The sage was told this but at the same time the king verified this by calling several Jyotishis to predict the future. All except one told that Siddhartha will become either a great king or a great saint whereas one jyotishi clearly stated that Siddhartha will become a buddha.I was not asking for the name of jyotishya text (why would I want it)
I'll give you one more chance, give me the name of the text/treatise which you claim describes ' prediction of Buddha's future asceticism based on jyotishya (horoscope as we commonly understand). Ashvagosha' s 'Buddhacarita' does not cut the ice, because, as per the 'Carita', sage Asita, who was living in the the buddhist heaven, was already informed by the gods that the future Buddha was born. So why would the sage need an Astral chart to know about something that he already is aware...
P.S: please try to answer without frothing at the mouth. You always have the option to remain silent and I'll let it pass.
Secondly, the sage did check some birth data to comfirm if this child is buddha. It was not spontaneous. Nevertheless, you need only to look at the other jyotishis summoned by the king to see that Jyotishya did exist in 500BC
Don't froth from your mouth by reading only snippets. If you can't reply, you always have the option of remaining silent and I will let it pass