Complex gain
Definition: Antenna-based amplitude and phase response that multiplies the true electric-field correlation.
Why it matters here: It is needed to answer If residual phase rms doubles from 10 degrees to 20 degrees, does coherence loss double? Compute or reason from the exponential form. and to interpret A baseline visibility is multiplied by one antenna gain and the complex conjugate of the other.
Relationships: Use it with Phase calibrator and Bandpass; the lecture model is \(V_{pq}^{\rm obs}(\nu,t)=g_p(\nu,t)g_q^*(\nu,t)V_{pq}^{\rm true}(\nu,t)+n_{pq}\).
Boundary or common confusion: A wrong calibrator model can transfer systematic error to every target. The phase-coherence approximation assumes zero-mean Gaussian residual phase and does not model direction-dependent structure.
Bandpass
Definition: The frequency-dependent complex response of the receiving and correlator chain.
Why it matters here: It is needed to answer If residual phase rms doubles from 10 degrees to 20 degrees, does coherence loss double? Compute or reason from the exponential form. and to interpret A baseline visibility is multiplied by one antenna gain and the complex conjugate of the other.
Relationships: Use it with Complex gain and Delay calibration; the lecture model is \(V_{pq}^{\rm obs}(\nu,t)=g_p(\nu,t)g_q^*(\nu,t)V_{pq}^{\rm true}(\nu,t)+n_{pq}\).
Boundary or common confusion: A wrong calibrator model can transfer systematic error to every target. The phase-coherence approximation assumes zero-mean Gaussian residual phase and does not model direction-dependent structure.
Delay calibration
Definition: Estimation of phase slope with frequency caused by path or clock offsets.
Why it matters here: It is needed to answer If residual phase rms doubles from 10 degrees to 20 degrees, does coherence loss double? Compute or reason from the exponential form. and to interpret A baseline visibility is multiplied by one antenna gain and the complex conjugate of the other.
Relationships: Use it with Bandpass and Flux calibrator; the lecture model is \(V_{pq}^{\rm obs}(\nu,t)=g_p(\nu,t)g_q^*(\nu,t)V_{pq}^{\rm true}(\nu,t)+n_{pq}\).
Boundary or common confusion: A wrong calibrator model can transfer systematic error to every target. The phase-coherence approximation assumes zero-mean Gaussian residual phase and does not model direction-dependent structure.
Flux calibrator
Definition: A source model used to establish the absolute amplitude scale.
Why it matters here: It is needed to answer If residual phase rms doubles from 10 degrees to 20 degrees, does coherence loss double? Compute or reason from the exponential form. and to interpret A baseline visibility is multiplied by one antenna gain and the complex conjugate of the other.
Relationships: Use it with Delay calibration and Phase calibrator; the lecture model is \(V_{pq}^{\rm obs}(\nu,t)=g_p(\nu,t)g_q^*(\nu,t)V_{pq}^{\rm true}(\nu,t)+n_{pq}\).
Boundary or common confusion: A wrong calibrator model can transfer systematic error to every target. The phase-coherence approximation assumes zero-mean Gaussian residual phase and does not model direction-dependent structure.
Phase calibrator
Definition: A nearby compact source observed repeatedly to track time-variable phase.
Why it matters here: It is needed to answer If residual phase rms doubles from 10 degrees to 20 degrees, does coherence loss double? Compute or reason from the exponential form. and to interpret A baseline visibility is multiplied by one antenna gain and the complex conjugate of the other.
Relationships: Use it with Flux calibrator and Complex gain; the lecture model is \(V_{pq}^{\rm obs}(\nu,t)=g_p(\nu,t)g_q^*(\nu,t)V_{pq}^{\rm true}(\nu,t)+n_{pq}\).
Boundary or common confusion: A wrong calibrator model can transfer systematic error to every target. The phase-coherence approximation assumes zero-mean Gaussian residual phase and does not model direction-dependent structure.