Astro Tutorial #1.4: Coordinate Systems of the night sky - ALT/AZ vs RA/DEC - V2.0

V2.0 - 22.01.2021 - Enhanced Audio Quality -
Welcome to the forth video of the tutorial session!
Today we discuss following items:
a) the nomenclature of important points and plains
b) coordinate systems of the night sky
c) finding stars with their coordinates in both systems
We use “Stellarium” to explore different aspects of the grids that help us to orientate in the night sky.
Download Stellarium here:
stellarium.org/
I hope you find this video helpful.
If you do: Hit like and subscribe!
Next video will be about
focal length
aperture
f-ratio and the
FOV
Subscribe to stay tuned!
Clear skies everyone and till next time here at catchingphotons!
Chris
Hashtags:
#ALZ/AZ
#RA/DEC

[@charimuvilla8693]

Can't wait to call my friends at 3am and tell them where Capella is. Thanks for the video!

[@catchingphotons]

You are very welcome chari!

[@josephlai9759]

Thank you so much. The difference between the two coordinate systems is very well explained and emphasized.

[@catchingphotons]

Thanks Joseph, your comment is very much appreciated. Clear skies!

[@hugbearsx4]

07:25 What I think you missed is exactly a key piece of information: for a specific place and time, how do I find out where RA 0h is?

[@budharpey]

thats exactly what i am wondering about , as i watch this right now, can somebody tell me?

[@nako7569]

Samee

[@catchingphotons]

Great question! Right Ascension (RA) and Declination (Dec) are the two coordinates used to locate objects in the sky, similar to how we use longitude and latitude on Earth. RA and Dec are fixed for an object in the sky, just like longitude and latitude are fixed for a location on the Earth's surface. However, because the Earth rotates, the RA and Dec for an object changes in the sky over time from the perspective of an observer on Earth. To answer your question: the point of RA 0h (0 hours) is determined by the location of the vernal equinox, also known as the "First Point of Aries". This is the point in the sky where the sun appears to cross the celestial equator from south to north. It marks the beginning of the celestial coordinate system. It's called the "First Point of Aries" because several thousand years ago, it was in the constellation Aries at the time of the vernal equinox. However, due to the precession of Earth's axis, it's currently located in the constellation Pisces. So how do we find out where RA 0h is for a specific place and time? Here's where star charts and modern technology come into play: Star Charts or Planispheres: These are maps of the sky that can be adjusted for any time and date. They display the celestial sphere as it appears from your location. By setting the chart for your specific time and date, you can see where RA 0h is relative to other objects in the sky. Astronomy Apps and Software: There are many smartphone apps and computer programs that can show you the current positions of stars, planets, and other celestial objects. Some popular ones include Stellarium, SkySafari, and Google Sky. You can input your location and the current time, and the software will show you the sky as it appears from your location. These programs often have grid overlays that show the RA and Dec coordinates, allowing you to see where RA 0h is. Remember, the Earth rotates, so the position of RA 0h in the sky changes throughout the night. Also, since the Earth orbits the sun, the position of RA 0h at a given time (like midnight) also changes throughout the year. This is why accurate charts or software are essential for precise observations.

[@hugbearsx4]

@@catchingphotons Thanks a lot for your effort!

[@beorn8988]

Thank you so much for explaining everything nice and beginner friendly!!!

[@catchingphotons]

You are very welcome!!!

[@jesusalbertoponcedeleon7124]

Hello , Hello, are you still producing videos as of 2024? congrats! Great work.

[@catchingphotons]

Sry for letting you wait so long 😞 I moved and had a LOT to do. But now things are settling and I'm planning on continuing my tutorial series. Cheers and thanks for the patience!

[@miguelfelipe435]

Best explanation by far

[@catchingphotons]

Thx

[@investinglearningmachine3951]

❤great video!

[@catchingphotons]

😎👍

[@texdoms]

Cristal clear now! Thank you.

[@catchingphotons]

You are very welcome! Clear skies!

[@kanewilliams1653]

great vid, thanks

[@catchingphotons]

You are very welcome!! Thanks for your comment!

[@cuvarsnova]

It is certain that this knowledge will be used less and less in addition to the GO-TO system. I bought all the electronic parts to make a dobsonian stand with a 3 step motor, connect it to the Stellarium program on the computer and connect it to the smart TV via wi-fi, so that I can remotely control it from the heat in the house, or if there are those who like to watch the stars while it is raining, not to get wet :) . The third is to rotate around the axis of the telescope. We are successfully improving things so that we can be more and more stupid :)~

[@catchingphotons]

Cool project! Yea so it is especially important to keep the basic knowledge alive. When I got my GOTO mount it needed to be star aligned (no PC connection back then). It slewed to the first position... was way off... and I was lost 🤣 Clear skies!!

[@sunnygarg7616]

Then why the dec of sun changes with time

[@catchingphotons]

The sun and all the other planetary bodies chance RA/DEC coordinates because they are not part of the fixed system. The earth rotates around the sun, the orbit is tilted and stuff. Think about: the axis is fixed against the equinox points, 90° degrees off that and the normal vector to the orbit plane. Thereby it's fixed in respective to distant stars but not to planetary companions or the sun or the moon. Clear skies!!

[@sunnygarg7616]

@@catchingphotons thanks

[@ralfjungnickel1220]

📡👍👍👍👍

[@catchingphotons]

Thx!

[@richardlee411]

First comment =)

[@catchingphotons]

=)

[@consti-xe8cj]

its pretty difficult to understand for a beginner

[@catchingphotons]

Yes true, it's a bit intuitive first but one gets used to it after a while. I recommend installing Stellarium and playing around with that to get a rough orientation. Clear skies!

[@consti-xe8cj]

@@catchingphotons today we are in croatia and in bortle 4 im really excited because its the first time i see more (i live in bortle 6) its 19:09