Author Topic: Sunrise/Sunset Times  (Read 8595 times)

wetterdale

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Sunrise/Sunset Times
« on: July 29, 2012, 02:53:38 AM »
Just converted over from LWC and all is great except one little thing that is driving me crazy.  My sunrise and sunset times are off by about 20 minutes.  I have triple checked my coordinates, verified that I have entered them correctly, N, W, etc.  Verified the coordinates from other sources on WWW and I just can't find the error.  It's has to be me if nobody else is having errors but i am at wits end here.  Any input would be appreciated.  Punkeydoodles Corners is in Ontario, Canada.  Go Canada Go.  [cheer] [cheer] [cheer]

One more thing, when I enter 80 for longitude, WC changes it to 080.  But accepts the 43 fine without changing it to 043?  Is this a clue?  I attached a screen shot.

Dale




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Stu's on vacation (Re: Sunrise/Sunset Times)
« Reply #1 on: July 29, 2012, 03:04:38 AM »
Hi Dale and WeatherCat fans,  [cat]

Welcome to the WeatherCat forum and so glad you've switched to da' cat!!  [bounce]

Nonetheless, we all know that all work and no play makes for a very unhappy Stu (Stuart Ball, developer of WeatherCat.)

So he is on vacation at the moment.  He should be back in about a week or so.  Hope you don't go stark raving mad in that time!  [goofy]

Cheers, Edouard  [cheers1]

Steve

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Re: Sunrise/Sunset Times
« Reply #2 on: July 29, 2012, 03:48:11 AM »
One more thing, when I enter 80 for longitude, WC changes it to 080.  But accepts the 43 fine without changing it to 043?  Is this a clue?  I attached a screen shot.

Hi Dale, and welcome to the WeatherCat forum!

A couple of us have seen differences in sunrise/sunset that is unexplainable, but not as much as you are seeing. Mine is only off by a couple of minutes, even thought everything is set correctly. Stu might have some suggestions when he returns.

As far as the leading zero, that's easily explained. Latitude can be as much as 180˚, so three places is normal, where longitude can only be as high as 90˚ (for Santa) so no leading zero needed.

Steve
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wetterdale

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Re: Sunrise/Sunset Times
« Reply #3 on: July 29, 2012, 03:24:09 PM »
Hi Guys:

Steve, you are only about 200 km from me so this created the opportunity for a little experiment.

Me, near Punkeydoodles Corners, Ontario
Google Maps: 43.3351 -80.7554 AKA 43?20.11' -80?45.32'
WeatherCat sunrise 5:52 sunset 20:29
The Weather Network sunrise 6:11 sunset 20:48 Link: http://www.theweathernetwork.com/weather/CAON0674
NOAA sunrise 6:10 sunset 20:48 Link: http://www.esrl.noaa.gov/gmd/grad/solcalc/

You, near Avon, Ohio
Google Maps: 41.4529 -82.0347 AKA 41?27.17' -82?2.08'
WeatherCat sunrise 6:02 sunset 20:30
The Weather Network sunrise 6:19 sunset 20:47 Link: http://www.theweathernetwork.com/weather/usoh1195
NOAA sunrise 6:21 sunset 20:48 Link: http://www.esrl.noaa.gov/gmd/grad/solcalc/

So I would conclude Steve that you have the same thing going on as I do.  The discrepancy also seems to be about 15-20 minutes.  The Weather Network Site probably picks up the closest major city so it is likely only approximate, but it is much closer to the NOAA calculator than WC.  What do you think?

Dale

WxOwl

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Re: Sunrise/Sunset Times
« Reply #4 on: July 29, 2012, 07:31:22 PM »
Hello Dale and All

Just converted over from LWC and all is great except one little thing that is driving me crazy.  My sunrise and sunset times are off by about 20 minutes.  I have triple checked my coordinates, verified that I have entered them correctly, N, W, etc.

Since about half-way through the early beta testing of WeatherCat I've had a constant 15 minute offset to the west in my sunrise/sunset times. Strangely, this only occurs on one computer. Loading the same program onto another nearly identical iMac produces the correct times. In fact I've run WeatherCat on three other Macs without error. Also the error is not present when looking at the UTC time of s/s - only when converted to local time.  Even tried deleting all the WC files I could find and then reloading a clean copy, but there it was again!

I am not too interested in the sunrise/sunset times in Kankakee, Illinois and would rather see the time at my location in northeast Indiana.  Hopefully someone will suggest a solution to this and help preserve our sanity.

Regards,
Dave

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Re: Sunrise/Sunset Times
« Reply #5 on: July 30, 2012, 02:30:42 AM »

You, near Avon, Ohio
Google Maps: 41.4529 -82.0347 AKA 41?27.17' -82?2.08'
WeatherCat sunrise 6:02 sunset 20:30
The Weather Network sunrise 6:19 sunset 20:47 Link: http://www.theweathernetwork.com/weather/usoh1195
NOAA sunrise 6:21 sunset 20:48 Link: http://www.esrl.noaa.gov/gmd/grad/solcalc/

Hi Dale,

Interesting results! Your location for me is close. I'm at 41˚ 26.21'N, 82˚ 2.86' W
However, WeatherCat calculates my surprise/sunset for today (July 29) as 06:23 and 20:51, 21 minutes different than what you calculated. This seems to be the trend here in our testing. Everyone gets a different answer to the same calculation!

