deletions | additions       diff --git a/2.tex b/2.tex  index 284b5ec..610dcb6 100644  --- a/2.tex  +++ b/2.tex 
...
\textbf{Method}  \section{SDSS \subsection{SDSS  - a brief introduction} The word “survey” in the astronomical context initially referred to what could be called a sky atlas - these were initially hand-drawn sky charts, and later photographic images. Currently the word survey largely denotes catalogues of astronomical sources and their properties (positions, fluxes, morphology, etc.). They are used to systematically map the universe and characterize its astrophysical components with the aim of discovering new types of objects or phenomena. Surveys are often preceded by the development and introduction of new technology. Where the technological advancement allows us to observe the sky in some new way, for example, viewing images in a previously unexplored wavelength range. The Sloan Digital Sky Survey (SDSS) is one such astronomical sky survey. 
...