Garmin 62s Sunset Time

[+janandsteve]

I have used several online sunset calculators to determine the sunset time at my location. All tell me 8:30pm for 29 April 2011.

 

I have noticed that the 62s always shows a few min before the times indicated on the online calc sites. Eg tonight my 62s is showing 8:27pm.

 

Any ideas why this may be so? I appreciate that its to do with the algorithm used by the 62s, but based on a few online sites which all agree with each other, the 62s is always wrong. Why?

[yogazoo]

I have used several online sunset calculators to determine the sunset time at my location. All tell me 8:30pm for 29 April 2011.

 

I have noticed that the 62s always shows a few min before the times indicated on the online calc sites. Eg tonight my 62s is showing 8:27pm.

 

Any ideas why this may be so? I appreciate that its to do with the algorithm used by the 62s, but based on a few online sites which all agree with each other, the 62s is always wrong. Why?

 

I wonder if the online calculators factor in elevation, which is an important factor in what time the sun sets. Find a clear view of the horizon and tell us which one was correct?

[+JBnW]

Janandsteve, this is an interesting question, and one I'd like to follow. Can you link your online calculators, and I'll give 'em a try here as well?

[+janandsteve]

I have used several online sunset calculators to determine the sunset time at my location. All tell me 8:30pm for 29 April 2011.

 

I have noticed that the 62s always shows a few min before the times indicated on the online calc sites. Eg tonight my 62s is showing 8:27pm.

 

Any ideas why this may be so? I appreciate that its to do with the algorithm used by the 62s, but based on a few online sites which all agree with each other, the 62s is always wrong. Why?

 

I wonder if the online calculators factor in elevation, which is an important factor in what time the sun sets. Find a clear view of the horizon and tell us which one was correct?

 

Thanks for your reply.

 

The online calculators always use sea level to calc the sunset times, as per the FAQs stated on the ones I have used.

 

As my 62s is always before the actual online times, it would suggest I am below sea level..... but I am above sea level and below 100ft, which is why I thought it strange that the 62s seems to be out????

[+janandsteve]

Janandsteve, this is an interesting question, and one I'd like to follow. Can you link your online calculators, and I'll give 'em a try here as well?

 

Thanks for your reply..... here are some that I tried....

 

http://www.sunrisesunset.com/custom.asp

 

http://www.sunrisesunsetmap.com/

 

http://www.usno.navy.mil/USNO/astronomical-applications/data-services/rs-one-year-world

 

http://www.schoolsobservatory.org.uk/astro/esm/sunrs_uk

 

http://www.dawnsun.net/astro/suncalc/

 

http://www.goflying.org/met/riseset/index.htm

 

Weatherunderground is also another site to check.....

 

I'd be interested to know if your 62s is displaying the same problem.

[yogazoo]

According to the Naval observatory's calculator, which is pretty much inline with other calculator for Sunrise/Sunset times, The Garmin is off. BUT the times vary according to date. Jump ahead and calculate the times for Septembger 1st 2011, you'll see that the Garmin is now a few minutes behind on Sunset and a few minutes ahead on sunrise. I'd be willing to bet Garmin uses some older algorithm which calculates things slightly differently. In a mountainous state such as Montana, it really doesn't matter a whole lot because of the mountainous terrain (objects that artificially raise the horizon).

 

Due to Garmins innacuracy I'm almost willing to write them at their Beta email address and ask them. Maybe a few people should to bring it to their attention. Again, generally not a huge issue unless your hunting and the hunting times are based on the sunrise/sunset times. By the way in Montana, the sunrise/sunset tables in the hunting regulation book jive with those calculators online and NOT with Garmins calculation.

 

Edited to add: Since Garmin's calculation is the outlier compared to ALL other calculators, I wrote them and made them aware of the issue. I would suggest to folks who find this error an annoyance to do the same.

Edited April 29, 2011 by yogazoo

[7rxc]

I'll have to look a bit at this... my old GPS was pretty good at matching them, but it was a marine unit and I think it dealt with MSL All the time... didn't even consider altitude.

 

Which brings me to a suspicion... Could this be related to Time Zone. I'm not sure what the relation would be, but possibly...

the posted time would be for somewhere in the zone near the middle... your observations directly would relate to a 'solar' day.

