Questions tagged [telescope]
Questions related to the physical instruments for astronomical observations.
691
questions
5
votes
1
answer
152
views
How to polar align equatorial mount if I see only small part of sky at south-east?
My mount is located on balcony where I can't see the polar star. I have only one window here which points to the eastern south. I limited by small piece of sky near the ecliptic plane between 120 ...
- 246
7
votes
6
answers
9k
views
Can a very powerful telescope show a person standing on the moon from the side rather than from directly overhead?
If we had a very powerful telescope with say a 150-meter diameter, placed in orbit around earth, would it be possible to get a side view rather than a top view of a person standing on the moon?
- 647
18
votes
3
answers
5k
views
Why are almost all modern telescopes reflectors?
I've noticed lately that reflector telescopes are used much more than refractors. The majority of telescopes I see in telescope shops or featured by people online are reflectors. Even the Hubble and ...
- 492
3
votes
1
answer
170
views
Does an umbrella reflector telescope exist?
I searched for use of an umbrella mechanism for a reflecting telescope but have not found anything. I was imagining that use of enough actuators on enough umbrella arms would allow fine tuning an ...
- 139
0
votes
2
answers
92
views
Which mobile/computer application can help me understand celestial coordinate systems better? [closed]
I wish to understand Equatorial and Altazimuth coordinate systems much better. Any applications or softwares which can help me out with the same?
- 627
6
votes
0
answers
122
views
Would it be possible to create a telescope from a hanging reflective cloth?
A chain suspended on two points hanging under gravity forms a curve called a Catenary, which can look pretty similar to a parabola. I'm not sure if this generalizes to the two dimensional case where ...
- 1,648
4
votes
0
answers
49
views
Are magnetic vortices capable of providing magnetic lensing when observed away from the poles
Magnetic vortices-(ESA cluster mission from observations November 2018)(article, ESA, science & exploration: 'Magnetic Vortices explain mysterious auroral beads'. An observer during Saturn's ...
- 49
1
vote
1
answer
101
views
Astrometry and Geometric Distortions
CCD's are widely used for astrometry. Since a spherical surface (the celestial sphere) is projected onto a rectangular surface, the plate scale or pixel scale (approximated with 1/focal length etc) is ...
- 332
2
votes
2
answers
157
views
What is stopping Event Horizon Telescope the size of the Earth’s orbit?
There is a proposal to include a radio sensor in a telescope going to the Sun-Earth L2, getting 120x improvement in angular resolution to EHT. Knowing nothing about interferometry, it seems pretty ...
- 123
9
votes
4
answers
4k
views
Planets looks like normal stars when I see them using telescope
I've been trying to see planets using my 114 mm (aperture) f=900 mm telescope. For the moon, I got very good quality pictures, but when I try to see planets they just appear to be as if I'm looking at ...
- 201
4
votes
0
answers
46
views
How does SDSS estimate photometric redshift of sources?
I'm looking through the data in SDSS DR 12:
...
- 2,404
6
votes
2
answers
620
views
How do you clean a foggy or dirty eyepiece of a telescope?
I'm wondering what the procedure would be to clean the eyepiece of a telescope when it looks foggy or there's dirt either on the outside or inside it.
I can get rid of loose dirt with a camel hair ...
- 343
4
votes
0
answers
117
views
Telescope's eyepieces got blurry over time [closed]
Right at the beginning: This is not a duplicate of questions involving blurry images through their eyepieces. I only get blurry images for 2 of my 3 eyepieces so it's not the telescope's fault and in ...
- 343
8
votes
1
answer
506
views
Why not build a swarm of space telescopes?
James Webb Space Telescope (JWST) has not yet started doing science, yet its successor LUVOIR is being discussed already. However I am curious; some countries have invested billions of dollars in ...
- 183
2
votes
1
answer
120
views
Where can I find data on SDSS filter profiles?
I've seen lots of filter throughput curves for the SDSS, such as this one:
from the SDSS camera page, but I'd really like to produce my own from the data. Is the filter response data per wavelength ...
- 2,404
1
vote
1
answer
142
views
Can the Celestron Powerseeker 127EQ observe the moon during day time?
I am able to find the moon with the finder scope during the day. However, when I use my 20mm lense, it seems like I am unable to focus the moon at all. Is there a fix to this?
3
votes
2
answers
1k
views
Focus Problems when using Barlow 3x or 4mm lens
So I just recently bought a Celestron Powerseeker 127EQ 12.7 cm f/7.87 Cassegrain telescope and I inserted a 20mm eyepiece and the telescope with the Moon.
That eyepiece seems to work fine, but when I ...
