calculate time when sun is 8 degrees below the horizon

[Jay Ess 6]

Hi

Can someone help to update a global variable with time that the sun will hit 8 degrees below the horizon?

Many thanks.

[SmartHomeEddy 1,005]

Do you mean some code to update a variable or do you mean calculate sunset?

 

like this code for sunset

 

 

[ppeterr 206]

Please login or register to see this link.

 

Maybe you need a little suncalc  I love this site, someday i will also work out how

to use the API. But here, you can select your exact position. And find out on what time

the sun gives shadow or sunlight on that position.

 

Cant help you with the API. 

Edited September 12, 2021 by ppeterr

[SmartHomeEddy 1,005]

Looks great. What could you do with it in Homeautomation?

[ppeterr 206]

2 hours ago, SmartHomeEddy said:

Looks great. What could you do with it in Homeautomation?

 

Well, move my luxaflex indoor powerview sun shades to preset positions when the sun 

stands on a certain degree so it keeps the sun out of the television

 

 - and put the somfy outdoor sunshades on position to keep the sun outside in the summer.

 

Well, something like that. I wil have it working before next summer

 

Anyway, back to @Jay Ess What do you want to achieve

Edited September 12, 2021 by ppeterr

[SmartHomeEddy 1,005]

A pity this API doesn’t gives back json 

 

 

 

Edited September 12, 2021 by SmartHomeEddy

[Jay Ess 6]

21 hours ago, SmartHomeEddy said:

Do you mean some code to update a variable or do you mean calculate sunset?

 

like this code for sunset

 

 

I am using this code in a vd to calculate the times, the problems i am having are two fold, one a minor issue is the sunset and sunrise times of the hc3 is different then the times this vd gives out by approx 1 minute, the second more important issue is the time which my vd gives as 8 degrees is out by approx 0.5 degree and am unsure how to fix this or to verify that the time is correct.

 

CODE of VD:

 

-- shortcuts for easier to read formulas
PI = math.pi
sin = math.sin
cos = math.cos
tan = math.tan
asin = math.asin
atan = math.atan2
acos = math.acos
rad = PI / 180
-- sun calculations are based on

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formulas
-- date/time constants and conversions
dayMs = 1000 * 60 * 60 * 24
J1970 = 2440588
J2000 = 2451545
 
function toJulian(date)
    return date / dayMs - 0.5 + J1970
end
function fromJulian(j)
    return (j + 0.5 - J1970) * dayMs
end
function toDays(date)
    return toJulian(date) - J2000
end
-- general calculations for position
e = rad * 23.4397 -- obliquity of the Earth
function rightAscension(l, b)
    return atan(sin(l) * cos(e) - tan(b) * sin(e), cos(l))
end
function declination(l, b)
    return asin(sin(b) * cos(e) + cos(b) * sin(e) * sin(l))
end
function azimuth(H, phi, dec)
    return atan(sin(H), cos(H) * sin(phi) - tan(dec) * cos(phi))
end
function altitude(H, phi, dec)
    return asin(sin(phi) * sin(dec) + cos(phi) * cos(dec) * cos(H))
end
function siderealTime(d, lw)
    return rad * (280.16 + 360.9856235 * d) - lw
end
function astroRefraction(h)
    if (h < 0) then -- the following formula works for positive altitudes only.
        h = 0 -- if h = -0.08901179 a div/0 would occur.
    end
    -- formula 16.4 of "Astronomical Algorithms" 2nd edition by Jean Meeus (Willmann-Bell, Richmond) 1998.
    -- 1.02 / tan(h + 10.26 / (h + 5.10)) h in degrees, result in arc minutes -> converted to rad:
    return 0.0002967 / math.tan(h + 0.00312536 / (h + 0.08901179))
end
-- general sun calculations
function solarMeanAnomaly(d)
    return rad * (357.5291 + 0.98560028 * d)
end
function eclipticLongitude(M)
    local C = rad * (1.9148 * sin(M) + 0.02 * sin(2 * M) + 0.0003 * sin(3 * M)) -- equation of center
    local P = rad * 102.9372 -- perihelion of the Earth

 
    return M + C + P + PI
end
function sunCoords(d)
    M = solarMeanAnomaly(d)
    L = eclipticLongitude(M)
    return {
        dec = declination(L, 0),
        ra = rightAscension(L, 0)
    }
end

