deletions | additions       diff --git a/2.tex b/2.tex  index c332f7d..505397c 100644  --- a/2.tex  +++ b/2.tex 
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\cite{25599966}Hey, welcome. Double click anywhere on the text to start writing. In addition to simple text you can also add text formatted in \textbf{boldface}, \textit{italic}, and yes, math too: $E = mc^{2}$! Add images by drag'n'drop or click on the "Insert Figure" button.  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.  The SDSS is a five-filter imaging survey consisting mostly of the Northern Galactic Cap combined with a spectroscopic follow-up program. The survey and its extensions (SDSS-II and SDSS-III) cover approximately〖〖14 500〗dgrees〗^2, which is nearly a third of the entire sky. SDSS’ main telescope is at Apache Point, New Mexico, and it is was specially designed to take wide field (3°×3°) images using a mosaic of thirty 2048×2048 pixel CCDs\cite{Djorgovski_2013}. The survey includes a spectroscopic survey of approximately 1.3 million objects — mostly galaxies, and quasars.