[ EDIT: I apologise for my lack of references. I only stumbled across this site whilst researching the complex issue of the censuses of Herod (around the time of Christ’s birth) and Quirinius (6 AD / 7 AD). I had copied and pasted various articles for my purposes without recording the sources. I will add a number of references I used here.
I also used Armand Puig i Tarrech’s: "Jesus: An Uncommon Journey – Studies on the Historical Jesus", by Armand Puig i Tarrech (2010), LINK: https://books.google.co.uk/books?id=elFp5tRSUH0C&redir_esc=y&hl=en
On the subject of the ‘eclipse of Herod’, here are some references about the two eclipses in 1BC, one in January 1 BC, the other in December 1BC. I tend to prefer the arguments of those who select the date of 29 December 1 BC for the eclipse. This would place Herod’s death probably in 1 AD and I would suggest Christ’s death in the autumn of 1 BC. This would make the beginning of Christ’s ministry in 29 AD and, assuming a 3½-year ministry with his ministry spanning four Passovers including the Passover of the Crucifixion, His crucifixion on 3 April 33 AD.
Of the two 1 BC eclipses, the first was apparently a full eclipse but IIRC began very late (about midnight). The one in December was only a 53% eclipse but because it started about dusk it is claimed that it would have been far more memorable and talked about:
http://www.biblearchaeology.org/post/2017/07/29/How-Lunar-and-Solar-Eclipses-Shed-Light-on-Biblical-Events.aspx (also deals with the year of the Crucifixion)
The date of the Crucifixion was I think calculated as 3 April 33 AD by Sir Isaac Newton. (I would also be interested to know what date the great Bishop Ussher assigned to it). I think most of the references to this date are readily available.
On the subject of the lunar eclipse in the early morning of 33 AD, here is the reference to the NASA site:
https://eclipse.gsfc.nasa.gov/LEhistory/LEhistory.html >>> scroll down to the section ‘ 1CE to 2000 CE’.
On the subject of Pilate’s letters, including the one referring to the blood moon, I looked at this reference:
http://www.orthodox.cn/patristics/apostolicfathers/herpilat.htm (Letters from Pilate)
It is titled ‘LETTERS OF HEROD AND PILATE’ and explains that they “connect Roman history with the death of Christ at Jerusalem. These letters occur in a Syriac manuscript in the British Museum, dated in the sixth or seventh century. There is a Greek copy in a Paris museum”.
I found this reference in ‘The Reports of Pilate, Anaphora Pilati’:
“Pilate observed in his correspondence sent to Tiberius Caesar that there was seen a blood moon eclipse at dusk — ‘…and the moon that was like blood..’; ‘And the moon, which was like blood, did not shine all night long though it was at the full, ‘; ‘…and the moon lost its brightness as though tinged with blood ‘; ‘ and the moon, as if turned into blood ‘; → The Reports of Pilate, Anaphora Pilati”.
I also googled - Reports of Pilate Anaphora Pilati - and got this link:
The Reports of Pilate, Anaphora Pilati.
Then I found this link:
…which on a Google search comes up with:
by AC Baudoin - 2016
22 May 2017 - Rome: the Anaphora Pilati, or “The Report of Pilate.” I shall first briefly intro duce this text and then focus on the paragraph that opens it in some manuscripts, prior to the first person narration. In a second part of the paper, I shall bring to. —————. 1 Baudoin 2012. 2 The creation of a German word reflects ...
This article from one of the young earth creationist groups throws some doubt on whether the lunar eclipse of 3 April 33 AD produced the ‘blood moon’ effects but suggests another possible cause. It is worth a read:
Finally on the subject of Christ having attended four Passovers, not three, I first of all offer the book: Baker’s Harmony of the Gospels (King James Version), ed. Benjamin Davies (1994) which I have on my shelves.
The main reference for the First Passover is John 2 vv 12-17.
The main references for the Second Passover are: Luke 6, John 5 vv 1-47 and Matthew 12 v 6.
The main reference for the Third Passover is John 6 vv 1-6.
The fourth Passover was attended on the night before Christ was crucified.
An identical reasoning is found in this 17-page pdf. to which I cannot link directly:
[PDF]the four passovers of jesus christ's ministry - A Voice in the Wilderness ...
THE FOUR PASSOVERS OF JESUS CHRIST'S MINISTRY. Thomas C. Trinka. 3-22-2014. During our preparation for the Passover each year, we tend to focus our attention on the last. Passover of Jesus Christ's ministry, and the events surrounding it. And rightly so. We should be ever mindful that our Lord and Savior ...
A similar scheme is to be found at:
...but he does not accept 33 AD as the year of the crucifixion ]
ORIGINAL POST FOLLOWS
My answer is that Luke is dating Tiberius' reign from when it started, viz. 28 September AD 14 (about a month after Augustus died). Here are my reasons.
This is one of the few dates in this period set in concrete. It is a fixed reference point around which other calculations or educated guesses may be made.
I noticed above that one poster referred to the date of Christ's crucifixion as 30 AD. That reckoning seems to be based on the outdated notion that the 'eclipse of Herod', if I can put it like that, occurred in 4 BC. Many recent articles suggest for very good reasons that the eclipse that Josephus was referring to was the prominent one that occurred on 29 December 1 BC. This in turn leads to the conclusion that Christ was born that year.
Most scholars who have thoroughly examined the accounts of Matthew and Luke consider that Christ was probably born around the Feast of Tabernacles ("He tabernacled amongst us"). We have the data about the time when it was Zechariah’s lot to burn incense in the temple (Luke 1 v 8), and we have other data in the early chapters of Luke and Matthew. The Feast if Tabernacles would fall in our September or October.
That being so, we also know that Christ did not enter His ministry until he was 'about 30 years of age', in order to fulfill the priestly requirements of Numbers relating to the age at which one could become a priest (Numbers 4 vv 3 and 23). So that places the beginning of His ministry in the autumn of 29 AD.
Now, setting aside for a moment all the discussion about the ways the Jews and the Romans reckoned years of reign, and when any 'co-regency' might have begun, the natural meaning of 'In the fifteenth year of Tiberius' brings us to the year beginning 28 September AD 28 (14 years after the beginning of Tiberius' reign) to 28 September AD 29 (15 years after). This would be wholly consistent with John the Baptist having commenced his ministry during this period, and Christ having commenced His ministry in the autumn of AD 29.
Above there is some debate about whether Christ attended three or four Passovers. All the reliable books I have seen document FOUR Passovers, the last one being the crucifixion Passover.
The date for Christ’s birth of autumn 1 BC then gives us a period of 33½ years until His crucifixion on a commonly accepted date: 3 April 33 AD. This was also the 14th day in the first month of the Jewish year, Nisan, thus precisely fulfilling the Passover day of the killing of the spotless lamb (Exodus 12 vv 6-7). Christ had entered Jerusalem on a donkey four days earlier, the 10th of Nisan, thus fulfilling Exodus 12 vv 1-5.
Worthy of additional note is Pontius Pilate’s letter to Tiberius, in which he described the night before Christ’s crucifixion in these terms: “The moon was like blood…it did not shine all night long though it was at the full…the moon lost its brightness as though tinged with blood”. Remarkable confirmation of this can be seen today on NASA’s website, which lists all historical lunar eclipses. There is one that began at 33 minutes past midnight on 3 April AD 33 and lasted for 2 hours 50 minutes.
I apologise for the lack of specific references in my post. I am new here (just joined) and will try to do much better in future.