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 example to check if I have do it fine. This example works perfectly but I want to check if my formulas are correct.

I have use this page to check it but I get different minutes values in both altitude and azimuth values.

I have checked on that page that I get the same LST value, but ALT and AZ have different values. This data I have tested:

Altitude: -15° 27' 40"
Azimuth:  273° 12' 34"


This is the data get it from that page:


Do you know if there is another web page or program to check if the result of my formulas are correct?

UPDATE:
I have tried to get Azimuth and Altitude using a date in year 2000 in web page and my program and this is the result (you can find my program's result at the bottom of the image):


Is this the same problem like the previous one (I'm not taking account for precession)?
Based on stellarium, I think you're not accounting for precession (more after the picture):



As you can see, Rigel's J2000 coordinates and Rigel's current coordinates are different by about the same amount as your calculation.