Time used to be like that before the zoning convention was created. Your local time now is not the same as 'solar', but is the accepted time for the whole zone. This might be some of it. I'm just realizing that it might just be the difference between the GPS and online site you are considering though, not the observed set... There are also differences in the definition of sunset as well.

There is a civil sunset and a navigational sunset for two. Based on the position of the sun disk in relation to the horizon. That definitely bears on the definition of twilight. As observed before, terrain can have effects on the local sunset, if you define that as when the sun disappears from view. Here one side of the valley has set, but the other won't for hours yet... but that isn't factored into sunset time... it's just a local concern.

 

Got to go read some more... fun topic. But I'm not well versed in it anymore.

 

Doug 7rxc

[+JBnW]

Janandsteve, this is an interesting question, and one I'd like to follow. Can you link your online calculators, and I'll give 'em a try here as well?

 

Thanks for your reply..... here are some that I tried....

 

http://www.sunrisesunset.com/custom.asp

 

http://www.sunrisesunsetmap.com/

 

http://www.usno.navy.mil/USNO/astronomical-applications/data-services/rs-one-year-world

 

http://www.schoolsobservatory.org.uk/astro/esm/sunrs_uk

 

http://www.dawnsun.net/astro/suncalc/

 

http://www.goflying.org/met/riseset/index.htm

 

Weatherunderground is also another site to check.....

 

I'd be interested to know if your 62s is displaying the same problem.

 

Again, generally not a huge issue unless your hunting and the hunting times are based on the sunrise/sunset times.

This is precisely my interest in this thread. Our local regs have the sunset/sunrise tables published for Wichita, and then add/subtract a minute for every 15 miles E/W from there. Never really figured out how far E/W from there we were... a LOT more North, so always went by the GPS (76 CSx). Will be very interested to find out how accurate that may be, but the clouds are now rolling in for the weekend, so it may take a few...

[+JBnW]

Well, I have a few minutes to check online posted v. 76 CSx:

 

The Weather Channel +2 minutes

Intellicast +2 minutes

Accuweather No report

Sunrise/sunset.com +1

Calendar updates +2

US Naval Observatory +2

 

Will keep checking. Thanks for creating this thread!

[+mpilchfamily]

I think 7rxc is on the right track. Sunrise/sunset times will vary across a given time zone. There can be up to an hour or more difference from one edge of a time zone to the other. Wouldn't your longitude, how far north/south you are, in that time zone affect that time? So exact sunrise/sunset time could vary based on your longitude, your latitude and altitude in a given time zone.

[+Freestylin]

If both the Garmins sunrise and sunset times are either too early or too late,(not one too early and the other too late) I vote that the Garmin unit does not factor in the "Equation of Time"

 

http://en.wikipedia.org/wiki/Equation_of_time

[+Freestylin]

aaaa

Edited April 30, 2011 by Freestylin

[+jgelliott]

I Think it just depends on what part of the satae you are in. I live in Venture County, Calif. and sunset on my Garmin 62s is at 7:36 PM

[yogazoo]

I think 7rxc is on the right track. Sunrise/sunset times will vary across a given time zone. There can be up to an hour or more difference from one edge of a time zone to the other. Wouldn't your longitude, how far north/south you are, in that time zone affect that time? So exact sunrise/sunset time could vary based on your longitude, your latitude and altitude in a given time zone.

 

The online calculators by NOAA and the Naval Observatory DO factor in your exact location (latitude and longitude). They are percise calculations not simply equivalant of the start of your time zone. Therin lies the problem with Garmin's calculations. They seem to vary for no reason. They also are the outlier in most every comparison.

 

I would suggest to everyone concerned with the aberration to contact garmin's beta email address to apprise them of your concern.

Edited April 30, 2011 by yogazoo

[7rxc]

After some quick refresher reading on the basics...

 

The traditional way of timing sunrise / set was given as... Find the sunrise/set tables and look up the answer...

 

The sunrise /set tables are calculated for the Prime Meridian of Longitude and then adjusted for Latitude and Date.

They are the same for any longitude on a given time/date. They can be determined for a specific location by using the example timess.

These are given for the center meridian of each time zone. Points east or west of that have to adjust for the difference in longitude. So much per degree up to either boundary meridian...

 

Now this is a shortened version of several sources, but Wikipedia has a lot on it. I tried to reduce it to essentials, not details.

A time zone is 15 degrees of longitude and takes about 1 hour to span... half would be 7.5 degrees or about 450 minutes/30 = 15 minutes of Longitude per minute of rotation. Whew!

