ComfortMyPeople

I recall the first time I read that in the Kingdom Come book. My first thought was to say to myself, everything said in that statement could be equally applied to our own chronology, its source material and interpretations. That was only my first thought!

For purposes of this discussion I will go ahead and learn something about Egyptian chronology. My goal was to focus on what the evidence shows for Neo-Babylonian chronology. 
My experience has been that there is one question that most of us are deathly afraid to answer as Witnesses, the same question I put to @scholar JW:
What BCE date does the astronomical evidence point to for the 14th year of Nebuchadnezzar?
[You can pick any particular year you like in his reign]
If you are like almost all other Witnesses in my personal experience, most will say they don't know. But for those who have some idea what the actual answer will be, they will invariably start obfuscating and talking about tiny disagreements among scholars, or Delta-T, or claim that only dates after Cyrus accession are accurate, or start talking about some other chronology issues, or put the onus back on me to solve some unrelated issues that they pretend are related. It's an amazing experiment, I've seen played out here a dozen times. 
I think that anyone here can easily learn how to use the astronomy software and use it to check eclipses and other solar and planetary phenomenon back to yesterday, to last year, and then scroll back through the last century, and the last millennium -- or use it to discover the next eclipse or the next planetary configurations. (I have a nice telescope and I also use the same software to set up viewings of planets up to a year in advance.)
In spite of the ease of use, try to get another Witness to check out a reading from Nebuchadnezzar's time, and let the deflections and diversions and excuses begin. 

This is another form of poisoning the well. The Watchtower relies on the world of archaeology to get the dates for Cyrus from flawed material. But the "ten-times-better" archaeological material is dismissed. The Watchtower does nothing but try to sow seed of doubt about the "ten-times-better" material. Note:
*** kc p. 187 Appendix to Chapter 14 ***
From a secular viewpoint, such lines of evidence might seem to establish the Neo-Babylonian chronology with Nebuchadnezzar’s 18th year (and the destruction of Jerusalem) in 587/6 B.C.E. However, no historian can deny the possibility that the present picture of Babylonian history might be misleading or in error. It is known, for example, that ancient priests and kings sometimes altered records for their own purposes. Or, even if the discovered evidence is accurate, it might be misinterpreted by modern scholars or be incomplete so that yet undiscovered material could drastically alter the chronology of the period.
Back in the 1870's when Barbour and Russell considered Ptolemy to be the only source of Cyrus 1st year as 586 BCE [sic], they praised Ptolemy as the astronomer with whom ALL reputable scholars agreed with. After it was discovered that it was the same data from Ptolemy that demolished 606 BCE, the WTS has done nothing but try to sow seeds of doubt about him. 
*** g72 5/8 p. 28 When Did Babylon Desolate Jerusalem? ***
As Ptolemy used the reigns of ancient kings (as he understood them) simply as a framework in which to place astronomical data, . . . Hence both Ptolemy’s Canon and “VAT 4956” might even have been derived from the same basic source. They could share mutual errors.
 
*** w77 12/15 p. 747 Insight on the News ***
How certain can we be of the presently accepted chronology of the ancient Babylonian Empire? For many years, chronologists have put heavy reliance on the king list of Claudius Ptolemy, a second-century Greek scholar often considered the greatest astronomer of antiquity.
However, in his new book “The Crime of Claudius Ptolemy,” the noted physicist Robert R. Newton of Johns Hopkins University offers proof that many of Ptolemy’s astronomical observations were “deliberately fabricated” to agree with his preconceived theories “so that he could claim that the observations prove the validity of his theories.”
In its comments on Newton’s book, “Scientific American” magazine notes: “Ptolemy’s forgery may have extended to inventing the length of reigns of Babylonian kings. Since much modern reconstruction of Babylonian chronology has been based on a list of kings that Ptolemy used to pinpoint the dates of alleged Babylonian observations, according to Newton ‘all relevant chronology must now be reviewed and all dependence upon Ptolemy’s [king] list must be removed.’”—October 1977, p. 80.
 
Not only have the accusations been thoroughly debunked, the WTS publications have been so anxious to present information that sows seeds of doubt, that they have been caught quoting authors and experts out of context to make it seem they were saying something that the author didn't say. One example is one that you allude to when you speak of the old Assyrian mythological king list where kings reigned for thousands of years instead of reasonable lengths of time. Quotations from books referring to those pseudo-chronologies have been used (even in the 1981 "kc" Appendix I quoted above) to make it look like they referred to the Neo-Babylonian chronology. Sometimes the "trick" has been to speak of ancient pre-astronomy Babylonian chronology (Nimrod/Hammurabi/etc) and make it seem like Neo-Babylonian chronology is being referred to. If this was done on purpose I guess that would be an example of what you called "deviant scholarship." At least I think you would have called it that if I had used such a "trick."
 

