On Tue 24 Mar 2020 at 19:05:32 (-0500), Anil Felipe Duggirala wrote:
> On Tue, 2020-03-24 at 23:31 +0000, Liam O'Toole wrote:
> > Are the dawn and dusk times correct in the Night Light configuration
> > window?
> > 
> There are two options. Manual or Sunset/Sunrise in Night light
> settings. If I choose Sunset/Sunrise, I believe, the system is supposed
> to get the Sunset/Sunrise times from some server online, based on some
> location (I pressume this location is that of my time zone, however, I
> belive one time zone can have different locations with different Sunset
> times). That is why I am asking if there is some way I can know how the
> program is getting its Sunset/Sunrise times. Or if maybe I have to
> activate the Location service for this to work (if that is the case,
> there should be some warning about this).

Yes, what matters is the Location and the time in UTC. The timezone
would only be relevant if the computer had access only to Local Time,
in order to answer the question "Which Local Time?"

You don't need a server to calculate sunrise/sunset, just some equations.
https://www.esrl.noaa.gov/gmd/grad/solcalc/solareqns.PDF

One other factor that's not included in that calculation is the length
of twilight but, not knowing how long NightLight takes to adjust,
I don't know whether that's relevant. It might be if you flip from one
colour temperature to another at high latitudes, where twilight can
really last in summer—up to all night.

(I didn't see references to Dawn/Dusk in the images of NightLight online.)

> I do remember that Redshift used to require that you set a location in
> order to have the automatic sunset/sunrise times working.
> 
> > I have found that Night Light is activated very gradually. You won't
> > see
> > an immediate and abrupt change at the relevant times.
> 
> I am aware of the gradual change. The issue is that the change is
> starting to happen a bit (about an hour) later than it should.

Cheers,
David.

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