44
votes
Are the stars distributed in uniform distribution, on the celestial dome, with respect to brightness?
Naked eye stars are not distributed uniformly in the sky. That is because the median naked eye star is at a distance of 440 light years, and this is far enough away that some of the details of ...
- 158k
16
votes
14,000 square degrees
The whole sphere has approximately 41,253 square degrees of solid angle.
$$4\pi\left(\frac{180}{\pi}\right)^{2}\approx 41,253$$
so for a hemisphere there should be half this number or about 20,627 ...
- 2,349
13
votes
Accepted
Is there any way to detect the three-dimensional distribution of baryonic gas in our Universe?
Yes!
The cosmic web
Matter in the Universe is distributed not uniformly, but in the so-called cosmic web. This large-scale structure consists of sheets and filament of dark matter, baryonic gas, and ...
- 39.1k
11
votes
Are the stars distributed in uniform distribution, on the celestial dome, with respect to brightness?
Alright I finally finished this program so I could take a look at each tier individually and see for myself.
First of all, the projection type does indeed matter, so I will explain it here. It needs ...
- 2,000
8
votes
Accepted
How do I create a galaxy stellar mass function?
Your approach is completely correct, just note three things:
Logarithmic distribution
First, since the distribution of masses is logarithmic in nature (as is most other things), be sure to bin them ...
- 39.1k
8
votes
Accepted
14,000 square degrees
GrapefruitIsAwesome has already explained why the sky is significantly larger than 3300 square degrees; I'd like to explain why the sky coverage is precisely the value it is.
The wording is admittedly ...
- 37.3k
7
votes
Accessing SDSS server SQL server via python
You can do it via the astroquery SDSS module; there is a function called query_sql.
- 4,914
7
votes
Are there any new/latest/recent radio sky surveys' data release which is publicly accessible?
"RACS and LoTSS have superb resolution and sensitivity."
Those are both post-2000; RACS was completed in 2020 and LoTSS is still taking data. So I'm not entirely sure why you seem to exclude ...
- 18.1k
7
votes
Accepted
Sky surface brightness vs magnitude limit visibility
The human eye has an angular resolution of about 1 arcmin.
This means that the light coming from point like stars would be visible if it significantly exceeds the luminance of the sky over an area of ...
- 1,002
7
votes
Are more stars or more galaxies cataloged, currently, and how has the ratio evolved over time?
There are a few easy points known to the graph of (#galaxies known) / (# stars known) over time:
let‘s say 2000 years ago: 5000 stars known, galaxies 1, as this is roughly the number of stars that ...
- 739
6
votes
Accepted
Google Sky Rectangle with No Stars
This is a known issue affecting multiple locations in Google Sky, including a region in Orion and this area in Pegasus. If you look closely at the interface, you can see that Google Sky gets its data ...
- 37.3k
6
votes
Is the discovery of a "mass gap" black hole by this tiny telescope just plain luck/serendipity or could it be the first of many similar discoveries?
Section 2 of Jayasinghe et al. (2021) explains why this system was studied. It wasn't discovered by KELT it was a known, single-lined spectroscopic binary, with radial velocity variations and an ...
- 158k
6
votes
Could more objects from the Oort cloud with highly elliptical orbits be discovered in the future?
If you consider "objects" to include comets, then yes, they will be, probably within a few months.
Extremely long-period comets are continually being discovered by various space telescopes ...
- 4,795
6
votes
Could more objects from the Oort cloud with highly elliptical orbits be discovered in the future?
Although, there hasn't been a confirmed direct observations of the Oort cloud, it is confirmed to be the home of long period comets. Some notable examples include C/1999 F1 (Catalina), C/2006 P1 (...
- 5,191
6
votes
How close are we to observing all of the sky all of the time?
To answer the first phrasing of the question: "Not yet". Approximate answer to the second phrasing below, after discussion. Adding to GrapefruitIsAwesome's answer, there are a couple of ...
