Questions tagged [coordinate-systems]
For questions regarding coordinate systems when they are used for astronomical scenarios.c
30 questions
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How is numerical precision/accuracy determined when converting RA/Dec in sexagesimal format to decimal degrees for angular separation calculations?
Problem
I'm trying to complete an assignment for my astronomy course, but I'm having trouble understanding how accuracy is determined when converting equatorial coordinates in sexagesimal format to ...
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Can someone please clarify why the angle KPX is (90+alpha)?
Question:
In the standard geometric construction of ecliptic coordinates on the celestial sphere, let
K be the north ecliptic pole,
P the north celestial pole,
X is the position of an object on the ...
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Minkowski vs FLRW coordinate time
Is $dt$ in the Minkowski metric mathematically equivalent to $dt$ in the FLRW metric for spatially flat, expanding universe? I'll be happy with the answer in comment.
I already know that the FLRW ...
user79958
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Is there a term to describe the direction of a planet's axial tilt?
The Earth's axis is tilted at 23.5 degrees. This number is very well known. This describes how far the axis is deflected away from the vector perpendicular to the ecliptic plane. If you drew a ...
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Calculating the position of Earth at a given point in time
I'm trying to understand the position of the Earth for a given point of time in the past.
I'm familiar with ICRS and FK5 coordinate systems but these can't do what I'm after because they essentially ...
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Calculating latitude and longitude from single GNSS constellation
I am trying to find a fast and reliable way to calculate latitude and longitude of an Android smartphone using a single GNSS constellation (For example BeiDou).
What I have done so far:
Collect raw ...
3
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Converting heliocentric galactic coordinates to ICRS using astropy
I have the "heliocentric galactic" cartesian coordinates of Proxima Centauri as given in the paper Kervella et al 2017 (Table B.1 of https://arxiv.org/abs/1611.03495). I would like to ...
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How could a human decode the position of Earth from the Golden Record from the distance of light years?
Based on our knowledge of mathematics, astronomy, and physics, what could be the most likely algorithm for decoding the position of our planet from the Golden Record at a distance of light years?
user65215
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How do we derive the sun's declination using right ascension?
It appears that there are 2 formulas to derive the sun's declination.
One is: $declination \approx 23.5 \times sin(\alpha)$ from the answer here
and another which is similar $\delta=−23.45°×cos(\frac{...
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Conversion from TAN- projection to SIN- projection
I have an SDSS r-band image as fits file which uses TAN- projection as per its header.
EQNX_SCN= 2000.00 / Equinox of the scan great circle. (years)
NODE = 95.00000 / RA ...
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What is the pupose of the heliocentric distance in determining the positional coordinates in the J2000 frame?
I copied and modified for my own purposes the following algorithm for determining the orbital positions of planets. I obtained this from the web. Can anyone tell me what is the purpose of step 5? The ...
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Why is this Horizons query suggesting a different date/time for Earth's minimum heliographic latitude than SunPy's get_earth()?
When I use Horizons to check this by setting the target body to Earth (body center) and the observer to Sun (body center), checking times from 2025-03-06 to 2025-03-08 every minute, and setting the ...
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Does WGS 84 use a flat metric?
The Geocentric Celestial Reference System (GCRS) and the International Terrestrial Reference System (ITRS) are based on an approximate Schwarzschild metric, as discussed for instance in Soffel & ...
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Can human body be used to measure angle to celestial objects? Like sextant?
Can the human body be used to measure the angle between a celestial object like the sun or star at dawn/dusk? I was considering using a thumb or finger up to try and duplicate the following picture of ...
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How to convert the derivatives of position vectors in polar form to/from rectangular form
If I am not mistaken, position vectors (celestial coordinates) in polar form (L longitude, B latitude, R distance) can be converted into rectangular form X,Y,Z and back as follows:
Polar to ...
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