 

So you adjust 1 minute per 15 minutes of longitude E or W regardless of latitude (ignore the polar regions though).

 

Anyway, the real problem will be with how Garmin or any GPS handles the calculation... as a lookup table of a real almanac, or derived from the satellite broadcasts (there is a lot of information available there) It would only take one sample(at 0,0 LL)

to give the whole world each day roughly. Or does the GPS work out it's own position and calc from that... perhaps just modifying the Sea Level readings for Altitude. Hard to say. but I am willing to bet for hunters etc. that the conservation officer / ranger or whatever you call them will simply enforce based on THEIR GPS READING plus/minus a fudge factor. That would be the practicable method for what you describe the need to be. Besides which it is constantly different per location anyway as they move.

 

That's almost enough for me... best bet ASK one of the enforcers what they accept... THEY might ask YOU what it is.

 

Doug 7rxc

[yogazoo]

I agree with most of the above statement. A few minutes here or there isn't going to matter. Sunrise/Sunset isn't a big deal as long as it's close, which it is. It's just wierd that Garmin is the outlier compared with autorities on the matter such as NOAA and the Naval Observatory. It does make me curious as to WHY though. Are there alternate methods of calculating this data and why does Garmin choose one way vs most every one else.

 

As far as the hunting enforcement goes, for me, it's a matter of ethics. My intention is not to preach from the pulpit here, as I've interpreted some hunting regulations toward the liberal end but a time is a time (atomic watches are always dead-on) I'll always go by the reg book down to the second on shooting times. I've had plenty of opportunities with just minutes till shooting light. I won't even rely on my Garmin for this data due to the few minutes error it usually gives vs the regulation book (which matches exactly with NOAA and the Naval Observatory by the way). True, the warden probably wouldn't give it a second thought but in my mind I would know that I didn't follow the rules. With enough unethical yahoos perpetrating even worse infractions, fudging by even a minute would be a difficult thing to justify in my mind.

[+janandsteve]

Thanks to all who have replied.

 

The 62s does change the sunset time if I move East/West within the same time zone, suggesting that it calculates the sunset from its sat position fix.

 

email already with the beta team at time of original post.

 

Please email them so that we can get this sorted for everyone...... 62-78Beta@garmin.com

 

Thanks for the support and interest.

[+Ground Buzzard]

Thanks to all who have replied.

 

The 62s does change the sunset time if I move East/West within the same time zone, suggesting that it calculates the sunset from its sat position fix.

 

email already with the beta team at time of original post.

 

Please email them so that we can get this sorted for everyone...... 62-78Beta@garmin.com

 

Thanks for the support and interest.

[+Ground Buzzard]

Thanks to all who have replied.

 

The 62s does change the sunset time if I move East/West within the same time zone, suggesting that it calculates the sunset from its sat position fix.

 

email already with the beta team at time of original post.

 

Please email them so that we can get this sorted for everyone...... 62-78Beta@garmin.com

 

Thanks for the support and interest.

 

I think Garmin simplifies the SR/SS calculation by omitting the correction for atmospheric refraction. In temperate latitudes, this has the effect of making the sunrise too late by about 3 minutes (the exact amount depends on latitude), and the sunset too early by the same amount. Atmospheric refraction always has the effect of "lifting" objects outside the atmosphere by a small amount.

[+janandsteve]

An interesting observation today.....

 

I performed a test comparison between my Garmin 62s and my OLD yellow ETREX from late 2002 - basic yellow without WASS. Todays accuracy on the ETREX was 21ft and that of the 62s was 10ft - so nothing that would make a huge difference to my 'location' and therefore the sunset times should be comparible.

 

Based on http://www.csgnetwork.com/sunriseset.html tonights sunset will be 8:34pm

 

Garmin 62s: 8:30pm

 

2002 ETREX: 8:33pm

 

+/- 1 digit is acceptable and therefore I conclude that my OLD ETREX from 2002 is ACCURATE and my GARMIN 62s is WRONG.

 

This means that Garmin DOES know the 'correct' sunset formula, so why the discrepancy in the 62s?

[+StarBrand]

Wow - 20 posts and not one person actually mentions going out on their deck and watching the sunset and noting the time on the unit as a comparison. Just differences with other calculations......

[xyzee]

My Magellans show sunset 2 min later than the Garmins do.

