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NSF Landing Page (Site Rules, Overviews Development, Feedback) => NASASpaceflight.com and NSF Forum Site Rules/News => Topic started by: ThreadSnake on 07/22/2020 05:29 pm

Title: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ThreadSnake on 07/22/2020 05:29 pm
I have been looking through posts on this board, and I've noticed some strange occurrences where the timestamps of posts do not line up particularly well with local times from live streams, and timestamps on other websites linked.

for some examples, the first time I noticed this was when I was gathering information on Starhopper's first tests in the SpaceX BFS - Phase 1 - StarHopper - Photos and Updates thread:

One example:

https://forum.nasaspaceflight.com/index.php?topic=47120.msg1927104#msg1927104

On LabPadre's stream, the suspected preburner fire was at 16:14:48CDT (UTC -5), or 21:14:48UTC.
But the forum post was at 20:19:10UTC, with an edit at 20:27:31UTC according to the forum, almost 50 minutes before the actual test occurs according to the stream.

Another example:

https://forum.nasaspaceflight.com/index.php?topic=47120.msg1925576#msg1925576 (https://forum.nasaspaceflight.com/index.php?topic=47120.msg1925576#msg1925576)
and
https://forum.nasaspaceflight.com/index.php?topic=47120.msg1925580#msg1925580 (https://forum.nasaspaceflight.com/index.php?topic=47120.msg1925580#msg1925580)

The tweet's timestamp was 2019-03-21T20:38:00.000Z, which is means 20:38:00 Zulu, or UTC.
The forum posts, however, were last edited at 19:45:26UTC and 19:52:05UTC, 46 minutes before the tweet was posted.

It looks as if some time stamps on this forum are an hour early from the rest; maybe it is getting confused with various daylight savings time standards? Such as in the southern hemisphere, they practice daylight savings in their summer, which is opposite from north's summer.

Before anyone asks, I have my time offset in my profile settings to 0, and this also matches my computer's UTC clock as well.

I made a post on the data collection thread I made explaining some of this 2 days ago, but haven't got responses there.
https://forum.nasaspaceflight.com/index.php?topic=51485.msg2109127#msg2109127 (https://forum.nasaspaceflight.com/index.php?topic=51485.msg2109127#msg2109127)
So that is why I made a thread to discuss why this is happening.

I think some information can be taken from this discussion I found on the subject of Simple Machine Forum timestamps:
https://groups.google.com/forum/#!topic/bit.listserv.ibm-main/_ogPJ2dMBQU (https://groups.google.com/forum/#!topic/bit.listserv.ibm-main/_ogPJ2dMBQU)
and specifically, this one highlights that there is some confusion with what local times use daylight savings or not:
https://groups.google.com/d/msg/bit.listserv.ibm-main/_ogPJ2dMBQU/hF7Uqw9LvOIJ (https://groups.google.com/d/msg/bit.listserv.ibm-main/_ogPJ2dMBQU/hF7Uqw9LvOIJ)
I have a hunch that this might have something to do with it, but it could be something completely different.

Let me know if you guys have any new explanations or already existing explanations I don't know about for what exactly is happening/happened with this problem.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: billh on 07/22/2020 05:54 pm
Probably time zone differences.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: intelati on 07/22/2020 06:07 pm
Probably time zone differences.

And a ten minute delay is reasonable. (an hour difference-50 minute error)
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ChrisWilson68 on 07/22/2020 06:18 pm
But the forum post was at 20:19:10UTC, with an edit at 20:27:31UTC according to the forum

Before anyone asks, I have my time offset in my profile settings to 0, and this also matches my computer's UTC clock as well.

This site doesn't give you timestamps in UTC.  It gives them in your local time.  Just because you set the current offset from UTC to zero doesn't mean it is giving you UTC for past posts.  It probably assumes you're in a time zone that observes daylight savings time that just happens to currently have a zero offset from UTC but a one-hour offset from UTC at other times of year.

The forum only lets you specify the current offset from UTC.  It doesn't let you set something like an Olsen name that would include daylight savings information.  But I've noticed that I don't have to change anything when the daylight savings change happens in my location, the forum just adjusts my offset automatically.

