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1  Overview

The LWA1 is the first LWA station to be completed in April 2011, and is located near the VLA site. LWA1 is a 256 element array, operating as a single-station telescope at frequencies between 10-88 MHz. One additional dipole antenna is placed at a distance of 300 m from the main array. Shared risk operations of the full LWA1 are ongoing alongside with commissioning activities.

This document intends to provide information about the basic functionality of the instrument for observing purposes. This document is under constant revision, and will be updated regularly. The most recent version will be found on the LWA Astronomer web pages lwa/astro.html.

1.1  Summary of Specifications

Table 1.1 summarizes the observational capabilities of the LWA1 station.

Frequency coverage ν10-88 MHz 
Number of antennas257 
Number of beams4 
Number of tunings2 per beamIndependently tunable
Number of polarizations, Npol2 per beam per tuning 
Bandwidth per beam and polarization, B19.6 MHz∼16 MHz usable bw due to bandedges
Number of channels, Nch32 
Minimum channel width, Δν7.8125 kHz 
Transient mode Narrow, TBN1-100 kHz bandwidthContinuous observing all dipoles
Transient mode Wide, TBW78 MHz bandwidthShort bursts of obserbing
Declination range−30 to +90 
Main beam FWHM2.274 MHzsec2 ZZ is zenith angle
SEFD zenith angle Z=[0, 65])[3, 17] kJyFrequency independent
Thermal noise (at zenith)11 JyFor 1s integration, B=16 MHz,
  Npol=2 and ν=74 MHz
Confusion noise (zenith)225 Jy/beamfor a 2 beam at 74 MHz

The thermal noise, as well as the confusion noise, will increase at angles away from zenith.
The confusion limit will be reached in about 1 msec using 8 MHz bandwidth. Longer integrations can be achieved for narrower bandwidths.

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