Hi Dave,

The software I used two or three years ago was a demo version of skymap 6. I went back recently and checked the altitudes of Sirius and Kochab on several different dates and could see that some of the readings were just not right. The new software that I used was a free demo version of Cybersky and it seems to work very well. This is actually not a very expensive program to buy and I am thinking about getting it. I believe that the 2450 b.c. date for the time the culminations of Sirius and Kochab were at the same respective altitudes above Giza is correct, but I would be happy for others to check this and see if they get the same date.