B2K is an experiment to study the Cosmic Microwave Background (CMB),
the weak fossil remnant of the first light produced in the universe,
about 15 billion years ago.
B2K uses a microwave telescope on board of a stratospheric
balloon to map the intensity and polarization of the CMB.
B2K inherits the technologies of the
experiment, which was flown in 1998 and produced in 2000
high quality maps of the CMB. From these maps we estimated
the average density of the Universe and other cosmological parameters.
The polarization of the CMB, i.e. the direction of oscillation of its
electromagnetic waves, is a novel measurement,
and will allow us to constrain the initial conditions and
the nature of primordial density fluctuations.
B2K has been launched on Jan.6 2003, at 05:00 UT.
After about 10 days of good data taking, we had to shut down
because the balloon lost altitude each day. This did not affect our
ability to make very clean measurements of CMB polarization. But eventually
the shear winds were too strong (at about 70kft) to control
the telescope pointing. The gradually falling payload altitude led to termination
on Jan. 21, on the side of the continent farthest from McMurdo.
We hope to recover the pressure
vessel with the data this season, though this is non-trivial.
In the meantime, we have the (lower bandwidth) satellite-transmitted
data from the whole flight in hand, which we believe is an extremely
interesting dataset. Analysis has already started.