Skip to main content

Questions tagged [angular-resolution]

Questions about the ability of any image-forming device to distinguish small details of an object.

Filter by
Sorted by
Tagged with
0 votes
1 answer
137 views

Just wondering if anybody knows how to do this question about angular resolution of the human eye?

Estimate the angular resolution of the human eye at the centre of the visible wavelength range during daylight. Using your answer, estimate the surface den- sity of rods (per mm2) on the retina, ...
Rob1's user avatar
  • 37
1 vote
1 answer
59 views

Visible angular size

Is it true that given two celestial objects of the same size and at the same distance, the fainter one will appear smaller? Is there a calculation that can be made about how smaller? Is it the same ...
Kim's user avatar
  • 11
5 votes
1 answer
558 views

Would it be possible to use existing radio-telescopes to do spot measurements of CMB?

With CMB peaking at roughly 158GHz would it be possible to create a more precise map of CMB just by sampling 'points' using existing Earth-based radio telescopes? I understand that large dish ...
user2820052's user avatar
1 vote
0 answers
39 views

CMB maps analysis (Planck, ESA, FITS)

I wanted to analyze Planck mission FITS files and was wondering about the parameters. So the map uses color coding for temperature-based anisotropies right? So the maximum angular resolution is ...
user2820052's user avatar
1 vote
1 answer
516 views

How to find the distance between stars

I wanted to calculate the distance between the end points of the Orion's belt (Alnitak and Mintaka). I searched in the internet and I found out their angular separation to be 2.736°. Then I searched ...
Snack Exchange's user avatar
8 votes
1 answer
543 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 ...
Sasha's user avatar
  • 183
2 votes
1 answer
231 views

Do point spread functions from large single telescopes using adaptive optics still look like Airy functions for narrow-band filters?

this answer to Claim that 30-m class telescopes will have resolution far superior to Hubble: true? mentions ...the possibility of attaining near diffraction-limited images using adaptive optics. The ...
uhoh's user avatar
  • 30.6k
5 votes
2 answers
244 views

Can the transit of satellite in front of Sun be visible in 10-inch telescope?

I have 10 inch Sky-Watcher telescope and I would like to know if a satellite passing in front of Sun can be visible. Suppose that satellite's angular diameter is 1˝. Yes, I know the formula $\theta=\...
undoredo's user avatar
2 votes
0 answers
59 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 ...
user3433489's user avatar
4 votes
0 answers
106 views

What exactly would the resolution of an exoplanet hypothetically imaged by using the Sun as a gravitational lens be?

This video talks about how by sending a spacecraft to around 600 AU and beyond, we would could use the Sun as a gravitational lens and take clear detailed images of exoplanets light-years away. What ...
user177107's user avatar
  • 2,689
0 votes
2 answers
218 views

What is the difference between these various Angular Resolution formulas?

I have recently learned about angular resolution and its dependence on the ratio λ/D. There seem to be three different equations for angular resolution that I have come across. One of these has the ...
Adrian S.'s user avatar
1 vote
1 answer
301 views

Can the interferometer called "Gravity" measure "a few centimeters on the Moon"?

Phys.org's Very Large Telescope sees star dance around supermassive black hole, proves Einstein right links to several ESO videos, including Interview with Reinhard Genzel (in English). After ...
uhoh's user avatar
  • 30.6k
2 votes
1 answer
260 views

Will the Magdalena Ridge Optical Interferometer be able to image extended objects like the surface of the Moon?

Inspired by several questions: When will a moon landing site be visible via telescope? Could the E.H.T. produce an image of the human artifacts on the moon? Picture of equipment left on the Moon? ...
uhoh's user avatar
  • 30.6k
3 votes
1 answer
211 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 ...
user30892's user avatar
24 votes
2 answers
6k 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 ...
Eric J.'s user avatar
  • 481
2 votes
1 answer
1k views

How to find inverse steradian from $\text{arcmin}^{-2}$ for density of galaxy

I am using a code on EUCLID future mission. The original author of this code has set a value for the density of galaxy equal to : ng = 354543085.80106884 I ...
user avatar
5 votes
1 answer
162 views

What actually determines the angular uncertainty of the source of a detected gravitational wave?

This answer and comments got me thinking. Astrometry 101 tells us that while we can use $\lambda/D$ as an estimator of resolution, if we can assume a point source we can determine the centroid or ...
uhoh's user avatar
  • 30.6k
3 votes
1 answer
601 views

What is the actual resolution of Event Horizon Telescope?

I am quite impressed with the recently published image of M87* black hole. It appears that this image achieves spatial resolution well above and beyond what was available until today. But how high ...
Alexander's user avatar
  • 131
5 votes
2 answers
203 views

What resolution would earth-moon telescope achieve?

