This is a great thread - another example of the collective spirit of this forum at work. I want to add some hard evidence to the discussion on these day/night dial UG aerocompax refs 890101s as I was recently lucky enough to land one and was discussing its merits with
@chronoboy64 in another post. I won't get into the color scheme criticisms other than to say I have no readability issues with black hands on black dial and I like the hands better than the silver ones.
I'll present a few other day/night 890101 examples and their serial #s all with 2583xxx.
Also note
@bubawatch day/night dial shown earlier in this thread is also a 2583xxx.
Here is one at sotheby's that sold last year (serial # is less than 10 off from mine):
http://www.sothebys.com/en/auctions/ecatalogue/2018/important-watches-n09879/lot.293.html?locale=en
And another at Bernadini Milano:
https://www.bernardinimilano.com/products/universal-geneve-aero-compax-4
Bernadini, Sotheby, and my day/nights all fall within 100 of each other and interestingly the Bernadini watch also shows the "HON" mark on the movement which would indicate imported to the US- like mine. I wish I could get the movement shot of the Sotheby's and
@bubawatch ones to see if that too was marked HON.
Another counterpoint to the main argument member
@Mlafra makes - that the day/night dial chrono register would probably tick every 30 seconds intervals- mine and the sotheby one doesn't (I can't say for the other two I mentioned). Mine counts at the proper intervals in regards to its dial- 1 minute ticks for 30 minutes.
Hopefully this can dispel some assumptions and add some more color regarding these beauties. If anybody has more to add in time we might be able to get deeper but for me the easiest explanation is that this 890101 day/night dial was just a variant that was offered in addition to all white dial 890101s that are more commonly seen/documented and all that I've seen fit within a reasonable range of serial #.
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