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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3
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1answer
30 views

Plotting Equatorial coordinates to X,Y plane (simulating telescope/camera view)

I would like to simulate a telescope camera view, projecting (RA, Dec) coordinate sets to a 2D plane. So effectively the need is to convert Equatorial coordinates to (x, y) coordinates, when we can ...
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45 views

Converting Declination and Right Ascension

If I am been given the Right Ascension and Declination of a celestial body, how do I convert it into the altitude and azimuth as the latitude and longitude varies?
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Establishing a telescope [closed]

Let’s say to locate a large telescope in one of these three countries Iceland, New Zealand or Ecuador. From which one would you be able to observe almost every object on the celestial sphere at some ...
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1answer
51 views

What is the longitude of the winter solstice for the various planets?

I am looking for data showing the longitude at which the various planets in the solar system reach their winter solstice. Where could I find this data?
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1answer
55 views

Orbit of Luhman 16?

I am studying some binary stars and brown dwarfs. Some orbits are known and easy to find, like Alpha Centauri. However, when I look for the orbital characteristics of Luhman 16 (AB), I only get the ...
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53 views

How to calculate longitude of Alcyone - η Tauri in the year 41050 BCE?

Using the following information from The Skylive, and simple arithmetic I tried to calculate longitude of Alcyone in the year 41050 BCE at a place: 29.9457 N , 78.1642 E. Galactic Longitude 166.67°, ...
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2answers
70 views

Solar Azimuth angle Derivation

I tried posting this on math stack exchange to no avail so I thought maybe it's more relevant here : I know a similar question has been posted here before but no links to any mathematical derivations ...
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0answers
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How is the incidence angle of the Sun related to the lean angle of the Cooks pines?

Auracaria columnaris (Cooks pine) on average lean towards the equator. Most of the pines in the Northern Hemisphere lean southward and most of the pines in the Southern Hemisphere lean northward. ...
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Getting XYZ coordinates of Luminous Red Galaxies catalogue

So I want to get the XYZ (rectangular/Cartesian) coordinates of the LRG (luminous red galaxies) catalog. The catalog is available for download from here: https://data.sdss.org/sas/dr16/eboss/lss/...
3
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1answer
32 views

Converting equatorial coordinates to Cartesian coordinates for extragalactic distances

I'm trying to search for galaxy clusters with the friends-of-friends (FoF) algorithm. I have the equatorial coordinates ($\alpha, \delta$) and redshifts ($0.5<z<2.5$) of galaxies that I wish to ...
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2answers
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When (yyyy-mm-dd) does the north pole of uranus most nearly point towards the sun?

When (yyyy-mm-dd) does the north pole of uranus most nearly point towards the sun? The information I've found suggests this happened in 1944 or 1945, but would like to find a more precise date or ...
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0answers
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Calculate Global (ECEF) coordinates of Observer

I have the local coordinates of satellite and global coordinates of satellites. I want to calculate the observer position in global (ECEF) system. How can I do this? I also explain this question with ...
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1answer
33 views

Third rotational angle in equatorial coordinates

Right ascension and declination identify an object's position in the sky, but if we are looking at something through a telescope, there is a third angle of interest, namely how our view is rotated ...
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What are Native coordinates in the World Coordinate System?

i am writing my first paper about our solar telescope, and i need to explain the optical transformations in terms of World Coordinate Systems. I am not sure if i got the following right, and would be ...
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102 views

Clarifications about distances in cosmology

I would like to get clarifications about some usual notions of distances in cosmoogy. First, the comoving distance is the current distance of objets whose light ...
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2answers
81 views

How to calculate geocentric transformation to heliocentric coordinates?

I have Sun data (lon+lat+distance) in geocentric coordinates: but I want to visualize in heliocentric way. How to calculate that?
2
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1answer
303 views

How to plot celestial equator in galactic coordinates? Why does my plot appear “backwards”? [duplicate]

I'm trying to plot celestial equator in galactic coordinates. Here is my code (based on this answer): ...
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1answer
38 views

What is a UBV source for stars or stellar objects?

I was using the V19(VizieR) catalog and the main identifier of the stars was in terms of an 'ID' number which they mentioned as being 'Star number in UBV source' I have no idea what that means. How ...
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2answers
284 views

Data to “check” Kepler’s first law

I want to "check" Kepler’s first law by using real data of Mars. From the equation of the ellipse, I derived $$\frac{1}{r}=\frac{a}{b^2}+\frac{a}{b^2}\cdot\epsilon\cdot\cos(\varphi),$$ where ...
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0answers
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Data for “milky way outline” [duplicate]

I am trying to make a software generated star chart, and want to include the outline of the milky way as shown in many such star charts. Does anyone have any idea where to obtain the data for that? ...
2
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1answer
81 views

Figure out the location of celestial objects relative to the Milky Way in x, y, z co-ordinates

I am trying to place various celestial objects the correct distance from the Milky Way, using x, y, z co-ordinates. So assuming the centre-of-mass of the Milky Way is at 0, 0, 0 - how can I figure out ...
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1answer
39 views

Why does M101 search string have RA variable from 0 to 360 and Dec variable from -90 to +90 in the Hubble Legacy Archive?

I was scraping some images off the Hubble Legacy Archive and I found that searching M101 with RA in range 0-360 and Dec in range -90 to +90 yields results. Now I understand that Messier 101 galaxy has ...
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2answers
176 views

Is the “mean orbit” centered on ellipse center or ellipse focus?

Mean longitude and mean anomaly of a body are calculated as the angle covered by the body along a fictious circular orbit, and this is ok. But where is this orbit centered? Five different sources say ...
2
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1answer
187 views

What is the difference between azimuth angle and hour angle?

