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I have an epoch date: -4361126400 (a date in the 1830s). When I use https://www.epochconverter.com/, I get the following result (I get the same result with other online converters also):

GMT: Friday, October 21, 1831 12:00:00 AM

Your time zone: Thursday, October 20, 1831 11:58:45 PM GMT+00:00

If I try another date such as -13482000 (a day in 1969) the result is fine showing the full hour offset for my timezone as expected. Another date in the 1810s (-5031071925) on the other hand has a 1 min 15s offset.

Can anyone explain what is going on here?

Thanks

Columbo
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1 Answers1

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You’re probably in Europe/London time zone. The UK changed their time in 1847. Before that time the clocks were 1 minute 15 seconds earlier. From 1847 (and uninterrupted until 1916, when summer time (DST) was introduced), they were on GMT (Greenwich Mean Time).

One way to see this is on Time Zone in London, England, United Kingdom on timeanddate.com, see the link at the bottom and choose 1800 – 1849 in the Time zone changes for dropdown. For the time up to 1846 it says:

No changes, UTC -0:01:15 hours all of the period

Then it announces the change in 1847:

1847 ons 1. dec, kl. 00.00 LMT → GMT +0:01:15 hours (TZ change) UTC

(sorry, my Firefox talks Danish).

When Epoch & Unix Timestamp Conversion Tools that you used shows 11:58:45 PM, the offset is 1 minut 15 seconds. So this is what you get in the 1810s and in the 1830s. When it displays your time zone as “GMT+00:00”, it’s really misleading because it has correctly applied “GMT-00:01:15” for the time displayed. It seems that they just display today’s offset (I haven’t investigated further, you may yourself, of course).

Links:

Ole V.V.
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  • Thanks Ole V.V., much appreciated. This explains all. I have corrected by poor methematics in the title also. Thanks again. C – Columbo Apr 03 '19 at 07:44