SunCalc = {}
-- calculates sun position for a given date and latitude/longitude
SunCalc.getPosition = function(date, lat, lng)
    lw = rad * -lng
    phi = rad * lat
    d = toDays(date)
    c = sunCoords(d)
    H = siderealTime(d, lw) - c.ra
    return {
        azimuth = azimuth(H, phi, c.dec),
        altitude = altitude(H, phi, c.dec)
    }
end
-- sun times configuration (angle, morning name, evening name)
times = {
    {-0.833, "sunrise", "sunset"},
    {-0.3, "sunriseEnd", "sunsetStart"},
    {-3, "curtaindawn", "curtaindusk"},
    {-6, "dawn", "dusk"},
    {-12, "nauticalDawn", "nauticalDusk"},
    {-18, "nightEnd", "night"},
    {6, "goldenHourEnd", "goldenHour"},
    {-4, "blueHourDawnEnd", "blueHourDusk"},
    {-8, "blueHourDawn", "blueHourDuskEnd"}
}
-- adds a custom time to the times config
SunCalc.addTime = function(angle, riseName, setName)
    table.insert(times, {angle, riseName, setName})
end
-- calculations for sun times
J0 = 0.0009
function julianCycle(d, lw)
    return math.round(d - J0 - lw / (2 * PI))
end
function approxTransit(Ht, lw, n)
    return J0 + (Ht + lw) / (2 * PI) + n
end
function solarTransitJ(ds, M, L)
    return J2000 + ds + 0.0053 * sin(M) - 0.0069 * sin(2 * L)
end
function hourAngle(h, phi, d)
    return acos((sin(h) - sin(phi) * sin(d)) / (cos(phi) * cos(d)))
end
-- returns set time for the given sun altitude
function getSetJ(h, lw, phi, dec, n, M, L)
    w = hourAngle(h, phi, dec)
    a = approxTransit(w, lw, n)
    return solarTransitJ(a, M, L)
end
-- calculates sun times for a given date and latitude/longitude
SunCalc.getTimes = function(date, lat, lng)
    lw = rad * -lng
    phi = rad * lat
    d = toDays(date)
    n = julianCycle(d, lw)
    ds = approxTransit(0, lw, n)
    M = solarMeanAnomaly(ds)
    L = eclipticLongitude(M)
    dec = declination(L, 0)
    Jnoon = solarTransitJ(ds, M, L)
    i, len, time, Jset, Jrise = nil
    result = {
        solarNoon = fromJulian(Jnoon),
        nadir = fromJulian(Jnoon - 0.5)
    }
    for i = 1, table.length(times) do
        time = times[i]
        Jset = getSetJ(time[1] * rad, lw, phi, dec, n, M, L)
        Jrise = Jnoon - (Jset - Jnoon)
        result[time[2]] = fromJulian(Jrise)
        result[time[3]] = fromJulian(Jset)
    end
    return result
end
-- moon calculations, based on

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formulas
function moonCoords(d) -- geocentric ecliptic coordinates of the moon
    L = rad * (218.316 + 13.176396 * d) -- ecliptic longitude
    M = rad * (134.963 + 13.064993 * d) -- mean anomaly
    F = rad * (93.272 + 13.229350 * d) -- mean distance
    l = L + rad * 6.289 * sin(M) -- longitude
    b = rad * 5.128 * sin(F) -- latitude
    dt = 385001 - 20905 * cos(M) -- distance to the moon in km
    return {
        ra = rightAscension(l, b),
        dec = declination(l, b),
        dist = dt
    }
end
SunCalc.getMoonPosition = function(date, lat, lng)
    lw = rad * -lng
    phi = rad * lat
    d = toDays(date)
    c = moonCoords(d)
    H = siderealTime(d, lw) - c.ra
    h = altitude(H, phi, c.dec)
    -- formula 14.1 of "Astronomical Algorithms" 2nd edition by Jean Meeus (Willmann-Bell, Richmond) 1998.
    pa = atan(sin(H), tan(phi) * cos(c.dec) - sin(c.dec) * cos(H))
    h = h + astroRefraction(h) -- altitude correction for refraction
    return {
        azimuth = azimuth(H, phi, c.dec),
        altitude = h,
        distance = c.dist,
        parallacticAngle = pa
    }
end
-- calculations for illumination parameters of the moon,
-- based on

