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davidwhogg / SloanAtlas

code to assemble the plates of the Sloan Atlas of Galaxies
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compare colors to color proxies #19

Open davidwhogg opened 11 years ago

davidwhogg commented 11 years ago

Ekta, as part of checking whether all SA quantities are ordered ugriz, can you plot g-r vs the g-r you would infer from the half-light sb quantities, ie

cg_sb50g - cg_sb50i

Also, can you take one reasonable galaxy in the highest color quartile (reddest) and plot

cg_r50 vs band

to see if they look reasonable? Same with one reasonable galaxy in the bluest quartile?

ekta1224 commented 11 years ago

to clarify in the first plot you want: g-r vs. (mu_50, g) - (mu_50,r) ?

and for the blue/red galaxy you want the surface brightness vs. the magnitude for each band for each of these two galaxies(ie, 2 plots that will just have five data points each)?

davidwhogg commented 11 years ago

Sure yes on both

ekta1224 commented 11 years ago

Okay, I can do that soon. Need to do some digging in tractor to retrieve surface brightnesses in bands other than i.

davidwhogg commented 11 years ago

wait -- didn't we put them into the structure, or did we put only i-band?

ekta1224 commented 11 years ago

Only the i band.

On Mar 19, 2013, at 5:26 PM, "David W. Hogg" notifications@github.com wrote:

wait -- didn't we put them into the structure, or did we put only i-band?

— Reply to this email directly or view it on GitHubhttps://github.com/davidwhogg/SloanAtlas/issues/19#issuecomment-15144279 .

davidwhogg commented 11 years ago

Oh but actually the SBs are just got from the R50s and the magnitudes, so they can be computed from the stuff in the SA file. So forget this plot and just plot the R50s vs band for a red galaxy and a blue one.

ekta1224 commented 11 years ago

okay, so here we have a red one: http://broiler.astrometry.net/~ep1091/red_test.pdf

and a blue one: http://broiler.astrometry.net/~ep1091/blue_test.pdf

and the band labels of course are under the assumption that we are consistent throughout with the ugriz ordering, which I will check on next and I'll just use the same two galaxies.

On Tue, Mar 19, 2013 at 8:30 PM, David W. Hogg notifications@github.comwrote:

Oh but actually the SBs are just got from the R50s and the magnitudes, so they can be computed from the stuff in the SA file. So forget this plot and just plot the R50s vs band for a red galaxy and a blue one.

— Reply to this email directly or view it on GitHubhttps://github.com/davidwhogg/SloanAtlas/issues/19#issuecomment-15152294 .

Ekta Patel

ekta1224 commented 11 years ago

Here are links for images and flipbooks:

http://cosmo.nyu.edu/hogg/sa/NGC_4374_SA_J122503.73+125313.6_irg.jpg http://cosmo.nyu.edu/hogg/sa/NGC_4449_SA_J122811.49+440538.2_irg.jpg

http://broiler.astrometry.net/~dwm261/flip-ngc4374.pdf http://broiler.astrometry.net/~ep1091/flipbooks/flip-NGC_4449.pdf

davidwhogg commented 11 years ago

I am reassigning this to myself for now.