Questions tagged [coordinate]
Questions on systems to uniquely determine position of a point or other geometric element on a manifold such as Euclidean space.
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Implementing polar coordinates correctly in solar system model?
I am working on a 2d solar system model using Python, but I'm unsure if my implementation of planet data is correct. I have the planet data stored in polar form (distance, velocity and angle), and I ...
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Deriving orbital inclination from equatorial coordinates?
I wanted to ask if it's possible to establish a correlation between the observed equatorial coordinates of a Solar System planet, especially declination, and the planet's orbital inclination with ...
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What is a "valid" coordinate system?
I was reading "Natural Coordinate System in Curved Spacetime" by Ying-Qui Gu. The first sentence of the abstract struck me (bold emphasis added by me):
In this paper we establish a ...
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Can you find your own location in space by measuring angles between stars?
Imagine you have 3 star points in 3D space A,B and C.
From your unknown position P in space you can measure the angles APC, APB, BPC and you know coordinates of A,B and C and therefore the distances ...
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Star rising times in a different place given the latitude and time of one place
I don't know astronomy that well, but I am preparing for the second stage of IJSO, and here in India they do add some questions like these ones.
A star is seen rising from Kolkata (23.5N 92 E) at 7 ...
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3
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Calculate position of the Sun in ECEF
I'm making a very basic orbit simulator in C# using the Helix Toolkit.
I want to position the Helix lighting object at the sun, but also be able to calculate solar eclipse by the moon and earth for a ...
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Calculating Local Sidereal Time [duplicate]
When calculating local sidereal time, 100.461 "is the value needed to yield the correct value of GMST" - David Hammen (left as comment on my previous question). How ...
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A beginner project in plotting celestial bodies in 3D coordinate space
As a data visualization task, I'd like to plot some celestial bodies in 3D coordinate space. I assumed there would be a lot of databases where celestial bodies are recorded along with an XYZ ...
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Finding a location using the direction of shadow, UT and date approximately
Does anyone know how to find a location by using :
the direction of shadow relative to the normal (for example azimuth
angle)
the Universal time (UT) and date
I have a satellite image and I know ...
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0
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Gaia coordinates in J2000 as done by the CDS
So I'm interested in knowing how the CDS calculates the J2000 equatorial coordinates from the Gaia DR3 equatorial coordinates (that are given in epoch 2016.0).
For example, for the star HD 308819 = ...
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103
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Satellite angular velocity at an angle
Suppose I am observing a satellite that is not at my zenith. I know the altitude(α) and azimuth(γ) of my telescope and I was able to get a relative angular velocity of the satellite.
Based on this ...
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Sky coverage plot using Python/Astropy
I want to recreate a plot where the area that is not visible from a certain point on earth (latitude and longitude) trough a full year. An example of this plots for example can be:
Where in white is ...
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Computing the sky coordinates using astropy
I need your help with an error I have been receiving while trying to obtain the sky coordinates using astropy module in python.
The code looks like the following,
...
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From TEME to RA DEC
I am using the SGP4 python package to get the coordinates of satellites at a given epoch. The algorithm computes the positions (X, Y, Z) in the True Equator Mean Equinox coordinate frame (TEME). From ...
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Figuring out camera pitch and roll given RA and DEC of center of image, as well as lat,long of camera and time taken
What I am trying to figure out is how to get the camera pitch and roll, as described in this image (the green yaw line is where the camera sensor is pointing
if given a RA, DEC (of center of image,ie ...
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How to use astropy to join data tables based on sky coordinates?
I have 2 astronomical tables, from a fits file and a csv file, that look something like this
...
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Derivation: Formula for projection of sun's motion onto parallel of declination
Consider the projected angular velocity of the sun along a parallel of declination. I was told that it is $$\frac{\cos\varepsilon}{\cos\delta_{\odot}} \frac{d\ell_{\odot}}{dt} \tag{1}$$
where we let $\...
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Why are the sky distributions of SDSS DR16 and DR16Q different?
I've downloaded the csv files for SDSS DR16 and DR16Q and made a map of their sky distributions:
The coordinates come from:
DR16: RA_ICRS and ...
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Plotting galaxies in 3-D
Suppose I have a catalogue of galaxies in a .dat file with each row representing information about a galaxy: right ascension of the galaxy, declination of the ...
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Azimuth and Altitude angle between two points in the sky
I want to know how to correctly calculate altitude and azimuth difference, separately, between two points in the sky. The same way will be with icrs coordinates.
For the altitude difference, I simply ...
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What is the relationship between true anomaly and solar longitude?
So, my ultimate objective is to map solar longitude values onto a pseudo-Gregorian calendar. I thought this would be simple, but it has turned out to be anything but.
I have asked several questions on ...
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Horizontal and equatorial coordinate systems
What is the difference between horizontal and equatorial coordinate systems apart from the notations (azimuth, altitude) and (right ascension and declination angle)? Please provide some measurements ...
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Clarifications about distances in cosmology
I would like to get clarifications about some usual notions of distances in cosmology.
First, is the comoving distance the current distance of objects whose light has been reached by us now, i.e. ...
user16492
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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 ...
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Issue translating World Coordinate system to cartesian coordinate
I have two fits images from the WFC3 that I am trying to combine with a C# program. When I try to combine multiple images I don't think the values I am getting for my x/y coordinates (calculated from ...