 

Non of us youngsters had watches back in the thirtys, and a lot of the adults didn't either. If close to a town, there was the fire station siren at noon, and the church bells on Sunday. Some lucky people had an AM radio at home, or a wind up alarm clock to go by. And there was Ma ringing the bell when it was time for lunch or supper, if you were close enough to hear it. So sunrise was when you could see the sun, and sunset was when it had dropped over the hill. Today, it's much the same for me, as the terrain east and west of me is very uneven, and sunset can be off several, or many minutes from the official set time. The GPS time was a good ballpark time for me to go by, home or elsewhere.

[+JBnW]

Wow - 20 posts and not one person actually mentions going out on their deck and watching the sunset and noting the time on the unit as a comparison. Just differences with other calculations......

but the clouds are now rolling in for the weekend, so it may take a few...

[yogazoo]

I can't find a single online calculator of SR/SS times that agrees with Garmin. In fact they are all mostly the same EXCEPT Garmin.

 

Bottom Line: For $450 (plus $200 in accessories/maps) I don't want "close enough", I don't want an outlier, I want an electronic device that is as accurate as possible in every regard. Why is that too much to ask? Close enough is good enough unless of course it's a feature YOU think is important.

 

What would it take, 30 minutes for a programmer to edit that part of the code that contains the equation?

[+dfx]

What would it take, 30 minutes for a programmer to edit that part of the code that contains the equation?

 

Probably not even that much. However, the question is: who is right? Maybe the Garmin is right and everybody else is wrong? Or maybe they're all right and it's just a matter of definition?

[yogazoo]

Probably not even that much. However, the question is: who is right? Maybe the Garmin is right and everybody else is wrong? Or maybe they're all right and it's just a matter of definition?

 

That's a good point and great question. However I'd probably go with the definition prescribed to by NOAA and the Naval Observatory (and just about everyone else) before I'd go with Garmin. Call me crazy.

Edited May 2, 2011 by yogazoo

[+janandsteve]

I can't find a single online calculator of SR/SS times that agrees with Garmin. In fact they are all mostly the same EXCEPT Garmin.

 

Bottom Line: For $450 (plus $200 in accessories/maps) I don't want "close enough", I don't want an outlier, I want an electronic device that is as accurate as possible in every regard. Why is that too much to ask? Close enough is good enough unless of course it's a feature YOU think is important.

 

What would it take, 30 minutes for a programmer to edit that part of the code that contains the equation?

AGREE. Thanks for the support.

[+Freestylin]

Like Ground Buzzard has said about the refraction, Garmin is likely taking a purely mathematical approach to the problem of sunrise/sunset based on spherical trigonometry.

 

When you have a good horizon, like when at sea, the sun is at a right angle to your zenith when it's lower limb is about 2/3's from the visible horizon. It is quite possible that the garmin unit uses that time as sunset since the sun is mathematically setting at that time.

 

Additionally it is possible that the unit does not take into account the difference between apparent solar time and mean solar time. (see equation of time)

 

To get it all correct the unit would have to have some additional almanac information which Garmin has probably ignored.

Likely the response will be "It's a consumer grade product"

[+StarBrand]

I can't find a single online calculator of SR/SS times that agrees with Garmin. In fact they are all mostly the same EXCEPT Garmin.

 

Bottom Line: For $450 (plus $200 in accessories/maps) I don't want "close enough", I don't want an outlier, I want an electronic device that is as accurate as possible in every regard. Why is that too much to ask? Close enough is good enough unless of course it's a feature YOU think is important.

 

What would it take, 30 minutes for a programmer to edit that part of the code that contains the equation?

Just out of curiosity, I checked my Oregon and Colorado today at sunset.

 

The sun actually set right at the time indicated by the units. Close enough for me!!

[+janandsteve]

Like Ground Buzzard has said about the refraction, Garmin is likely taking a purely mathematical approach to the problem of sunrise/sunset based on spherical trigonometry.

 

When you have a good horizon, like when at sea, the sun is at a right angle to your zenith when it's lower limb is about 2/3's from the visible horizon. It is quite possible that the garmin unit uses that time as sunset since the sun is mathematically setting at that time.

 

Additionally it is possible that the unit does not take into account the difference between apparent solar time and mean solar time. (see equation of time)

 

To get it all correct the unit would have to have some additional almanac information which Garmin has probably ignored.

Likely the response will be "It's a consumer grade product"

 

See my earlier post.

