WeeWX Returning Moon phase as Full when it should be Waning Gibbous

[Steeple Ian]

It has been noticed that moon phase is still showing as Full when it has been Waning Gibbous since November 16.

            <td class="label">Phase</td>
            <td class="data">Full<br/>
              94% full</td>

[Steeple Ian]

This was a fresh clean install of 5.1 using pip into RaspberryPI OS Bookworm with all the latest updates.

[Steeple Ian]

https://claydonsweather.org.uk/seasons/

[Greg from Oz]

Mine says the same:

https://weather.ubeaut.work/

[michael.k...@gmx.at]

What is the problem? The percentage, or the fact, the phase is named "Full"?

[Greg from Oz]

It is now:

Phase:
Waning gibbous
(92% full)

https://weather.ubeaut.work/

It takes a while to change....no problems I guess?

[michael.k...@gmx.at]

:)
Two hours later:

[Greg from Oz]

Original post said 2 days ago.

Anyway, it does change eventually.

[Steeple Ian]

Yes it has changed for me now. The point is that all other sources I looked at (XWeather API, online calculators etc) where correctly saying Waning Gibbous from the November 16 when WeeWX was still reporting as Full.

I am aware of different methods of calculating the fullness description but a two day difference in transition from Full to Waning Gibbous seems to be "odd" to me.
Ian

[gjr80]

I suspect you will find the 'granularity' in the calculation used by WeeWX to determine where we are in the lunar cycle in percentage terms is the main factor that contributes to 'delays' in WeeWX displaying the Moon phase. It would also not surprise me that, depending on the time of day of full moon (ie the precise point in time when the Moon is fully illuminated rather than the ill-defined period where the Moon is said to be 'full'), this delay can be seen to be exacerbated on occasions.

We could of course look at changing the calculations used by WeeWX; perhaps someone might like to start by providing clear definitions of the 8 Moon phases used by WeeWX.

Gary

[Dave Vaughan]

How about using https://de.wikipedia.org/wiki/Mondphase as a starting point. The link points to the German page, but in the left column you will find many languages. 

Dave Vaughan

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[Steeple Ian]

Gary,

The English version is here: -

https://en.wikipedia.org/wiki/Lunar_phase

Ian

[Karen K]

There is a formula in weeutil.Moon.py that divides the full cycle (month) of the moon into 8 equidistant parts. Each part is 12.5% of the time (month). That applies to full moon and new moon as well. 

[steepleian]

Karen,

It is that calculation that appeared to be 2 days out of sync with with the other sources mentioned in my original post.

Ian

https://claydonsweather.org.uk

On 20 Nov 2024, at 07:34, Karen K <kk44...@gmail.com> wrote:

There is a formula in weeutil.Moon.py that divides the full cycle (month) of the moon into 8 equidistant parts. Each part is 12.5% of the time (month). That applies to full moon and new moon as well. 

To view this discussion visit https://groups.google.com/d/msgid/weewx-user/efd268d4-b313-4294-9581-a5a7bbd4f39cn%40googlegroups.com.

[Karen K]

I am not sure, but I guess it is.

[Steeple Ian]

Gary,

I have been passed the attached piece of code. It looks as though it could be of some use to modify the WeeWX calculations.
Ian