@Arauna, just to respond more comprehensively.
It is not "scholarly deviancy" to claim that the WTS only relies on Babylonian sources. The WTS rejects the accuracy of the later Greek sources as shown in the comments about those sources in "Insight." The WTS rejects the accuracy of Olympiad dates that later Greek sources began tying events to.  And Insight admits very explicitly that it was ONLY Babylonian sources which gives them the date 530 BCE. And the date 530 is for the beginning of Cambyses reign (not the death of Cyrus)  The 530 date itself is not attested in the evidence, only the date, 523 and 522 which are said to be in the 7th year of Cambyses, so it's a matter of counting back from 523. If the WTS is only using the source they claim to be using, then it is only an assumption that Cyrus also ended his reign in 530. That assumption is based on the business tablets, and the fact that there have only been tablets discovered for years 0 through 9 of Cyrus. The WTS rejects that these same business tablets tell us about the rest of the Neo-Babylonian chronology. The WTS indicates that evidence may someday be found that would adjust the chronology in favor of the WTS, so the mere fact that the last discovered tablets in Cyrus reign are for his 9th year is not very meaningful if a 10th or 11th year might show up in the future.   The WTS explains in the Insight's Chronology article why those Greek sources are not irrefutable. Those Greek sources might also assume (correctly) that Cyrus died in his 9th year, but they do NOT tell us that year was 530 BCE.  Therefore, the "impression given above" was actually correct, and not a "deviancy."  The tablet the WTS uses is actually a tablet of inferior quality, a much later copy of a copy, with multiple corrections, and places where the copyist admits he had to try to fill in gaps because it was damaged and needed to be restored.
So, if the relatively poor and indirect evidence pointing to 530 BCE is absolute, then it is most definitely NOT the only date that is secularly absolute. ALL of the dates of the Neo-Babylonian period can be discovered in exactly the same way, including the date for Nineveh's fall in 612 BCE, the Battle of Carchemish in 605 BCE, Nebuchadnezzar's 18th regnal year in 587 BCE, and Cyrus' accession year in 539 BCE. But there are something on the order of 40,000* of these business tablets dated to Nebuchadnezzar's reign. 
The reign of Nebuchadnezzar is attested not only with about 40,000 tablets, averaging about 1,000 for every year, but several of the years of his reign are attested in the exact same manner astronomically as the 7th year of Cambyses, as explained in the Insight book. And although several of these are also through eclipses, there are also several more important planetary observations which Rolf Furuli himself admits (in his book) can ONLY be associated with a year of his reign that places his 18th year in 587 BCE.
*I got the 40,000 number when I attended a seminar when I visited the British Museum in 2018 and met a man named Dr. Gareth Brereton who works there as a curator of Assyrian and Babylonian artefacts. He was in charge of a lecture on Assyria and Ashurbanipal at the time. I was also able to contact him one additional time in 2020 for some related follow-up questions. 
If you are right, that 530 is an absolute date, then ALL of Nebuchadnezzar's years are at least ten-times-better absolute dates. 

Sometimes, just for fun, I sometimes try to predict the responses of the more easily predictable participants, and put it in white on white text to show my oldest son what I was guessing. You can just take your mouse and highlight the blank text after the last sentence. In this case, you had two responses. I missed the first one about needing to supply an event, but I hit the second one right on target. In case your mouse highlight thing doesn't work I'll show you what I had typed:

In this case, of course, m.o. means modus operandi. I just meant that the usual thing to do instead of answering a question is to try to "poison the well" of astronomical evidence by associating it with an apostate. In this case, an apostate who was disfellowshipped specifically for sharing his research with other Witnesses instead of keeping it to himself as he was told to do.
For the record, of course, no one has to produce a specific event to attach a BCE year to a specific year of a king's reign. If you know someone reigned for 43 years and you know the BCE date for year 7 is, then you know also know year 17, and 18, and 19, and 20. He could have been asleep the entire year, or insane and eating grass the entire year, or conquering Tyre for all we know. If you know that I'm 66, and you don't know any specific event in my life during 1968, it doesn't mean I didn't exist in 1968.
Still, I can always change the question but I think you will either say you don't know or you will be otherwise just as evasive as you were with this last one: 
What year does the astronomical evidence point to for Nebuchadnezzar's 17th year? (Or, you can use his 16th or his 14th or his 25th, 26th, 27th or 28th or 32nd, or his 42nd year.) Nothing this time, sorry.

It's almost like I paid you to say that. But I know you say that as your opening "salvo" in every single discussion of NB chronology I have ever seen you join. What's funny though is that I just said the following in the Nineveh thread:
And, of course, you did exactly that. In fact, this thread is not focused at all on when Jerusalem was destroyed. The focus is on whether anyone can attach a BCE date to the years of Nebuchadnezzar's reign, and thus to any and all of the reigns of every Neo-Babylonian king. 
I keep finding that the question most Witnesses are afraid to answer and terrified to research is the question: What year does the astronomical evidence point to for Nebuchadnezzar's 18th year?
Once that question is asked the evasion becomes too obvious. Usual m.o.: poison well with COJ

Wow!! Aruana. Great to hear from you again. How are you doing in your new place?
The Watchtower publications show that what you are saying is incorrect. Here's the ACTUAL way that the Insight book admits the date is determined.
First of all, we should notice that there is a dependence on clay tablets, astronomical tablets, king lists matching the one Ptolemy used, and the fact that these were indeed Babylonian sources. Cyrus moved his capital to Babylon where the same scholars and astronomers/astrologers continued to work. Note that "Insight" below even refers to it as evidence from Babylon. In fact, many clay tablets under Cyrus continue to refer to events and people that were there in Babylon going back continuously through the Neo-Babylonian kings as if nothing changed - business as usual.
*** it-1 p. 453 Chronology ***
A Babylonian clay tablet is helpful for connecting Babylonian chronology with Biblical chronology. This tablet contains the following astronomical information for the seventh year of Cambyses II son of Cyrus II: “Year 7, Tammuz, night of the 14th, 1 2⁄3 double hours [three hours and twenty minutes] after night came, a lunar eclipse; visible in its full course; it reached over the northern half disc [of the moon]. Tebet, night of the 14th, two and a half double hours [five hours] at night before morning [in the latter part of the night], the disc of the moon was eclipsed; the whole course visible; over the southern and northern part the eclipse reached.” (Inschriften von Cambyses, König von Babylon, by J. N. Strassmaier, Leipzig, 1890, No. 400, lines 45-48; Sternkunde und Sterndienst in Babel, by F. X. Kugler, Münster, 1907, Vol. I, pp. 70, 71) These two lunar eclipses can evidently be identified with the lunar eclipses that were visible at Babylon on July 16, 523 B.C.E., and on January 10, 522 B.C.E. (Oppolzer’s Canon of Eclipses, translated by O. Gingerich, 1962, p. 335) Thus, this tablet points to the spring of 523 B.C.E. as the beginning of the seventh year of Cambyses II.
Since the seventh year of Cambyses II began in spring of 523 B.C.E., his first year of rule was 529 B.C.E. and his accession year, and the last year of Cyrus II as king of Babylon, was 530 B.C.E. The latest tablet dated in the reign of Cyrus II is from the 5th month, 23rd day of his 9th year. (Babylonian Chronology, 626 B.C.–A.D. 75, by R. Parker and W. Dubberstein, 1971, p. 14) As the ninth year of Cyrus II as king of Babylon was 530 B.C.E., his first year according to that reckoning was 538 B.C.E. and his accession year was 539 B.C.E.
 
