All Questions
Tagged with fundamental-astronomy coordinate
16
questions
2
votes
1
answer
139
views
What is a "fundamental location", and why is Mosting A defined as one for the moon?
The crater Mosting A was chosen to be the "fundamental location" for the Moon's coordinate system (latitude and longitude). But what exactly is a "fundamental location"? What does ...
- 3,166
4
votes
1
answer
322
views
How can the IAU 2000A vs IAU 2000B nutation comparison be reproduced?
I am attempting to plot how the IAU 2000A nutation model degrades as its terms are omitted. As a spot-check, I decided to compare it to IAU 2000B, which includes only the 77 most important lunisolar ...
- 1,135
6
votes
2
answers
8k
views
Difference between J2000, FK5 and ICRS coordinate systems? Which one does the Yale Bright Star Catalog use?
I have no background in astronomy. I have been wanting to write code to make star charts for a given location and time, which led to this question.
I figured out that I would need to convert the ...
- 163
2
votes
0
answers
135
views
Why do astronomers use the equatorial coordinate system that moves, instead of one based on fixed, distant stars?
As an outsider to the field, I am surprised to learn that astronomers commonly use the equatorial coordinate system, in which fixed stars are not actually fixed.
Isn't that making life harder than it ...
- 505
2
votes
1
answer
181
views
Need help with the calculations/conversion of a celestial object
I'm developing a telescope controller open-source application. I started this project with a very little knowledge of Astronomy.
Basically, the app is going to send data to telescope over a wireless ...
- 121
1
vote
1
answer
66
views
How to find if a set of objects lies within a given resolution (5 arcsec) on a telescope?
I am new to astronomy and I was given the task of finding out if there are objects which can't be resolved by a telescope of resolution 5 arcseconds.
I was given the values of RA and Dec of these ...
- 136
1
vote
0
answers
62
views
Attempting to determine astronomy values in a parameter file
Recently I inherited quite a few old QuickBasic programs which perform various astronomical calculations. I'm attempting to understand these programs and rewrite some of them in Python. I do not ...
- 119
0
votes
1
answer
533
views
Calculating azimuth from equatorial coordinates
I try to get the azimuth of an object from its equatorial coordinates using this formula:
$a = \arctan2(\sin(θ - α), \sin φ * \cos(θ - α) - \cos φ * \tan δ)$
Where
φ = geographic latitude of the ...
- 61
2
votes
1
answer
3k
views
Converting ecliptical to equatorial coordinates
When looking for a formula to convert polar ecliptic geocentric coordinates of an object to equatorial coordinates I find various sources that give these formulae (like Wikipedia):
Declination $δ = \...
- 61
8
votes
2
answers
468
views
Planetary reference systems and time
I am researching into how coordinate systems of solar systems objects are created by reading some of the reports written by the Working Group on Cartographic Coordinates and Rotational Elements (e.g. ...
- 181
1
vote
1
answer
2k
views
Calculation of hour angle
I need to determine Right Ascension and Declination from Azimuth and Altitude, working in C#. The problem is that the formula for calculating hour angle, for some reason, doesn't work. Here's the code:...
- 23
3
votes
1
answer
810
views
Which is the shape of the sky?
I'm a software developer and I'm developing a planetarium and the first thing that I don't know is: What is the shape of the sky?
First, I though that it is a semi-sphere, but searching on Internet I ...
- 657
2
votes
3
answers
1k
views
How to calculate position of an unknown star knowing positions of some other stars from an image?
Suppose I know the coordinates (right ascension and declination) of the stars marked with red. How should I calculate the coordinates of an unknown star, marked with yellow?
Searching over the web, I ...
- 21
1
vote
1
answer
279
views
How to convert horizontal coordinates using NOVAS?
I'm using NOVAS 3.1. I know that I can convert equatorial coordinates to horizontal coordinates using the equ2hor function.
Is it possible to make NOVAS do the ...
- 111
7
votes
1
answer
804
views
Calculation of Horizontal Coordinates
Given a fixed coordinate location on Earth (i.e. a latitude and longitude), and a fixed equatorial coordinate location of a particular astronomical object in the sky (i.e. right ascension and ...
- 243