Signal to Noise

The rms noise can be computed from

where

• is the system temperature in scale (150 K below 110 GHz, 300 K at 115 GHz, 500 K at 230 GHz)
• is the conversion factor from Kelvin to Jansky (25 at 3mm, 45 at 1.3mm)
• is an efficiency factor due to atmospheric phase noise (0.9 at 3 mm, 0.6 at 1.3 mm)
• is the number of antennas (5), and is the basic number of configurations (1 for D, 2 for CD, 3 for BC)
• T is the integration time per configuration in seconds (3 to 8 hours, depending on source declination)
• B is the channel bandwidth in Hz (500 MHz for continuum, 40 kHz to 2.5 MHz for spectral line, according to spectral correlator setup)