27 April 2004

Dear Colleagues,

It is with great pleasure that we offer the full release of the IRAC data
from the Spitzer First Look Survey.  Spitzer's First Look Survey was
executed in December 2003 and January 2004 by the SSC to provide the
astronomical community with a characteristic "first-look" at the
mid-infrared sky at sensitivities that are ~100 times deeper than previous
systematic large-area surveys. The details of the survey can be found at
http://ssc.spitzer.caltech.edu/fls/.

These data have been processed through scientifically validated pipelines
(version S10.0). Much of the work of the SSC over the course of the last
several months has focused on the validation of these pipelines.  With a
new observatory and new instruments operating at unprecedented sensitivity
levels, this was a significant challenge.  It required enormous efforts by
many people, both from the Spitzer Science Center and our partners in the
Instrument Teams.  I want to personally thank all of these people for
their commitment to making this happen.

The pipelines for IRAC were validated early enough that we were able to
process and release these data prior to the formal archive opening, which
is scheduled for May 11, 2004. We are working hard on the validation of
the MIPS and IRS pipelines. The calibrated data that are available in the
Spitzer Data Archive, with the accompanying documentation, are for the
scientific community to use in their research. We plan to have the MIPS
First Look Survey data available to the community at the archive opening.

This First Look Survey data release is a major milestone for us. The
formal archive opening in two weeks will open the floodgates as we begin
to release the data from the Spitzer Legacy programs. The rapid public
release of large quantities of data from one of NASA's Great Observatories
is unprecedented, and is a great tribute to the hard work and dedication
of the staff at the Spitzer Science Center. They have worked tirelessly to
insure the quality of the Spitzer data for the use by the science
community.

We will be reprocessing the data we have acquired since December 2003
(with validated pipelines) and filling the archive as rapidly as possible.
We hope to eliminate the backlog by the end of July, at which point all of
the Spitzer Legacy data will be entering the public archive as soon as it
is processed in our pipelines.

With best wishes,

B. Thomas Soifer

Director, Spitzer Science Center