Ephemeris vs Photopills

alan72

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Not sure where is the best forum for this question.

I like to plan shots with alignment of the sun / moon with landmarks etc. looking out to a few weeks time in July and have my eye on a shot from Richmond Park where the sun rises close to and through / over the (formerly) BT tower.

I have the ephemeris and PhotoPills mainly for Astro, I like different elements of their interfaces, together they would make the perfect app

However in this case they are giving me quite some difference in the position of the sun when it rises over the days in question. When considered from the same position in Richmond Park, I’m curious if other people have found significant differences in the apps forecast of sunrise / set time and bearing. You would think they would be consistent in how they calculate the sunrise as this is well understood. That said I realise I am looking at a very specific very narrow subject 13km away so it might just be the accepted margin of error.

It might all be moot as it will rely on clear or fairly clear skies which is a lottery ticket in the UK at the moment!!

Any thoughts welcome.
 
Could you choose another landmark locally with today/tomorrows date and see which one gives the most accurate result?
 
I'd suggest King Henry's Mound in RP (direct line of sight to St Paul's), but I would be sure Alan knows this already...
 
Could you choose another landmark locally with today/tomorrows date and see which one gives the most accurate result?

I'd suggest King Henry's Mound in RP (direct line of sight to St Paul's), but I would be sure Alan knows this already...
Thanks, yes I’ll do a test tomorrow, I’m hoping to shoot the moonrise over london centre and I’ll see how reality compares with the apps, I just wondered if anyone had a view on accuracy of 1 vs the other. It might not be an issue usually but when aligning sunrise with an object 13km away I’d prefer to minimise the number of silly o'clock alarm calls with some confidence in the predicted alignment
 
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