What is the difference between an hour angle and an azimuth angle? When I see illustrations of the two, the angles look very similar.
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2answers
60 views

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 $\pi$?
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Using altitude, azimuth to determine a baseline vector?

I know the equatorial coordinates of a “beam” pointing from an Earth-based observer toward some distant star. I have converted those coordinates to altazimuth coordinates for that observer and a ...
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1answer
97 views

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 ...
3
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1answer
105 views

Calculation to Convert from Equatorial to Heliocentric coordinate systems

Can anyone help me with the formulas to convert Equatorial coordinates (Right Ascension / Declination) into Heliocentric coordinates (Angle and Distance in relation to the Sun) ? i.e. Ra/Dec of 6.7659/...
2
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1answer
188 views

$\eta$ and $\xi$ coordinate system

Is there a standard definition for $\eta$ and $\xi$ in terms of Ra and Dec, as used in an astronomical coordinate system? I'm used to working with Ra and Dec, and am not sure how to precisely ...
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1answer
50 views

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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2answers
259 views

Different times of sunset at the same location due to elevation

Me and my friend were watching the sunset on the same location (at my country the latitude is approximately 40 degrees). I am at sea level and my friend is at an elevation. He observed the sunset with ...
4
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1answer
115 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 ...
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28 views

Rotating observer plane inside celestial sphere with a given coordinates, time and date [duplicate]

I have plotted stars around the surface of a celestial sphere. At the centre of this sphere, I have a brown plane which is the land. This plane can be rotated in the x,y and z axis. When x,y,z ...
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72 views

Position Angle Relative to North

I am trying to find the position angle of a star whose Ra and dec are known. I have already looked at the 'Measuring misalignment between two positions on sky' question and answer, but the answer ...
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1answer
87 views

Unable to detect stars and constellations in simulation of stars from the Hipparcos catalogue

I am creating a planetarium program using Unity3D and C# to plot out stars from the Hipparcos catalogue. Using the Plx, _RA.icrs and _DE.icrs columns of the dataset, I have managed to work the ...
3
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1answer
60 views

How to plot curvilinear coordinates in the frame of a Cartesian telescope field of view

I am wondering what projection is used to produce plots like this: (Image taken from here, author: NASA/Ames/JPL-Caltech, Image credit: Software Bisque) More generally, I am trying to figure out the ...
2
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1answer
68 views

Where do the symbols $\lambda$ and $\beta$ come from for celestial latitude and longitude?

I'm reading Episodes From the Early History of Astronomy, and the author mentions the system of celestial coordinates based on the ecliptic. In this system, the two coordinates are latitude and ...
3
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0answers
72 views

How do I plot field of view of an earth-based observatory in Galactic Coordinates?

I would like to plot in Galactic Coordinate the sky field-of-view of an earth-based observatory (e.g. MAGIC). Something like this from Liu et 2016. I already know how plot source positions on a 2D ...
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0answers
45 views

Determine distance to Moon after diurnal parallax?

So, I want to find the distance to the Moon/any body after performing the correction for diurnal parallax. Unfortunately, the resources I have do not cover how to do this. Is there an easy algorithm ...
1
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1answer
77 views

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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2answers
283 views

How to make a star chart from entries in a Bright Star Catalogue?

I know very little in astronomy, but I want to use the data in a Bright Star Catalogue to create star map projections for a specific time and place. For example one line is ...
3
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1answer
249 views

What is meant by *topocentric* right ascension and declination?

I'm looking up how to convert an azimuth/elevation measurement from a specific location on Earth's surface to right ascension/declination. I'm coming across the terms "topocentric declination" and "...
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0answers
40 views

Detect sources near image edge with python photutils

As my question suggests, I 'm trying to use a python library photutils in order to detect sources from MUSE cube. MUSE (Multi Unit Spectroscopic Explorer) is an ...
4
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1answer
124 views

Astronomical Term *Mezzocielo*

What is the name of the point of intersection of the great circle passing through the celestial north pole P and the Zenith Z, with the celestial equator? (Point T in the figure) In Italian this point ...
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260 views

Transforming Galactic Coordinates in Cartesian with Distance

Lets say I have galactic coordinates of an object, l and b. I figured out that i can transform them to cartesian system using the formula: $$ \begin{align} X &= \cos(b)\cos(l)\\ Y &= \cos(b)\...
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1answer
139 views

Can I use the parallax coefficients for observatories as a proxy for latitude using arctan2(sin, cos)?

In How are the three character IAU Minor Planet Center's Observatory Codes assigned? Why are some letters so popular? I looked at the distribution of the first alphanumeric character versus the value ...
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4answers
831 views

Latitude, longitude and altitude of Ckoirama Observatory; where can things like this be looked-up?

This answer to Is Starlink 1130 (Darksat) really dimmer? links to the March 16, 2020 paper in arXiv First observations and magnitude measurement of SpaceX's Darksat which finds only a modest decrease ...
4
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1answer
178 views

Usefulness of the hour angle (HA)

The Hour Angle (HA) is measured west from the observer's meridian in hours, mins, seconds. How is the Hour Angle used to help plan observations during the night at a telescope?
4
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1answer
90 views

Information about known objects in the Universe

I want to retrieve coordinates, photos, and information (size, atmosphere composition, distance from Earth, etc.) about every known object in the universe. Ideally, the information is available via an ...
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1answer
57 views

What coordinate system is at rest relative to the center of the galaxy?

I am given equatorial coordinates and I need to transform them into a coordinate system that is at rest relative to the center of the galaxy. The closest thing I could find is galactic coordinates ...

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