測光系統(tǒng)轉(zhuǎn)換u,g,r,i,z

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Therehavebeenseveraleffortsincalculatingtransformationequationsbetweenugriz(oru'g'r'i'z')andUBVRcIc.Here,wefocusonsixofthemostcurrentefforts:

Jesteral.(2023),whoderivedtransformationequationsforstarsandforzugriz================

QuasarsatzUBVRcIc================

QuasarsatzUBVRcIctransformationsistheuseoftwocolorsineachequation,whichisparticularlyhelpfulfortheu-gtransformation.

UBVRcIc->ugriz================

Starswith0.3UBVRcIc================

Starswith0.3

ThesetransformationequationsappearedinBilir,Karaali,andTuncel(2023,AN326,321).Theyarebasedupon195dwarfstarsthathavebothugrizphotometryandLandoltUBVphotometry.

UBVRcIc->ugriz================

Dwarf(MainSequence)Starsg-r=1.124*(B-V)-0.252r-i=1.040*(B-V)-0.224g=V+0.634*(B-V)-0.108

West,Walkowicz,andHawley(2023)

ThesetransformationequationsappearedinWest,Walkowicz,andHawley(2023,PASP117,706).TheyarebaseduponphotometryofMandLdwarfstarsfromSDSSDataRelease3.

UBVRcIc->ugriz================

M0-L0Dwarfs,0.67u'g'r'i'z'=====================

MainSequenceStars

u'-g'=1.101(+/-0.004)*(U-B)+0.358(+/-0.004)*(B-V)+0.971

g'-r'=0.278(+/-0.016)*(B-V)+1.321(+/-0.030)*(V-Rc)-0.219r'-i'=1.070(+/-0.009)*(Rc-Ic)-0.228r'-z'=1.607(+/-0.012)*(Rc-Ic)-0.371

Lupton(2023)

TheseequationsthatRobertLuptonderivedbymatchingDR4photometrytoPeterStetson'spublishedphotometryforstars.Stars

B=u-0.8116*(u-g)+0.1313;sigma=0.0095B=g+0.3130*(g-r)+0.2271;sigma=0.0107

V=g-0.2906*(u-g)+0.0885;sigma=0.0129V=g-0.5784*(g-r)-0.0038;sigma=0.0054

R=r-0.1837*(g-r)-0.0971;sigma=0.0106R=r-0.2936*(r-i)-0.1439;sigma=0.0072

I=r-1.2444*(r-i)-0.3820;sigma=0.0078I=i-0.3780*(i-z)-0.3974;sigma=0.0063

HereistheCASSQLqueryRobertusedtoperformthematchupofDR4photometrywith

Stetson's:select

dbo.fSDSS(P.objId)asID,name,

S.B,S.Berr,S.V,S.Verr,S.R,S.Rerr,S.I,S.Ierr,psfMag_u,psfMagErr_u,psfMag_g,psfMagErr_g,

psfMag_r,psfMagErr_r,psfMag_i,psfMagErr_i,psfMag_z,psfMagErr_z,casewhen0=(flags_u&0x800d00000000000)andstatus_u=0then1else0endasgood_u,

casewhen0=(flags_g&0x800d00000000000)andstatus_g=0then1else0endasgood_g,

casewhen0=(flags_r&0x800d00000000000)andstatus_r=0then1else0endasgood_r,

casewhen0=(flags_i&0x800d00000000000)andstatus_i=0then1else0endasgood_i,

casewhen0=(flags_z&0x800d00000000000)andstatus_z=0then1else0endasgood_zfrom

stetsonasS

joinstarasPonS.objId=P.objIdjoinfieldasFonP.fieldId=F.fieldIdwhere

0=(flags&0x40006)

EstimatesfortheugrizColorsofVegaandtheSun

AssumingV=+0.03andU-B=B-V=V-Rc=Rc-Ic=0.00,wefindfortheA0VstarVegathefollowing:

g=-0.08(+/-0.03)u-g=+1.02(+/-0.08)g-r=-0.25(+/-0.03)r-i=-0.23(+/-0.02)i-z=-0.17(+/-0.02)

whereweusedtheBilir,Karaali,andTuncel(2023)transformationforgandtheRodgersetal.(2023)transformations(plustheu'g'r'i'z'-to-ugriztransformations)fortheu-g,g-r,r-i,andi-zcolors.Theerrorbarsinparenthesesareroughestimatesofthesystematicerrorsbaseduponthedifferentvaluesthatdifferentsetsoftransformationequationsyield.

AssumingM(V)=+4.82,U-B=+0.195,B-V=+0.650,V-Rc=+0.36,andRc-Ic=+0.32,wefindfortheSunthefollowing:

M(g)=+5.12(+/-0.02)u-g=+1.43(+/-0.05)g-r=+0.44(+/-0.02)r-i=+0.11(+/-0.02)i-z=+0.03(+/-0.02)

where,again,weusedtheBilir,Karaali,andTuncel(2023)transformationforgandtheRodgersetal.(2023)transformations(plustheu'g'r'i'z'-to-ugriztransformations)