Wednesday 1 September 2010

Orion

I just observed that there was no sample on this blog, only on the Swedish language blog Haccationes. So here yet another sample for this blog. The constellation Orion, the upper one generated by mkmap (2010-09-01), the lower one the SVG version (PP3 generated) residing on Wikimedia Commons.

mkmap currently generates a map in the Lambert Conformal Conic Projection, which is very popular on orientation maps (especially military maps) covering a small area because an angle is the same as in reality, and a distance on the map is nearly the same scale irrespective of direction where measured. This is a pretty good quality for star maps too, unless a major part of the sky is to be depicted by the image.

The Wikimedia image, besides being more mature and differently colored, has one great disadvantage from mkmap: only the bright star constitute a realistic picture as seen in the night, and when observing fainter stars, one cannot recognize star patterns from that map. This is because the Wikimedia map doesn't draw stars with a radius according to the apparent magnitude, instead it first sorts the star into one of the magnitude categories -1, 0, 1, 2, 3, 4, 5 and possibly 6, then draws all stars with a certain magnitude with one radius only. So the Wikimedia map simply cannot be used for astronomical observations because the astronomer won't be able to recognize the star patterns in the sky based on that star map.

4 comments:

Mattias Carlsson said...

Ser ärligt talat skithäftigt ut :D

Rursus said...

THX*10^3! Jag tror kartan funkar för amatörastronomer. Men koden är inte på långt när användningsfärdig än.

THX*10^3! I believe the map works for amateur astronomers. But the code is nearly not ready for usage yet.

Mattias Carlsson said...

Any possibility of changing the background in the css for comment fields? Standard response text is black on black background once it's displayed on the comment page ;)

Rursus said...

I hope it will work now: I set the background color to #DDEEFF instead of black. The error didn't show up in Mozilla that seemingly disrespects the bad color setting that I had.