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Why do default coordinates from IR-optical observatories are usually not trustworthy, while from radio interferometers they usually are?
I have noticed in my experience that the coordinate solution within the headers of default reduced images from radio interferometers are commonly trustworthy to the arcsecond or less. From IR and ...
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Code for getting the pixel coordinates of an object with known RA DEC not working
I’m working on a project of which one of its functions is determining the XY pixel coordinates of an object given the object RA DEC coordinates and a platesolved image (this assumes that the target is ...
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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 ...
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0
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calculating paralax angle from observations
Say I have 2 records, in horizontal coordinates of the azimuth ($A_z,A_z^{'}$) and altitude ($\alpha,\alpha^{'}$) of the moon at the same time in two different places that are $\theta$ degrees apart (...
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Coordinates reduction python
How can I calculate position (alt, az) of star for observer at some station (longitude, latitude) on specific date and time? I need full coordinates reduction with all elements included in calculation ...
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How big is one arcsecond at various distances?
I've been reading this article
https://en.wikipedia.org/wiki/Celestial_coordinate_system
and a question came to my mind.
The minimum units are seconds ( ″ ). I picture an angle of 1 second as being ...
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Celestial navigation from scratch
Is it possible to establish one's longitude and latitude by observing the stars? Can you use observations of the stars to find the relative distance between two locations, which would be useful in map-...
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Pleiades galactic coordinates
Is there a practical way to determine the galactic coordinates directly from the equatorial system?
Specifically, I can't find the $(l,b)$ for the Pleiades star cluster (M45) anywhere. I am trying ...
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2
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Ecliptic coordinate ranges in radians
In ecliptic coordinates, what are the ranges of ecliptic longitude and latitude in radians? Do they both go from $-\pi$ to $\pi$?
user23921
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If I was in a coma and woke up at night in the desert, what knowledge would I know instantly and after 30 days?
If I was in a coma and woke up at night in the desert, what knowledge would I know instantly and after 30 days of observation?
Can I figure out the general directions, i.e. where North, South, East, ...
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Does the retrograde movement affect the true angular distance between 2 planets?
I need to calculate the relative angular path between two planets in the geocentric view or in other words the number of degrees of a circle one planet travels away from another planet around the ...
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Is the Vernal Point a fixed point on the sky?
The Vernal Point is a reference point in the Equatorial Coordinate System, from which R.A. is measured. My book says that the zero point of Right Ascension, i.e. the Vernal Point keeps moving in the ...
user47535
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At what time of the day of autumnal equinox the Sun's equatorial coordinates reach max value?
I'm trying to solve this task:
At what point in time of autumnal equinox day, at sunrise or sunset will
a) the declination of the Sun
b) the right ascension of the Sun
reach the maximum value?
I'm ...
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Altitude of Polaris is latitude
How to prove geometrically that the altitude of Polaris is equal to the latitude?
I have seen in handouts that the altitude of the pole star gives the latitude of that place.
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Journal standard for plotting section of skymap?
I'm a physics graduate student hoping to plot ~10°x10° sections of the sky in right ascension and declination (eventually I will want to plot points on this section at appropriate locations ...
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How to convert ra&dec between different epoches?
For example, how to convert B1950.0 into J2000.0?
Do we need to know the proper motion of the star and the time it was observed?
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What's the difference between GSR and Grf
I note there are two terms about Galactic rest frame in literatures:
Galactic Standard of Rest (GSR) and Galactic Rest Frame (Grf).
Are they the same frame? If not, what's the difference?
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What do these latitudinal and longitudinal lines and accompanying hours and degrees represent?
I'm a beginner in Astronomy. What do these latitudinal and longitudinal lines and accompanying hours and degrees represent (in blue: +12h , +11h.. and +45° +60°.. , in orange: +330° , +15°) ?
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rotate right ascension, declination based on delta time
Assuming I was observing a source at a given right ascension $\alpha_0$ declination $\delta_0$ at a given time $t_0$ under a certain azimuth $A$ and elevation $a$ angle.
If I now change my time to $...
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Horizontal to Equatorial Conversion - Code
Following this tutorial I have been able to convert from Equatorial to Horizontal Coordinates and am now searching for a way to do the reverse.
I understand this kind of question has been asked and ...
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What direction does 0° in the J2000 epoch point towards on January 1, 2000?
Is 0 degrees in the J2000 Epoch 'right ascension' is a line from Earth to the sun on January 1, 2000? Or is 0 degrees the direction towards the ascending node 'equinox'? Which is NOT towards the Sun ...
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How to make projection from altitude and azimuth to screen with screen coordinate system?
Thanks to @ohoh for helped translate ra and dec into alt and az. Now that I have this data(altitude and azimuth), how can I plot it in something like this, with the coordinate system going like this?
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Plotting Galactic Longitude from 180 to -180
I made a scatter plot in Python that looks like this:
However, I want galactic longitude, l, to be plotted from 180 to -180 like these graphs from Iorio and Belokurov (2019):
Here is the ...
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Calculate declination of Galactic N. Pole given obliquity of Ecliptic, rt. ascension of Galactic N. Pole, & angle between Galactic & Ecliptic Pole
I’m trying to back-calculate a value in astronomy using spherical trigonometry. (This is not a homework problem, I'm retired).
Using the following formula, where δ = the Declination of the Galactic ...
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