What is not mentioned here is how the WTS has determined that Cyrus' son, Cambyses began reigning immediately upon the death of Cyrus. How do we know there was not one or more kings between them, older brothers who were first in line, usurpers, a sickness that delayed Cambyses reign, overlapping regnal years, etc. It's because they also rely on the equivalent of a "King List" to tell them that Cambyses immediately followed Cyrus. That King List is the equivalent of what Ptolemy used, often called Ptolemy's Canon. Note the quote from Parker and Dubberstein 1971. Parker and Dubberstein were able to find complete support for Ptolemy's Canon, not just for every single year but even more accurately to the month and sometimes the day when one king transferred rulership to the next. They were able to validate "Ptolemy's Canon" going back to Nebuchadnezzar and even before to Nabopolassar and even before that. And they had enough tablets to even determine the methods used for adding the "leap" months to the calendar, to get a much more accurate picture of the Babylonian calendar. 
One might try to claim that because a few centuries later (in the 200's BCE) the Greeks began tying some of these older historical dates to a longer Olympiad period. This is true, but there is ZERO evidence that Olympiad dating was used until SEVERAL HUNDRED YEARS after Cyrus. Besides, the Watchtower publications REJECT the Olympiad dating as inaccurate even for Artaxerxes, who is even more recent than Cyrus in the Persian period. 
It should be clear that none of this evidence helps the WTS calculate 607. Claiming to rely on later Greek historians like Herodotus or Xenophon or others is also problematic. What they got, they copied from Babylonian and Persian sources. Note what the Insight book says:
*** it-1 p. 457 Chronology ***
Included among ancient Greek historians are: Herodotus (c. 484-425 B.C.E.); Thucydides (c. 471-401 B.C.E.); Xenophon (c. 431-352 B.C.E.); Ctesias (fifth-fourth century B.C.E.);  . . . *** it-1 p. 457 Chronology ***
All of these lived after the Assyrian and Neo-Babylonian period and only the first four mentioned lived during the period of the Persian Empire. For the Assyrian and Neo-Babylonian periods, then, none of these writers present information based on personal knowledge, but they record, rather, the traditional views they heard or, in some cases, may have read and copied. The accuracy of their data obviously depends on the accuracy of the sources used.
Not only this, but what we know of their writings is today dependent upon copies of copies, the oldest copy often dating no farther back than the medieval period of the Common Era. We have already seen how the chronologies of Manetho and Berossus were mutilated by copyists. As to the qualifications and reliability of the other ancient historians of the classical period, the following is noteworthy: . . 
Herodotus’ approach to history—asking a question, looking for relevant information, and then drawing a conclusion—is spoken of highly. But it is also said that at times “his data were unsatisfactory” and that “he offers a rational explanation side by side with the irrational.” It has also been said that he belongs “distinctly to the romantic school” and so was as much a storyteller as a historian. (The New Encyclopædia Britannica, 1985 edition, Vol. 5, pp. 881, 882; 1910 edition, Vol. XIII, p. 383) As to Xenophon, it is said that “objectivity, thoroughness, and research were not for him” and that he adorned his narratives with “fictitious speeches.” (The New Encyclopædia Britannica, 1987, Vol. 12, p. 796) George Rawlinson accuses Ctesias of deliberately extending the period of the Median monarchy “by the conscious use of a system of duplication.” He further states: “Each king, or period, in Herodotus occurs in the list of Ctesias twice—a transparent device, clumsily cloaked by the cheap expedient of a liberal invention of names.”—The Seven Great Monarchies of the Ancient Eastern World, 1885, Vol. II, p. 85.
Concerning Roman history of the kingly period (preceding the establishment of the Republic), we read that it “stretches back into the regions of pure mythology. It is little more than a collection of fables told with scarcely any attempt at criticism, and with no more regard to chronological sequence than was necessary to make the tale run smoothly or to fill up such gaps . . . 

As you probably already know, the WTS publications are correct when they state:
*** kc p. 187 Appendix to Chapter 14 ***
Business tablets: Thousands of contemporary Neo-Babylonian cuneiform tablets have been found that record simple business transactions, stating the year of the Babylonian king when the transaction occurred. Tablets of this sort have been found for all the years of reign for the known Neo-Babylonian kings in the accepted chronology of the period.
Literate Babylonians from various cities all over the empire could write "17th year of Nabopolassar" [with the month and day] or "18th year of Nebuchadnezzar" [with the month and day] just as readily as we would write 2/25/2024. And there is apparently an average of about 1,000 of these contracts per year covering EVERY year of EVERY Neo-Babylonidan king.
This means that if you could just put them in the right order, you would have the entire string of dates covered from Nabopolassar, to Nebuchadnezzar, to Amel-Marduk, to Neriglissar, to Labashi-Marduk, to Nabonidus, to Cyrus, to Cambyses, etc.
At that point you would only need to identify the BCE year for any ONE of those years and you would know the entire Neo-Babylonian chronology of every king. Evidence for any one year, serves as evidence for every other year. All of them interlock with no exceptions and no contradictions.
In other words, if you had evidence somehow that the first year of Cyrus was 538 BCE, that would also serve as evidence that the 14th year of Nabopolassar was 612 BCE. If you had evidence that the last year of Nabopolassar was 604, that would serve as the same evidence that Nebuchadnezzar's accession year was 605, and his first year was 604, and his 18th was 587 and his 43rd was 562. 
This is why a discussion of the actual 'solid' evidence for the Neo-Babylonian chronology is the best foundation for discovering the date of Nineveh's destruction, or the fall of Jerusalem, or the fall of Babylon, or the start of Evil-Merodach's reign.
I think you can tell, @xero, that a discussion that focuses on just the secular evidence would be useful to more easily reach exactly the same goal. And that goal could not only be more easily reached, but also more easily verified and double-checked and triple-checked, and quadruple-checked from various independent sources. 
I say this because there is no astronomical event recorded for the 14th year of Nabopolassar which is the evidenced date for the Fall of Nineveh.
But there is an astronomical event dated to the accession year of Nabopolassar in 626 BCE. That fact alone can tell us that Nineveh fell in 612 BCE. There is a separate astronomical event dated to the 18th year of Nabopolassar in 616. That fact alone can tell us that Nineveh fell in 612 BCE. And putting those two independent pieces of evidence together we have double-checked the date. But when the entire string of Neo-Babylonian kings is put in the right order, we also have astronomical observations reported for Neb 14 = 591, Neb 16 = 589, Neb 18 = 587, Neb 25 = 580, Neb 26 = 579, Neb 27 =578, Neb 28 = 577, etc. Each one of those pieces of evidence is ALSO therefore evidence that Nabopolassar 14 = 612, so that even an observation under Nebuchadnezzar becomes evidence that Nineveh fell in 612 BCE.  Of course, this also means that, when you put the entire string of Neo-Babylonian kings in order, any evidence that 539 is the correct date for Cyrus conquering Babylon is the same evidence that Nebuchadnezzar's 18th is 587. There is no such thing as choosing one without the other, UNLESS you are willing to discard the evidence from literally THOUSANDS of business documents, and also discard the double-checked, triple-checked, . . . octuple-checked astronomical data. And it would be highly hypocritical, because whatever reason you tried to give for discarding THOUSANDS of piecies of excellent evidence would apply moreso against the much weaker and less attested evidence for Cyrus in 539.
The reason for moving that kind of a discussion to another thread is because there will invariably be someone who is so fearful of the actual evidence that they will quickly say that first you have to prove exactly when the 70 years started and ended. Or, first you have to tell me why secular scholars haven't decided on whether it was Nebuchadnezzar's 18th or 19th year when Jerusalem was destroyed. Or, first you have to prove that Russell was really wrong in promoting Zionism. Those types of new goal posts and moving of goal posts can be distracting to someone who is more interested in the strength of the evidence for attaching BCE dates to the Neo-Babylonian chronology. 

