27
votes
How did asteroid (7482) 1994 PC1 get its "face"? Is it reconstructed from optical or radar imaging, or something else?
These are images taken from Nasa's Eyes on Asteroids site. It lets you see the orbit and get information about the asteroid in a nice interactive way. For asteroids with a known shape and surface ...
- 104k
12
votes
Accepted
Did this satellite streak past the Hubble Space Telescope so close that it was out of focus? If so, how close was it?
As you note, that particular image has been identified as due an "out of focus" satellite (the other images presumably show more distant satellites in e.g. geosynchronous orbits). The Nature ...
- 15.7k
7
votes
How do I calculate the moment of the solstice?
Per @PM 2Ring's comment, I needed to use apparent RA/declination rather than GCRS (which is the default returned by astropy.coordinates.get_body). In astropy, this ...
- 711
5
votes
How exactly is UT1 measured/calculated?
("How exactly is UT1 measured/calculated?" -- with "interest in fine details about how UT1 time is measured.")
(edited 2023/Mch/27 to add references including text+image extract of ...
- 1,186
4
votes
Does syzygy mean only three aligned bodies, or at least three aligned bodies?
Yes, syzygy can be more than 3, but not less.
3
votes
How do I find out when sidereal time was 13:30 on a certain date and location?
So the local sidereal time is the right ascension of objects on the Meridian at the given time.
Lehi on 25th of February (assuming US style date) is in Mountain time zone, UTC-7, so 13:30 is 20:30 ...
- 104k
3
votes
Why does X-shooter use double passes through prisms for Echelle cross-dispersion instead of gratings?
Maybe this is a bit too late, but I think I can answer this question, from my experience with developing echelle spectrometers (not for astronomy though).
As pointed out, both gratings and prisms can ...
- 131
3
votes
Accepted
How (the heck) does an astronomical Celescope work? And how did it get its name?
Unless otherwise indicated all of the information in this answer is from Project Celescope: an Astrophysical Reconnaissance Satellite (PDF).
Question 1:
How were these four telescopes used? Were they ...
- 1,721
2
votes
Accepted
2D Galaxy Spectrum taken by long-slit-spectrograph
In the plot, the spectrum is clearly more bright on the left
One possibility is that this was taken with a blue-sensitive CCD, and/or the diffraction grating has a higher efficiency in the blue. In ...
- 15.7k
2
votes
How did asteroid (7482) 1994 PC1 get its "face"? Is it reconstructed from optical or radar imaging, or something else?
The face situation is getting curiouser and curiouser!
At first, when I went to the actual page in NASA Eyes for the asteroid https://eyes.nasa.gov/apps/asteroids/#/asteroids/7482_1994_pc1 I could not ...
- 31k
2
votes
SKA 101: How will it "perform the most precise tests of Einstein's theories" and Australia & South Africa arrays be "made to work seamlessly together"
To answer the first part of your question:
Einstein's theory included predictions about the nature of black holes and the delays they would cause to light travelling through space, so astronomers ...
- 2,080
1
vote
What parameters about galaxies can be measured using SAO DS9?
SAO DS9 is a powerful software tool for viewing and analyzing astronomical images, and there are many other parameters you can determine for galaxies using DS9. Here are some additional parameters you ...
- 111
Only top scored, non community-wiki answers of a minimum length are eligible