Never ending Daylight Saving Time Issues

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tommy273
Posts: 7
Joined: Sun Mar 03, 2019 10:25 am

Never ending Daylight Saving Time Issues

Post by tommy273 » Sat Apr 18, 2020 6:07 am

Hello Zwo Team,

as soon as daylight savings time is on, the troubles start. I am getting so frustrated with this.

During winter time everything works fine, I am UTC+1, during DST UTC+2. Mount is a GEM45, I am using ASIair and SkySafari. Had similar problems with an EQ3 last year.

When I enter everything according to DST time in the mount and in the Android device: after start-up of ASI air everything works fine, except that the time displayed in ASIair is one hour off = winter time. But after connection to SkySafari and and slewing to an object, the telescope is one hour off the target. This can be fixed by plate solving and syncing the mount, but then automatic meridian flip doesn't work and the mount doesn't return to the correct zero position. With the EQ3 this also messed up the ASIair PA routine and crashed the scope into the mount. That's why I am now only using iPolar.

I tried to fix the issue by messing with the time settings on the mount and Sky Safari. I put both to "no daylight savings time", UTC+1, and entered winter time in both devices. For some unknown reason, ASIair now shows UTC+0 time and somehow the time on the mount is reset to 00:00:00.

I have read of other users having similar issues with different types of mounts, trying all kinds of workarounds. In the light of possible telescope crashes and damage, I am wondering, is this so hard to fix?

Any help would be greatly appreciated.

Best regards
Thomas

astrosatch
Posts: 64
Joined: Tue Sep 25, 2018 7:46 am

Re: Never ending Daylight Saving Time Issues

Post by astrosatch » Sat Apr 18, 2020 9:17 am

Hi Thomas.

I have (had?) the same problem. When started Asair it usualy shows utc +1 which is wrong. Then I switch to Skysafari and connect it to scope. It takes 1 min ro connect to my scope, I don't know why. Switch back to Asiair and it shows utc+2. And it works fine. However, next time when I start asiair and if I didn't close Skysafari before, the Skysafari is allready connected to my mount but Asiair shows utc+1. So I have to disconnect mount in Skysafari and connect it again and then it shows utc+2 in asiair again. This is my usual procedure to get daylight savings time correct in Asiar. I use Heq5 pro EQmod cable.
One more thing. Do not press sync to mount under phone info in mount page. It resets to utc+1.
Hope this helps.

P.s.
Question for ZWO: Whay does it take so long (1 min ) to connect Skysafari to my mount and why problem with daylight savings time?

Br,
Andrej

tommy273
Posts: 7
Joined: Sun Mar 03, 2019 10:25 am

Re: Never ending Daylight Saving Time Issues

Post by tommy273 » Sat Apr 18, 2020 8:49 pm

Hello Andrej,

great remarks, thank you! I did exactly the same thing when I was using the EQ3 mount, it was bit annoying, but it worked. Unfortunately, with the iOptron mount it doesn't seem to work this way.
I experience the same slow start-up of SkySafari that you are describing. I believe this is caused by synchronisation issues between the apps and the mount and maybe related to the DST issue.
I really hope Zwo is taking this on. Is it really so hard to have the time and RA/Dec synchronized and displayed correctly and get the apps to start up properly at the first try?

Clear Skies and best regards,
Thomas

astrosatch
Posts: 64
Joined: Tue Sep 25, 2018 7:46 am

Re: Never ending Daylight Saving Time Issues

Post by astrosatch » Sun Apr 19, 2020 1:40 pm

Sorry, can't help you with Ioptron .Yes, I believe that time/date should be controllable.
There should be more options that user can change. This way might be less problems overall and more way to tweak better performance. At this stage I understand that Asiair is generaly meant for simplicity and beginners but don't see the reason why it can't become more serious astrophotography tool in the future. I know I won't be using computer for imaging, only for processing.
So my wish would be that ZWO focus more on improving image acquisition and guiding performance and less on live stacking and postproccesing which is domain of powerful astrophotography programs anyway.
I see the bright future of this little gadget.👍
Clear sky,
Andrej

W7AY
Posts: 265
Joined: Fri Jan 25, 2019 3:38 am
Location: Portland, Oregon, USA

Re: Never ending Daylight Saving Time Issues

Post by W7AY » Sun Apr 19, 2020 6:34 pm

Hi folks,

If your hand controller has a Daylight Saving Time (DST) setting, turn it off. You should then enter UTC offset and local time as if it is winter.

