Science IPT 20 July 2004

De Breuck, Zwaan, Wilson, MAngum, Hogerheijde, Radford, Wootten, Emerson, Kawabe,
Wilson, Sterling, Hills, Saito, Richer

Wootten read through the items on the agenda.

Emerson reported on Cloudsat, a cloud radar at 94 GHz to be launched April 2005 as a part of the
'A-train' which consists of 5 satellites; this is the only active satellite.  Two of the satellites
are in orbit.  The horrifying aspect of this is the power involved.  The peak power is 1.8 kW
into a 64 dB gain antenna producing 4 x 10^9 W looking down.  As seen by a 12m antenna there
would be 60 mW of power, enough to destroy a receiver.  The subsatellite points repeat every
16 days and subtend 170 km or so.  At ALMA there will be 5-6 passes above the horizon.  Only when
pointed straight up will we couple to the satellite.  Stow position should avoid the zenith,
as should source tracking.  This is officially a two year project but will surely be extended.
Apart from destruction of receivers, there are other disturbing effects.  Sidelobes coupling
is quite low--we'd see a line of 10 mK or so.  However, if our beam is pointing at the satellite
and it points elsewhere we would pick up power enough to saturate the B3 rx.  Satellite takes
about 15 minutes max to cross horizon to horizon.  It is possible for the footprint to skim the
edge of ALMA.  In sixteen days, probably two passes come over some portion of the extended ALMA.
There is a similar plan in Europe with 2012 launch.  Operationally we need to never point at
the satellite--always stow with attenuator in place.  We will have mm wave interference.  This
is predictable.

RH: Surely the actual amoung of time in the beam is small.
DTE: Horizon to horizon 5-6 passes per day, worst case 15 minutes transit across the sky.
The main beam crosses any one antenna in one second.  So in toto, this is a few seconds every
two weeks.  Probability is less than once in ten thousand years that we would accidentally
observe the satellite.
RH: We don't ignore it but we don't run screaming to the barricades.

TLW: The Allen array also worries about this.  The scheduler can take this into account.

Hesser is actively working on charges.

Project Scientist reports
Kawabe:  Agreement has been reached between the bilateral partners and Japan.  JP will sign
the agreement by early September.  The Science IPT activities are joint works between the three
partners.  JP nominates several people for subgroups.  Secondly, we would like to join in other
activities.  We would like to join the CSV group.  Current candidates are Saito, Morita, and
KAwabe.  One person will be hired to work as ALMA-J system scientist who will work with that
group and the science IPT, within about a half year.  There is an internal meetin in jAPAN soon
of Science IPT to decide.  

DTE: Describes new design of the total power backend.  There are still ramifications for the
CIPT in that their plans to send the data on a CAN bus cannot handle this higher datarate.

ARCS

Calibration Group.  Plan for frequency of meetings and communication.  First topic is to move
the calibration plan from draft into a more final form.  This was broken into sections with
assignments for work on that.  Continuation of the work will follow the structure of the Plan.
Welch 28.5 GHz work to be circulated, it is an Icarus preprint.

DRSP Cal attributes have not progressed owing to teaching pressures.

RH: Heard likely to be delays in interferometry.  WVR demo wanted during winter period.

SSR face-to-face meeting 1-2 October.  Looking at ACA requirements.  Going through requirements
that need finer granularity.  Andy Hale hired to help with testing.  CDR2 results reported by Lucas.
CW: From point of pipeline.  

Radford: