英语翻译
AOobservationsofthegalacticcenterwerecarriedoutbetween2004and2012,withsubstantially,moredataperepochbeingobtainedin
2006andonward.Previouspublicationscontain
theobservationaldetailsforthefirstnineepochs
ofAOobservations(7,14–16).Wecollected12
furtherepochsofAOobservationsbetweenMay
2008andMay2012,usinganobservational
setupidenticaltothoseforallAOobservations
obtainedin2006andonward.Forallbuttwo
epochs,thehigh-orderAOcompensationwas
basedonobservationsofabright[Rband∼10
magnitudes(mag)],on-axis,laserguidestar,
generatedwiththeKeckIIsodiumlaser;andthe
low-order(tip-tilt)AOcorrectionsweredeterminedfrommeasurementsofthenaturalguide
starUSNO0600-28577051(R=13.7magand
ΔrSgrA*=19′′)(ΔrSgrA*,distancetoSgrA*).
TableS2providesthedetailsofthe20AO
epochsthatareusedhere.
Thedataanalysisforthisstudyfallsintoseveral
distinctstages(17).First,foreachepochof
observations,weconstructedanaverageimage
ofallthehigh-qualitydatacollectedaswellas
threesubsetimages,eachcomposedofone-third
ofthedata(seeFig.1forazoomintotheregion
ofanAOimagewhereS0-102,S0-2,andthe
electromagneticmanifestationoftheblackhole,
SgrA*,reside).Second,bothpreviouslyknown
andnewlydetectedstarswereidentifiedinthe
images,alongwiththeirphotometricandastrometric
characteristics,withthepointspread
function(PSF)fittingprogramStarFinder(18).
Third,thepositionsofthestarsineachepoch
weretransformedintoacommoncoordinate
system.Fourth,orbitalmodelfitstothepositions
ofstarswithsignificantorbitalphasecoverage
providedestimatesofeachstar’sorbital
parameters.
Thegravitationalpotentialinthisregionof
theGalaxyisdominatedbytheblackhole,andto
agoodapproximationthestarsfollowKe