I don't know how it's deciding the daylight savings time rules for your account, but I think it is deciding them for you.  Maybe it gets it from your browser.  Maybe it uses your IP address to infer a location.  Maybe it just assumes based on your UTC offset.  I don't know.  But I think the evidence suggests the timestamps it's giving you include daylight savings.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: starskale on 07/22/2020 06:28 pm
I've confirmed the issue here. The posts in question are during daylight savings observation and my timezone is currently observing daylight savings. The post with the tweet is the easiest way to see the issue.

I can see that this post matches the time on my computer's clock (PDT) and so all posts should be correctly displaying in PDT (UTC-7). Adding 7hr to the post times shown gives a time that is too early by an hour.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ThreadSnake on 07/22/2020 06:48 pm
But the forum post was at 20:19:10UTC, with an edit at 20:27:31UTC according to the forum

Before anyone asks, I have my time offset in my profile settings to 0, and this also matches my computer's UTC clock as well.

This site doesn't give you timestamps in UTC.  It gives them in your local time.  Just because you set the current offset from UTC to zero doesn't mean it is giving you UTC for past posts.  It probably assumes you're in a time zone that observes daylight savings time that just happens to currently have a zero offset from UTC but a one-hour offset from UTC at other times of year.

The forum only lets you specify the current offset from UTC.  It doesn't let you set something like an Olsen name that would include daylight savings information.  But I've noticed that I don't have to change anything when the daylight savings change happens in my location, the forum just adjusts my offset automatically.

I don't know how it's deciding the daylight savings time rules for your account, but I think it is deciding them for you.  Maybe it gets it from your browser.  Maybe it uses your IP address to infer a location.  Maybe it just assumes based on your UTC offset.  I don't know.  But I think the evidence suggests the timestamps it's giving you include daylight savings.

If it was inferring that I am in daylight savings time, wouldn't displayed times be one hour ahead?
(I am in the northern hemisphere in the US observing local time EDT at the moment)
I'd suggest people that see this to check if they have the same predicament on their own devices. The method I used to get the twitter timestamp is with the inspect element tool on the date in the tweet.
If we know that we can reproduce the problem, we can have a better idea of what's happening.

As a sidenote publically, there are several things that could be going on here, so try to approach it with an open mind.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ChrisWilson68 on 07/22/2020 07:05 pm
If it was inferring that I am in daylight savings time, wouldn't displayed times be one hour ahead?
(I am in the northern hemisphere in the US observing local time EDT at the moment)

If it thinks you are currently observing daylight savings and it thinks your current offset from UTC is 0 hours, then it believes that during non-daylight-savings times of year you are one hour behind daylight savings.  So when showing you a timestamp that is noon UTC it would tell you it's 11:00am in your local time.  If you interpret that 11:00am as being UTC, the timestamps would seem to you to be 1 hour before the times they actually represent.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: JonathanD on 07/22/2020 07:11 pm
Yet one more reason to kill Daylight Savings!
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ThreadSnake on 07/22/2020 07:14 pm
If it was inferring that I am in daylight savings time, wouldn't displayed times be one hour ahead?
(I am in the northern hemisphere in the US observing local time EDT at the moment)

If it thinks you are currently observing daylight savings and it thinks your current offset from UTC is 0 hours, then it believes that during non-daylight-savings times of year you are one hour behind daylight savings.  So when showing you a timestamp that is noon UTC it would tell you it's 11:00am in your local time.  If you interpret that 11:00am as being UTC, the timestamps would seem to you to be 1 hour before the times they actually represent.

That is a good theory, but the problem in this situation is that the posts in question are also posted in times of the year where daylight savings time exists in the US.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: DigitalMan on 07/22/2020 07:16 pm
If it was inferring that I am in daylight savings time, wouldn't displayed times be one hour ahead?
(I am in the northern hemisphere in the US observing local time EDT at the moment)

If it thinks you are currently observing daylight savings and it thinks your current offset from UTC is 0 hours, then it believes that during non-daylight-savings times of year you are one hour behind daylight savings.  So when showing you a timestamp that is noon UTC it would tell you it's 11:00am in your local time.  If you interpret that 11:00am as being UTC, the timestamps would seem to you to be 1 hour before the times they actually represent.