- 161
5
votes
What is the completeness of an observation and how do I calculate it?
a) What is the definition of completeness?
Completeness is the number of objects in a data set that are detected over the number that exist. In astronomy, completeness is often estimated for a ...
- 16.3k
4
votes
What is the largest (angular) dark area in the sky?
Barnard 68 is the first thing that comes to mind for me, it is a little over 10' across and is opaque in the visible spectrum.
I'm sure there could be something much larger out there, but like I ...
- 734
4
votes
How does one "use" the Pan-Starrs data?
If you are looking for images of a particular moving object, the Solar System Object Image Search (SSOIS) at the Canadian Astronomy Data Centre (CADC) has indexed the Pan-STARRS collection. You can ...
- 41
4
votes
How does one "use" the Pan-Starrs data?
There are two main datasets available from the PanSTARRS survey which are available from the archive at MAST/STScI. These are the Object Catalog, a (large) list of parameters such as position, ...
- 8,732
4
votes
Accepted
What is the dimensions of the smallest object detectable by an optical fiber from a specific distance?
Assuming you are using single mode fiber, the entrance (mode diameter) is small, usually a few microns (extremes can range from 1 to say 30 microns, but 2-8 microns is common for visible SMF).
The ...
- 30.6k
4
votes
Accepted
How did TESS scientists choose which stars to observe at a "2 minute cadence" in each field?
A combination of algorithm and by committee.
The majority of targets are bright, low-mass dwarf stars. The primary goal of TESS is to discover planets by transit, and these targets offer the best ...
- 158k
4
votes
Accepted
spider image in Samuel Oschin Schmidt Telescope DSS imagery
Those are almost certainly "ghosts" caused by the internal reflection of light from very bright stars. (That is, the light is reflecting off the insides of the camera, filter, etc.) The ...
- 18.1k
4
votes
Star visibility above horizon map likewise day & light map or moonlight world map
As long as we can live with a few tens of kilometers accuracy, we can treat the Earth's surface as a sphere.
The subpoint of the object (the point on Earth at which the object appears at the zenith, ...
- 30.6k
4
votes
Accepted
What does the celestial sphere look like in thermal IR?
Let me see if I can provide some examples of the general background (not including small-angular-size sources like planets and individual stars). These are all-sky projections in Galactic coordinates, ...
- 18.1k
3
votes
Any plans for TESS after it finishes northern sky survey?
NASA missions that have gone beyond their original Prime Mission lifetime, such as TESS, go into the NASA Senior Review process every 3 years. The most recent one of these was the 2019 Senior Review ...
- 8,732
3
votes
How to check what telescopes were looking at a certain portion of sky at a particular time?
The areas of the sky covered by the major Near Earth Object (NEO) surveys are reported to the Minor Planet Center. You can plot visualizations of that sky coverage data using the sky coverage form ...
- 8,732
3
votes
Accepted
Are 3D coordinate data from Sloan DSS-III available & easily accessible to non-pros?
BTW if anyone wants a quick and fast query to solution do the following:
Go to https://skyserver.sdss.org/dr12/en/tools/search/sql.aspx. Paste a query like this:
...
- 326
3
votes
Are 3D coordinate data from Sloan DSS-III available & easily accessible to non-pros?
SDSS DR12 Catalog Data
looks like a good starting point,
apparently pretty open to those willing and able to figure it out.
Their
SciServer Compute
site hosts Jupyter notebooks to query CasJobs in SQL....
- 18.7k
3
votes
Accepted
Stuck with SDSS data
The header of a FITS file is ASCII, and points you to further information. Calling head -n 1 example.fits directs you to "'Astronomy and Astrophysics', volume 376, ...
- 2,285
3
votes
Stuck with SDSS data
You should go to the site https://fits.gsfc.nasa.gov/ where you can read about the FITS data format. This site also has utilities for examining and viewing the data. Most of your concerns about this ...
- 4,514
Only top scored, non community-wiki answers of a minimum length are eligible