To leave the frames behind, click here

As of January 2004, the L-Narrow receiver has been de-commissioned
to make way for the ALFA system.

Basic Information

Calibration & Beam Parameters

RFI Situation

Recent Events

Receiver History

Contact Info

1. Basic Information:


Frequency Range (GHz): 1.28 - 1.50
Plot of frequency response can be found here

Name and Number:

L-Narrow (lb, lbn, 6)
Measured Sensitivity (K/Jy): 8-10*
Measured System Temp (K): 26-32*
Native Polarization: Dual Circular**
Beam Size (at 1415 MHz): 3.1 x 3.5 arcmin*
Available Filters: click here

*See calibration info below for a more accurate description of the telescope parameters!

**Note that the polarization of the L-narrow receiver is reversed from what is common --
the left circular polarization comes in channel B while the right circular polarizatin comes in channel A

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2. Calibration & Beam Parameters:

Gain and Tsys Cal Values Beam Maps Polarization Misc. Info

  • Gain & System Temperature

  • Cal Values

  • Beam Maps

    Data and plots showing side lobes at different locations on the dish. (Data gathered in May 2000.)

  • Polarization

    Information on the L-Narrow Polarization and Mueller Matrix Elements, as derived in September, 2000, can be found

  • Misc. Calibration Info

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    3. RFI situation:

    Table of known RFI Puntas Salinas
    Frequency Hopping Radar
    Future RFI Issues at L-band


    The most common RFI found in the L-narrow frequency ranges are given in the table below. If you are planning on observing in the L-narrow frequency range, you should also check out the latest RFI plots from our hillside RFI monitor, which can be found here

    Please note - to keep this table current you need to fill out RFI reports after each night of observation!

    Fractional Occupancy
    (% of time seen while observing)
    Strength (typical)
    (% Tsys)
    Length & Frequency of Burst
    1217, 1227.5, 1265.0, 1313.0       Pico del Este Radar
    1222.32, 1231.28, 1240.24, 1249.2, 1258.16, 1267.12, 1276.08, 1285.04, 1294.00, 1302.96, 1311.92, 1320.88 1329.84, 1338.80, 1347.76, 1356.72, 1365.68, 1374.64, 1383.60, 1392.56 Always in some mode     Puntas Salinas Freq. Hopping Radar. (More info available below)
    1241.7, 1246.2, 1256.7 Occasionally     Military - Tethered Baloon
    1287.5, 1299.84,1300.,1399.83, 1400.,1411.52,1412.5. Should not occur   Distomats
    1270.9/1289.8 Occasional (and only one of the two freq. at a time) >100% 12s pulse FPS20-93a radar located in Ramey but controlled by the folks at Puntas Salinas
    1320.5 Occasional (and only one of the two freq. at a time) >100%   Ramey
    1324,1340 Occasional (only during war games) >100% 2s pulse Naval "landing system"
    1330/1350 ALWAYS >100% 400micros pulse FAA Radars (Pico del Este) BLANKER AVAILABLE
    1340/1347.2/1362.6 ALWAYS 10-40% 400micros pulse Modes of FAA Radars BLANKER AVAILABLE
    1366.3,1382.7 Occasional (only during war games) >100% 2s pulse Naval "landing system"
    1371.0,1387.3 Occasional (only during war games) >100% 2s pulse Naval "landing system"
    1381.1 Variable 10% - >100% Variable GPS L3 satellites
    1417.5 Should not occur 20-40% ~Constant Dome Cameras??
    Ask operators to turn off cameras

    Other RFI Issues - The PRANG (Puntas Salinas) Frequency Hopping Radar:

    This radar runs in the range from 1220 - 1400 MHz and has the potential for completely killing most HI observations at Arecibo. Fortunately, through considerable work by the RFI folks here at Arecibo, an agreement has been made between us and the folks at Puntas Salinas. If a request is put in in advance, Puntas Salinas can restrict the frequencies used to so they do not interfere with your observations. This means you must state on your proposal form that you wish to have coordination with Puntas Salinas. If you do not, there is a good chance PS will be transmitting at ALL of their frequencies. (More info on the PS radar modes can be found here)

    On occasion, although we did request that PS use a particular mode, they may forget to switch to that mode. If this occurs, simply ask the on-duty telescope operator to telephone our contact at PS and ask them to check that they are transmitting in the correct mode. Before doing this, though, be sure to check that the to have the operator help you check that the RFI you are seeing is from Puntas Salinas.

    Future RFI Issues at L-band:

    • The Galileo Project (next generation of GPS): 1164-1300 MHz & 1559-1610 MHz
    • The FCC ruling on the proposed Ultra-Wide Band devices (potentially including a variety of frequencies below 2GHz) (info)

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    4. Recent Events:

    • New gain curves and cal values are available for data taken after 15 August, 2001!
    • On 16 May, 2002, a 1282 MHz highpass filter was installed on the front end of the receiver.
    • L-narrow receiver de-commissioned (Jan 2004).

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    5. Receiver History:

    January, 2004: L-narrow receiver de-commissioned
    Early June, 2002: Switchable filterbank installed
    15 May, 2002: Bandpass filter installed
    18 December, 2000: Re-measured cal values
    27 July - 7 August 2000: Receiver warm-up & amplifier change (Note)
    05 July 2000: Annual Refrigerator service completed. Receiver re-cooled.

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    6. Contact Info:

    For further information on this receiver, please contact Murray Lewis at
    blewis (append

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