That is a good theory, but the problem in this situation is that the posts in question are also posted in times of the year where daylight savings time exists in the US.

Have you looked at your own posts and noticed a time difference?
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ChrisWilson68 on 07/22/2020 07:17 pm
If it was inferring that I am in daylight savings time, wouldn't displayed times be one hour ahead?
(I am in the northern hemisphere in the US observing local time EDT at the moment)

If it thinks you are currently observing daylight savings and it thinks your current offset from UTC is 0 hours, then it believes that during non-daylight-savings times of year you are one hour behind daylight savings.  So when showing you a timestamp that is noon UTC it would tell you it's 11:00am in your local time.  If you interpret that 11:00am as being UTC, the timestamps would seem to you to be 1 hour before the times they actually represent.

The two examples in your original post are from dates in March that are after daylight savings starts in the US but before it starts in the UK and other parts of Europe.  Since you told it your offset from UTC is zero, it could well be assuming you're in a European time zone where you are currently in UTC because of daylight savings but in mid-March you were one hour behind UTC because you weren't in daylight savings then.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ThreadSnake on 07/22/2020 07:23 pm
Quote
I think you could be on to something. I will try changing my offset to -6 and see if it changes the relative difference.

No, it did not solve the problem by changing the time to Boca Chica's local time

Either the forum is inferencing time zones from something else, or it inferencing time zones isn't the problem
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ThreadSnake on 07/22/2020 07:59 pm
I'm pretty sure that the Twitter timestamp is most likely to be accurate of the sources, so by extension, this forum is the most likely to be 1 hour early for whatever reason.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: starskale on 07/22/2020 08:17 pm
If it was inferring that I am in daylight savings time, wouldn't displayed times be one hour ahead?
(I am in the northern hemisphere in the US observing local time EDT at the moment)

If it thinks you are currently observing daylight savings and it thinks your current offset from UTC is 0 hours, then it believes that during non-daylight-savings times of year you are one hour behind daylight savings.  So when showing you a timestamp that is noon UTC it would tell you it's 11:00am in your local time.  If you interpret that 11:00am as being UTC, the timestamps would seem to you to be 1 hour before the times they actually represent.

The two examples in your original post are from dates in March that are after daylight savings starts in the US but before it starts in the UK and other parts of Europe.  Since you told it your offset from UTC is zero, it could well be assuming you're in a European time zone where you are currently in UTC because of daylight savings but in mid-March you were one hour behind UTC because you weren't in daylight savings then.

I live in PDT and can confirm the same issue exists. And yes, I can confirm the timestamps of my posts match the correct time.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: TomH on 07/23/2020 06:20 am
One semantic nit: It is Daylight Saving Time, not Daylight Savings Time. In this context saving serves as a verbal adjective, while savings is a verbally derived noun, e.g. savings is what you have in the bank.

Think of it this way, is the Heimlich a life savings maneuver or a life saving maneuver?
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ChrisWilson68 on 07/23/2020 01:18 pm
One semantic nit: It is Daylight Saving Time, not Daylight Savings Time. In this context saving serves as a verbal adjective, while savings is a verbally derived noun, e.g. savings is what you have in the bank.

Think of it this way, is the Heimlich a life savings maneuver or a life saving maneuver?

It's not as simple as that.

Here's what the Oxford Dictionary of American Usage and Style has to say on the subject, as quoted by Wikipedia:

Quote
Although the singular form daylight saving time is the original one, dating from the early 20th century—and is preferred by some usage critics—the plural form is now extremely common in AmE. [...] The rise of daylight savings time appears to have resulted from the avoidance of a miscue: when saving is used, readers might puzzle momentarily over whether saving is a gerund (the saving of daylight) or a participle (the time for saving). [...] Using savings as the adjective—as in savings account or savings bond—makes perfect sense. More than that, it ought to be accepted as the better form.