Turn off DST and if your city observed DST, set the Date and Time of the mount by subtracting an hour off current observed UTC offset and add an hour to the local time.

Long answer:

I just looked at what the ASIAIR is sending to my mount simulator. My longitude is about -122º (I am in the Pacific Time zone), and my current time zone offset is -7 hours, with Daylight Saving active.

The local time is about 10:30 AM and the Local Sidereal Time (LST) is 23:16.

When I ran my simulator and connected the ASIAIR to it, the ASIAIR firmware sends 9:30 AM and a UTC offset of -8 to my virtual mount.

Notice that local time 10:30 AM with UTC Offset of -7 Hrs and DST on will convert to the same UTC as local time of 9:30 AM with UTC offset -8 and DST off.

The time ASIAIR sends to the mount will generate the correct UTC if you also turn any DST flag off. If the DST flag on your mount/hand-controller is on, then the time that ASIAIR sends will be an hour off.

UTC is normally used to compute the Local Sidereal Time (LST) from the local Longitude. Those three numbers are related, and they don't change with the seasons. It is very important to get LST correct -- that means UTC and Longitude needs to be correct.

The Right Ascension (RA) of an object is related to the LST by: RA = LST - HA, where HA is the hour angle of your mount. If the mount is physically pointed at the Meridian, its hour angle is precisely zero.

The LST is how the mount determines the RA of the object in the sky, from the HA on the ground. The HA is the mechanical angle of the polar axis and does not change if the mount is not moving or tracking.

If Local Time, UTC Offset and Daylight Saving is wrong, then UTC is wrong. If UTC is wrong, or Longitude is wrong, then LST is wrong. If LST is wrong, then RA is wrong. If RA is wrong, nothing works properly -- GOTO will move to the wrong coordinates, Meridian flips will occur at the wrong time, etc.

As long as the UTC is correct, all should be good.

However, if you have turned on DST on your mount or hand controller, then the local time that ASIAIR pushes to your mount will be converted to the wrong UTC if the mount thinks it is operating in Daylight Saving Time.

In one of the past versions, all you need to do is not click on the "Sync To Mount" button. That way, the mount keeps its own preset time. Sometime in the last couple of releases (there has been so many beta releases, I no longer remember when), ASIAIR always pushes the local time and UTC offset (but without DST) to the mount upon initial connection.

So, again, turn off DST on your mount, let the ASIAIR send the wrong time to the mount with the non-DST UTC-offset. The UTC should then be correct.

If your hand controller also reads out UTC, you can check to confirm.

My primary mount (RainbowAstro RST-135) also has an LST display. If your hand controller has LST display, you can check that too with the LST time that you can get from web applications, or with the SkySafari's advanced data and time window. Remember that penultimately, everything depends on the Local Sidereal Time, and not on Local Time, and not even on UTC.

At least you can test it all out in the day time.

For what its worth, my RainbowAstro (Korean) mount also does not understand DST. China and South Korea do not use DST, so unless their engineers are western trained, they may not be sensitive to the problems from seasonal time changes.

Clear skies,
Chen

astronomos
Posts: 9
Joined: Thu Apr 16, 2020 7:24 am

Re: Never ending Daylight Saving Time Issues

Post by astronomos » Sun Apr 19, 2020 10:54 pm

Great explanation Chen,
I am in the same timezone as you, down in California, and just experienced this last night, could not get the mount to go to the right location.

let me see if i get this straight, on the controller.
1- turn off Day light savings on controller, ok will do that.
2- adjust the UTC offset to -480
3- when it asks for the time, enter the center the winter time, which would be one hour behind, right?

what got me confused is your next sentence

Turn off DST and if your city observed DST, set the Date and Time of the mount by subtracting an hour off current observed UTC offset and add an hour to the local time.