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formulas and
-- Chapter 48 of "Astronomical Algorithms" 2nd edition by Jean Meeus (Willmann-Bell, Richmond) 1998.
SunCalc.getMoonIllumination = function(date)
    d = toDays(date)
    s = sunCoords(d)
    m = moonCoords(d)
    sdist = 149598000 -- distance from Earth to Sun in km
    phi = acos(sin(s.dec) * sin(m.dec) + cos(s.dec) * cos(m.dec) * cos(s.ra - m.ra))
    inc = atan(sdist * sin(phi), m.dist - sdist * cos(phi))
    angle = atan(cos(s.dec) * sin(s.ra - m.ra), sin(s.dec) * cos(m.dec) - cos(s.dec) * sin(m.dec) * cos(s.ra - m.ra))
    return {
        fraction = (1 + cos(inc)) / 2,
        phase = 0.5 + 0.5 * inc * (angle < 0 and -1 or 1) / math.pi,
        angle = angle
    }
end
function hoursLater(date, h)
    return date + h * dayMs / 24
end
-- calculations for moon rise/set times are based on

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article
SunCalc.getMoonTimes = function(date, lat, lng)
    t = date
    hc = 0.133 * rad
    h0 = SunCalc.getMoonPosition(t, lat, lng).altitude - hc
    h1, h2, rise, set, a, b, xe, ye, d, roots, x1, x2, dx = nil
    -- go in 2-hour chunks, each time seeing if a 3-point quadratic curve crosses zero (which means rise or set)
    for i = 1, 24, 2 do
        h1 = SunCalc.getMoonPosition(hoursLater(t, i), lat, lng).altitude - hc
        h2 = SunCalc.getMoonPosition(hoursLater(t, i + 1), lat, lng).altitude - hc
        a = (h0 + h2) / 2 - h1
        b = (h2 - h0) / 2
        xe = -b / (2 * a)
        ye = (a * xe + b) * xe + h1
        d = b * b - 4 * a * h1
        roots = 0
        if d >= 0 then
            dx = math.sqrt(d) / (math.abs(a) * 2)
            x1 = xe - dx
            x2 = xe + dx
            if math.abs(x1) <= 1 then
                roots = roots + 1
            end
            if math.abs(x2) <= 1 then
                roots = roots + 1
            end
            if x1 < -1 then
                x1 = x2
            end
        end
        if roots == 1 then
            if h0 < 0 then
                rise = i + x1
            else
                set = i + x1
            end
        elseif roots == 2 then
            rise = i + (ye < 0 and x2 or x1)
            set = i + (ye < 0 and x1 or x2)
        end
        if rise and set then
            break
        end
        h0 = h2
    end
    result = {}
    if rise then
        result.rise = hoursLater(t, rise)
    end
    if set then
        result.set = hoursLater(t, set)
    end
    if not rise and not set then
        result[ye > 0 and "alwaysUp" or "alwaysDown"] = true
    end
    return result
end
-- ---------- NOT PART OF THE ORIGINAL SCRIPT - HAD TO BE ADDED FOR THE SCRIPT TO WORK IN LUA ----------
function math.round(num, numDecimalPlaces)
    local mult = 10 ^ (numDecimalPlaces or 0)
    return math.floor(num * mult + 0.5) / mult
end
function table.length(T)
    local count = 0
    for _ in pairs(T) do
        count = count + 1
    end
    return count
end
--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==--==
function getKeysSortedByValue(tbl, sortFunction)
    local keys = {}
    for key in pairs(tbl) do
        table.insert(keys, key)
    end

 
    table.sort(
        keys,
        function(a, b)
            return sortFunction(tbl[a], tbl[b])
        end
    )