https://en.wikipedia.org/wiki/Daylight_saving_time

Note that while the official title of the Wikipedia article uses "saving", the very first sentence of the article says it is also called "daylight savings time".
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ThreadSnake on 07/23/2020 02:38 pm
I want to gather more information on what posts/times of the year this occurs, to get a larger dataset to analyze. I will make some more posts on here once I have that information, but for now, I will be using any other sources I can find linked to the events I'm researching.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: launchwatcher on 07/23/2020 07:59 pm
I want to gather more information on what posts/times of the year this occurs, to get a larger dataset to analyze. I will make some more posts on here once I have that information, but for now, I will be using any other sources I can find linked to the events I'm researching.
Rather than treating this as a black box problem, you could look at the code underlying the forum (like I just did).

Download one of the source archives from: https://download.simplemachines.org/index.php?archive;b=4;v=99

Inside, find the definitions of the underlying database schema.   Observe that it uses an integer to store post timestamps.

Post timestamps are stored in a database as a POSIX timestamp (seconds since 1970-01-01 00:00 UTC, not counting leap seconds).

Conversions are done by the PHP code in .../Sources/Subs.php.

But then observe how it adjusts the integer timestamp with both a user and forum offset in hours prior to feeding the timestamp into strftime().   strftime() then does its own DST adjustments based on a complex set of location-dependent rules managed by the standard UNIX timezone package.   There's a bit of garbage in, garbage out going on here -- you're going to see some possibly errnoneous adjustments, especially for events occurring near DST adjustments.

my recommendation would be to set your timezone offset in your forum profile to 0 for any timestamp analysis and hope that the server is actually running in UTC rather than in TZ=Europe/London.

Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: tacoLover7916 on 07/23/2020 08:08 pm
If it was inferring that I am in daylight savings time, wouldn't displayed times be one hour ahead?
(I am in the northern hemisphere in the US observing local time EDT at the moment)

If it thinks you are currently observing daylight savings and it thinks your current offset from UTC is 0 hours, then it believes that during non-daylight-savings times of year you are one hour behind daylight savings.  So when showing you a timestamp that is noon UTC it would tell you it's 11:00am in your local time.  If you interpret that 11:00am as being UTC, the timestamps would seem to you to be 1 hour before the times they actually represent.

The two examples in your original post are from dates in March that are after daylight savings starts in the US but before it starts in the UK and other parts of Europe.  Since you told it your offset from UTC is zero, it could well be assuming you're in a European time zone where you are currently in UTC because of daylight savings but in mid-March you were one hour behind UTC because you weren't in daylight savings then.


ChrisWilson68 makes a good point. The referenced posts are in the window between the USA and Europe change for DST. I don't think it has anything to do with the user's preferred UTC offset. I think it has to do with when the site changes it's time to DST. By the looks of things it uses a later date that the US to change to DST.

My bet is that the site has a single time that it does the time change from standard to DST. Perhaps the site uses the last Sunday of March as many European countries do. Since Boca Chica changed its time on the second Sunday of March as the US does, leaping ahead one hour, this would make sense of the discrepancy. In Boca Chica the time was an hour ahead because it had changed to DST already but the site hadn't realized the change.

The website was just waiting another week or two to adjust the time forward and thus Boca Chica appeared to be one hour in the past.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: launchwatcher on 07/23/2020 08:59 pm
My bet is that the site has a single time that it does the time change from standard to DST. Perhaps the site uses the last Sunday of March as many European countries do. Since Boca Chica changed its time on the second Sunday of March as the US does, leaping ahead one hour, this would make sense of the discrepancy. In Boca Chica the time was an hour ahead because it had changed to DST already but the site hadn't realized the change.
That's consistent with a quick look at the underlying forum code -- it uses the system's default DST transition rules and then adds in your offset from GMT, rather than trying to use a client-dependent, client-supplied set of rules for DST transition.

