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430-MHz Gregorian
Basic Information

Calibration & Beam Parameters

RFI Situation

Recent Events

Receiver History

Contact Info

 

 

 

1. Basic Information:

 

Frequency Range (GHz): 422-442 MHz
Plot of frequency response can be found here

Name and Number:

430-MHz Gregorian
Measured Sensitivity (K/Jy): 11*
Measured System Temp (K): 50*
Native Polarization: Dual circular
Beam Size (at 0.430 GHz): 10' x 12'
Available Filters: 10 MHz, 20 MHz and 30 MHz
click here
Warnings and Important Notes: click here

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

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2. Calibration & Beam Parameters:


Gain and Tsys Cal Values Beam Maps Polarization Misc. Info


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3. RFI situation:

Very strong RFI at 427 and 432 MHz was seen to affect 430 MHz receivers in both channels since the last week of February 2003 until the start of 2005.
The problem is due to in-band intermodulation products of the carriers of two TV stations (in nearby channels 14 and 22), which have recently increased their transmitting power. Two such products fall within the 430-MHz bandpass, this severely corrupted many 430-MHz radio astronomical observations.
The installation in February 2005 of higher dynamic-range amplifiers and suitable notch filters has largely reduced the problem.

Previous to the appearance of this problem, there were several UNIDENTIFIED radio FREQUENCY INTERFERENCEs, these were located at:
- 426.25 MHz
- 426.60 MHz
- 433.40 MHz
- 434.00 MHz (This can saturate the receiver)

For RFI with known identifications, click here.

NEWS: E-2 Hawkeye airborne radar is no longer operational from Naval Station Roosevelt Roads. E-2 Hawkeye airborne radar, which operated near 430 MHz. This used to completely destroy your observation.

Daily RFI monitoring plots for the past several years from the Observatory "hill-top" monitoring system can be found in binders in either the telescope Control Room or by asking the Arecibo Spectrum Manager.
  • For the current daily average 430-MHz RFI plot from the Arecibo "hill-top" monitoring system, click here .

  • For the current frequency v time 430-MHz RFI plot from the Arecibo "hill-top" monitoring system, click here .

  • For the current frequency v time 430-MHz RFI plot (with band-pass correction) from the Arecibo "hill-top" monitoring system, click here .

  • For the current daily rms/mean v frequency 430-MHz RFI plot from the Arecibo "hill-top" monitoring system, click here .

The occurrence of RFI versus frequency by month and year since Jan 2001 can be found via the 430 link on this web page.

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4. Recent Events:

    Link to electronics department containing updated receiver log

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5. Receiver History:

This receiver has seen a marked improvement in system temperature over the last few years, which make it competitive with the CH receiver even for observations near the Zenith. Recently, a 20 MHz front-end filter was installed, which will particularly benefit pulsar observations. An even wider front-end filter of 30 MHz was tried, but unfortunately, this increased the amount of RFI in the band very significantly. Installation of a front-end filterbank is imminent.

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6. Contact Info:

For further information on this receiver, please contact Paulo C. Freire at
pfreire (append @naic.edu)

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