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Astron 193 Lecture 2, Jan.28, 2015 NOTES 1/ Data vs. Inference Difference between observed data 2/ Orion star cluster image data 3/ How do we obtain the data in Astronomy? 3A/ Observations raw data not readable > ocessed by pipeline r by using the specific software) > you can see your observations Pr (o and have additional calibration files to proceed, Look at your datand perform initial analysis extract the spectrum, make an image, make a a background image, extract a lightcurve Perform analysissource detection to generate the list of sources, how strong are my sources, what is the detection limit? what can we say about the source intensities, distribution across the field > you understand the data quality, instrument properties, conditions at which the observations were taken etc. 3B/ Data Archives calibrated data and access to raw data > > you can recalibrate the data if needed, measure quantities of interest, such as for example flux of a source, generate a spectrum or lightcurve. 3C/rom online Catalogs F > already processed and calibrated gives fluxes, magnitudes, colors, time of the observations, positions and other source characteristics includes the measurement errors, uncertainties on parameters etc. > usually description of the data processing is given, so one can understand the process, access to large data bases SDSS, HEASARC, NED, IPAC, MAST many catalogs accessible via web interface can search, download etc. 4/ Data Storage View Your Data Software to read the data files rrent Astronomy Formats FITS inary with standards, Cu b defined keywords, but may become not good enough for large data of the future LOFAR, SKA in radio, LSST ds9 display the data mage gui, but also access to catalogs download and image the files i event files contain all the information about the observation photons, energy, arrival times image binned onto the sky/detector sum photons in each pixels spectrum binned in energy, wavelength sum the photons in the wavelength bins lightcurve binned in the time sum the photons (flux) in time bins Fits viewers the specific analysis package in FV, PRISM in CIAO see the file content


TOPCAT ccess to many catalogs, browse files, crosscorrelate etc. use to operate on files a http://www.star.bris.ac.uk/~mbt/topcat/ Astropy I/O ad the FITS and Ascii formats into Python code re http://www.astropy.org/ VO projectData discovery tool VO data formats http://www.usvao.org/sciencetoolsservices/vaotoolsservicesdatadiscoverytool/ Some archives: NED extragalactic data base tp://ned.ipac.caltech.edu/ ht combined information about extragalactic sources main source parameters, access to data, list of publications SDSS sky server tp://dr12.sdss3.org/ ht Sloan Digital Sky Survey data base access to optical data from the optical sky survey, images, photometry, spectra MAST Space Telescope archives tps://archive.stsci.edu/ ht data base with optical, ultraviolet and infrared data direct observational data, and pipeline processed data