What's odd is that if I add "%Z" (timezone name) and "%s" (UNIX/POSIX timestamp in decimal) to the Time Format string in the Profile, it displays "BST" as a timezone but displays times consistent with UTC/GMT:
Current forum time: 2020-07-23, 20:55:27 (BST: 1595537727)

while on my end if I ask for London time I get:
TZ=Europe/London date +"%Y-%m-%d, %H:%M:%S (%Z: %s)"
2020-07-23, 21:56:55 (BST: 1595537815)

which is British Summer Time (UTC+1)


Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ChrisWilson68 on 07/23/2020 09:26 pm
My bet is that the site has a single time that it does the time change from standard to DST. Perhaps the site uses the last Sunday of March as many European countries do. Since Boca Chica changed its time on the second Sunday of March as the US does, leaping ahead one hour, this would make sense of the discrepancy. In Boca Chica the time was an hour ahead because it had changed to DST already but the site hadn't realized the change.
That's consistent with a quick look at the underlying forum code -- it uses the system's default DST transition rules and then adds in your offset from GMT, rather than trying to use a client-dependent, client-supplied set of rules for DST transition.

What's odd is that if I add "%Z" (timezone name) and "%s" (UNIX/POSIX timestamp in decimal) to the Time Format string in the Profile, it displays "BST" as a timezone but displays times consistent with UTC/GMT:
Current forum time: 2020-07-23, 20:55:27 (BST: 1595537727)

while on my end if I ask for London time I get:
TZ=Europe/London date +"%Y-%m-%d, %H:%M:%S (%Z: %s)"
2020-07-23, 21:56:55 (BST: 1595537815)

which is British Summer Time (UTC+1)

I think that's because it uses the offset you have set in your profile as a hack on top of using Europe/London for timezone information.

A nice fix for this would be to allow an Olsen time zone name (such as Europe/London or America/Los_Angeles) to be selected in the user profile rather than a numeric offset from UTC.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: launchwatcher on 07/23/2020 09:35 pm
My bet is that the site has a single time that it does the time change from standard to DST. Perhaps the site uses the last Sunday of March as many European countries do. Since Boca Chica changed its time on the second Sunday of March as the US does, leaping ahead one hour, this would make sense of the discrepancy. In Boca Chica the time was an hour ahead because it had changed to DST already but the site hadn't realized the change.
That's consistent with a quick look at the underlying forum code -- it uses the system's default DST transition rules and then adds in your offset from GMT, rather than trying to use a client-dependent, client-supplied set of rules for DST transition.

What's odd is that if I add "%Z" (timezone name) and "%s" (UNIX/POSIX timestamp in decimal) to the Time Format string in the Profile, it displays "BST" as a timezone but displays times consistent with UTC/GMT:
Current forum time: 2020-07-23, 20:55:27 (BST: 1595537727)

while on my end if I ask for London time I get:
TZ=Europe/London date +"%Y-%m-%d, %H:%M:%S (%Z: %s)"
2020-07-23, 21:56:55 (BST: 1595537815)

which is British Summer Time (UTC+1)

I think that's because it uses the offset you have set in your profile as a hack on top of using Europe/London for timezone information.

No, that's from the "Current Forum Time" displayed on the profile page which does not include the time offset - it shows a UTC timestamp rather than my local time.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ThreadSnake on 07/23/2020 09:43 pm
My bet is that the site has a single time that it does the time change from standard to DST. Perhaps the site uses the last Sunday of March as many European countries do. Since Boca Chica changed its time on the second Sunday of March as the US does, leaping ahead one hour, this would make sense of the discrepancy. In Boca Chica the time was an hour ahead because it had changed to DST already but the site hadn't realized the change.
That's consistent with a quick look at the underlying forum code -- it uses the system's default DST transition rules and then adds in your offset from GMT, rather than trying to use a client-dependent, client-supplied set of rules for DST transition.

What's odd is that if I add "%Z" (timezone name) and "%s" (UNIX/POSIX timestamp in decimal) to the Time Format string in the Profile, it displays "BST" as a timezone but displays times consistent with UTC/GMT:
Current forum time: 2020-07-23, 20:55:27 (BST: 1595537727)

while on my end if I ask for London time I get:
TZ=Europe/London date +"%Y-%m-%d, %H:%M:%S (%Z: %s)"
2020-07-23, 21:56:55 (BST: 1595537815)

which is British Summer Time (UTC+1)

Thanks for taking a look at what it's doing in the code! I didn't know where to go to get the code before your post.

