We analyse the BOOMERANG and MAXIMA results in the context of models with $\Omega_{\rm Total} = 1$ and $n_s = 1$. We attempt to constrain three other parameters---$h$, $\Omega_B$, and $\Omega_m$---from these observations. We show that: (a) the value of $\O

2

t

c

O

7

1

2

v

90

3

1

/

h

p

-

o

rt

sa

:v

i

X

r

aConstraintson B, mandhfromMAXIMAandBOOMERANGT.PadmanabhanInter-UniversityCentreforAstronomy&Astrophysics,PostBag4,Pune411007,Indiapaddy@iucaa.ernet.inandShivK.SethiMehtaResearchInstitute,ChhatnagRoad,Jhusi,Allahabad211019,Indiasethi@mri.ernet.inABSTRACTWeanalysetheBOOMERANGandMAXIMAresultsinthecontextofmodelswith Total=1andns=1.Weattempttoconstrainthreeotherparameters—h, B,and m—fromtheseobservations.Weshowthat:(a)thevalueof Bh2istoohightobecompatiblewithprimordialnucleosynthesisobservationsat95%con dencelevel(b)universewithagegreaterthan12Gyrisruledoutat95%con denceleveland(c)thevalueof mhistoohightobecompatiblewiththeshapeofthepowerspectrumofgravitationalclustering.Ine ect,ouranalysisshowsthatmodelswith Total=1andns=1areruledoutbyBOOMERANGandMAXIMAobservations.PrecisedeterminationofCMBRanisotropieshaslongbeenexpectedtogiveaccuratevaluesofcosmologicalparameters(seee.g.Bond,Efstathiou&Tegmark1997andreferencestherein).

ThesecosmologicalparametersincludeparametersofbackgroundFRWmodel( Total, Λ,h, B,etc.),parametersthatdeterminetheformationofstructureintheuniverse(σ8,scalarspectralindexns,etc.),andtheparametersrelatedtothere-ionizationoftheuniverse(theopticaldepthtothelastscatteringsurface,τetc.).

WhilethefutureexperimentsMAPandPlanck1,largelyowingtotheirall-skycoverage,areexpectedtodeterminemostoftheseparameterswithafewpercentaccuracy(Jungemanetal.1996,Zaldarriagaetal.1997,Prunetetal.1999),recentobservationshavealreadybeguntogiveimportantcluesaboutsomeoftheseparameters(Milleretal.1999,Mauskopfetal.2000,Netter ledetal.1997,forasummaryofobservationupto1998andparameterestimationfrom