1
vote
0
answers
400
views
Why does my 10mm eyepiece produce blurry images?
I own a tabletop Sky-Watcher Heritage 130mm tabletop Dobsonian with a f/5 130mm aperture and 630mm focal length. 25mm wide-field eyepiece and a 10mm narrow-angle eyepiece. Last night I took it out to ...
- 6,613
4
votes
2
answers
433
views
Why are photos from telescope stretched at their edges?
You may know the issue that photos from (at least some) telescopes are stretched at the edges, so that the star locations do not fit compared to if this location would be on the center of the photo.
...
- 143
9
votes
2
answers
4k
views
Why aren't reflector telescopes built with an offset secondary mirror?
Reflector telescopes (normally?) have a parabolic primary mirror that reflects the light to a secondary mirror which is placed at the center of the telescope. The construction holding that mirror and ...
- 202
1
vote
0
answers
36
views
uvotdetect sometimes doesn't make valid .fits files for DS9 to read (Swift UVOT, Heasoft)
I have downloaded galactic center sky images from the Swift database (https://www.swift.ac.uk/swift_live/index.php#doSimpleSearch.php?catname=swiftmastr&searchpos=galactic+center&searchrad=10&...
- 11
4
votes
3
answers
918
views
How to choose eyepieces and other accessories for a Celestron 70mm f/5.7 portable refractor?
I have a Celestron Specialty Series Travel Scope 70mm refractor which came with 10mm (40x) and 20mm (20x) eyepieces.
Specifications:
Focal ratio: f/5.71
Optical Design: Refractor
Aperture (mm): 70 mm
...
- 41
2
votes
1
answer
566
views
How far can the best telescope see in outer space from Earth?
I was wondering what is the farthest the best optical telescope can see into outer space from Earth. What causes them to see so far?
- 151
3
votes
0
answers
57
views
Metric to estimate measuring accuracy
I need help/suggestions on which metric/approach to use.
I am trying to estimate pointing precision by measuring the offset of the experimentally measured values from the real, theoretical values, ...
- 171
9
votes
1
answer
384
views
How to determine the scale on astronomical images?
I've always been amazed at the many beautiful images of objects in the night sky. The Andromeda galaxy is a superb example. But it was only a few years ago that I discovered that Andromeda in those ...
- 1,359
8
votes
1
answer
498
views
General process of calculating what a telescope's diffraction spikes would look like?
I was reading this question about the JWST's diffraction spikes, and I was rather surprised by the magnitude of the 4 sets of diffraction spikes.
The large hexagonal spike pattern I believe is formed ...
- 4,137
7
votes
0
answers
300
views
How are the aberrations seen in early JWST images corrected?
I found this image on space.com and it can also be found in NASA's JWST blog. This is one step in the process of aligning the 18 mirrors on JWST. A single relatively-isolated star has been selected. ...
- 1,359
6
votes
2
answers
241
views
JWST mirrors each can be "positioned in tip, tilt, piston, horizontal & vertical decentering and clocking". What does this mean?
This interesting paper by Robert Warden refers to each mirror segment on JWST as having six actuators providing six degrees of freedom in positioning (plus one more to tweak the curvature). These ...
- 1,359
6
votes
2
answers
229
views
Why aren't concentrated solar power plants use for astronomical observations of some type?
Concentrated solar power plants use reflecting surfaces to gather the sun rays for energy production.
Currently they sit idle at night and are not used for anything.
These have huge collection areas, ...
- 71
2
votes
1
answer
3k
views
Camera adaptor won't focus [duplicate]
I'm trying to use my DSLR camera (Canon EOS-40D) with my kids' Celestron First Scope.
I bought a 3x Celestron 1.25" barlow, Celestron 1.25" T-adaptor, and the Canon ring. These things all ...
- 121
7
votes
1
answer
563
views
What does par. lines mean in relation to a telescope aperture in 19th century German astronomical publications?
I am trying to understand what is meant by par. lines in an 1867 article "The Aberration of the fixed stars after the wave theory" by Prof. W. Klinkerfues of Royal Astronomy Works of ...
- 121
1
vote
0
answers
58
views
Is it possible to observe the full Moon using this telescope?
I'm trying to solve this task:
For amateur observations, a small telescope with a lens focal length of 120 cm was brought to the Byurakan Astrophysical Observatory. If this telescope is directed ...
- 1,027
3
votes
2
answers
132
views
Is a mirror cell only necessary for collimation?
I'm building a truss Newtonian, and I'm planning on achieving collimation using turnbuckle-style trusses, as demonstrated in this thread. If I'm collimating this way, is there any reason to support ...