My looking through forum posts, going into the beginning of April, times began to be accurate, aligning with British Time's Daylight Savings Time beginning.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ThreadSnake on 07/24/2020 05:36 pm
I've seen that the time on posts are accurate when British Daylight Savings is active.

When it starts:

1 Hour Behind:
https://forum.nasaspaceflight.com/index.php?topic=47120.msg1928296#msg1928296

On time:
https://forum.nasaspaceflight.com/index.php?topic=47120.msg1929468#msg1929468


And when it ends:

On time:
https://forum.nasaspaceflight.com/index.php?topic=48895.msg2008158#msg2008158

1 Hour Behind:
https://forum.nasaspaceflight.com/index.php?topic=48895.msg2009195#msg2009195

Definite Correlation here.

The fact that the times are 1 hour behind when British DST isn't active, makes me wonder if in northern winter when DST isn't active, if the forum posts from when it is active will be 1 hour ahead or not. That is my hunch for now. (If that makes sense and if someone can confirm that theory or disprove it, that would be welcome)
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: Llian Rhydderch on 07/24/2020 05:59 pm
Idea:  why don't we do on NSF the same thing as we do on all spaceflight, human and satellite:  use UTC.  Gives one time stamp for all spaceflight related events, for everyone around the globe.

When local times matter, like local launches from Florida or Guiana or Satish Dhawan, it would make only a single adjustment to UTC rather than the multiple ones required to get times from two local timezones synced up, given disparate political daylight savings rulz, etc.



Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ChrisWilson68 on 07/24/2020 06:10 pm
Idea:  why don't we do on NSF the same thing as we do on all spaceflight, human and satellite:  use UTC.  Gives one time stamp for all spaceflight related events, for everyone around the globe.

When local times matter, like local launches from Florida or Guiana or Satish Dhawan, it would make only a single adjustment to UTC rather than the multiple ones required to get times from two local timezones synced up, given disparate political daylight savings rulz, etc.

I vote against that.  In my daily life, I use my local time zone.  So does nearly every human on Earth.  Virtually every web site supports that.  Virtually every piece of electronic equipment.  Virtually every piece of software.  It would be inconvenient for me to have to see all the timestamps on this site in UTC and try to mentally translate that into the local time which I use for the rest of my life.

This is an obscure bug that makes the timestamps of old posts in a window for a few weeks in March show a timestamp that's off by an hour.  That's far less of a pain than having to mentally translate UTC all the time.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ChrisWilson68 on 07/24/2020 06:15 pm
If this site just let us choose an Olsen time zone name in our profile and used that correctly, then anyone who wanted to see UTC could choose to see it and anyone who wanted to see any other time zone could see that.

From what people on here have said, the server software for this site is actually calling library routines that can handle any Olsen time zone correctly.  It's just not choosing to let the user set an Olsen name and passing that through to these routines.  Instead, it's using the system time zone of the server and hacking on an offset of a number of hours different from UTC.  This could be changed.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: Ken the Bin on 07/24/2020 11:24 pm
I've found that the simplest thing to do is when the timestamps on posts are not correct is to go to Profile > Modify Profile > Look and Layout.  Then I click "(auto detect)" next to the Time Offset and it gets changed to the needed value to make the timestamps correct.

I find that I need to do this more than just twice/year.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ChrisWilson68 on 07/24/2020 11:32 pm
I've found that the simplest thing to do is when the timestamps on posts are not correct is to go to Profile > Modify Profile > Look and Layout.  Then I click "(auto detect)" next to the Time Offset and it gets changed to the needed value to make the timestamps correct.

I find that I need to do this more than just twice/year.

The issue isn't with the time for current posts.  That can be fixed by changing the time offset value.

