Date:   September 30, 2008 (Tuesday)
Time:   3:30 pm EDT (refreshments at 3:20 pm)
Place:  Green Bank Auditorium
         (Video: CV-230/AOC-AUD)

Speaker:  Rick Fisher, NRAO-Charlottesville

Title:  "Beam-Forming Array Measurements at Green Bank"

Abstract:

Our BYU colleagues conducted the second test of their 19-element
beam-forming array on the 20-meter in July.  Their array calibration
algorithm achieved a tsys/(aperture efficiency) of about 100 K using a
new set of uncooled LNAs.  We will describe noise measurements that
confirm that we have a reasonable understanding of the array noise
budget.  The formed beams in the array's field of view are good, and we
will show a map of the Cygnus-X region.  An astronomically useful
array on the GBT will require a relatively expensive
correlator/beam-former and a new digital, fiber-optic data
transmission system between the telescope and the lab.  The cost
will depend on the required bandwidth, array size, and number of beams
formed so we would like to begin a discussion on the minimum
requirements for a first array.  Array science requirements and
specifications written in 2001 may be found at

   http://www.cv.nrao.edu/~rfisher/ArrayFeed/science_doc.pdf


Future Colloquia:

http://www.gb.nrao.edu/colloquia/colloquia.html