Event horizon achieved earth-size telescope by using seperate telescopes around the world to interpolate an image of a black hole at resolution of 60 arcmicroseconds. What resolution could we get if ...
lietus's user avatar
  • 151
4 votes
2 answers
1k views

How does making a refracting telescope very long reduce the chromatic aberration of an uncorrected lens?

Below are two cropped views of "Johannes Hevelius's 8 inch telescope with an open work wood and wire "tube" that had a focal length of 150 feet to limit chromatic aberration." from ...
uhoh's user avatar
  • 30.6k
4 votes
1 answer
862 views

Under what situations can an aperture mask improve the resolution of a small/medium amateur telescope? Is this demonstrable mathematically?

@antlersoft's answer describes some of the challenges to seeing any details in the small disk of Mars in small amateur telescopes. In the case of reflecting telescopes, it mentions the use of either ...
uhoh's user avatar
  • 30.6k
5 votes
0 answers
106 views

Estimate the number of pixels required to map the full primary beam of a Radio Telescope station

I am practising some exam questions for a radio interferometry exam, and I am struggling with this question: The physical size of a single LOFAR station, operating at 150MHz is about 50m. Estimate ...
Naz's user avatar
  • 163
0 votes
1 answer
209 views

Why is the opening in the Anglo-Australian Telescope's dome so small?

Many older or "classic" telescope domes have a horizon-to-zenith opening in the dome, and this helps speed up the thermal equilibration between the inside and outside air, decreasing turbulence and ...
uhoh's user avatar
  • 30.6k
3 votes
0 answers
427 views

Are they really sure this isn't an Airy disk? How was that ruled out?

How do they know that this is a spherical shell of gas, and not just something like an Airy pattern-like artifact produced by the VLT's large interferometric aperture? Image from: https://www.eso.org/...
uhoh's user avatar
  • 30.6k
1 vote
0 answers
173 views

How does Canada's radiotelescope CHIME manage polarization-dependent apodization of the fast f/0.25 optics?

CHIME, the Canadian Hydrogen Intensity Mapping Experiment uses four parabolic cylinder reflectors and a dense linear array of 256 x 2 polarization feeds along each focal line. Each feed is a dual ...
uhoh's user avatar
  • 30.6k
3 votes
1 answer
612 views

What is the cause of all of these sharp, concentric rings around bright stars in this HST image?

ESA's HST page heic1819 — Photo Release; Hubble reveals cosmic Bat Shadow in the Serpent’s Tail is of course beautiful and stunning, but my eyes are drawn to the diffraction artifacts of the bright ...
uhoh's user avatar
  • 30.6k
12 votes
1 answer
417 views

How would astronomical seeing on Mars differ from that on Earth?

Astronomical seeing is the limiting factor for the resolution of all but the smallest Earthbound telescopes. Source Stunning advances in adaptive optics (along with it's predecessor speckle ...
uhoh's user avatar
  • 30.6k
6 votes
1 answer
418 views

How did VLT's adaptive optics obtain this resolution for Neptune? Is it really working in visible wavelengths?

This image of Neptune taken with the VLT is really impressive. The resolution is achieved by recent improvements in the adaptive optics. Gizmodo: New Super-Crisp Images of Neptune Show How Far Our ...
uhoh's user avatar
  • 30.6k
1 vote
0 answers
55 views

Tracking a heliographic coordinate on CCD

Given the latitude and longitude of a heliographic coordinate, I want to place the point on a CCD image and simulate its motion for a particular duration. Though I am able to track the motion of a ...
amrita's user avatar
  • 11
7 votes
2 answers
1k views

Can Drizzle Integration increase resolution beyond theoretical resolution of telescope?

So I was wondering, if drizzle integration actually increases details in your image if the drizzled image results in higher resolution in terms of arcseconds / pixel than the telescope would allow (...
RononDex's user avatar
  • 466
2 votes
1 answer
491 views

Why is this HST WFPC2 image so much fuzzier than the WFC3 image of the same field?

I was looking at the comparison of 2007 and 2015 HST images of the "disappearing" star N6946-BH1 in Phys.org's article Collapsing star gives birth to a black hole. The 2007 images is from ...
uhoh's user avatar
  • 30.6k
1 vote
1 answer
196 views

What resolution is needed to see a quasar through the galactic center?

The center of the galaxy is densely packed with stars and obscured by a whole lot of dust between us and it. For those reasons, groups that study the motion of stars around the super-massive black-...
Sean Lake's user avatar
  • 2,946
8 votes
1 answer
986 views

Plot of best available resolution vs wavelength - radio through gamma rays?

What I'm looking for is a graphic that shows in a general way the best available telescope resolution vs wavelength throughout the entire wavelength spectrum. So for example, there might be two very ...
uhoh's user avatar
  • 30.6k
7 votes
1 answer
795 views

How could a 20 inch space telescope "be able to make out Earth-size planets" orbiting Alpha Centauri?

