ROCK - Radio Observatory on Columbia in Kennewick

The ROCK - Radio Observatory on Columbia in Kennewick

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The ROCK was inspired by a colleague's (i.e., Peggy's) interest in radio astronomical research at Green Bank. At present, the ROCK consists of a commercial DBS 24" dish antenna with 12 Ghz LNB feed, an Olde Antenna Lab 1.42 Ghz helix antenna, and a satellite "finder" total power receiver with an internal buzzer and DC amp. A 13.8 VDC potential is coaxially-fed to the receiver and LNB from a commercial, regulated supply. The receiver has been modified so that the buzzer can be disabled and the output of the DC amp interfaced to the 16-bit sound card of a PC. The PC runs Radio-SkyPipe (RADIOSKY.COM) for data acquisition. Components of the ROCK are pictured above.
The 12 Ghz region is suitable for probing thermal radiation from external (e.g., Sun and Jupiter) or Earth-based sources (e.g., trees or humans). Galactic hydrogen can be detected at 1.42 Ghz, the hydrogen spin-flip resonance (see "COMING SOON!", below).
Where is the ROCK?
The ROCK is located near a ridge in west Kennewick, WA – the eastern desert of Washington state.

SECOND LIGHT! (OK. FIRST LIGHT is below)
Much prettier. On July 11th, we recorded an E-4^* scan of the Sun for the second time (signal and Sun system's position at maximum, above) overcoming the ROCK's previous impedance problems. The air temperature is 102F this evening, and the dish was a little HOT to the touch - ouch! But our dry desert climate assured a moisture-free electrical connection.
A simple method for calculating the resolution (diffraction limit) of the ROCK's dish at 12 Ghz:
angular resolution ~ arcsin(radio wavelength detected/dish diameter) = arcsin(2.5cm/60.96cm) = 2.35 degrees.
A little guestimate gives a FWHM time ~ 13.7 minutes for the Second Light signal. That represents 3.42 degrees of Earth rotation. The Sun's angular diameter is 0.527 degrees, so...how're we doin' ;-)

FIRST LIGHT
It's not pretty. On July 9th, we first recorded an E-4^* scan of the Sun. In the recorded scan (above), the internal receiver buzzer was enabled. The buzzer seems to change octaves (and impedance) at certain signal strength levels. This gave rise to the dramatic, rapid offset spikes in the scan. Also above is a sky chart generated using the ROCK's favorite charting program, Cartes du Ciel (ASTROSURF.COM/ASTROPC/), showing the position of the Sun system and the sky around the ROCK, both taken at the time of the scan.
Positions and times of the Sun near maximum of FIRST LIGHT E-4 scan on:
Date: 9JUL03
Local time: 17:48
Az.: 273d 21m
Alt.: 28d 29m
Sid: 12:02
RA: 7h 15m 24.16s
DEC: 22d 18’ 21.8”
Temperature: 94F
Weather: clear blue sky and sunny

COMING SOON! Hydrogen spin-flip line at 21 cm!
The commercial LNB of a standard satellite TV dish down-converters 12.2-12.7 Ghz to 950-2250 Mhz - for which the satellite “finder” receiver is optimized. The ubiquitous hydrogen spin-flip resonance (e.g., HI regions) near 1420 Mhz is centered within this bandwidth. So, we’ve ordered Olde Antenna Lab’s 1420 Mhz helix antenna (15 turn, 18dB) and Down East Microwave’s SETI-LNA to receive at 1420 Mhz. With this front end, that should have >39dB pumping into our receiver. The ROCK is located in a low RFI area (the desert), but if necessary we will acquire Radio Astronomy Supplies’ 4-pole 1420 Mhz filter. So far, the cost of the 1420 Mhz front end for the ROCK is ~$295.
^*An Earth Frame-Of-Reference (E-FOR or E-4) scan is sometimes referred to as a "drift scan". A "drift scan" apparently gets its name from the fact that the Sun appears to "drift" across the position of a stationary antenna as data is collected. This apparent "drift" is actually due to the rotation of the Earth below the antenna. It has nothing to do with "drift", but alot to do with acquiring data in the Earth's frame-of-reference as it rotates in our heliocentric, planetary system.

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