- 185
2
votes
0
answers
181
views
Can JWST be damaged by looking at a bright star?
Can JWST be damaged by looking at a bright star?
The Sun as well as particularily bright solar-system objects like Jupiter, Venus or the Moon not meant with this question.
- 920
5
votes
1
answer
120
views
Why orient a refracting telescope to the North?
I'm a french Guide of french military heritage. I have to prepare visit about "L'observatoire de la Marine, moulins du faouëdic" (Former windmill which served as an astronomical and ...
- 51
1
vote
0
answers
553
views
How to find the aFOV of a eyepiece?
How do I find the apparent field of view (aFOV) of a eyepiece using simple math (if possible)? I need the aFOV to give as a value to Stellarium’s custom eyepiece
I found a Q&A about this subject ...
- 11
5
votes
2
answers
160
views
How do telescopes avoid blurry images?
Telescopes rotate with the Earth. If a telescope isn't fixed on something like the North Star then everything in its field of view is moving pretty rapidly, yet photos from these devices are crystal ...
- 901
6
votes
2
answers
189
views
Does a star shaped mirror present problems either optically, or in signal processing over a more nearly circular mirror?
Pure speculation about a future replacement for the JWST that I almost certainly won't live to see.
The JWST's mirror (and then some) would fit unfolded and flat into the Starship's 8m diameter ...
- 69
2
votes
1
answer
80
views
Is it possible to take the same images in HST palette as the optic telescope but with radio telescope?
Is it possible to detect signal from SII, H$\alpha$, OIII using radio telescope and make the similar images as optic telescope? If no, can we use the different elements to take signal?
What minimal ...
- 246
1
vote
2
answers
94
views
How much magnification would I get by this Dall-Kirkham telescope?
I'd like to know how much magnification I would get by this telescope. The main specs are as follows:
Focal length: 2563 mm
Focal ratio: F/7.2
Number of lenses: 2
Optical diameter of Primary mirror: ...
- 13
3
votes
1
answer
135
views
Improving portability of truss Newtonian
I'm designing a 10in f/6 truss Newtonian as a sort of big travel scope; something that I can break down into parts to fit in a backpack or similar but will still give me decent angular resolution. In ...
- 185
6
votes
3
answers
2k
views
Trouble Seeing Distant Planets Such as Jupiter and Uranus
I am a beginner and I am using a Celestron AstroMaster 114 telescope. Whenever I try to view distant planets such as Jupiter I am presented with a black circle that has black lines leading from it. In ...
- 61
1
vote
0
answers
86
views
Maximum number of pixels across a synthesized beam in an ALMA image?
I have some ALMA data, from which I have created images using the TCLEAN task in CASA.
I understand that with this type of data, it is necessary to have at least 2 pixels across the FWHM of the ...
- 1,366
2
votes
1
answer
77
views
How much do collimation and viewing conditions affect magnification and viewing?
Before I start this post, I'd first like to make clear that this account is an alternate of my SovereignInquiry account--at the moment, accessing this account is much more convenient, so if things I ...
6
votes
2
answers
191
views
Will the James Webb Space Telescope need re-alignment of primary mirror segments?
I couldn't find an answer to this question.
James Webb Space Telescope will align primary mirror segments and secondary mirror in space.
Question is whether these will need re-alignment during the ...
- 225
1
vote
1
answer
352
views
The most precise way to point the true north
Since all of my telescopes have equatorial mount and It needs to be placed with respect to North direction, what is the best way to point the North.
Expecting answers that doesn't suggests methods ...
- 2,610
4
votes
1
answer
173
views
Hoping to do some viewing and astrophotography with a large-ish Dobsonian and a DLSR, is this scheme workable?
I haven't put a camera behind a telescope since the lunar eclipse of 1975 except for a few experiments with a cell phone held behind a pair of binoculars.
I want the occasional thrill of using a ...
- 31.3k
1
vote
1
answer
113
views
Can I use an achromatic focal reducer to reduce chromatic aberration?
I am using 75/1000 Plano convex lens to build telescope. Can I use an achromatic focal reducer to reduce chromatic aberration?
1
vote
1
answer
229
views
Can I use 75mm Plano convex lens to build telescope [closed]
I want to see Jupiter with moon.
So am planning to build telescope. Can I use 75mm Plano convex lens with 1000mm focal length?
3
votes
2
answers
1k
views
Will these simple 2 convex lens arrangement telescope see the moon clearly?
Hi readers, I am planning to build my telescope. Does this very simple 2 convex lens arrangement even possible to observe the moon clearly with high magnification? I am planning to buy 5 cm diameter ...
- 33