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kevinboone / solunar_cmdline

Command-line utility for displaying solar and lunar ephemera
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sun set times are off by a three minutes(compared to NOAA website and other libraries). #3

Closed mb12 closed 5 years ago

mb12 commented 6 years ago

Steps to reproduce:

  1. Run solunar like this. ./solunar -s -l 37.33085,-121.880779 -d "31/01/2018"

It shows the following: Sunrise: 07:11 Sunset: 17:28

the sunset time should be 17:31, which is what the NOAA website shows.

https://www.esrl.noaa.gov/gmd/grad/solcalc/

Additional Info

1.) It looks like a bug because it seems to be always off by 3 minutes.

2.) I also tried the following utility. Its sunset time always matches the NOAA one.

https://sourceforge.net/projects/solunar/?source=typ_redirect

kevinboone commented 6 years ago

Hi

I just fixed a bug that was causing sunset times to be 2-3 minutes too early. The cases I tried were now within a minute of figures published by the BBC, which is what I test against. Sorry about that -- slip of the fingers. I just pushed the changes to the github repository.

I don't think it's realistic to expect sunrise/set times to agree to closer than a minute or so. A difference of that magnitude could be accounted for by differences in rounding, for example. At the same time, however, I am aware of the fact that I am using algorithms and data that were published in the 70s. If the results of my code are consistently different by more than a minute or two from other reliable sources, I will have to consider upgrading the math. However, that will be a pain, and I don't want to do it unless I have to.

Best wishes Kevin

On Wed, Jan 31, 2018 at 1:40 AM, mb12 notifications@github.com wrote:

Steps to reproduce:

  1. Run solunar like this. ./solunar -s -l 37.33085,-121.880779 -d "31/01/2018"

It shows the following: Sunrise: 07:11 Sunset: 17:28

the sunset time should be 17:31, which is what the NOAA website shows.

https://www.esrl.noaa.gov/gmd/grad/solcalc/ Additional Info

1.) It looks like a bug because it seems to be always off by 3 minutes.

2.) I also tried the following utility. Its sunset time always matches the NOAA one.

https://sourceforge.net/projects/solunar/?source=typ_redirect

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kevinboone commented 5 years ago

Since I've not heard anything else on this matter, closing the issue now.