Linked Questions
13 questions linked to/from Need Simple equation for Rise, Transit, and Set time
11
votes
4
answers
10k
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Why is twilight longer in summer than winter and shortest at the equinox
I recently decided to set my alarm clock to wake me up when it is "dark" out. In the end, I decided to set my clock to the earliest time that nautical sunrise is in my state (Illinois) and stick with ...
- 231
13
votes
2
answers
2k
views
Cancelling out earth rotation speed, Altazimuth mount
I have a Dobsonian telescope.
It is using Altazimuth mount.
Basic idea of using it is to target the object by moving telescope vertical axis perpendicular to the ground, and an elevation axis that is ...
- 233
1
vote
1
answer
2k
views
Determining sunrise and sunset times based on azimuth and elevation
If I observe the sun and measure the local azimuth and elevation, and I also have my latitude, can I calculate the local sunrise and local sunset times? If so, how would I calculate it?
Further, can ...
- 113
2
votes
1
answer
1k
views
Finding hour angle, altitude
I know the latitude and longitude of a city ($41^\circ 87'$ N, $87^\circ 62'$ W), the declination and right ascension of a star($16.51^\circ$, $68.98^\circ$) and the local time, date (27.12.2017, 1:20 ...
- 51
1
vote
1
answer
718
views
How can we estimate if a certain astronomical object will be visible from a place on earth?
If we have the RA/DEC of an object that we want to observe, how can we tell if that object is visible from our place on earth (at a particular time of the year)?
Given that the part of the sky we are ...
- 147
3
votes
2
answers
193
views
Is there any formulae to calculate whether the sun will depress 18 degrees or more below the horizon on a certain day / location?
I'm trying to code a piece of software which will calculate some times for me that would greatly help me in my day to day but none of my formulae work if the sun doesn't go at least 18 degrees below ...
- 39
2
votes
3
answers
334
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). ...
- 21
0
votes
0
answers
244
views
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 ...
- 101
0
votes
2
answers
139
views
Can someone explain me this diagram from an article?
How should I understand this 59 degree mentioned below, what does it mean? I could not get it. The photo is a diagram from an article dedicated to the invention of the ecliptic. The photo is from my ...
- 111
0
votes
2
answers
153
views
Distance from W(West) to vernal equinox
I am pretty new to astronomy and the project I am currently working on requires some knowledge of equatorial coordinate system.
As long as I have been researching this question, I understood that ...
0
votes
1
answer
151
views
ra for sun vs stars
There is formula for stars sideral time:
$$ra - \arccos(-\tan(dec)*\tan(lat)).$$
where $ra$ - is right of ascension at the vernal equinox.
$lat$ = latitude
$dec$ = declination
Is it applicable ...
3
votes
1
answer
108
views
Deducing the hour based on RA
I'm making a technological project. The goal is to write a program that gets an image of the nightsky and predicts the hour in which the photo was taken.
I implemented a well-known method using the ...
2
votes
0
answers
74
views
Daytime length and sunrise / set cardinal directions
Let me illustrate the question with an example. On Feb 2nd 2022, the sun rises in Los Angeles at cardinal direction 110 and sets in direction 250 (according to timedate website). This means that the ...
- 21