What is UT offset for UK in KStars

[teoria_del_big_bang]

As title, and I am sure this should be obvious as it is 0 but just checking if this is correct and that is knows if daylight saving time is in action or not.

Steve

[Ouroboros]

It’s ages since I set this up but I’m pretty certain it’s 0. 
 

Am I also right in recalling that the choice of DST (daylight saving time) rules is only EU? There’s no GB I think. 

Edited January 8, 2021 by Ouroboros

[teoria_del_big_bang]

Thats what I would expect but everytime I set it to 0 and press OK if I go back into it again it is back to 1 ????

Steve

[Ouroboros]

44 minutes ago, teoria_del_big_bang said:

Thats what I would expect but everytime I set it to 0 and press OK if I go back into it again it is back to 1 ????

Steve

I’ve just checked mine and it’s the same. Well, I’ve used KStars for sometime and know it works. Is it because we’re one hour behind EU time? 

[teoria_del_big_bang]

45 minutes ago, Ouroboros said:

I’ve just checked mine and it’s the same. Well, I’ve used KStars for sometime and know it works. Is it because we’re one hour behind EU time? 

Thanks for that, I thought it must be correct, cheers 🙂 

Steve

[Davey-T]

UT is zero at the Greenwich Meridian line, if your going to have an offset it's going to be either plus or minus an hour or more depending how far round the globe you are, wouldn't think Skipton is far enough away to affect it.

It's unaffected by BST.

Dave

Edited January 8, 2021 by Davey-T

[Davey-T]

Here you go Skipton is 0 UTC offset

Dave

[lenscap]

2 hours ago, teoria_del_big_bang said:

Thats what I would expect but everytime I set it to 0 and press OK if I go back into it again it is back to 1 ????

Change the UT offset for Skipton to zero then press the + button to add a new version of Skipton with the correct (zero)  UT value.

Then select the old Skipton and delete it with the - button.

The DST rules should be "EU". We were in the EU when the software was written and are still using the same rule for daylight saving time (British Summer Time) AFAIK

[Davey-T]

1 hour ago, lenscap said:

The DST rules should be "EU". We were in the EU when the software was written and are still using the same rule for daylight saving time (British Summer Time) AFAIK

DST should have no bearing on UTC.

Dave

[teoria_del_big_bang]

12 hours ago, lenscap said:

Change the UT offset for Skipton to zero then press the + button to add a new version of Skipton with the correct (zero)  UT value.

Then select the old Skipton and delete it with the - button.

The DST rules should be "EU". We were in the EU when the software was written and are still using the same rule for daylight saving time (British Summer Time) AFAIK

Thanks that worked fine and now is 0.

Odd though after a power down it was back at Greenwich as my location anyway. I need to try connecting to my mount anyway and see if it communicates with the internal GPS to get the correct coordinates. I know in the past i have struggled to get this working.

Just tried it again and after powering down it just goes back to Greenwich. If I check then Skipton is still in the list and I can just celect it so the fact that I made a new location called skipton has worked and is in the memory but for some reason it does not keep the location in KStars.

Steve

[teoria_del_big_bang]

Tried all sorts of ways to select my location but just reverts back to Greenwich after a reboot.

Steve

[StevieDvd]

12 hours ago, Davey-T said:

DST should have no bearing on UTC.

Dave

Local time is UTC +/- an offset, the offset can change based on a rule such as DST. So for the software to work out local UK time it needs to know the offset and the date hence we are on GMT/UTC now but will be UTC +1 when the clocks change in March.

[lenscap]

52 minutes ago, teoria_del_big_bang said:

Tried all sorts of ways to select my location but just reverts back to Greenwich after a reboot.

Try selecting Bradford, United Kingdom and see if that sticks after reboot.

If so it is so close that it will make no practical difference.

36 minutes ago, StevieDvd said:

hence we are on GMT/UTC now but will be UTC +1 when the clocks change in March.

This is not correct. The offset is the difference between UT and the local standard time. It is the same all year round. Provided you specify the correct DST rule the software will allow for British Summer Time when appropriate.

