Need Professional Astronomers Help

[mnemeth1]

So lately I've taken to pouring over the Sloan Digital Sky Survey (SDSS) images looking for any oddball galaxies.

During my searching, I ran into this little guy.



The redshifts listed above are taken from the NED virtual observatory.

I also have the complete break down from the SDSS spectrometers availible here, along with a bunch of other "peculiar" objects that I couldn't get full spectra on.

http://sites.google.com/site/cosmologyq ... ft-objects

Now for comparision, the NED listed redshifts say this about the distance:
Large Red Galaxy .049801 = Distance = 202.74 Mpc = 661,249,440 ly
Foreground QSO .049648 = Distance = 202.14 Mpc = 659,292,502 ly

However the SDSS emission line redshift calculation says:
Large Red galaxy 0.048 = 638,157,569 ly
Foreground QSO 0.049 = 650,975,514 ly

Which of course would put the foreground QSO behind the large galaxy.

I was just wondering if there was anyone here who knows how to really interpret all the data for these objects.

[Steve Smith]

Mel Acheson is a professional astronomer (at least he has a degree in astronomy):

"I wouldn't call that an anomaly: it's just 4 bits of data, probably within the
margins of error of the measurements. (As far as I know, NED data [which are
based on all the data available in the literature] are more precise than SDSS
[which, I think, are single bits from a much less precise wide-angle
spectrometer--check the SDSS site]. But all 4 are "within the ballpark," so
there's no "anomaly" as such. If there were a significant difference in
redshifts--if the QSO had a z that put it far behind the galaxy--it would be
worthwhile examining its spectrum for absorption lines from the galaxy: if there
were none (or low-intensity ones), that would indicate that the QSO was
physically in front. THAT would be an anomaly, as with NGC7319."

[mnemeth1]

Tell him thanks for the reply.