"Find images in the same area" formula AstroBin Platform open discussions community forum · Francis Moreau · ... · 4 · 84 · 0

0.00 Francis Moreau ... · view views · Share link
Hello, In the "Find images in the same area" menu, what is the formula for finding the distance? Is it a simple application of the Pythagorean theorem in the plane or is it a calculation based on spherical geometry? Thanks Like

Salvatore Iovene ... · view views · 1 like · Share link
Hi Francis, it's nothing that complicated. Given an image with RA center X and dec center Y, and a "look around value" of n degrees, it finds all images where: center RA <= X - n/2 <= X + n/2 center dec <= Y -n/2 <= Y + n/2 Source code here: https://github.com/astrobin/astrobin/blob/master/astrobin_apps_platesolving/services/solution_service.py#L90 Like

0.00 Francis Moreau Topic starter ... · view views · Share link
I've looked into the matter and it seems to me that there's an error in the calculation when ra is around 0. For example, with ra = 1 and degree = 4, the calculation (ra_min = ra - degrees * .5) gives -1 when the correct result should be 359. The same problem applies to dec around ±90°. Like

Salvatore Iovene ... · view views · 1 like · Share link
Francis Moreau: I've looked into the matter and it seems to me that there's an error in the calculation when ra is around 0. For example, with ra = 1 and degree = 4, the calculation (ra_min = ra - degrees * .5) gives -1 when the correct result should be 359. The same problem applies to dec around ±90°. Thanks! Will add this to the internal issue tracker. Like

Salvatore Iovene ... · view views · 1 like · Share link
@Francis Moreau, this is now live on AstroBin. Thanks again for reporting! Like

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Distribution of astrophotographers

This table shows the number of distinct astrophotographers who have been assigned and IOTD/TP award compared to the total number of images awarded.
	Distinct awarded users	Total awarded images
Image of the day
Top picks
Top pick nominations

Distribution of subject types

This table shows the distribution of awards per subject type, compared to the popularity of images of that subject type.
	Image of the day	Top pick	Top pick nominations	Total submitted
Deep sky
Solar system
Extremely wide field
Star trails
Northern lights
Noctilucent clouds
Landscape
Artificial satellite

Distribution of data sources

This table shows the distribution of awards per data source, compared to the popularity of images acquired from that data source.
	Image of the day	Top pick	Top pick nominations	Total submitted
Backyard
Traveller
Own remote observatory
Amateur hosting facility
Public amaeteur data
Professional, scientific grade data
Mix of multiple sources
Other
Unknown