My 'consumer grade' yellow Etrex from 2002 shows the sunset time accurately based on online comparisons. My 62s is WRONG.

Garmin know the 'true' calculation, so why change it for the 62s?

Almost 10 years on and they seem to have gone backwards....

[+Ground Buzzard]

Like Ground Buzzard has said about the refraction, Garmin is likely taking a purely mathematical approach to the problem of sunrise/sunset based on spherical trigonometry.

 

When you have a good horizon, like when at sea, the sun is at a right angle to your zenith when it's lower limb is about 2/3's from the visible horizon. It is quite possible that the garmin unit uses that time as sunset since the sun is mathematically setting at that time.

 

Additionally it is possible that the unit does not take into account the difference between apparent solar time and mean solar time. (see equation of time)

 

To get it all correct the unit would have to have some additional almanac information which Garmin has probably ignored.

Likely the response will be "It's a consumer grade product"

 

This thread seems to have taken on a life of its own. Since I have over 40 years experience as a professional astronomer (and now am retired), I feel my qualifications might be of some value to the discussion.

 

FIRST POINT: The entire algorithm for calculating sunset/sunrise times, in excruciating detail, can be found on Wikipedia under "Sunrise Equation". This, or another not significantly different, is the procedure the Naval Observatory uses. It is totally standard stuff. It does assume that the observer is at sea level, that his horizon is exactly 90° from the zenith (in other words, that his horizon lies in a precisely horizontal plane), and that standard meteorological conditions prevail. Any deviation from these ideal conditions will introduce a modest error in the result. Such error will increase with increasing distance from the equator, and can become quite significant at latitudes above, say, 50°.

 

SECOND POINT: Contributions to this thread suggest that Garmin units of different ages give age-dependent differences in SR/SS times. In order to see for myself what the effect might be, I rounded up 9 different Garmin hand-held units, differing in age over a range in excess of 10 years. Specifically, these were the following, with their approximate years of manufacture: (1) eMap (1999), (2) GPS III Plus (1999), (3) GPSMAP 76S (2002), (4) Geko 301 (2005), (5) Etrex Legend HCx (2008), (6) Etrex Vista (2009), (7) GPSMAP 60CSx (2006), (8) Foretrex 401 (2010), and Oregon 550t (2010). Today, I ran each one of these at my residence, and noted what the SR/SS times were from each unit for today (3 May 2011). Every last one (NO EXCEPTIONS!) gave sunrise at 06:13 MDT and sunset at 19:52 MDT. These can be compared with the results computed from the standard algorithm (FIRST POINT, above): sunrise at 06:13:14 MDT, sunset at 19:53:18 MDT. I see no meaningful difference from the result given by all the Garmin units.

 

THIRD POINT: In my earlier post, I suggested that Garmin might be omitting allowance for atmospheric refraction. I no longer see any justification for this suggestion, and I hereby withdraw it.

 

FOURTH POINT: I don't see any reason to stomp on Garmin's SR/SS calculations. I don't know how to account for the discrepancies reported by others.

 

End of diatribe!

[+Red90]

Just tested my Colorado 300 and it matches up with the online calculators here in Calgary.

[+janandsteve]

Firstly, thank you for taking the time to reply to my thread.

 

This thread seems to have taken on a life of its own.

How?

 

Since I have over 40 years experience as a professional astronomer (and now am retired), I feel my qualifications might be of some value to the discussion.

I'll read on.... respect.

 

FIRST POINT: The entire algorithm for calculating sunset/sunrise times, in excruciating detail, can be found on Wikipedia under "Sunrise Equation". This, or another not significantly different, is the procedure the Naval Observatory uses. It is totally standard stuff. It does assume that the observer is at sea level, that his horizon is exactly 90° from the zenith (in other words, that his horizon lies in a precisely horizontal plane), and that standard meteorological conditions prevail. Any deviation from these ideal conditions will introduce a modest error in the result. Such error will increase with increasing distance from the equator, and can become quite significant at latitudes above, say, 50°.

Totally standard stuff - I agree.