The issue is that if you're in the US then when you look at old posts from the middle of March the timestamps are one hour off while the posts for the rest of the year have correct timestamps.  Those in timezones whose daylight savings time changes are the same as the UK's will not see this issue.  The same is presumably true for posts from a few weeks in the fall between the end of Summer Time in the UK and the end of Daylight Savings Time in the US.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: Ken the Bin on 07/24/2020 11:49 pm
The issue is that if you're in the US then when you look at old posts from the middle of March the timestamps are one hour off while the posts for the rest of the year have correct timestamps.  Those in timezones whose daylight savings time changes are the same as the UK's will not see this issue.  The same is presumably true for posts from a few weeks in the fall between the end of Summer Time in the UK and the end of Daylight Savings Time in the US.

Interesting.  I've never noticed that, and I am in a US time zone that observes DST.

Having both the server and the database values in UTC seems to be the best option.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ThreadSnake on 07/25/2020 02:49 pm
I've found that the simplest thing to do is when the timestamps on posts are not correct is to go to Profile > Modify Profile > Look and Layout.  Then I click "(auto detect)" next to the Time Offset and it gets changed to the needed value to make the timestamps correct.

I find that I need to do this more than just twice/year.

The issue isn't with the time for current posts.  That can be fixed by changing the time offset value.

The issue is that if you're in the US then when you look at old posts from the middle of March the timestamps are one hour off while the posts for the rest of the year have correct timestamps.  Those in timezones whose daylight savings time changes are the same as the UK's will not see this issue.  The same is presumably true for posts from a few weeks in the fall between the end of Summer Time in the UK and the end of Daylight Savings Time in the US.

The period of innacuraccy isn't just in March. It's any time that British Daylight Savings time is not in affect.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ChrisWilson68 on 07/25/2020 03:30 pm
I've found that the simplest thing to do is when the timestamps on posts are not correct is to go to Profile > Modify Profile > Look and Layout.  Then I click "(auto detect)" next to the Time Offset and it gets changed to the needed value to make the timestamps correct.

I find that I need to do this more than just twice/year.

The issue isn't with the time for current posts.  That can be fixed by changing the time offset value.

The issue is that if you're in the US then when you look at old posts from the middle of March the timestamps are one hour off while the posts for the rest of the year have correct timestamps.  Those in timezones whose daylight savings time changes are the same as the UK's will not see this issue.  The same is presumably true for posts from a few weeks in the fall between the end of Summer Time in the UK and the end of Daylight Savings Time in the US.

The period of innacuraccy isn't just in March. It's any time that British Daylight Savings time is not in affect.

Can you point to a post that shows that there is a problem on a date when neither the UK nor the US is observing daylight savings?
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: Hog on 07/25/2020 04:39 pm
I've always noticed a weirdo bug that affects the resultant time on this site.  Many time zones in the United States and in Canada are shared.  Not sure about Mexico though. 
I live in a timezone that "celebrates" either EST(Eastern Standard Time) or EDT(Eastern Daylight Time).  EST is 5 hours behind and EDT is 4 hours behind the UTC(Universal Time Coordinated/Universal Coordinated Time).  UTC is also known as GMT for Greenwich Mean Time, as the geographical Prime Meridian, where all Earth time zones originate from, passes through the Royal Observatory, Greenwich, London, England in the UK.
I do suggest reading a bit about GMT as some context must be given if trying to compare GMT directly to UTC. Interesting stuff.
Wiki page GMT https://en.wikipedia.org/wiki/Greenwich_Mean_Time

Corporal: "Private, get up its your turn for "fire picket"."
Me: "What time is it?"
Corporal: "Time for you to get your butt out of bed, into uniform and outside for fire picket."

Fire picket is where a service member wakes up, dresses and walks around an assigned area looking for fire. After his/her usually one-hour "fire picket", you awaken the next member and they get up, walk around and search for fire for the next hour.  Fire picket is a normal part of certain military life.  The reason why I didnt like it was because it was often used as a form of punishment. There was one day during morning inspection, while standing at attention, Sergeant Rodgers was in my face and he caused me to laugh.  He gave me a few chances to correct myself, but I was unable.
He said "Private S-alphabet-horn" we'll see how much you're laughing tomorrow morning after a night of fire picket."
Usually that means 2 sessions of fire picket. And one of them is almost always either the first hour of fire picket, or the last hour before reveille. Either one of these time slots allows you to either stay in uniform or get into uniform an hour early before you start your normal day.  Well I lucked out and saw that I had both the first AND the last shifts for fire picket which would give me a nice 4 hour solid block of time for sleeping, but unluckily I noticed that I had been scheduled for  THREE hours of fire picket. I hour is normal, 2 hours is punishment, 3 hours means that you really PO'ed someone.

