Dark in, Dark out

[FrenchyArnaud]

Hi guys, 
pretty much every day, I need to look at different apps/website to have an idea of sun times, moon phase, moon times. It's the same story on repeat, groundhog day: "ok, the sun goes down at 20:01, count 21:00 or 21:30 for astro darkness, the moon is rising around 23:45, but it's only at 5% so I am probably ok until it reaches 15 or 20 deg up around 2 in the morning, so all in all, I have from 21:00 to 02:00 for imaging, with proper dark from 21:30 to 1am... let's see how it is tomorrow and this week-end and the next one...

I always thought it'd be just cool to have a calendar, a simple one-page-says-it-all calendar for astrophoto darkness: a calendar that would simply tell you WHEN both sun and moon are below the horizon. So that I could just look at the page and point at the next favourable day without any headache. 

But after long research, it just does not seem to exist! 

So I created it. The maths are a bit complex but I did it for now through a simple spreadsheet - it would be pretty simple to make it a purely graphical printable calendar, a website or even an android app; all of these options are on.  For simplicity reasons (and bulk access to the data I need) it's now only for london and only for the next 100 days, but again, doing it for any point in the world, at any time, would take one click provided that I get the moon/sun time tables. 

Right now the variables that can be customised are the ideal moon illumination and its maximum acceptable, the delay after/before sun times for acceptable darkness, and the minimum length of time of darkness within these settings to make the night favourable. 

Before I begin to really get my energy into coding an app/website, all input welcome! Especially if you already know of such a calendar  

 

[gentlebear76]

I'm using https://www.suninfo.dk/index.php?lang=en for looking up when my site is usable. It is both in Danish and in English (small flag top right corner). I really like it as it makes it easy to see the moon phases i relation to darkness - and it's very visual which I like a lot 🙂 Unfortunately you can't use it to modify the darkness. Astronomical twilight is back-ish (midnight till 3 am) where I am but no night until mid August and then only for an hour between 1 am and 2 am.

[AstroMuni]

On 25/07/2022 at 17:11, FrenchyArnaud said:

Before I begin to really get my energy into coding an app/website, all input welcome! Especially if you already know of such a calendar  

Have you taken a look at the Clear Outside app/website from FLO? https://clearoutside.com/forecast/50.7/-3.52

[FrenchyArnaud]

4 hours ago, gentlebear76 said:

I'm using https://www.suninfo.dk/index.php?lang=en for looking up when my site is usable. It is both in Danish and in English (small flag top right corner). I really like it as it makes it easy to see the moon phases i relation to darkness - and it's very visual which I like a lot 🙂 Unfortunately you can't use it to modify the darkness. Astronomical twilight is back-ish (midnight till 3 am) where I am but no night until mid August and then only for an hour between 1 am and 2 am.

I like the presentation for each day, but again, this lacks the critical ability to see the calendar at once. In essence, it tells you if a particular day is favourable, not when the next favourable day is...

 

3 hours ago, AstroMuni said:

Have you taken a look at the Clear Outside app/website from FLO? https://clearoutside.com/forecast/50.7/-3.52

Of course.  However because it is a weather app primarily, it's limited to a few days (and to be fair, it has repeatedly proven to be relying on a flawed model even within 12hours). So again, it lacks the ability to point out directly the next favourable days/times (dark-wise) for, say, end of the month when I am off. Or to tell me when I should book my hollidays in October if I want the best chances, weather willing, to go out at the darkest nights of the period. 

 

[AstroMuni]

1 hour ago, FrenchyArnaud said:

it lacks the ability to point out directly the next favourable days/times (dark-wise) for, say, end of the month when I am off.

Thats true. If someone could model which days are going to be cloudless more accurately then I am sure that person will soon become rich. :-) In our local astro group we tend to use different apps to forecast and each one says differently. So in the end its a matter of averaging the results or relying on your own sources, including your own sky temperature sensor etc. So having a tool to forecast in advance will be a great addition!

And when you live in a country where the Gulf stream and Jet stream influence your weather so much, its key to forecast the behaviour of these two!

Edited July 29, 2022 by AstroMuni

[Mandy D]

On 25/07/2022 at 17:11, FrenchyArnaud said:

Hi guys, 
pretty much every day, I need to look at different apps/website to have an idea of sun times, moon phase, moon times. It's the same story on repeat, groundhog day: "ok, the sun goes down at 20:01, count 21:00 or 21:30 for astro darkness, the moon is rising around 23:45, but it's only at 5% so I am probably ok until it reaches 15 or 20 deg up around 2 in the morning, so all in all, I have from 21:00 to 02:00 for imaging, with proper dark from 21:30 to 1am... let's see how it is tomorrow and this week-end and the next one...

 

 

I like the idea. Perhaps extend it using the available statistical weather data, which appears to be available here:

https://www.ceda.ac.uk/blog/uk-weather-station-records-now-freely-available-to-all-midas-open/

You have to register, but it is free. Then your app could be used to help observers decide where to view (say) an eclipse from with good chance of clear skies, months in advance. Obviously, this would make it a much bigger project, even just for the UK, but a lot more useful.

[FrenchyArnaud]

2 hours ago, AstroMuni said:

 If someone could model which days are going to be cloudless more accurately then I am sure that person will soon become rich. :-)

You bet 🤣 I'd pay pretty money for a reliable forecast at 24H!

But again, it's not about the weather, it's about the darkness - for scheduling purposes.  The weather here is irrelevant

[FrenchyArnaud]

2 hours ago, Mandy D said:

I like the idea. Perhaps extend it using the available statistical weather data, which appears to be available here:

https://www.ceda.ac.uk/blog/uk-weather-station-records-now-freely-available-to-all-midas-open/

You have to register, but it is free. Then your app could be used to help observers decide where to view (say) an eclipse from with good chance of clear skies, months in advance. Obviously, this would make it a much bigger project, even just for the UK, but a lot more useful.

I like that! That sounds like a great way to increase your chances to schedule your days off or field trip on a good night 👍 I am going to look into it straight away.

[Alex_]

Love the idea of this. Planning camping trips and days off would be so much easier with something like this. I've been relying on Clear Outside myself and that's ok for planetary observation, but since I just ordered a refractor to start AP, darkness prediction would be great too!