 

SECOND POINT: Contributions to this thread suggest that Garmin units of different ages give age-dependent differences in SR/SS times. In order to see for myself what the effect might be, I rounded up 9 different Garmin hand-held units, differing in age over a range in excess of 10 years. Specifically, these were the following, with their approximate years of manufacture: (1) eMap (1999), (2) GPS III Plus (1999), (3) GPSMAP 76S (2002), (4) Geko 301 (2005), (5) Etrex Legend HCx (2008), (6) Etrex Vista (2009), (7) GPSMAP 60CSx (2006), (8) Foretrex 401 (2010), and Oregon 550t (2010). Today, I ran each one of these at my residence, and noted what the SR/SS times were from each unit for today (3 May 2011). Every last one (NO EXCEPTIONS!) gave sunrise at 06:13 MDT and sunset at 19:52 MDT. These can be compared with the results computed from the standard algorithm (FIRST POINT, above): sunrise at 06:13:14 MDT, sunset at 19:53:18 MDT. I see no meaningful difference from the result given by all the Garmin units.

Thank you for taking the time to perform these extensive tests, which conclude without doubt that all previous Garmin units tie in with the 'standard calculations' and those of the online sites. This just gives us more evidence that the 62s is WRONG and needs reprogramming with the 'correct' formula, so that this 'top-of-the-line' flagship model is as accurate as its predecessors.

 

Not too sure of the dates on (1) & (2) above from 1999, as "Selective Availability" was discontinued On May 2, 2000 - unless of course they were military spec.

 

THIRD POINT: In my earlier post, I suggested that Garmin might be omitting allowance for atmospheric refraction. I no longer see any justification for this suggestion, and I hereby withdraw it.

I didnt think this was the case, hence why I didnt reply to your previous post. My simple comparison between my yellow etrex from 2002 ( ties in with the standard calculation and online sites ) and my flagship 62s model from 2009 gave me enough confidence that the 62s is WRONG and needs reprogramming with the correct formula.

 

FOURTH POINT: I don't see any reason to stomp on Garmin's SR/SS calculations. I don't know how to account for the discrepancies reported by others.

With the conclusions from your extensive testing ( thanks again ) and the forum posts by others on this thread, it is easy to account for the discrepancy - the 62s simply isnt programmed with the correct formula. This is also backed up from my own simple test with my yellow etrex from 2002.

 

I see every reason to 'stomp' on Garmins formula, as you have concluded yourself, it is simply NOT RIGHT for the flagship model - the 62s.

 

End of diatribe!

Not for me it's not.... and I guess for others who want it correcting, it wont be either. Close enough is just not good enough, when you have proved beyond doubt that Garmin do in fact know the correct formula, otherwise those units that you tested would be wrong as well.

 

I do not find any of my posts bitter or abusive in nature. I just simply want whats right and I guess others do too.....

Edited May 4, 2011 by janandsteve

[+dfx]

Thank you for taking the time to perform these extensive tests, which conclude without doubt that all previous Garmin units tie in with the 'standard calculations' and those of the online sites. This just gives us more evidence that the 62s is WRONG and needs reprogramming with the 'correct' formula, so that this 'top-of-the-line' flagship model is as accurate as its predecessors.

 

I would assume that the 62 gives exactly the same times are the Oregon 550 (which was mentioned) as they run essentially the same software.

[+janandsteve]

Thank you for taking the time to perform these extensive tests, which conclude without doubt that all previous Garmin units tie in with the 'standard calculations' and those of the online sites. This just gives us more evidence that the 62s is WRONG and needs reprogramming with the 'correct' formula, so that this 'top-of-the-line' flagship model is as accurate as its predecessors.

 

I would assume that the 62 gives exactly the same times are the Oregon 550 (which was mentioned) as they run essentially the same software.

Refering back to previous posts, the 62/s is off for a few of us, so not too sure why the 550 is correct.....

[+dfx]

Refering back to previous posts, the 62/s is off for a few of us, so not too sure why the 550 is correct.....

 

If you tell me your approximate location, I can tell you what times my 450 reports.

[+janandsteve]

Refering back to previous posts, the 62/s is off for a few of us, so not too sure why the 550 is correct.....

 

If you tell me your approximate location, I can tell you what times my 450 reports.

Thanks for agreeing to do this for me.

I'm from Doncaster in the UK: 53°31.611'N, 1°07.990'W

My 62s is showing 8:36pm for 4th May 2011.

http://www.srrb.noaa.gov/highlights/sunrise/sunrise.html is showing 8:39pm

http://www.goflying.org/met/riseset/index.htm is showing 8:40pm

My yellow etrex from 2002 shows 8:40pm

 

It would be good to see what the 450 reports.

