Astromaster 114eq Star pointer finder scope help required

Just got a Celestron Astromaster 114eq as a christmas present and I have tried setting up the Star Pointer in the daylight. I did not use the red dot method as in the instruction manual, instead, I ...
3
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2answers
4k views

Why is the moon a fuzzy, white ball?

I currently own a telescope, I'm an amateur astronomer and currently just trying to view the moon. I own the Celestron PowerSeeker 70AZ. Link for information on the telescope: http://www.celestron....
3
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1answer
268 views

Telescope choice

Which one is better? Features: 1)Magnification: 18x - 90x Eyepiece Diameter: 5mm (18x), 10mm (60x) Objective Diameter: 50mm Focal Length: 36cm Tripod Height: 38cm Main tube Color: Silver Net ...
3
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1answer
473 views

Do primary mirrors in large observatories undergo regular removal and re-coating of the aluminum? Why?

Performance of astronomical mirrors that are exposed to the environment for long periods of time can experience a slow degradation of performance. They usually need to receive some kind of regular ...
2
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1answer
159 views

Is there available space images taken by the south pole Gregorian telescope?

I searched the internet for images taken by the South Pole Telescope but without successes in finding it. Edit:Some images
2
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1answer
214 views

UTC to UT1 time corrections

Astronomic observations in geodesy. It is well understood that sun and star positions may be expressed in Greenwich hour angle and declination. Or Right Ascension Declination. And may be published ...
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0answers
47 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 ...
2
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2answers
398 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 ...
2
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1answer
204 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. ...
2
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2answers
105 views

Source of mirror reflectivity data

I am trying to find a source of mirror reflectivity versus wavelength for the typical protected overcoat Aluminum mirrors used in astronomy. I need this to cover the whole visible range (300-1200nm) ...
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2answers
200 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? ...
1
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2answers
66 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
536 views

Is the Celestron astromaster 130 EQ Model able to see nebulas and galaxies?

Is the Celestron astromaster 130 EQ Model able to see nebulas and galaxies? If this telescope is not able to see nebulae, please suggest me the best one telescopes for nebulas.
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3answers
132 views

Air temperature range recommendation for observations in a summer night with an entry level telescope?

Recent nights where I try to make my first observations with the entry levell telescope Seben with 114 mm mirror it seems that for lenses less than 6 mm details go lost due to warm air refraction (as ...
1
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1answer
96 views

what does it mean of different eyepieces?

what is the difference between 4mm and 24mm and 30mm eyepieces? could I buy an eyepiece from another brand? I have the Gskyer telescope.could I buy for Celestron eyepieces? thanks.
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1answer
77 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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1answer
162 views

Which telescope should I buy? [closed]

I'm wondering which telescope I should buy, by the way, I'm new to astronomy and if you know any others that are under $100, It'd be appreciated. You don't need to take the price difference into ...
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2answers
69 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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