# Questions tagged [coordinate]

Questions on systems to uniquely determine position of a point or other geometric element on a manifold such as Euclidean space.

26 questions
Filter by
Sorted by
Tagged with
3k views

### Need Simple equation for Rise, Transit, and Set time

I've been looking, unsuccessfully, for hours for a simple set of equations: Input: RA and Dec of an object Observers Lat and Lng Current Time Output: Rise Time Transit Time Set Time (and, ...
7k views

### Local Sidereal Time

I am trying to understand how to calculate local sidereal time and have found the following formula: $$\text{LST} = 100.46 + 0.985647 \cdot d + \text{long} + 15 \cdot \text{UT}$$ Here, $d$ is the ...
221 views

### How was the galactic plane established?

As pointed out in this answer the axes of galactic coordinates are defined such that galactic longitude and latitude (0, 0) point toward the galactic center. But then the plane defined by galactic ...
346 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 ...
583 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 ...
563 views

### Can you translate a GPS coordinate to a Galactic coordinate?

I am a complete newbie to astronomy and all the related. So if i say something stupid i am sorry. But i was wondering if it is possible to translate GPS coordinates like the following: ...
1k views

### 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 ...
9k views

### Could someone explain RA/dec in simple terms?

The equatorial coordinate system isn't too complicated. However, for people new to this, it seems rather intimidating at first. Is there an easy way to explain it?
2k views

### Software to convert RA and DEC into ALT and AZ

I have implemented the formulas to convert AR and Dec into altitude and Azimuth in C++ following the book Practical Astronomy with your Calculator or Spreadsheet 4th Edition. In the book there is an ...
491 views

### Measuring misalignment between two positions on sky

Let's say I have the (RA,Dec) for two positions on the sky. I want to measure the position angle between these two positions. In other words, if I had the Cartesian coordinate vectors for these two ...
9k views

### How to find Greenwich Mean Sideral Time?

I'm writing a program that converts position in the ECI (CIS, EPOCH JD2000.0) coordinate system to WGS 84 (CTS, ECEF) coordinates. To do so, I'm following what's described in this document and ...
1k views

### Angle from 2 point on celestial sphere

I'd like to find the angle in radians between two equatorial coordinate i.e from RA dec of point 1 and RA and dec of point 2.
887 views

### Where and how to look up the coordinates and magnitude of the star in this occultation prediction?

The motivation for this question comes from this question. A star is named in the occultation prediction shown below, from AsteroidOccultations.com's News & Announcements for 2014 MU69 on ...
143 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 ...
344 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. ...
602 views

### What are the RAs of the boundaries between traditional zodiacal signs?

I'm trying to figure out at what right ascension (RA) — not celestial longitude — the sun enters the various traditional (Western) astrological signs of the Zodiac; but I can't figure out how to ...
5k views

### 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 ...
3k views

### Convert coordinates between RA/dec and WGS 84 (SRID=4326)

I've imported the HYG Database from http://www.astronexus.com/node/34 and now I need to convert all RA/dec stars positions to fit in a WGS 84 coordinates (SRID=4326) PostGIS map (-180 to 180, 90 to -...
839 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 ...
73 views

### Protocol for establishing longitudinal meridians on other heavenly bodies

When we first observe a new heavenly body (it could be a new star, asteroid, etc.,or a minor planet in our own solar system), are there any procedures set in place for establishing a system of ...
212 views

### Position of specific stars in the sky as a function of time

I'm a beginner in astronomy and I'm trying to figure out how to model the positions of stars in the night sky mathematically (ie a function which spits out azimuth and altitude as a function of time). ...
122 views

### Why is declination positive in the northern hemisphere?

Simple question -- why is declination positive in the northern hemisphere? Seems like it should've been called "inclination" since the word originated north of the equator.
28 views

### How does the rock Simurgh Saxum (-25.32°, 4.05°) on 101955 Bennu define its prime meridian and serve as the basis for its coordinate system?

Spaceref's NASA's "Tour of Asteroid Bennu" Selected for Prestigious Computer Graphics Film Festival says: It's hard to imagine what the surface of asteroid Bennu might look like - it's ...
519 views

### 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 ...