Linked Questions

11 votes
1 answer
2k views

Why the blank wedges in this very early 21 cm map of the Milky Way? (Oort et al. 1958)

Jan Oort was a pioneer in radio astronomy. Wikipedia says: It has been written that “Oort was probably the first astronomer to realize the importance” of radio astronomy. “In the days before radio ...
uhoh's user avatar
  • 30.7k
5 votes
2 answers
755 views

How does the Event Horizon Telescope implement the interferometry?

The BBC article Event Horizon Telescope ready to image black hole describes the Event Horizon Telescope, a coordinated observing technique with several radio telescope arrays across the globe forming ...
uhoh's user avatar
  • 30.7k
6 votes
1 answer
336 views

What causes "North-South ambiguity" when doppler radar imaging a planet surface equator?

I'm having a hard time understanding why there would be this ambiguity. Also, why would this be not the case if the planet was viewed pole on? Edit: "North South ambiguity" is a term used in ...
MinYoung Kim's user avatar
3 votes
3 answers
649 views

Optics: "Airy disc" and size of objects

Jupiter has a minimum brightness that is brighter than stars. Is the reason an “airy disc”, concentric rings as a diffraction effect, is seen around stars and not Jupiter because Jupiter has an ...
Stark's user avatar
  • 31
2 votes
1 answer
557 views

How did single dish (or single receiver) radio telescopes originally generate images?

That actually sums up my question nicely: How did single dish (or single receiver) radio telescopes originally generate images? - or at least 2D intensity maps or contour plots. Early radio ...
uhoh's user avatar
  • 30.7k
3 votes
1 answer
445 views

How do astronomers convert radio signals received by their antenna to images?

I'm very new to radio astronomy and I am curious how an the signals received by a radio antenna are converted to data on a computer and then images? Is there a popular software to use for this, or do ...
Thomas's user avatar
  • 161
4 votes
1 answer
188 views

What can be learned from low frequency radio astronomy available outside of Earth's ionosphere?

As discussions and answers to How large does refraction become in radioastronomy? point out, it is difficult to do radio astronomy much below 30 MHz (or 10 MHz depending on how aggressive you are in ...
uhoh's user avatar
  • 30.7k
5 votes
1 answer
474 views

What is the highest granularity focal-plane array on a dish radio telescope? Or is this the ONLY ONE?

There is a short Wikipedia article Focal Plane Arrays that enumerates some projects, but my question is more along the lines of what is (at least) nearly complete or in "first light" phase, ...
uhoh's user avatar
  • 30.7k
6 votes
1 answer
156 views

Reference request (explaining) how optical correlators combine light from multiple telescopes to produce ultra-high resolution interferometric images?

This is a reference or resource-request because it may be too challenging to explain in an answer post, but if you'd like to attempt a short summary as well, that will be great! I have a basic ...
uhoh's user avatar
  • 30.7k
3 votes
1 answer
185 views

What is the physical geometry of this apparent "eclipse" of a tiny moon of Asteroid Florence?

Below is a small GIF made from a small subset of images contained in the original 36MB GIF found at https://cneos.jpl.nasa.gov/images/news/florence.p5us.1Hz.s382.sep01.gif as I just found in the Sky ...
uhoh's user avatar
  • 30.7k
3 votes
1 answer
232 views

Open source library to calculate image from signals of a distributed set of radio dishes?

The National Radio Astronomy Observatory's Q&A "How To Make Images With a Radio Telescope" says The most straightforward way to make a radio image with your satellite antenna system, ...
B--rian's user avatar
  • 5,636
2 votes
1 answer
104 views

Is radar interferometry used, or feasible, for ground based astronomy?

I've heard of "interferometric synthetic aperture radar" being used for Earth observation from satellites and airplanes. Is active radar used interferometrically for astronomical purposes too? Such as ...
LocalFluff's user avatar
  • 11.4k