Daylight savings time

[barres]

I notice that all posting times are listed at GMT -6 hours, which would be fine, except that Central Daylight Time (which we are under right now) is GMT -5 hours.

The question is do you moderators want to change the time setup for the board only to have to change it back in a month or so, or do you just want to make a note for next year's DST?

[Crossfire]

Barres -

That is a personal setting. You can change it in your profile.

[jimlongley]

Actually, strictly speaking, GMT does not exist any more, it was replaced by UT (Universal Time) some years ago (1961?). Both refer to a mean time, with UT based on UTC (Coordinated Universal Time), which is the current standard, while GMT was based on a previous standard, and there are several variations of UT. UTC, UT, and the rest were established by international treaties, which some nations choose not to follow.

The time zones are referred to in two ways; aviation, naval, and ham radio time keepers often refer to the zones by letter designations, with the Greenwich zone labelled "Z" or zulu. The standard definition for time zones is to number them by an offset, in integer hours, from the standard meridean, thus Dallas is in the UTC-6 zone, which is adjusted locally to UTC-5 while the zone number remains UTC-6.

Most computers today understand this and adjust for it under the user's control. OTOH, where it says "All times are GMT - 6 hours" is so confusing I just ignore it.

[barres]

Barres -

That is a personal setting. You can change it in your profile.

oops

I overlooked that when I was trying to figure out how I posted that the escaped inmate yesterday was recaptured about 30 minutes before the time at which the event occurred!

[EASTTEXGLOCKER]

I seem to remember that back in the 1800*S the railroad industries were responsible for the various times zones that we have come to know, in NORTH AMERICA. They are ET,CT,MT,PT, for the Continental states. The national institute of standards and technology out of BOULDER,CO. OFFER VARIOUS SERVICES, one being the atomic clock which many folks are familiar with , but to name a few other INTERNET time services,radio Sta time, radio Sta WWVB,rad Sta WWV, rad Sta WWVH, and their are more but this is a few services that are provided.

[jimlongley]

I seem to remember that back in the 1800*S the railroad industries were responsible for the various times zones that we have come to know, in NORTH AMERICA. They are ET,CT,MT,PT, for the Continental states. The national institute of standards and technology out of BOULDER,CO. OFFER VARIOUS SERVICES, one being the atomic clock which many folks are familiar with , but to name a few other INTERNET time services,radio Sta time, radio Sta WWVB,rad Sta WWV, rad Sta WWVH, and their are more but this is a few services that are provided.

303-499-7111 for the time tick.

The history of the time zones is quite interesting, but way too complicated to even consider hijacking the thread with.

[Zero_G]

And if you want to really pick nits, it's "Daylight Saving Time", not "Daylight Savings Time"

[mcub]

Well if you want to get serious move to Local Side Real Time.


It verys by Log. Lat. and Elevation !!

[phddan]

Well I think its about time for an adult sodee pop

Dan

[jimlongley]

Well if you want to get serious move to Local Side Real Time.


It verys by Log. Lat. and Elevation !!

sidereal, one word, not two.

Sidereal time, calculated from the apparant motion of the vernal equinox, relates only to longitude, not lattitude or elevation. Sidereal time, is by definition, local to the meridean, but is the same all the way along that meridean.

You may be referring to "True Local Time" which may also be referred to as "Solar Time" and "Apparant Solar Time" according to who you are talking to, an astronomer, an astrologer, or someone else who has need or interest in determining the apparant time at any particular location on the face of the earth. The term "True Local Time" is primarily used by astrologers and does use a spherical geometric calculation based on sidereal time, lattitude, and elevation.

[mcub]

Well if you want to get serious move to Local Side Real Time.


It verys by Log. Lat. and Elevation !!

sidereal, one word, not two.

Sidereal time, calculated from the apparant motion of the vernal equinox, relates only to longitude, not lattitude or elevation. Sidereal time, is by definition, local to the meridean, but is the same all the way along that meridean.

You may be referring to "True Local Time" which may also be referred to as "Solar Time" and "Apparant Solar Time" according to who you are talking to, an astronomer, an astrologer, or someone else who has need or interest in determining the apparant time at any particular location on the face of the earth. The term "True Local Time" is primarily used by astrologers and does use a spherical geometric calculation based on sidereal time, lattitude, and elevation.

BY definition yes, but to align a telescope the apparent angle to the horizon is offset by elevation in relation to scopes distance to the earth’s rotational axis. Hence the higher your elevation, the greater the adjustment for the parallax error from the theoretical horizon to the actual one. Naturally as you move "UP" or "Down" if in the southern hemisphere, in latitude, the closer to the axis you become. Since all star charts are based on RA/DEC to the theoretical horizon at sea level on the equator, most astronomers offset sidereal time with LAT & LON and Elevation. It is simply easier than adjusting the RA/DEC for your location every time you want to center your CCD on a new object.

Remember it is called Local, as it is based on concept the clock starts when the target star "Shows on the horizon"

Perhaps it have been more accurate for me to have said try using LocalSide real time,

Also my spell checker forces the words apart when I copy and paste.

[jimlongley]

Remember it is called Local, as it is based on concept the clock starts when the target star "Shows on the horizon"

Perhaps it have been more accurate for me to have said try using LocalSide real time,

Also my spell checker forces the words apart when I copy and paste.

So fix your spell checker.

Still, sidereal time only apllies to the meridean, the Right Ascension, Declination, and elevation above the mean axis of rotation are applied to the sidereal time to locate the desired object, sidereal time itself has no lattitudinal or elevation component.

I used to teach this stuff, and even how to do the calculations using a non-memory low significant digit calculator, or even a slide rule.

[barres]

Wow! This is exactly where I thought this thread would go when I started it!

But, please, don't stop. This is an interesting discussion.

[mcub]

I do tend to get carried away, I still find it fascinating that time is a totally human invention, calendars and such are simply what we choose to say they are. This is why no one can agree on how to come to the current time. What I just to like about astronomy where the endless arguments over mundane things, like how long an astronomical second should be.

Well back to the subject of guns in another tread….

[phddan]

Wow! This is exactly where I thought this thread would go when I started it!

But, please, don't stop. This is an interesting discussion.

Dan