 
    return keys
end

 
function formatTime(tm)
    return os.date("%H:%M", math.floor(tm / 1000))
end

 
local events = {
    ["nauticalDawn"] = 1,
    ["blueHourDawn"] = 2,
    ["dawn"] = 3,
    ["blueHourDawnEnd"] = 4,
    ["sunrise"] = 5,
    ["sunriseEnd"] = 6,
    ["goldenHourEnd"] = 7,
    ["solarNoon"] = 8,
    ["goldenHour"] = 9,
    ["sunsetStart"] = 10,
    ["sunset"] = 11,
    ["blueHourDusk"] = 12,
    ["dusk"] = 13,
    ["blueHourDuskEnd"] = 14,
    ["nauticalDusk"] = 15,
    ["night"] = 16,
    ["nadir"] = 17,
    ["nightEnd"] = 18
}

 
function dump(o)
    if type(o) == "table" then
        local s = "{ "
        for k, v in pairs(o) do
            if type(k) ~= "number" then
                k = '"' .. k .. '"'
            end
            s = s .. "[" .. k .. "] = " .. dump(v) .. ","
        end
        return s .. "} "
    else
        return tostring(o)
    end
end

 
local location = api.get("/panels/location")
local lat = location[1].latitude
local lon = location[1].longitude

 
function QuickApp:sunCalc()
    local mDate = os.time() * 1000
    local sunTimes = SunCalc.getTimes(mDate, lat, lon)
    local sunrise, sunset, dawn, dusk, solarNoon, curtaindusk, blueHourDuskEnd =
        formatTime(sunTimes["sunrise"]),
        formatTime(sunTimes["sunset"]),
        formatTime(sunTimes["dawn"]),
        formatTime(sunTimes["dusk"]),
        formatTime(sunTimes["solarNoon"]),
        formatTime(sunTimes["curtaindusk"]),
        formatTime(sunTimes["blueHourDuskEnd"])
    local PlagHamincha = formatTime(sunTimes["sunset"] -(((sunTimes["sunset"] - sunTimes["sunrise"])/12)*1.25))
    -- print(sunrise, sunset, dawn, dusk);
 
    fibaro.setGlobalVariable("Sunrise", sunrise)
    fibaro.setGlobalVariable("Sunset", sunset)
    fibaro.setGlobalVariable("SunriseTwilight", dawn)
    fibaro.setGlobalVariable("SunsetTwilight", dusk)
    fibaro.setGlobalVariable("midDay", solarNoon)
    fibaro.setGlobalVariable("curtaindusk", curtaindusk)
    fibaro.setGlobalVariable("shabbosEndTime", blueHourDuskEnd)
    fibaro.setGlobalVariable("plagHamincha", PlagHamincha)
 
    self:updateView(
        "lblStatus",
        "text",
        "?" .. dawn .. "|" .. "?" .. sunrise .. "|" .. "?" .. sunset .. "|" .. "✨" .. dusk
    )
    local sortedKeys =
        getKeysSortedByValue(
        sunTimes,
        function(a, b)
            return a < b
        end
    )
    local dayPart = nil
    for _, key in ipairs(sortedKeys) do
        if sunTimes[key] <= mDate then
            dayPart = key
        end
    end
    dayPart = dayPart or "night"
    self:updateProperty("log", dayPart)
    dayPart = {dayPart = dayPart, dayPartIndex = events[dayPart]}
    fibaro.setGlobalVariable("DayPart", json.encode(dayPart))
end
 
function QuickApp:onInit()
    self:debug("onInit")
    self:updateProperty("deviceIcon", 1014)  
    self:sunCalc()
    setInterval(
        function()
            self:sunCalc()
        end,
        1000 * 60 * 1
    )
end

Edited September 13, 2021 by Jay Ess
incorrect format

[SmartHomeEddy 1,005]

That is a whole lot of calculations from @10der ?

 

Did you compare the results from the HC2 and HC3 to for example the link @ppeterr posted: 

Please login or register to see this link.

 

Just to know which one is more accurate?

 

 

 

Edited September 13, 2021 by SmartHomeEddy

[Jay Ess 6]

@SmartHomeEddy thank you for that, there was no comment in the vd and was not sure who had written it originally.