The NY Times article Telescope to Seek Earthlike Planet in Alpha Centauri System describes a proposed effort to put a telescope into orbit fairly quickly with a narrowly defined purpose - to look for ...
uhoh's user avatar
  • 30.6k
5 votes
3 answers
1k views

Question about Telescopes , observations and explanations of the observations

Though I am active on Physics, I am new to Astronomy. I am an amateur astronomer, actually even worse than amateur. I have just started it. I have a 60 mm objective 700mm focal length refractor which ...
Shashaank's user avatar
  • 153
3 votes
1 answer
413 views

Will the E-ELT use Adaptive Optics at visible wavelengths?

In this recent BBC article I read that the European Extremely Large Telescope or E-ELT is in final design and is planned to be on line by 2024, and that (of course) it will rely heavily on adaptive ...
uhoh's user avatar
  • 30.6k
12 votes
2 answers
889 views

Why aren't ground-based observatories using adaptive optics for visible wavelengths (circa 2016)?

Adaptive Optics (AO) techniques allow ground based observatories to dramatically improve resolution by actively compensating for the effects of Astronomical Seeing. The atmospheric effects are quite ...
uhoh's user avatar
  • 30.6k
1 vote
2 answers
508 views

Solar Elevation Angles -- Anomaly?

"The solar elevation angle is the altitude of the sun, the angle between the horizon and the centre of the sun's disc." - Wikipedia The meridian is when the sun is directly facing earth and is at ...
Adam D.'s user avatar
  • 111
11 votes
2 answers
894 views

Would Adaptive Optics be Useful in Radio Astronomy?

The question Why is this video showing radio waves transmitted from a radio telescope? and this answer to it got me thinking. If atmospheric seeing at visible wavelengths is the result of refractive ...
uhoh's user avatar
  • 30.6k
1 vote
1 answer
1k views

Seconds of Arc and the Unaided Eye

I've been presented with this problem: Say that Jupiter, with its diameter of 142,000 km, was located where Mars now orbits. What would be the angular size of (the newly-relocated) Jupiter ...
Jester Jeffrey's user avatar
3 votes
1 answer
2k views

What would be the maximum theoretically possible angular resolution?

I have studied some basic astronomy, but I have difficulty conceptualizing the physics of luminosity and optics. We use electromagnetic spectra to detect existence and properties of distant planets, ...
DoctorWhom's user avatar
4 votes
1 answer
479 views

Beamsize in radio/microwave observations

In radio/microwave observations, I understand the beamsize is the response of the telescope to a point source - effectively, the telescope's resolution. Now, the Planck satellite (par exemple) ...
user1991's user avatar
  • 844
3 votes
2 answers
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{...
mmh's user avatar
  • 394
5 votes
4 answers
2k views

Claim that 30-m class telescopes will have resolution far superior to Hubble: true?

This article makes the claim that the Giant Magellan Telescope (GMT, number 4 in the list) will have resolution 10 times better than that of Hubble, while the Thirty Meter Telescope (TMT, number 3 in ...
NeutronStar's user avatar
  • 2,673
6 votes
2 answers
991 views

Why does radio astronomy offer higher resolution images than optical?

According to this lecture,"Radio astronomy has several advantages over optical astronomy...We can make the highest resolution images, and see things happening on the smallest scales." Why is this? If ...
user avatar
2 votes
1 answer
2k views

What is the typical resolving power of the largest optical telescopes?

I'd like to estimate the typical resolving power of the largest optical telescopes. I've calculated the theoretical resolving power of the VLA for 21 cm light, $$R=\frac{\lambda}{B}=\frac{2.1 \times ...
user avatar
8 votes
1 answer
377 views

Is there a cosmic, rather than technological, upper limit to what a telescope can resolve?

Space radio interferometers could have a baseline of millions of kilometers, but is there a point where a larger baseline doesn't improve the resolution anymore because the photons observed are ...
LocalFluff's user avatar
  • 11.4k
6 votes
1 answer
454 views

Why can't the surfaces of stars be observed?

If I'm correctly informed, only three stars: Sol, Betelgeuse and Altair have surfaces which have been resolved by telescopes. All other stars are only point sources of light, even in the greatest of ...
LocalFluff's user avatar
  • 11.4k
81 votes
6 answers
12k views

Is the Moon only 60x60 pixels?

In doing research on vision, I have learned that "20/20" vision corresponds to a visual acuity of being able to resolve details 1 arcminute in size, that most people have around 20/15 vision,...
Phrogz's user avatar
  • 937
4 votes
1 answer
306 views

Inability of Hubble to clearly resolve nearby celestial objects

The Hubble space telescope performs incredibly detailed and stunning imaging of celestial bodies that are many, many light years away, and yet when it attempts to image objects within our own Solar ...
user3532993's user avatar