I am intending to develop a free web-based tool where kids can plot a 2D skymap based on terrestrial coordinates and local time. I am aware of the fact that multiple sites provide already accurate sky maps, yet I'd like the output to be much more child-friendly (target audience between 6-12 years of age).

Before diving into the specific calculations, I just wanted to check if this high-over step by step schedule is correct in order to create the required output:

  1. Input terrestrial coordinates (latitude, longitude) + local time

  2. Translate terrestrial coordinates into Angle of Declination

    a. Latitude = Declination

  3. Translate longitude and local time into Right Ascension

    a. [formula to calculate local sidereal time from longitude and local time]

  4. Translate Declination into Altitude coordinates

  5. Translate Right Ascension into Azimuth coordinates

  6. Plot the applicable celestial objects on a 2D map (Alt-Az grid lines), boundaries determined by:

    a. Alt = Lattitude -90 degrees, + 90 degrees

    b. Az = LST -6hrs, + 6 hrs

I have noticed that already a lot of information has been provided on this particular subject. However, most are answers to questions which cover part of my puzzle. As a newcomer to astronomy with a background in finance and teaching, it is quite challenging from time to time.

Many thanks in advance!

  • $\begingroup$ What do you mean when you say angle of declination and RA here? Are you talking about the location of the celestial equator? Or the Ra and Dec of your local zenith point? In any case, the only thing your latitude is exactly equal to is the angle of Polaris to the horizon $\endgroup$
    – Justin T
    Jan 7, 2022 at 21:14
  • $\begingroup$ Hi Justin. Thanks for your response. Angle of declination and RA refer to the celestial coordinates of the celestial object. Various literature states that a star's declination is equal to earth's latitude. RA determines when this object can be seen from ones location based on local sidereal time, correct? $\endgroup$
    – Jesse
    Jan 10, 2022 at 8:53
  • $\begingroup$ I think I see what you’re referring to; when it says that RA and dec are like latitude and longitude, it does not mean that there’s a direct equivalence for you’re given measurements and a star at any given time. You can imagine the night sky as a big sphere, and that every point on the sphere can be assigned angular coordinates in the same way everywhere on the earth can be assigned angular coordinates. Let’s take the North Star as an example, the declination of the North Star is about 90 degrees, but you don’t have to be in the North Pole to see it; you can see it on northern half of earth $\endgroup$
    – Justin T
    Jan 11, 2022 at 16:01


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