The Bible mentions the specific reigns of certain foreign kings during the Judean Babylonian exile, and the post-exilic period. It mentions Nebuchadnezzar, Amel-Marduk, Belshazzar, Cyrus, etc. Mostly it mentions Nebuchadnezzar: his 1st year, his 2nd, his 7th, his 18th, his 19th, his 23rd, and the Bible also gives an indication that it must have been around his 43rd year when Amel-Marduk (Evil-Merodach) began to reign right after him. No other foreign king is mentioned in the Bible as much as Nebuchadnezzar.
So let's say we want to start putting actual BCE dates on the Neo-Babylonian kings. It looks like Nebuchadnezzar is a good place to start. To save space I will abbreviate his name as NEB and abbreviate his years of reign as NEB18 for his 18th year of reign, NEB7 for his 7th, etc. Other kings of the period will also be abbreviated like E-M for Evil-Merodach, NER for Neriglissar, NAB for Nabonidus, CYR for Cyrus etc.

And, as discussed previously about Gerard Gertoux on the forum, the above link you provided gets into some of those exact details that show how the Neo-Babylonian chronology is "set in stone:"
In your link, Gertoux states:
The fall of the Assyrian empire, which took place in October 609 BCE after the battle of Harran, is characterized by a quadruple synchronisms, since the year of Assur-uballit II corresponds to year 17 of Nabopolassar to Josiah's year 31 and year 1 of Necho II.
According to the biography of Adad-Guppi12, mother of Nabonidus, Nabopolassar reigned 21 years, then Nebuchadnezzar 43 years, Amel-Marduk 2 years, Neriglissar 4 years just before Nabonidus. According to the Hillah's stele there were 54 years between the destruction of the temple of Sin, in Harran, and the beginning of the reign of Nabonidus. According to a Babylonian chronicle (BM 21901) and Adad-Guppi's stele, the temple of Harran was destroyed in the year 16 of Nabopolassar.
Dated lunar eclipses are: year 1 and 2 of Merodachbaladan (March 19/20 721 BCE, March 8/9 and September 1/2 720 BCE); year 5 of Nabopolassar (April 21/22 621 BCE); year 2 of !ama#-#uma-ukîn (April 10/11 666 BCE); year 42 of Nebuchadnezzar (March 2/3 562 BCE). A diary (VAT 4956) contains numerous astronomical conjunctions in years 37 and 38 of Nebuchadnezzar dated from astronomy in 568 and 567 BCE. An astronomical journal (BM 38462)17 list some lunar eclipses in the years 1 to 27 of Nebuchadnezzar which are dated from 604 to 578 BCE.
I think it was pretty brave of Gerard Gertoux to stand up against the WTS tradition publicly and show just why the accepted, evidenced chronology is so difficult to change and try to discredit.

Excellent point made here in the link you provided:
"The durations of the Babylonian reigns, from Eriba-Marduk (770-761) to Nabonidus (556-539), are all known. The chronology of these Babylonian kings is anchored on the dates set by the astronomy of five precisely described lunar eclipses."
Sometimes when we read about Babylonian or Mesopotamian chronology being revised, we think of the Neo-Babylonian period which, unfortunately for the WTS tradition, has been "set in stone" and therefore can't really be revised. 

I would love to discuss the 70-year exile, too, and I'm as tempted to do so as anyone else. So I would also propose a separate thread for discussing the evidence for the years of the exile. But I think we would have a better foundation for any discussion of the BCE years attached to the exile, only after we discuss the basic evidence for the BCE years in the first place. 

