Projects/IsisArray/IsisDeploymentGreenbank/IsisArray/IsisDeploymentGreenbank/RadioStarCalibration

Radio Star Calibration Results

Several radio sources are available. The most common ones are:

• Sun

• Cas A (3C 461)

• Cyg A

Cassiopeia A

3C 461 radio star (actually radio supernova remnant):

• Coordinates (Epoch J2000):

  • Right Ascension: 23 23 24.0 Declination: +58 48 54.0

• Flux measurements from Kraus' book show 11,000 Jy at 178 MHz from the 3rd Cambridge survey, and 3120 Jy from the Caltech 960 MHz survey.

• Two EISCAT references contained in some of Brian Jackel's documentation of the Algonquin bistatic project cite a flux density at 440 MHz of approximately 6100 Jy.

• The definite reference seems to be the paper by Baars et al, 1977 which quotes a spectral falloff equation. Using this, the flux at 440 MHz is 5122 Jy.

• As Jackel notes, this is the total power at all polarizations, so we would then observe half of this when peaked up on the source. Since 1 Jy = 1E-26 W/(m2 Hz), the measured flux in the LCP channel should be 2.561E-23 W/(m2 Hz).

• Labeling \eta as the aperture efficiency and using a Boltzmann constant of 1.3807E-23 J/K, we then expect a LCP received temperature of:

Updated Information

Further information shows that Ott et al, 1994 is an update to Baars et al, 1977 for frequencies > 1.4 GHz, and in particular describes secular flux variation rates. A paper discussing flux calibrators at 408 MHz is Riley, 1988.

2005-12-21 Experiment Results

Among several data types collected on 2005-12-21 was a dedicated experiment looking at Cas A from both Millstone and Green Bank.

Note: Operator error (PJE) resulted in the data below having channel numbers of 100, 104, and 108 INSTEAD of the desired 200, 204, 208 on aten.