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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2answers
44 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
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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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1answer
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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/...
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131 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
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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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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 ...
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1answer
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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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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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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
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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 ...
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1answer
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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 ...
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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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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 ...
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1answer
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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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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 ...
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1answer
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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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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 ...
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1answer
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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 ...
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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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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 ...
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1answer
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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?
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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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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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Calculating angle between the sun and a perpendicular to earth given lon/lat & time

If you had your longitude/latitude, and the time/date, how could I go about working out the angle between your normal and the sun? At first I was doing a simplistic approach of assuming elliptical ...
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How can one determine the declination range of stars visible for a certain amount of time above a specific airmass at a certain location?

Let's assume you want to observe stars at Kitt Peak (32 degrees North) at an airmass above 2, for 2 hours (30 degrees of Earth rotation). My attempt: The angle between the zenith and celestial ...
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1answer
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Latitude of given altitude of Sun

From Question #6 of USAAAO First Round 2018 (1 point) For the following problem find the range in which the answer lies: on the day of summer solstice, on which geographic latitude is the sun ...
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1answer
238 views

How to calculate parallactic angle from a fixed alt-az position?

Say we have an observer at a specified latitude and longitude on Earth who would like to observer a specific fixed alt-az sky position (rather than RA and dec), for example to look at geosynchronous ...
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1answer
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When is the best time to observe M81 from the Northern Hemisphere?

I have read that the best time to view M81 is during the spring. Considering its RA is ~10h and Dec. is +69°, wouldn't February 21st be the best time to view it since this is about when it transits my ...
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1answer
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Determining Horizontal Coordinate System data (azimuth, altitude) for geographic locations

I would like to determine, specifically, azimuth and elevation data for any given location on the surface of the earth relative to another location on the surface of the earth (for my purposes, the ...
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How to determine Az-El pointing of a telescope spiral scan?

I am writing a simulation of an automated telescope observation program. One part of this is to run a spiral scan pattern on and around objects of interest. I would like to tile this scan pattern so ...
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2answers
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Is the sun flipped on the other side of the world?

As the orientation of the moon is different in the northern and the southern hemisphere, is the orientation of the sun different in both hemisphere? Does a sunspot appearing in the Sun northern ...
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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 ...
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1answer
309 views

Why do J2000 coordinates change with time in Stellarium?

I'm new to the field so I'm sure this is a basic misunderstanding. As I currently understand it, J2000 equatorial coordinates describe the position of objects by referencing a specific point in time (...
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Coordinate system for space [closed]

I am high school student, I have doubt if I have to locate a planet or any star in space, how do I locate it, because we have no perfect coordinate system, I have read in some books, that time is ...
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1answer
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How to query a region on the sky when given only ecliptic coordinates?

I am new at using the Python packages astropy/astroquery and what I want to achieve is to use it to find stars that lay on the TESS continuous view zone (CVZ). I ...
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1answer
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SPICE Alt Az example

Original question below, but my question is now about how can I supply lat/lon coordinates for other locations other than the one in the example below? It is possible to use NASA's SPICE toolkit to ...
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2answers
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Geo Helio and RA

please assist me , i'm using Zet 9 and there is Geo longitude , Helio longitude and RA , what is the difference between them. example : ...
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2answers
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How to create unique 3d star maps?

I have been trying to create a calculator which finds the distance between two stars that the user chooses. But I'm having a hard time visualizing where these stars are in real space. Do you know of ...
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1answer
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Turn celestial coordinates into light years

I have a question about celestial coordinates. I have been working on a calculator that takes in different stars and tells you how far apart they are, and their coordinates (x, y, z). But I didn't ...
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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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What exactly is a Right Ascension clock and how was one (mounted on a telescope) used in practice, historically?

@MikeG's answer to Why does this Lowell Observatory telescope have so many knobs? What do they all do? explains that item #6 labeled in the image there (and cropped version here) is likely to be a "...
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How do I plot galactic coordinates using matplotlib and astropy in python?

I want to make a projection of millisecond pulsars on the galactic plane, much like this one from Sala et al. 2004: I have tried several methods, and have not gotten anywhere. This is my current ...
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Eccentricity from Analemma

Can the eccentricity of a planet's orbit be found just from the analemma of its star? We can draw an analemma given the axial tilt and eccentricity, but how do we find the reverse? Note: I already ...
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1answer
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Is the longitude assigned to sunspots spherical or projected?

Sunspot maps are created from a projection of the sun, so the coordinates of sunspots (or active regions in general) are assigned according to it. Do these coordinates correspond to actual spherical ...
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1answer
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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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Calculating the range of visible Right Ascension and Declination from specific location + time

Given a specific date and time, and coordination of a location on earth, how can I calculate (myself, or using a python package) range of visible RA and Dec? For example (but I'm looking for a ...
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1answer
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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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1answer
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How to calculate the ground track of the Moon's position on the Earth's surface?

I would like to project the Moon's position on to the surface of the Earth, starting with its position expressed as Right Ascension in degrees. I know that the declination of the Moon corresponds to ...
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1answer
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Finding angle between a given sky position and ecliptic pole

Given a right ascension in degrees and declination in degrees (say, 88 degrees RA, -63 degrees DEC) I want to find the angle between that location and the ecliptic pole (90 degrees RA, -66 degrees DEC....