There is NO Bible evidence for 539 BCE. There is NO Bible evidence for 587 BCE. There is NO Bible evidence for 607 BCE.
I think most of us understand that by now. So, I propose this new thread/topic where we shift the focus almost exclusively to the basic, fundamental question about the strength of the secular evidence in the Neo-Babylonian period. Why do we rely on it? Why does the WTS rely on secular Babylonian astronomer's evidence for Cyrus in 539? Why does the WTS reject the same evidence for Nebuchadnezzar's 18th year?  Is the evidence for Nebuchadnezzar's years actually 10 times better than for Cyrus?
When that question is solved, it also resolves the entire question about the 70 years, the WTS 20-year gap, the years of those kings that came just before and just after. And it will automatically link to the resolution of dates for events like the Fall of Nineveh, the Battle of Carchemish, the death of Josiah, the years of Zedekiah, the BCE dates for the three different exile events reported in Jeremiah 52. And, of course, it should answer the question about the complete lack of evidence for 607 as Nebuchadnezzar's 18th year.  
So in this new thread/topic there would need to be NO discussion of:
the 70 years of Jewish Exile, or the 70 years of Babylonian domination over other nations the purpose of the WTS 20-year gap 1914 Daniel 4, Gentile Times, the length of the 7 times/years, the length of the 2,520 days making up those 7 years Not even any discussion of Bible prophecies or "70-year" references in: Jeremiah, 2 Chronicles, Isaiah, Zechariah, Daniel.  Just the years of Nebuchadnezzar's reign, and the ACTUAL Neo-Babylonian evidence for it. Any discussion of other topics can be moved back to the topic where this came up and from where I just copied this post. ( https://www.theworldnewsmedia.org/topic/90904-trying-to-nail-down-612-bce-as-the-date-of-ninevehs-destruction/ )

Turns out that ALL the astronomical events recorded for the entire period agree perfectly well with the Biblical text. Remember that the Biblical text has no BCE dates. There is NO real contradiction between the astronomical events recorded and the Biblical text regarding the Babylonian period.
In fact, the WTS would do much better to follow the same pattern it does for all the other areas where secular history supports the Bible's own version of history. It could be used as evidence to show that there is additional external support for the Bible's accuracy that might have been overlooked.
It's true that there were naysayers about the existence of Belshazzar by Bible skeptics looking for excuses not to trust the Bible. Turns out there wasn't really that much evidence for outright denial, but a lot of skepticism based on other issues with Daniel. But the WTS is guilty of similar skepticism coming from another perspective -- and I don't just mean the admission that no one can identify this Darius the Mede, nor the fact that the WTS rejects the Bible's own chronology of Daniel 1:1 and 2:1. 
Here's an example for another time from "Insight." The Hebrew term transliterated "Ahasuerus" in the Bible is pretty much an expected transliteration for the Persian "Xerxes." (Which can also refer to Artaxerxes.) But notice how the WTS publications deny that the Bible's use of Xerxes/Artaxerxes (Ahasuerus) can refer to him in Ezra, but says it does refer to him in Esther:
*** it-2 p. 613 Persia, Persians ***
From Cyrus’ Death to Darius’ Death. The reign of Cyrus the Great ended in 530 B.C.E. when he died while on a warring campaign. His son Cambyses succeeded him to the throne and was successful in conquering Egypt. Though not referred to by the name Cambyses in the Bible, he is evidently the “Ahasuerus” to whom the opposers of the temple work sent false accusations against the Jews, as stated at Ezra 4:6.
*** it-2 p. 613 Persia, Persians ***
The Reigns of Xerxes and of Artaxerxes. Xerxes, Darius’ son, is evidently the king called Ahasuerus in the book of Esther.
As it turns out, there is really no good reason for the Watchtower to speculate that Ahasuerus/Xerxes is Cambyses in Ezra and Ahasuerus/Xerxes is Xerxes in Esther. The WTS could just as easily have made them both Xerxes and Ezra would actually be giving an even clearer timeline without the unnecessary speculation. I just include it to show how easily and sometimes nonchalantly the WTS will speculate about "outside" history that they believe is contradicted in the Bible. In this case the WTS creates a kind of Bible contradiction about who Ahasuerus was. 
If anyone wishes to discuss, and has the time, there are a few more of these types of WTS-created Bible contradictions, some which might come up anyway in a full discussion of the chronology of the period.

This might be true to a very small extent, but if true, it means that the WTS has no right to claim that 539 BCE was some kind of absolute, pivotal year. 539 is based wholly, 100% on these judgment calls and assumptions. Besides, the date of 587 BCE for the 18th year of Nebuchadnezzar is at least 10 times better documented than the 539 BCE date (for the accession year of Cyrus). 
There are some assumptions used, it's true. But these adjustments or "calibrations" to account for the slowing down of the earth have been known about for a long time. And if we were to use calculations from astronomy today and didn't know about the rate of slowing, we would only be off by about 6 hours going back more than 2700 years. 
That means that the eclipses recorded by Neo-Babylonian/Persian/Greek scholars would still have happened on the same day, but the background stars which were also reported in these records would have passed them up 6 hours earlier. The article you point to is admitting the same thing as this article:
https://www.science.org/content/article/ancient-eclipses-show-earth-s-rotation-slowing
Overall, Earth's spin has slowed by about 6 hours in the past 2740 years, 
 
----- and here comes the tldr; part to ignore ----------
Even without this data we already knew that the earth's day was getting longer just from satellite data from year to year. Even though the day lengthens by only microseconds at a time, it adds up to hundreds of seconds of difference when you go back several centuries. And when you go back 2,700 years (27 centuries) it's a difference that approaches 20,000 seconds (5.5 hours).
That means that when you look for an eclipse, even if you had a good record of the observation for 685 BCE, trying to calculate it without knowing about the earth's slower rotation, would be about 5.75 hours off from the time you expected. That doesn't seem like much time to be off, but it means that the eclipse will likely be seen on the correctly calculated day, but against a background of stars that are nearly half-way across the sky.
The Babylonian "scholars" recorded those stars in the background, so it makes the eclipse seem like it doesn't match any eclipses in the year given.  That is, until you notice that the same pattern holds for ALL the eclipses and that they make a much better fit for the observation when you realize the earth rotated just a wee bit faster back then.
But it's pretty consistent throughout this period:
Near 700 BCE observations hovered around 20,000 seconds off, or 5.5 hours Near 600 BCE observations hovered around 19,000 seconds off or 5.25 hours Near 500 BCE observations hovered around 18,000 seconds off, or 5 hours Near 400 BCE observations hovered around 17,000 seconds off, or 4.75 hours Near 300 BCE observations hovered around 16,000 seconds off, or 4.5 hours Although I'm rounding to the nearest thousand and relying on the article's regression-line analysis to "average" out the anomalies, you can easily see the pattern. And by the time you reach AD/CE readings you would expect closer to 3 hours off, and that's right where the readings end up.
But those lunar eclipse readings can be double-checked by the half-dozen solar readings during the period from 350 to 150 BCE and these line up even closer to the regression line, helping to confirm the same calculations of "delta-T" [change in time].
The point is that this slowdown of the earth's rotation is only a few hours, not days, but when these calibrations are added to the observations and predictions already observed and recorded in ancient Assyria/Babylon/Persia you can now set a specific formula to account for that curve (parabola). That formula is built into all the major astronomy applications which is why they all give the same results. And it turns out that when you do this, the calculations are further confirmed by making an excellent accounting not just of both the lunar and solar data, but also various planetary calculations that the Babylonians also recorded.

