tim-from-pa
Member
My favorite doctor? Shouldn't I be in the health forum? No, this is a different type of doctor. This is a screenshot of an "excel" program I created to calculate Declination (D), Right Ascension (R) from my local Latitude (L) to my local altitude and azimuth useful in astronomy. So, I named the program "DRL" and the extension of an excel file like this is .ods (open document spreadsheet). One day while using it I noticed that in the upper bar is read "DRL.ods" and my mind saw it as "DR Lods". 
In a nutshell, the left side of the spreadsheet are spherical trig calculations. I have the cursor over B7 to show a typical formula, in this case based on the spherical law of cosines. Data is entered in the colored boxes and it spits out altitude and azimuth below. Notice I have 4 azimuths. That's because for those of you that understand trig know that taking the inverse of a trig function yields two angles opposite each other. Instead of placing the conditional criteria in the formula, I visually check the criteria and pick the proper Azimuth. I found from experience I rarely get the wrong answer that way.
The right side calculates the "equation of time" (ET) using Keplers Law and the spherical trig calculations on the left. That's useful for sundials. Again I have several visual conditions in the ET column because the ET ranges approximately +/-15 minutes and adding the complimentary angles yield obvious nonsensical results so it's easy to pick out the right one.
This program can be used to calculate sunrise and sunset times (with a little maneuvering), ley lines on the earth, direction to any two points on the earth, and similar calculations with no trouble.
View attachment 2348
In a nutshell, the left side of the spreadsheet are spherical trig calculations. I have the cursor over B7 to show a typical formula, in this case based on the spherical law of cosines. Data is entered in the colored boxes and it spits out altitude and azimuth below. Notice I have 4 azimuths. That's because for those of you that understand trig know that taking the inverse of a trig function yields two angles opposite each other. Instead of placing the conditional criteria in the formula, I visually check the criteria and pick the proper Azimuth. I found from experience I rarely get the wrong answer that way.
The right side calculates the "equation of time" (ET) using Keplers Law and the spherical trig calculations on the left. That's useful for sundials. Again I have several visual conditions in the ET column because the ET ranges approximately +/-15 minutes and adding the complimentary angles yield obvious nonsensical results so it's easy to pick out the right one.
This program can be used to calculate sunrise and sunset times (with a little maneuvering), ley lines on the earth, direction to any two points on the earth, and similar calculations with no trouble.
View attachment 2348