2300-lights out
2300-2400 Shift #1
0000-0100 off
0100-0200-off
0200-0300 Shift #2
0300-0400-off
0400-0500 Shift #3
0500-reveille

So as you can see that at midnight I had 2 hours to remove my boots/uniform/sleep/awake/redress, fire picket at 0200-0300 then 1 hour to remove my boots/uniform/sleep/awake/redress for an 0400-0500 fire picket.

During the next mornings morning inspection Sergeant Rodgers steps in front of me, right in my face, I can see all the hairwax gobbed into his moustache holding his moustache up into these gigantic handlebars in order to keep his moustache "within regulations" and says "Private S-alphabet-horn, somethings different today" and pauses and puts a finger up to his ear in the dead silent room.  "I don't hear any laughing." with a big manure eating grin on his face. He said "Have a great day Private." and moves on to the next soldier.

He was right, no I wasn't laughing, and I never forgot that day, nor his name some decades later.  BTW At the end of that course,  I was outside alone having a cigarette. Sgt. Rodgers walked up to me, lit his cigarette.  He said "Every so often I see a Private that has that "special something" that will make them an excellent Sergeant in the future.   You Private Schermerhorn, have that "special something"."  With that he reaches into his pocket and pulls out an extra set of his Sergeant chevrons(3 chevrons with a Maple Leaf above them and places them into my hands.  "I don't want to hear about you wearing these around base, but maybe they will remind you that I noticed the good part of your efforts, and not just the bad."  He then shakes my hands and walks away.  Wow, such a simple gesture made such a HUGE impression on me. I'll never forget it.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: ChrisWilson68 on 07/25/2020 05:00 pm
UTC is also known as GMT for Greenwich Mean Time

Actually, no.  GMT and UTC are close, but they are not the same thing.

As the first and second paragraphs of the Wikipedia article on GMT you linked to say:

Quote
At different times in the past, it has been calculated in different ways, including being calculated from noon;[1] as a consequence, it cannot be used to specify a precise time unless a context is given.

English speakers often use GMT as a synonym for Coordinated Universal Time (UTC).[2] For navigation, it is considered equivalent to UT1 (the modern form of mean solar time at 0° longitude); but this meaning can differ from UTC by up to 0.9 s. The term GMT should not thus be used for certain technical purposes requiring precision.

GMT is based on the rotation of the Earth.  That speeds up and slows down very slightly over time.  It gives variable day lengths.

That's why people came up wtih UTC, as something better to use than GMT.  All modern timezones are based on offsets from UTC, not GMT.

UTC is based on seconds of a fixed length defined independent of the variable rotation of the Earth.  It is close to UT1, a time that is based on the rotation of the Earth and essentially a better-defined version of GMT.  When the variable rotation of the Earth starts bringing UTC close to being 1 second away from UT1, a leap second is either added or removed from UTC to keep it close to UT1.  This leap second system to keep UTC in sync with solar days is really not much different in principle from leap years which are used to keep the Gregorian calendar in synch with solar years.

Anyway, what all this means in terms of terminology is that we should really be using the terms UTC or "coordinated universal time" when that's what we mean, not GMT.  UTC is what all timezones are based on and what computers actually use (as closely as they can) for virtually all purposes.
Title: Re: Forum Timestamps Inconsistent with Other Accounts of Events
Post by: Hog on 07/26/2020 02:06 pm
You are technically correct of course, GMT and UTC are NOT the same thing.

In an attempt to reduce the population of nits, I included this sentence "I do suggest reading a bit about GMT as some context must be given if trying to compare GMT directly to UTC. Interesting stuff."   
Nits are pesky insects though.
Maybe I should have asked Sgt Rodgers if his fire picket schedule was following UTC or GMT? 
(from ZULU (UTC) is the correct answer)