 

Thanks.

Steve

[+Red90]

...it is simply NOT RIGHT for the flagship model - the 62s.

 

The 62 is just one of the handheld models. It is not the "flagship" model.

 

As stated, the firmware and calcs are most likely the same in the x50 Oregons as the 62, so there is something more to this. Perhaps there is something wrong with your unit or you are doing something wrong.

[+janandsteve]

The 62 is just one of the handheld models.

Here's me thinking it was the only one Garmin did....

 

It is not the "flagship" model.

GARMIN's claim not mine. I was merely pointing out that their 'top-of-the-line' model should be accurate.

 

As stated, the firmware and calcs are most likely the same in the x50 Oregons as the 62, so there is something more to this. Perhaps there is something wrong with your unit or you are doing something wrong.

Others have reported similar probs - maybe its a batch thing.....

What can I be doing wrong? You just read the data field.......

[+dfx]

Thanks for agreeing to do this for me.

I'm from Doncaster in the UK: 53°31.611'N, 1°07.990'W

My 62s is showing 8:36pm for 4th May 2011.

http://www.srrb.noaa...se/sunrise.html is showing 8:39pm

http://www.goflying....seset/index.htm is showing 8:40pm

My yellow etrex from 2002 shows 8:40pm

 

It would be good to see what the 450 reports.

 

Running the latest beta firmware version. Using GPS simulator mode to put myself in your location, it shows me the same as you see on the 62, sunrise at 5:26 and sunset at 20:36. Funny enough, with GPS demo mode off and using the "search near" thingie of the sun/moon screen and picking the same location, I get the sunrise 2 minutes earlier and the sunset 1 minute later, but showing in the local time zone. But that's probably just a time zone thing, when I pick May 3rd using this method, I get the same values again.

[+janandsteve]

Thanks for agreeing to do this for me.

I'm from Doncaster in the UK: 53°31.611'N, 1°07.990'W

My 62s is showing 8:36pm for 4th May 2011.

http://www.srrb.noaa...se/sunrise.html is showing 8:39pm

http://www.goflying....seset/index.htm is showing 8:40pm

My yellow etrex from 2002 shows 8:40pm

 

It would be good to see what the 450 reports.

 

Running the latest beta firmware version. Using GPS simulator mode to put myself in your location, it shows me the same as you see on the 62, sunrise at 5:26 and sunset at 20:36. Funny enough, with GPS demo mode off and using the "search near" thingie of the sun/moon screen and picking the same location, I get the sunrise 2 minutes earlier and the sunset 1 minute later, but showing in the local time zone. But that's probably just a time zone thing, when I pick May 3rd using this method, I get the same values again.

 

Thanks for confirming that this seems to be an issue across the range of 62 and 400 series. Wonder if the 500 series is indeed the same or has that got the 'correct' formula, considering the test result pasted earlier in the thread.

 

Garmin replied back within the last hour ( they have had my email for a while, but appreciate they will be busy with the latest software feedback ) and they confirm that they will look into why there is a descrepancy.

 

Thanks again for the confirmation.

[+dfx]

Thanks for confirming that this seems to be an issue across the range of 62 and 400 series. Wonder if the 500 series is indeed the same or has that got the 'correct' formula, considering the test result pasted earlier in the thread.

 

The 450 and 550 run exactly the same firmware.

[+janandsteve]

Thanks for confirming that this seems to be an issue across the range of 62 and 400 series. Wonder if the 500 series is indeed the same or has that got the 'correct' formula, considering the test result pasted earlier in the thread.

 

The 450 and 550 run exactly the same firmware.

This been the case, I dont understand GroundBuzzard's post and results as below, with ref to the 550t.....

 

..... I rounded up 9 different Garmin hand-held units.....Oregon 550t (2010)....I ran each one of these at my residence, and noted what the SR/SS times were from each unit for today (3 May 2011). Every last one (NO EXCEPTIONS!) gave sunrise at 06:13 MDT and sunset at 19:52 MDT. These can be compared with the results computed from the standard algorithm (FIRST POINT, above): sunrise at 06:13:14 MDT, sunset at 19:53:18 MDT. I see no meaningful difference from the result given by all the Garmin units.

 

I cannot see it been a location thing - one of the other posters on here tried their 62s in the US ( Montana ) and they get the same discrepancies as what I do. Your tests also confirm the difference.... so I wonder why Mr Buzzard gets his bang on?.....maybe he can enlighten us?