Referenced in Acts 1 (Pentecost 33 C.E.)  and in Luke 22 (the Last Supper)
I also appreciated his references to Eusebius etc....

I really like the fact that you are trying to work it out for yourself.
Because I was always so skeptical of the accepted, secular chronology I thought it was important to "start from scratch" and work the whole thing out for myself. 
I think most Witnesses don't realize that ANY time we see a B.C.E. date in the WTS publications, it means that we are relying on SECULAR chronology.
Personally, I'm convinced that the Bible is sufficient on its own to keep us fully equipped, therefore without any need to rely on secular chronology, so I give no special credence or reliance to any specific years with a BCE date attached to them. Doesn't mean they can't be helpful in trying to figure out the order of events, but even here, those secular dates aren't necessary in order to understand the Bible, and figure out the order of Biblical events. 
And from a purely Biblical perspective we aren't going to get any definite mentions of an eclipse or some other astronomical event that is tied to a specific month and day and year of a specific king. Therefore there can be no BCE dates calculated from the Bible. 
In my opinion, there are two main stumbling blocks that always hamper any chronology discussion, and they are related:
Witnesses are told that we are defending Biblical chronology based on a pivotal ('absolute') date of 539 BCE and the Biblical 70 years.  When arguing with Witnesses, Non-Witnesses don't (or won't) admit that the most logical and common-sense understanding of the 70 years favors the WTS viewpoint. 

Yes. I think that's correct. There are no RULES against engaging in fornication. That doesn't mean it's not sinful, just as murder and theft and creating divisions and contentions are sinful.
No. Paul explained quite the opposite. 
(Romans 2:12-15) . . .For all those who sinned without law will also perish without law; but all those who sinned under law will be judged by law. For the hearers of law are not the ones righteous before God, but the doers of law will be declared righteous.  For when people of the nations, who do not have law, do by nature the things of the law, these people, although not having law, are a law to themselves.  They are the very ones who demonstrate the matter of the law to be written in their hearts, . . .
But Christians still end up being "doers" of the law by fulfilling the law without written rules, i.e., the "royal law" of Christ. They have the law written in their hearts (their true motivations). 
(James 2:8) . . .If, now, you carry out the royal law according to the scripture, “You must love your neighbor as yourself,” you are doing quite well. 
 

By the way, we look at the decree in Acts 15 and say that because it was "guided by holy spirit" that it becomes some kind of "law" for Christians today. But don't we believe that Paul was also "guided by holy spirit" in writing Timothy?
Yet how many congregations make a list of widows 60 and over and base it on the requirements listed here?
(1 Timothy 5:9, 10) . . .A widow is to be put on the list if she is not less than 60 years old, was the wife of one husband,  having a reputation for fine works, if she raised children, if she practiced hospitality, if she washed the feet of holy ones, . . .
Was this one of those cases where you might think the Pauline decree to Timothy turned out not to be a wise thing to do?

Yes. Those principles do not become rules, however. When the Law is written on our hearts, we don't need rules of any kind.
The imposition of ANY rule is a kind of "judaizing."
There is no rule against fornication, there is no rule against eating blood. But we don't and won't do either, because we will continually want to know more about God and his love, and try to reflect it wherever possible. If we love God we would want to try to understand, as best as we are able, the Law to Noah and the Law to Moses. Even if we can't figure out all the details behind those laws, we will likely appear to be following rules to those on the outside, but our motivation will be a much higher motivation: love for God, his Son, and love for neighbor. Jesus spoke to actual Jews under Law and was already transitioning them toward this new teaching, showing them that you will never murder because you will work on removing hate, you will never commit adultery or steal because you will work on not even desiring what would take away from your neighbor/brother.  To someone on the outside you might seem like a much stricter rule-follower than they are, but you won't even be thinking about any rules.
However, you are right that a congregation is going to set rules that make sense to keeping order and making it possible for Christians to fellowship, and they are based on mutual agreement. These are mundane things, however, and have nothing to do with the New Covenant or salvation. A congregation can decide through mutual agreement to have a gathering on Sunday at 10am, or Wednesday at 8pm, or Saturday at midnight. Older men and overseers can help preside over such decisions, wisely, and their love and respect for the flock will help them avoid the decision to meet at midnight on Saturday. It would be a hardship on the congregation, and they would waste their hard work preparing to teach when there will be no one to hear. But those "rules" might even claim to be based on Mosaic principles, as we used to emphasize for our 3 conventions a year. They are still mundane, like the "widows on the list who are least 60 years old" in 1 Timothy. 
It's hard for me to imagine it that way. Efficiency is not any part of the purpose of the New Covenant. During a time of transition the Old Covenant served as a model, precedent, and teacher -- but it doesn't make those things a part of the New Covenant. Notice:
(Galatians 3:23-25) . . .However, before the faith arrived, we were being guarded under law, being handed over into custody, looking to the faith that was about to be revealed.  So the Law became our guardian leading to Christ, so that we might be declared righteous through faith.  But now that the faith has arrived, we are no longer under a guardian.

