Status of the S-Band Radar System

1999 April 22: Several asteroids, the planet Mercury, and the SOHO spacecraft were observed during the second half of 1998. There have been a number of problems with the high-voltage power supply, so that no observations were possible during winter of 1998/9. A new cable was installed on 1999 March 13, and the system seems to be functioning normally. The gain is about 8 K/Jy, and the system temperature is 30-35 K. We hope that each of those numbers can be improved by about 20\%.

The S-Band transmitter was tested at 1 MW over the summer, and has been used at 900 KW in an (unsuccessful) attempt to get a return off of a target on October 29th, November 2nd, December 20, and March 9. Transmitter difficulties have been common, as we are still debugging the system. The full-power system has recently been reinstalled.

1998 April 6: The receiver horn with shutter has been installed. Cooled amplifiers have been placed on the receiver horn, but one polarization was bad (microphonic). A preliminary measurement of the system temperature on the "good" channel was in the high 30s. The reason for this (high) value are being investigated.

Pointing has been tested to be within about 7 arcsec on the transmit horn in January. Construction since then may have degraded that number somewhat, as substantial testing awaits full azimuth motion. The receiver horn offset has been computed. To date, the S-Band transmitter horn is the standard for pointing tests.

1997 October 27: A room-temperature broadband receiver was placed on "other polarization" side of the S-Band transmitter horn. The system temperature was measured to be about 130K. Beam maps indicated a sensitivity of a bit over 8 K/Jy near zenith (J0318+164 near transit), and a bit under 8 K/Jy near 12 degrees ZA.

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Last update: 1999 April 22.

Mike Nolan