Have compared it to with the link you have given me and this is what i get:

Point of time -  VD time - Web Time(web time rounded up)

Sunrise Twilight - 06.05 - 6.03.47 (6.04)

Sunrise - 06.40 - 6.38.51 (6.39)

Sunset - 19.32 - 19.29.47 (19.30)

Sunset Twilight - 20.07 - 20.04.43 (20.05)

8 degrees below - 20.21 - 20.19

 

in the morning it is about 1 minute out and in the evening about 2 minutes out, i have found the -8 degrees to be out by up to 3 minutes and either the calculation are out a little or maybe some other issue is there?

[SmartHomeEddy 1,005]

How did the HC3 do in this check?

 

[Jay Ess 6]

according to hc3 get.value(1,"sunrseHour")

sunrise 6.38 - 

and sunset 19.30

 

so hc3 is a minute early for sunrise from the web and is the same as the web for sunset,

[Sjakie 156]

Let me also drop a dime in the pocket.

The calculations done have a deviation and I dont know where to find it.

In my opinion sunset and sunrise in HC3 with your deviation is not to much?

I use sunset/sunrise from HC3 and I add a correction factor for each month and for % clouds. Its also not "watertight" but I can deal with it.

If you do that you dont need to recalculate? Or what do I miss?

Curious for your answer,

//Sjakie

[Jay Ess 6]

for sunset and sunrise you are correct the difference is one minute, however i need to get the time when the sun is 8 degrees below the horizan and i need it to be correct which is why i am using the suncalc vd, however it is the results are off by around 0.4/.5 degrees especially for the -8 degree time, i have found a vba spreadsheet which someone has made which is more exact but need o work through it to be able to understand either where the vd os going wrong or how to convert it to lua. It is a little bit over my head so was hoping for some help from the gurus on here lol.

[Sankotronic 2,370]

Hello,

 

I have found one interesting API on this link:

Please login or register to see this link.

 

They provide all necessary data for sun and moon and have free plan with limit to 1000 calls per day which makes it possible to refresh data every 2-3 minutes.

Is maybe this solution usable for you @Jay Ess?

 

BTW I have tested it on HC2 and ti is working

[Jay Ess 6]

@Sankotronic thank you for that however the link you wont give me the 8 degrees below the horizan.

 

have found some code in vba which i am trying to convert back to lua to see if i can get it to work as it should be.

 

LOL with limited experience in coding am hoping i will get there LOL

 

do you know if i have a number for example 7198.6714 how i can get the whole integer part without rounding, so would like to get 7198?

[Jay Ess 6]

after looking at this code and other codes with similar functions, i think there is a tiny error in the calculation of the degrees of the sun in the original code as posted above, would any one be able to review the code and spot the mistake as the morning times are spot on it is the afternoon and evening times which are out in particular the 8 degree below which is out and is instead showing when the sun is at 8.44 degrees.

i am using suncalc.org to check against.

Edited September 15, 2021 by Jay Ess

[ppeterr 206]

I like precision, but I'm very curious why this has to be so exact. What is your user case?

Also - see my pm

Edited September 15, 2021 by ppeterr

[Jay Ess 6]

Thank you thought I had removed it lol but should now be gone. 
 

For the Jewish calendar holidays and Saturday finishes when the sun is 8 degrees below. I have set my lights to automate for these times and am wanting to play a sound file at this time. 
 

 

@ppeterr thank you for the heads up on the link. 

[ppeterr 206]

11 minutes ago, Jay Ess said:

Thank you thought I had removed it lol but should now be gone. 
 

For the Jewish calendar holidays and Saturday finishes when the sun is 8 degrees below. I have set my lights to automate for these times and am wanting to play a sound file at this time. 
 

 

@ppeterr thank you for the heads up on the link. 

 

You made me google it, learned something today  

 

Anyway its above my head

 

But i also found this:  

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Hebcal.com offers a REST API for fetching Jewish calendar data. The output format is in JSON.

It can calculate tzeit hakochavim......uhhh little complex for me

 

Take a look at it.

 

 

Edited September 15, 2021 by ppeterr

[Jay Ess 6]

i am already using it for getting dates LOL but the times given is different in different places so gets quite complicated hence why i am trying to fine tune the code i have.