[teoria_del_big_bang]

15 minutes ago, lenscap said:

Try selecting Bradford, United Kingdom and see if that sticks after reboot.
If so it is so close that it will make no practical difference.

Tried that and still back to Greenwich.

[teoria_del_big_bang]

Just now, teoria_del_big_bang said:

Tried that and still back to Greenwich.

Maybe it's easier if I move to Greenwich 🙂 ha ha

[teoria_del_big_bang]

Ha Ha done it.

When Stellarmate powers up it automatically opens KStars.
I Trued all ways to change to either Skipton, Bradford, Leeds but always went back to Greenwich. Tried clicking on settings - Geographic and changing there and also clicking on settings - Startup Wizard and set it there but always went back to Greenwich.

What I never did was change it and then close KStars down before rebooting.
This time I first closed KStars and re-opened it and it was still on Skipton.
So now I have rebooted and still on Skipton, so the missing bit of the puzzle seemed to be closing the application after changing the location.

Thanks all for the help 🙂 

Steve

[Davey-T]

2 hours ago, StevieDvd said:

Local time is UTC +/- an offset, the offset can change based on a rule such as DST. So for the software to work out local UK time it needs to know the offset and the date hence we are on GMT/UTC now but will be UTC +1 when the clocks change in March.

It's only DST that alters though so UTC stays the same for your location, I can run my mounts on UTC  and ignore DST, don't know why all mounts don't run on UTC and avoid the
DST confusion.

Dave

[Ouroboros]

I think I must have been running KStars wrongly set on UTC+1 for years and never noticed. I just changed it to +0 and as Teoria says it reverts to 1 when you restart the programme.  It needs saving by clicking the thing that looks like a floppy disk. Funnily enough it remembered my location name, coordinates etc, so I must have saved it at some time. 

The funny though perhaps not surprising thing is that the polar alignment routine still worked as did the plate solving to calibrate the pointing model.  

So thanks @teoria_del_big_bang for asking the question. I’ll check it out when government lifts restrictions and I’m no longer socially distanced from my telescope which is 200 miles away.  

[teoria_del_big_bang]

3 minutes ago, Ouroboros said:

I think I must have been running KStars wrongly set on UTC+1 for years and never noticed. I just changed it to +0 and as Teoria says it reverts to 1 when you restart the programme.  It needs saving by clicking the thing that looks like a floppy disk. Funnily enough it remembered my location name, coordinates etc, so I must have saved it at some time. 

The funny though perhaps not surprising thing is that the polar alignment routine still worked as did the plate solving to calibrate the pointing model.  

So thanks @teoria_del_big_bang for asking the question. I’ll check it out when government lifts restrictions and I’m no longer socially distanced from my telescope which is 200 miles away.  

Must admit not sure how mine has been running the past year. I am actually setting up a new RPi with Stellarmate. Previously I have had another RPi running Astroberry which I should look at.
I am a bit embarrassed to say but my mount, scope and all my gear had been in cases since I took them on holiday to south coast last September. Weather just not been brilliant since and had other things going on in life just have not done any imaging back end of last year.

But I think I had that set up to update KStars from the GPS in the mount so maybe all this is not a big issue anyway, and hopefully thats how it will work with this setup. It was just annoying me and I was sure there was a way of getting it working so just kept trying to see how to do it.

Steve

[StevieDvd]

I was going to answer this in a little more detail but it's a complex issue to simplify.

For those interested have a look at references to ISO 8601 e.g:

https://www.nhc.noaa.gov/aboututc.shtml

https://www.w3.org/TR/NOTE-datetime

Given 2 times (from different locations) in the fullest format I can calculate the number of hours, minutes between those values without knowing the DST rules for those places. This is because the offset is provided for each having the rules accounted for. So in UK in can be +1:00 or +0:00 depending on our DST setting.

When your mount asks for a time & date it expects you to give it more details of whether you are in DST period so knows you will have entered the time on your watch and clicked DST yes. Or the equivalent time on your watch and the current UTC offset of 1.

In modern computer systems the date, time and location plus the offset, are passed to a standard routine which works out if DST rules are valid for that date and if necessary amends the offset accordingly.

And that's the abbreviated version 🙂