[evlatests] Flux Density Results

[Rick Perley]

The recent 24-hour D-configuration 'flux density' observation (09/10 March) provides accurate measurements  of the spectra flux densities of our standard calibrators, plus some other point sources observed to assist in calibration.

The weather was outstanding, and instrumental performance was, overall, the best I've seen (other than the problem with baseline boards, which took out a couple spectral windows — a minor loss).

Attached are two plots showing the derived flux densities from L through Q bands (the P-band results are being reviewed — I'll add these later). All values are based on the PB 2018 values for 3C286 (which are based on Mars and Cygnus A).


The first plot shows our standard sources:  3C286, 3C48, 3C123, 3C138, 3C147, 3C196, and 3C295.  The solid lines show the current values, the dashed lines are from PB2018.  We expect no changes for 3C123, 3C196, and 3C295 — and indeed, the dashed and solid lines are not distinguishable, except at Q-band, where the accuracies are not high.  3C48 has increased slightly at high frequencies, and 3C147 has declined slightly.  Both have compact cores, and these changes are not surprising.
As is well known, 3C138 is undergoing a major flare, the effect of which is easily seen in the plot — the flux at 48 GHz is about a factor of 5 higher than in 2018.

The other plot shows results from some compact sources:  3C84, J2007+4029, J0217+7349, J1153+8058, J1800+7828, and J0555+3948.  These are all variable sources, so no particular conclusion is to be drawn.

Future plots will show the polarization results.

Rick








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