Edited May 4, 2011 by janandsteve

[yogazoo]

I think Groud Buzzard has the question wrong. He compared multiple units and got the same SS/SR times. That isn't the point of contention here. The problem is that Garmins calculation (I'll assume used on all models) isn't in line with the NOAA, Naval Observatory, and just about every other precision calculator out there. NOAA in particular has an excellent interface which allows you to zoom in on your exact location with Google Maps (very spatially precise). Based on this descrepancy with SS/SR times compared to calculators that DO take into account the refraction equation I'll go ahead and predict that the refraction equation isn't figured into Garmins results.

 

I received an email from Garmin and they are looking into why the calculations are different and why the calculation difference varies depending on the day. Garmins team of programmers is very good at communication these days and very attentive at addressing issues users have. I would expect a correction to the calculation in the next release.

[+janandsteve]

I think Groud Buzzard has the question wrong. He compared multiple units and got the same SS/SR times. That isn't the point of contention here. The problem is that Garmins calculation (I'll assume used on all models) isn't in line with the NOAA, Naval Observatory, and just about every other precision calculator out there. NOAA in particular has an excellent interface which allows you to zoom in on your exact location with Google Maps (very spatially precise). Based on this descrepancy with SS/SR times compared to calculators that DO take into account the refraction equation I'll go ahead and predict that the refraction equation isn't figured into Garmins results.

 

I received an email from Garmin and they are looking into why the calculations are different and why the calculation difference varies depending on the day. Garmins team of programmers is very good at communication these days and very attentive at addressing issues users have. I would expect a correction to the calculation in the next release.

Thanks for the continued positive feedback.

 

I too had an email from Garmin today confirming they are looking into the differences, so I too hope that the correction is made in the next release.

 

Still strange why Mr Buzzard claims his 550t is bang on when others are reporting the issue. Maybe he has the special professional astronomer version......

[+Red90]

I think Groud Buzzard has the question wrong. He compared multiple units and got the same SS/SR times. That isn't the point of contention here. The problem is that Garmins calculation (I'll assume used on all models) isn't in line with the NOAA, Naval Observatory, and just about every other precision calculator out there.

 

Ummm, no.... He clearly stated that the times matched the NOAA calculation exactly.

[yogazoo]

I think Groud Buzzard has the question wrong. He compared multiple units and got the same SS/SR times. That isn't the point of contention here. The problem is that Garmins calculation (I'll assume used on all models) isn't in line with the NOAA, Naval Observatory, and just about every other precision calculator out there.

 

Ummm, no.... He clearly stated that the times matched the NOAA calculation exactly.

 

Ummm, no.... He clearly states "no meaningful difference". That to me isn't the definition of "exactly". The definition of "meaningful" is entirely subjective.

Edited May 4, 2011 by yogazoo

[+Red90]

That to me isn't the definition of "exactly". The definition of "meaningful" is subjective.

 

He gave ACTUAL NUMBERS to the second. Man you like to argue for no reason, don't you.

[yogazoo]

After looking for days with greater than a two minute deviance (which seems to be standard for my location)I found that on April 6th, 2011 has a three minute difference in sunset and 1 minute in sunrise.

 

Go to the following link and check out your location for this day.

NOAA improved Sunset / Sunrise Calculator

 

There may be differences with regards to specific latitudes but one thing is clear, Garmin doesn't use the same equation or perhaps rounds a value somewhere along the line when they shouldn't.

 

With regards to what is "significant" error? I don't know the answer, what's significant to one may not be for another. Like other noted errors in Garmin calculations such as Trip Odometer vs Tracklog etc, the differences may bother some people more than others. I would say however that in all cases the individual is entitled to request of Garmin to improve upon certain calculations to increase accuracy based on a certain set of standards.

[yogazoo]

"He gave ACTUAL NUMBERS to the second."

 

Yeah, and they don't match "exactly". What's more is that if you calculate using different dates the error can be as much as four minutes.

 

From a purely mathematical perspective the numbers don't match even if you round the final results. Mathematically speaking the numbers are different therefore the equation is different and does not match the equation used by NOAA or the Naval Obervatory.

 

If you we're using the calculator function on your unit and input 2+2 and received an answer of 3.95 wouldn't you be concerned? I mean it's close, but who want's to nitpick right?

Edited May 4, 2011 by yogazoo