I have just been to Niels Noordhoek's site where the 'Bahtinov Grabber' was available, only to see the very sad news that he is no longer with us.
Niels wrote this superb bit of software and made it available to us for free.
I often suggested to him that he charged a small price for it but he always refused.
Niels was a brilliant programmer and was very skilful at writing software that analysed images. I once suggested to him that it would be great to have a small programme that would scale and rotate two images of the same region of space so that they could be compared to search for asteroids, novae etc.
He had it done within 24 hours!
A sad day.
George
http://www.njnoordhoek.com/