deletions | additions       diff --git a/2.tex b/2.tex  index e05c101..1fda68c 100644  --- a/2.tex  +++ b/2.tex 
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SDSS's most used data products are imaging, and spectroscopy. Image parameters measured for each object include the position, flux, and morphology of detected the object.The spectroscopic parameters include redshift, and spectral classification. The number of objects loaded in the databases, observing conditions for imaging fields and for spectroscopic plates, and other parameters are included in the data products. \cite{Stoughton_2002}. Optical data in particular helps to establish the source's distance and to classify the object. Source mophology on the other hand helps to identify emission mechanisms and properties of the media surrounding our objects. (http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1995ApJ...450..559B&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf)  \subsubsection{Faint \subsection{Faint  Images of the Radio Sky (FIRST)} Figure 1. Histogram of peak flux densities for sources in the FIRST survey. (http://iopscience.iop.org/0004-637X/742/1/49/pdf/apj_742_1_49.pdf) 
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      \subsection{The Liu Quasar Pair Catalogue}  Summarize main points from section 2.2. in Liu et al. 2011