JUNO-Ground-Radio / Long Wavelength Array Station 1

Friday 8 January 2016, by Baptiste Cecconi

The Long Wavelength Array Station 1 (LWA1) is located in New Mexico (USA). It is sensing radio frequencies from 10 to 88 MHz with an array of 257 crossed-dipole antennas. More info.

NameLong Wavelength Array Station 1
Frequency Bandwidth10-88 MHz
Antenna TypeFolded Bow-Tie crossed-dipoles (sky noise dominated)
Number of Antenna256
Beams4 independently-steerable, 2 tunings per beam
PolarizationsDual linear (with full Stokes capability)
Bandwidth< 16 MHz x 2 tunings x 4 beams
Beam FWHM< 3.2° × [(74 MHz)/ν]
Instrument Sensitivity6 kJy zenith System Equiv. Flux Density [1 Jy = 10-26 W/m2/Hz]
Beam Sensitivity≈ 8 Jy (5σ) for 1 s, 16 MHz, Z = 0 (inferred from SEFD)
Array Geometry256 Antenna stands, 100 m x 110 m elliptical footprint + 2 outrigger antennas for calibration; pseudo-random arrangement to suppress aliasing

Observation Modes

  • Real time beamforming mode (DRX mode) with full Stokes capability, 19.6 MSPS (the maximum sample rate), Two “tunings” (center frequencies), each Nyquist sampled 4-bits “I” + 4-bits “Q”: 264.91 GB/h. Other sample rates: can be extrapolated from the above numbers. Rates available range from 0.250 to 19.6 MSPS in 7 steps. Sensitivity: 5σ, 1s, 16 MHz zenith = 5 Jy. Beamformer data rate is 0.27 TB/hour, 4 hours is 1.1 TB. Typical DRX mode Jupiter Observations: 16 MHz bandwidth with 0.21ms and 5 kHz resolution
  • Spectrometer mode, 19.6 MSPS, two tunings, 32-channel FFT, 6144 FFTs averaged (Thus, 612.5 kHz x 10.03 ms): 192.69 MB/h. minimum is 7.8 kHz. Spectrometer data rate (1024x768) = 1.4 GB/hour. Typical Spectrometer mode Jupiter Observations: 1024, 768 (I, V) channels gives 40ms and 19.1 kHz resolution