Thanks @scholar JW for a succinct and clear summary of your position on the 20-year gap (several pages back).
MY SUMMARY below adds 4 or 5 items that I didn't spell out in posts yet, but the rest are a subset of the points from posts already in this thread.
The Watchtower publications depend on SECULAR chronology to be able to attach a BCE date to any Bible event. There are no BCE or CE (AD) dates in the Bible anywhere. Per the current Watchtower Library going back to 1950 for the Watchtower and the 1970's for other publications: there are 11,857 separate references to BCE dates in the current "Watchtower Library" and the MAJORITY of them are for the three dates: 539, 537 and 607.  Every time we ever read in a WTS publication the term "B.C.E." it means the WTS has depended on SECULAR chronology.
The WTS fully accepts the SECULAR chronology indicating Cyrus conquered Babylon in 539 BCE. The exact same SECULAR chronology indicates that the 18th year of Nebuchadnezzar was 586 BCE. The exact same SECULAR Chronology indicates that the 19th year of Nebuchadnezzar was 587 BCE. The Bible associates Jerusalem's destruction with the 18th year of Nebuchadnezzar The Bible also associates Jerusalem's destruction with the 19th year of Nebuchadnezzar The Bible associates both years with this event, so SECULAR scholars must choose between 587 and 586 The Bible's ambiguity here is "cleverly" reassigned from the Bible to SECULAR scholars so that it can repeatedly be used as a means to discredit scholars -- so that both dates can be dismissed Discrediting scholars feeds into the repeated idea that 539 is now part of Bible chronology but 587/586 is only SECULAR chronology This allows the WTS to keep the original theory promoted by Barbour and Russell that all one has to do is go back 70 years from 536 (now 539*/538/537) to get the destruction of Jerusalem in 606 (now 607) and both of these dates can be promoted as BIBLE chronology. Any attempt to show the fallacy of the argument, or the evidence against the interpretation, can now be associated with choosing SECULAR experts over the BIBLE, and not recognizing that the SECULAR "wisdom of the world is foolishness with God" This tradition/theory/interpretation that we now call "BIBLE chronology" now requires that ALL the evidence for the SECULAR chronology that we accept for 539 must otherwise be rejected in order to support 607. Therefore the WTS must add 20 years to ALL the chronology evidence BEFORE 539 and not touch any dates from the same evidence AFTER 539. Unfortunately for the WTS theory, the Bible locks in the length of the reigns of Nebuchadnezzar to 43 years, and in support of external evidence for 539, the WTS is partially reliant on SECULAR inscriptions referring to the length of the reign of the last king conquered by Cyrus in 539 (the 17 years of Nabonidus) That would mean that the 20-year gap must be theorized to fit within a period known to be only 6 years long according to ALL the existing chronological evidence of the period (from the exact same set of evidence accepted for 539) The need to turn that 6-year period into a 24-year period becomes an awkward quest because of the inscriptions, kings lists, and astronomy tablets that give consistent evidence that there is not even a one-year gap anywhere in the period. NOT PRESENTED YET: The evidence from the TENS of THOUSANDS of mundane business documents is just as damaging to the WTS theory. These small clay tablets are spread throughout EACH and EVERY year of the entire documented period from Nebuchadnezzar's father, Nebuchadnezzar, Evil-Merodach, Nabonidus, Cyrus, etc. They even exist for EACH and EVERY year for the short reign of the two kings in those 6 years where the WTS needs to place the 20-year gap. NOT PRESENTED YET: There are business tablets for EVERY year of the known reigns of EACH king, and sometimes thousands of tablets for some of those years, but still absolutely NONE to show evidence for any of the theorized gap of 20 years. (Out of say 50,000 existing tablets, we should therefore expect about 20,000 additional tablets to cover those years, yet not one of those "20,000" missing tablets has shown up. (The WTS has proposed that evidence may exist but has just not been discovered yet.) Therefore, while 100% of the tablet evidence supports the known chronology, there is still ZERO tablet evidence for any possible longer reigns or additional reigns for anyone during the period. Worse yet for the WTS theory, there are even connecting tablets that give us the transition between each king and the next king which makes the gap theory impossible, according to all the evidence. NOT PRESENTED YET: There is even a subset of these business documents all related to the same "banking institution" that provides a separate chronology of transitioning "bank presidents" throughout the same entire period. They provide the exact same connected, relative chronology as the Babylonian king lists, the astronomy tablets, the official Babylonian chronicles, and other inscriptions. NOT PRESENTED YET: The WTS admits that the Babylonians were able to predict eclipses based on various nearly-18-year lunar cycles. If they weren't using an extremely accurate calendar they couldn't have done this. Any currently undocumented gap in the chronology would have completely thrown off their ability to predict eclipses. To add "support" for the 20-year gap theory, the WTS quotes from experts about evidence from astronomy and inscriptions and often adds (with no explanation) the WTS chronology in parentheses or brackets in very close context to the quotations from experts and scholarly references and encyclopedias. Sometimes even adding the bracketed WTS chronology within the quotation marks from the expert sources, giving the impression that there is expert scholarly support for WTS chronology. To add further "support" for the 20-year gap, the ACTUAL evidence that has been consistently supported and presented for the last 150 plus years by HUNDREDS of other scholars, is often simply called to "Carl Olof Jonsson's evidence" or "COJ's evidence." Because COJ was disfellowshipped for presenting the evidence already supported by hundreds of others, it "cleverly" leads the average JW to believe that SECULAR evidence is apostate evidence. (Except when the WTS uses the same set of evidence for 539.)  To add further "support" for the 20-year gap theory, the WTS made use of Rolf Furuli's book in two articles in the Watchtower in 2011  (*** w11 11/1 p. 25) claiming that some of the lunar data on a tablet dated to a specific year of Nebuchadnezzar's reign is a better fit for a different year of his reign, 20 years earlier. (Same idea had been tried for a different reign in a 1969 Watchtower, *** w69 3/15 pp. 185-186) Furuli's ideas about this tablet and the WTS focus on it has tended to imply to that this tablet (VAT 4956) is somehow all-important to the secular chronology. But it is only one piece of many that consistently point EXACTLY to the 587 date for the 18th year of Nebuchadnezzar and EXACTLY to the 586 date for the 19th year of Nebuchadnezzar. NOT PRESENTED YET: Furuli's ideas about the tablet have been thoroughly debunked and shown to contain numerous amateurish errors. Furthermore the book inadvertently contains evidence against itself which indicates the real strength of the evidence against the WTS use of "607." Russell did not directly use the 7 times of Daniel 4 to prove 606 (now 607) and indicated that methods using the 7 times (based more on Leviticus, not Daniel) were inferior methods to the use of "God's dates" (meaning counting forward 40 years from 1874). The use of (and definition of) what happened in 1914 changed after 1914, and the predicted fulfillments were moved to 1915, then 1918, then 1925. The Watchtower even temporarily used the expression "End of the Gentile Times in 1915." After the slippage and failures of expectations, the only useful prediction that remained was that the "Gentile Times Ended in 1914." But this was not about Jesus' invisible parousia (still 1874) or Jesus' invisible enthronement as King (still 1878) but was an expression directly related to the visible Zionist movement in Palestine. After an adjusted emphasis on Zionism AFTER 1914, along with a new emphasis on on Jesus' coming/arriving/returning to his temple for judgment in 1918, Rutherford finally dropped the Zionist connection to the "End of the Gentile Times" around 1929, and 1874/1878 was also soon dropped so that both the parousia and the kingship both were now associated with 1914. And the Gentile nations merely lost their "lease" to rule, even though they were now ruling more powerfully than ever.