I read this as, set local time in DST and subtract one hour from UTC, so it would be -420 minutes

so which should i do, first instructions, or second instructions?

I have an Ioptron CEM25p it has GPS on it and eventually it overwrites the coordinates to where i am . I am not sure if it also tries to set the time and date as well, so it will over write.

Thank you

jose

W7AY
Posts: 265
Joined: Fri Jan 25, 2019 3:38 am
Location: Portland, Oregon, USA

Re: Never ending Daylight Saving Time Issues

Post by W7AY » Mon Apr 20, 2020 2:07 am

Sorry for being unclear, Jose.

>> I read this as, set local time in DST and subtract one hour from UTC, so it would be -420 minutes

I see where I led you astray :-).

What I meant to say is to follow the three steps that you'd mentioned earlier: (1) switch off Daylight Saving Time, (2) turn the UTC offset back 1 hour (in our cases, to -8 Hours), And (3), look at your watch, subtract 1 hour from it, and enter that time into the mount (i.e., do the opposite of "Spring forward, Fall back").

See if that works. If it had worked in Winter, it should also work now.

By the way, Jose, before I retired in 2005, I used to work for that company at One Infinite Loop. Went to that university in Palo Alto for grad school in 1969, and remained 36 years in your great State. Much better climate than Oregon for astrophotography purposes :-).

Cheers,
Chen

tommy273
Posts: 7
Joined: Sun Mar 03, 2019 10:25 am

Re: Never ending Daylight Saving Time Issues

Post by tommy273 » Mon Apr 20, 2020 8:17 pm

Hello guys,

thanks for all the input, and Chen for taking the time to check this out and explain.

Today I tried to get to the bottom of this. It is clear to me now, that the problem is SkySafari. As long as I only use the mount and ASiair, everything is fine. The RA displayed on the mount is the same as in ASiair. It doesn't matter whether I input the time in DST and the "Y"-flag or the standard time and the "N" flag in the mount, the result is always ok. The calculated time for the meridian flip in ASiair is also always ok. It is just important that the UTC time is not changed on the mount, so in my case UTC +60 Mins has to remain the same during summer and winter time and not corrected (at least that's how it is with the iOptron mount).
As soon as I start up SkySafari, everything goes haywire. ASiair shows strange RA values and in the mount the UTC-Time changes to UTC +120. So that's when the shift of 1 hour occurs. But it is not always the same, the behaviour seems quite erratic, and I haven't found a workaround yet. I guess until this has been fixed, I will not connect SkySafari to the mount anymore. It is not clear to me however, if this issue can be fixed within ASiair or if it has to be resolved in SkySafari. But it would surely be nice if Zwo could get behind this.

Cheers,
Thomas

astronomos
Posts: 9
Joined: Thu Apr 16, 2020 7:24 am

Re: Never ending Daylight Saving Time Issues

Post by astronomos » Thu Apr 30, 2020 8:43 am

Hi Chen,
thanks for the clarification.
I have been doing what you mentioned and so far its been working and I am able to get goto running.

Yes, I live not too far from your previous employment site.

Clear skys and stay safe

stubblejumper
Posts: 47
Joined: Thu Aug 30, 2018 12:01 am

Re: Never ending Daylight Saving Time Issues

Post by stubblejumper » Fri Jul 17, 2020 4:22 am

My CEM25P is set to -480 min (UTC -8) and standard time (I live near Vancouver BC). Yet ASI Air Pro shows UTC -8 and daylight saving time. That's clearly wrong. My initial GoTo's are off by 10-15 deg. That suggests the time may be off by 1 hour.

Don

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