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parejkoj
2009-May-05, 10:11 PM
I'm posting this for two reasons. One, the result is very nifty. Two, I'm friends with the coauthors.

Astrometric Redshifts for Quasars by Kaczmarczik, Richards, Mehta and Schlegel (http://arxiv.org/abs/0904.3909)

Figure 1 (on page 17) gives a good overview of the technique. And Figure 2 demonstrates the theory behind it.

The basic idea is that our atmosphere shifts different incoming wavelengths by different amounts (this is why the sky is blue (http://en.wikipedia.org/wiki/Rayleigh_scattering)), which is called differential chromatic refraction. The paper describes a technique that uses this effect on incoming light from quasars to improve our photometric redshift estimates by using this refraction as an "extra bandpass." I think it's pretty neat: using something that is otherwise just an annoyance (the atmosphere's effect on light from distant sources) to give improved measurements.

antoniseb
2009-May-06, 12:24 PM
That is very cool!

George
2009-May-14, 03:34 PM
I'm posting this for two reasons. One, the result is very nifty. Two, I'm friends with the coauthors.

Astrometric Redshifts for Quasars by Kaczmarczik, Richards, Mehta and Schlegel (http://arxiv.org/abs/0904.3909)

Figure 1 (on page 17) gives a good overview of the technique. And Figure 2 demonstrates the theory behind it. That seems very clever.


The basic idea is that our atmosphere shifts different incoming wavelengths by different amounts (this is why the sky is blue (http://en.wikipedia.org/wiki/Rayleigh_scattering)), which is called differential chromatic refraction. [DCR is different than Rayleigh scattering.]

parejkoj
2009-May-14, 04:15 PM
[DCR is different than Rayleigh scattering.]

Granted. But the idea is similar. I guess I misspoke above.