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Whatisanimage?
Asyoumayknow,animageisamatrixofnumbersthatcointainsthespecificbrightnesslevelthatcorrespondstoagivenpixel.Andfromtheretheconceptsevolvesandaddschannelsofcolouranddepth.Butfornow,let’sjustthinkaboutmonochromaticimages(onlyonechannel).InAstronomy,imagesareusuallyconsideredsetsofscientificdata,observations,thatcontaininformationaboutanspeficictargetintheskyseenthroughtanspecificfilterandthelevelsofbrightnesscorrespondtothebehaviouroftheopticalsensor(CCDcamera)inrelationwiththenumberofelectronsthathitaparticularpixelthroughanspecificwaveband.SomethingelsetoconsideristhattheskyisnotflatwiththisImeanthatthecelestialvaultislikeaspheresurroundingusthereforecartesiancoorditanesarenottheparamentersusedtoidentifypointsinspace,thereisanothersystemcalledWCS(WorldCoordinateSystem)henceaconversionbetweenpixelsandWCScoordinatesexists.Asyouarerealizingnowjustoneimagecancontaintonsofinformationrelatedtoit,nowimaginethatmultipliedforterabytesandterabytesofstars,galaxies,planets,nebulaeoranyobjectinspace.Fortunatelyinastronomythisissolvedusinganimageformatthatcointainstheimageanditsowninformation.
FITSfiles
Thisformatisthestandarddataformatusedinastronomy,cancontainoneimage,multipleimages,tablesandheaderkeywordsprovidingdescriptiveinformationaboutthedata.Thewayitworksisthatthisformatcancontainatextfilewithkeywordsthatcomprisetheinformationabouttheobservationandamultidimensionalarraythatcouldbeatable,oranimage,oranarrayofimages(datacube).Thisfilescanbemanagedindiffetentways,withanimagepreviewuseDS9,forhandingthedatainaprogramusethePythonpackagePyFITS.
WFC3ERSM83DataProducts
TheselecteddatasettotestthedatamininglibrariesIfoundisaseriesofobservationsofM83at9differentwavelengths,theoriginalimagescanbefoundinthiswebpage,http://archive.stsci.edu/prepds/wfc3ers/m83datalist.html,thespecificinformationaboutthemcanbefoundinTable\ref{tab:uno}.ThisparticularimageswereobservedthroughHSTwiththeWFC3/UVIScamera.