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Recommended continuum frequencies

The ATCA allows significant flexibility in setting the observing frequency. For continuum observations, where the exact frequency is not of significant importance, the table below gives the recommended observing frequencies. These frequencies have been chosen for a variety of reasons, such as low system temperature and little radio frequency interference. As many observers will use these frequencies, it is likely that there will be less set-up effort than with other arbitrary frequencies. Consequently these frequencies should generally be used when possible.

With the old (pre-March 2009) correlator, observing frequencies were carefully chosen (at odd multiples of 64 MHz) to minimise various instrumental effects. With the (post-March 2009) CABB, there are no such constraints.

For the 20cm and 13cm bands, the receivers will limit the useful bandwidth to ~500MHz, though RFI may further limit the useful bandwidth in practise, particularly in the 20cm band. In addition, note that:

  • Simultaneous 6cm and 3cm observing continues to be possible, but that simultaneous 20am and 13cm observing is not (at least until the 20/13cm frontend upgrade).
  • At 12mm, 7mm, and 3mm wavelength, the two IF frequencies can differ by more than previous constaint of 2.7 GHz, but must be less than 6 GHz and will depend on the observing frequencies chosen.
  • The 7mm and 3mm frequencies given below for CABB are nominal. Some sets of observing frequencies in these (wide) bands suffer from poor image rejection and so these recommended frequencies will be revisited once more experience is obtained with CABB.

Note: All frequencies below are centre frequencies.

Band CABB Freq1 (& b/w) CABB Freq2 (& b/w) Old Freq1 Old Freq2
20 cm 1750 MHz (500 MHz)   1384 MHz1  
13 cm 2450 MHz (500 MHz)     2368 MHz2
6 cm 5500 MHz (2048 MHz)   4800 MHz  
3 cm   9000 MHz (2048 MHz)   8640 MHz
12 mm 17000 MHz (2048 MHz) 19000 MHz (2048 MHz) 18496 MHz 19520 MHz
7 mm 33000 MHz (2048 MHz) 35000 MHz (2048 MHz) 34496 MHz 34624 MHz
7 mm 43000 MHz (2048 MHz) 45000 MHz (2048 MHz) 44096 MHz 44224 MHz
3 mm 93000 MHz (2048 MHz) 95000 MHz (2048 MHz) 93504 MHz 95552 MHz

Notes:

  1. With the old correlator, when observing with both IFs set to 20cm continuum, the recommended frequencies were 1344 and 1432 MHz.
  2. With the old correlator, when observing with two IFs set to 13cm continuum, the recommended frequencies were 2368 and 2496 MHz. Note that there is strong, narrowband interference at 2493 MHz from Globalstar satellite mobile phones.
Original: Bob Sault (04-Sep-2005)
Modified: Phil Edwards (04-jun-2009)