\documentstyle[pptwocol,epsf]{preprint}

\def \um             {\ifmmode \mu \hbox{m}\else $\mu $m\fi }

\begin{document}

\title{HALOGENS IN THE GIANT PLANETS: UPPER\\
~\\ 
LIMITS TO HBr IN SATURN AND JUPITER}
\author{Keith S.~Noll\/\thanks{Visiting Astronomer at the NASA 
Infrared Telescope Facility, which is operated by the University of 
Hawaii under contract with the National Aeronautics and Space 
Administration.}\\
\\
Space Telescope Science Institute\\
\\
3700 San Martin Drive\\
\\
Baltimore, MD 21218\\
\\
phone: 410-338-1828, fax: 410-338-4767\\
\\
email: noll@stsci.edu}

\pub{Icarus}
\recacc{3 April 1996}{11 July 1996}
\maketitle

\abstract{I have searched for absorptions from the molecule HBr in the
4\thinspace\um\ spectra of Jupiter and Saturn and find upper limits
to the mole fraction of HBr to be q(HBr)~$\le$ 1.6~ppb in Saturn and
q(HBr)~$\le$ 3~ppb in Jupiter, or two and four times the solar abundance 
of bromine in Saturn and Jupiter respectively.  The upper limit for 
Saturn is lower than the global abundance of bromine, if, as expected, 
bromine is enriched in Saturn relative to C1 carbonaceous chondrites.  
This deficiency is most likely the result of local sinks for HBr.  Less 
likely is a global depletion of bromine, conceivably related to the low 
condensation temperature of bromine-containing solids in the presolar 
nebula. Searches for HCl in the 4\thinspace\um\ window are also possible, 
but require large enrichments of Cl for detection with existing data.}