Just to kind of stir things up with your friendly neighborhood JW, you might want to first direct him to the reference to VAT4956 in the WT 72?(don't have the cd rom on me). They basically discredit it, say it's a piece of junk, etc... What a difference 40 years makes! Now it's the most reliable piece of info directing us to 607. Amazing.
The irony is if you examine the astronomical data, it points to 587. Another line in the tablet refers to Jupiter being in Scorpius near Antares. It is in that area in 568. In 588 it is way over near Aquarius/Pisces. Another falsification of the Watchtower claim. I will let the reader decide if their conclusion is due to poor scholarship, sloppy research or dishonesty.
I have used Stellarium to find planets, asteroids and comets I could not see with the naked eye. I have also used it to find deep sky objects such as galaxies. When Comet Elenin came by, I used it to track its course, and demonstrate that the prophecy smack people were lying about it damaging the earth. It works, and is available for Mac and Linux for those who have kicked the Microsoft habit.
The Cartes du Ciel program is found here. http://www.ap-i.net/skychart/ I have used it several years ago. It does the job too. The Watchtower really blundered this time, big blunder. In these articles they demolished any shred of credibility they may have had left.