Steve
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wetterdale

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Re: Sunrise/Sunset Times
« Reply #6 on: July 31, 2012, 01:57:14 AM »
Thanks for your feedback folks.  Well this thread certainly hasn't gone in the direction that I thought it would!  Very interesting.  I guess the only solution for me at this point is to buy a new Mac!   [bounce] [bounce] [bounce]

evans.matt

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Re: Sunrise/Sunset Times
« Reply #7 on: September 03, 2012, 06:33:11 PM »
Hi fellow Weathercatters, did this issue ever get resolved for you?  I too am having difficulty figuring out why the sunrise and sunset times are off by about 7 minutes for me.  I have compared the results of Weathercat to several different sources and while the 3rd party sources are all in agreement, Weathercat seems to be off by about 7 minutes.  I should mention that the length of sunlight seems to be correct though.  It looks like at least one person switched computers to fix.  Unfortunately, I can't switch servers, I only have one! 

Here's a dumb question, does elevation play into the calculation?

Thanks!

188.4 m
40? 36.217' N
122? 21.180' W

Weathercat:  Sunrise 6:46 am, Sunset 7:44 pm
Weatherunderground (and other 3rd parties):  6:39 am, Sunset 7:37 pm

wetterdale

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Re: Sunrise/Sunset Times
« Reply #8 on: September 04, 2012, 12:45:24 AM »
Hi Matt: 

No I haven't found or heard of a solution as of yet.

Dale

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Re: Sunrise/Sunset Times
« Reply #9 on: September 04, 2012, 04:26:51 AM »
Nope, still screwy. My WeatherCat sunrise/sunset is different than the Davis VP2 Console and several other local sources.

Steve
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WxOwl

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Re: Sunrise/Sunset Times
« Reply #10 on: September 04, 2012, 08:32:19 PM »
HI Matt, Dale, Steve and others with s/s errors

I spent part of the past weekend moving WeatherCat to a new (to me-although used) Mac Mini Server. The sunrise /sunset times are now right on with the VP2, WU, NOAA, etc. Still don't know why the 27" iMac insisted on adding 15 minutes to the times.  All other WC conversions from UTC to local time seemed to be correct. I'm going to continue to pursue the problem however.

(Note: There really were reasons other than getting s/s times correct that lead to the new machine for the weather station.)http://athena.trixology.com/Smileys/default/biggrin.gif

Here's a dumb question, does elevation play into the calculation?
188.4 m
40? 36.217' N
122? 21.180' W

Matt: Unless you are an astronomer or celestial navigator, or live at very high altitude, you can ignore the effect of elevation on the sunrise/sunset time calculation. For your elevation of 188.4 meters the change of time from the usual mean earth calculation would be sunrise earlier and sunset later by about 8 seconds. Roughly the effect is about 1 minute per 1500 meters of elevation.

Regards,
Dave

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Re: Sunrise/Sunset Times
« Reply #11 on: September 04, 2012, 09:28:32 PM »
For what it's worth; sunrise and sunset are respectively 1 and 2 minutes off for me - which is negligible. Still a bit strange though... Is WC picking this up from the VP2 console (which would seem logical to me)?

I'm running WC 1.02 on a 4 month old Mac Mini with Lion (10.7.4) and am located in the Netherlands.

Jos

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Re: Sunrise/Sunset Times
« Reply #12 on: September 04, 2012, 11:47:49 PM »
My WC Sunrise/Sunset times are a minute off today, other times i have checked and they have been spot on.
Perhaps something to do with the way it rounds the seconds up or down to the nearest minute?

I'm happy with it.

What distance would a station need to be from the official coordinates  to effect a 1 minute change?

Tony

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Re: Sunrise/Sunset Times
« Reply #13 on: September 05, 2012, 12:18:18 AM »
Hi WeatherCat Gang
 My Sunrise and Sunset at Weather Underground on the forecast page is correct but on the current conditions page it is off by 1 minute so there must be something going on at WU
 [cheers1]


Update: My forecast page at WU is from the city closest to me which is 3 miles to the East and is correct
             But my current conditions page is from the city from my zip code which is 20 miles to the west           of my station which is off by 1 minute so this could be the reason why they are off by minutes


How far are you from the city which is your zip code in?
 [cheers1] [cheers1]

sportshoes

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Re: Sunrise/Sunset Times
« Reply #14 on: November 25, 2012, 02:45:10 AM »
With respect to Dale's original post. I too am in Ontario. I'm SE of his location and my Sunrise/Sunset times are also 20 minutes early on WeatherCat. Has anyone figured this out?

Thanks