The point of the thread is the self-imposed 20-year gap in the Watchtower's chronology schema. This discussion about 1914 is definitely related even if it looks out of place. I think it's good to see just how far one needs to stretch things to make it look like SOMETHING happened in 1914 that might be visible to the world AND that supposedly gives the WTS bragging rights for having predicted it in advance. 
The only thing we have left of all the predictions that Russell made is not about the War, but simply the expression he used: that it would be "The End of the Gentile Times." To Russell that meant what it said: the complete and final end of the national (gentile) governments. Originally that they would be brought to nothing, and no nations or governments would exist after October 1914 because the ONLY legitimate government on earth after 1914 would be a Jewish government out of Palestine. The timeframe kept slipping and the WTS gave up on that idea completely around 1929/30. 
Now the entire expression "End of the Gentile Times" has drifted so far away from its original meaning that it has nothing to do with Gentiles vs Jews at all. And the Gentiles don't stop ruling after all. There are more Gentile nations now than ever! And they are more powerful now than ever! And the "Jews" are now identified spiritually as the remnant of spiritual Israel, and yet they somehow get trampled and made captives after 1914 (especially 1918-1919). Some are even killed and put in prison, especially in the 1940's.
So all that's left of that expression now is empty: the nations still rule even though their "time" has ended, but they have lost their "lease" to rule, but they aren't even aware of that. 

Just to be clear then. I absolutely do NOT liken the conflict between Arabs and Jews to currently applicable Biblical prophecy. Jesus said "nation would fight against nation" but the end is not yet. In other words not even world wars were a sign of the end. All nations fighting other nations is just another sign that we are living in a world that cannot govern itself and needs Jehovah's Kingdom as the ONLY permanent solution. Conflicts between nations provide an opportunity for Christians to prove their neutrality and to prove that they do not sacrifice lives to the god of this world by supporting wars and divisive politics. But there is no specific spiritual significance to conflicts between natural, physical Jews today and any other nations. Biblical lessons, yes, specific currently applicable prophecy, no, imo.
And I hope I never try.
Good question. He definitely examined Zionism, repeatedly.
You should read the following book if you haven't aleady:

As far as Russell's general involvement in politics, I agree it wasn't as steeped as Rutherford's, but it was there. Did you read C.T.Russell's open letter to President McKinley (and openly racist, too) about how Japan should get the Philippine Islands because Filipinos are basically lazy, and the Japanese are industrious?
Anyway, here's the Watchtower's answer to your question in the 1975 Yearbook. The last paragraph is also my position on the prophetic angle you mentioned.
*** yb75 pp. 53-54 Part 1—United States of America ***
Then, again, it might have been New York city’s noted Hippodrome Theatre, where Russell addressed a large Jewish audience on Sunday, October 9, 1910. Regarding that discourse, the New York American of October 10, 1910, said, in part: “The unusual spectacle of 4,000 Hebrews enthusiastically applauding a Gentile preacher, after having listened to a sermon he addressed to them concerning their own religion, was presented at the Hippodrome yesterday afternoon, where Pastor Russell, the famous head of the Brooklyn Tabernacle, conducted a most unusual service.” Scores of rabbis and teachers were present. “There were no preliminaries,” said the newspaper. “Pastor Russell, tall, erect and white-bearded, walked across the stage without introduction, raised his hand, and his double quartette from the Brooklyn Tabernacle sang the hymn, ‘Zion’s Glad Day.’” As reported, eventually the audience ‘warmed up’ to the speaker. Next there was applause, finally enthusiastic response. The discourse over, Russell signaled again and the choir “raised the quaint, foreign-sounding strains of the Zion hymn, ‘Our Hope,’ one of the masterpieces of the eccentric East Side poet Imber.” The effect? This, according to the press account: “The unprecedented incident of Christian voices singing the Jewish anthem came as a tremendous surprise. For a moment the Hebrew auditors could scarcely believe their ears. Then, making sure it was their own hymn, they first cheered and clapped with such ardor that the music was drowned out, and then, with the second verse, joined in by hundreds. At the height of the enthusiasm over the dramatic surprise he prepared, Pastor Russell walked off the stage and the meeting ended with the end of the hymn.”
Times have changed, and so have Christian views of Biblical prophecies once thought to apply to natural Jews in our day. With increased light from God, his people have discerned that such words foretell good things for the spiritual “Israel of God,” Jesus Christ’s anointed followers. (Rom. 9:6-8, 30-33; 11:17-32; Gal. 6:16) But we have been reviewing the early twentieth century, and this is how things were in those days.
 

While this is sometimes true, there has been a lot of leeway given to what is considered "academic use" in terms of discussion forums. Especially if we are commenting on the contents. The Watchtower Society, for example, has both won and lost in different cases attempting to keep people from posting and/or discussing copyrighted content.
I think you are aware, however, that it neglects the author's rights even more to post their work without attribution, or to post it in such a way that it makes it appear the author said something they didn't. And this happens more often when the poster assumes something about the contents, but doesn't try to comment on the actual contents or the context. 
And then the Gentile British Empire up until about 1947. You can read in old Watchtowers that Rutherford thought Britain was the "disgusting thing standing where it ought not" because they were standing on soil intended for Zionists.