There is an authentic record on Kṛṣṇa’s exit year but no authentic info on his birth year. What is handed down through generations is Kṛṣṇa’s birth star, tithi and month and not the year name or year number. The rationale of celebrating his birthday on tithi explained here: https://jayasreesaranathan.blogspot.com/2018/09/janmashtami-from-cosmic-angle.html?spref=tw
In the history of Sanatanic practice of tracking time, there is only one feature that is being tracked. That is the current age of Kali that started 3179 years before the beginning of Shalivahana Shaka on 78 CE. This is specifically mentioned in this way to make it known to people that this is how time is being mentioned in computation manuals of Panchanga. For the purpose of easy tracking with smaller number, we take the year in the current Shalivahana Shaka and add 3179 to get the Kali Yuga year. Those who are attempting to ‘date’ the Itihasa-s (there are only 2 Itihasa-s Valmiki Ramayana and Vyasa Mahabharata which were never tampered with – the justification given in my book ‘Mahabharata 3136 BCE’), should have known this and must have had some hands-on experience in cracking epigraphic records on the Kali yuga and the Shaka date given in them. Without such experience and with western astronomy simulator, the current generation of people are being fed with all sorts of mis-interpretations.
On the topic of Kṛṣṇa’s birth, there is no anniversary year for his birth date that so many number of years have elapsed since his birth. Whereas there is authentic record of his exit year which is recognized as the beginning of Kali Yuga that is in use practically all through India and found recorded in the inscriptions for all these intervening 5000 + years. This year was 3101 BCE which is got by adding 3179 years to the beginning of Shalivahana Shaka. So, it is apt to say that Kṛṣṇa left 5123 years ago. But there is no way to say he was born so many years ago.
Dr. B.V. Raman attempted that by going 125 years backwards of 3102 BCE (Julian year equivalent of the Gregorian year 3101 BCE). He was led by a verse in Srimad Bhagavatam that Kṛṣṇa lived for 125 years. Given as a unique feature to glorify Kṛṣṇa this cannot be true but a later addition in the text for it does not make it unique for Kṛṣṇa. If agreed, this would make Arjuna to have outlived Kṛṣṇa. Not only Arjuna, even Bheema, Yudhishthira and Kṛṣṇa’s brother Balarama must have lived more than 125 years. So, what is the big deal about Kṛṣṇa having lived for 125 years? This has a parallel with what is being said for Rama – that he ruled for 11,000 years – which means that all his brothers, Vibhishana, Sugreeva and Hanuman et al also lived for 11,000 years, because all of them were present until Rama shed his mortal coils. Read my article on this issue here: https://jayasreesaranathan.blogspot.com/2009/07/did-rama-rule-for-11000-years.html
So, the 125-life span is just for glorification and not to be taken at face value. Coming to Dr. B.V. Raman’s attempt on constructing Kṛṣṇa’s horoscope, he just shifted backward in time by 125 years and made something as follows:
This has no support from scriptures if we go by what the famous astrological text ‘Kala Prakashika’ says about Kṛṣṇa’s birth time. Quoting Brahma Samhita it says the Pitamaha (Brahma) told Narada the following details of the planetary positions at the time of Kṛṣṇa’s birth. https://books.google.co.in/books?id=e_8MaBfTncgC&pg=PP7&lpg=PP7&dq=kalaprakasika+translation&source=web&ots=7096Yp5mnG&sig=_pN0EIEn38u-y2pjz277r4gtheM&hl=en&sa=X&oi=book_result&ct=result#v=onepage&q=kalaprakasika%20translation&f=false
This is almost like Rama’s horoscope with 5 planets in exaltation and two planets in own houses. A very rare occurrence indeed. The main clue is the position of Saturn in Libra and Jupiter in Cancer. Based on Saturn’s position during the Mahabharata war that I established in my book, the only probable year was 3086 BCE when these two matched but not others.
As per the above simulation, the age of Krishna at the time of the Mahabharata war was 50 years.
The reasons for the mismatch are obvious – that I explained in my Mahabharata book. Even the tithi will not match with star for dates prior to 3136 BCE in any software due to loss of one tithi in 3136 BCE by a cosmic hit on the moon (refer my Mahabharata book). This applies to Rama’s date too. You cannot reproduce Shukla Navami on Punarvasu with the sun in Aries. Without understanding the intricacies of that issue, we are happily showing off with the modern astronomy software.
Back to the topic, what is authentic? Brahma Samhita narration on location of planets or Bhagavatam’s version of 125 years? Perhaps seeing the inconsistencies and the limitations in reproducing the exact planetary combinations, none in the past harped on the ‘birth anniversary’ of Kṛṣṇa but only focused on birth star-tithi-month. Even then the north Indians started ignoring the importance of the location of the sun and often land up with a date when the sun would not be in its own house (Simha).
Our ancestral rishis and acharyas have only stuck to month-tithi-star for both Rama and Kṛṣṇa - the combination identified for birth days of these Gods. With our limitations, let us not feed the eager Hindu population with mis-interpretations and wrong notions but stick to what is being handed down to us. Without being aware of the issues as highlighted above let us not spread our own versions which will invite terrible karma for ourselves. Manipulation of the texts is the worst crime of Kali Yuga which is a sign of worsening of Kali.