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The Max-Planck-Institut für Radioastronomie (MPIfR) and the Max-Planck-Society, in partnership with SARAO, have equipped MeerKAT with S-band receivers to complement the UHF and L-band receiver systems, providing coverage in the 1.75 - 3.5 GHz frequency range. These receivers are now available for early science on a shared-risk basis.
Basic characteristics of the system are known, and limited list of calibrators have been characterised. Investigation is still under way regarding the following:
expanding the S-band calibrator listcharacterising gain/phase stability
determining maximum distance to phase calibrator
gain curves
off-axis polarisation performance and calibration
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While the receiver and digitizer bandwidths are 1.75 GHz, the MeerKAT correlator can only process 875 MHz at a time. Digital band selection allows the band to be centred at 2.2, 2.4, 2.6, 2.8 or 3.1 GHz.
Sub-band | Frequency range |
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S0 | 1750 - 2625 MHz |
S1 | 1968 - 2843 MHz |
S2 | 2187 - 3062 MHz |
S3 | 2406 - 3281 MHz |
S4 | 2625 - 3500 MHz |
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Switching between sub-bands requires 'rebuilding' of the sub-array. Including time for delay calibration and subsequent operator quality assurance checks, this process takes about 15 - 20 minutes. Note that if wider frequency coverage is required in the same time slot, but sensitivity is not as vital, multiple sub-arrays with a subset of antennas can be run simultaneously in different bands. |
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| Note |
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Due to logistical issues, availability of the S-band receivers is somewhat lower than that of UHF and L-bands. Users should assume a lower limit of 54 56 antennas for sensitivity estimates. |
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3 April 2023 The sensitivity calculators have been updated to include S-band characteristics. |
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Commissioning results
Antenna pointing
Many of the earlier S-band commissioning reports mention antenna pointing as a possible cause of gain variations resulting in imaging artefacts and gain/flux scale transfer errors. This is an active area of work currently and is expected to improve was improved over the course of 2023.
The current mean blind pointing of the antennas is 40" at night and 50" during the day. Referenced pointing procedures are currently under development.
Users are advised to inspect the SDP calibration reports (or their own preliminary gain solutions) for high scatter in gain solutions before selecting a reference antenna.
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