Resonances in the sband high (3-4 Ghz receiver)

may03

Sections:

29jul02: resonances in the sbh receiver using VirgoA.
10jan03: on/offs using J1609+266
09may03: on absorber and sky.

Plots :

29jul02 : resonances in the sbh receiver using VirgoA.
10jan03: resonances in the sbh receiver using J1609+266
10may03: resonances in the sbh receiver using sky and absorber.

The sband high receiver was searched for resonances on:

29jul02 - doing on/off position switching on VirgoA
10jan03 - doing on/off position switching on J1609+266
09may03 - measuring the cal while on sky and absorber.

Since the OMT of sband high is cooled to 20K, the resonance signature will differ from the receivers with a 70K OMT (lbw). Blank sky (plus scattered radiation) is close to the OMT temp so there will not be a large resonance bump on blank sky. Strong sources/absorber should have a large negative dip (see resonances in the lbw receiver for more info).

29jul02: on/offs on Virgo A (top)

VirgoA was chosen because it was the only strong source available during the test time. It is actually too strong/extended and did not give very good baselines. The correlator was run with 4 by 25 Mhz bandwidths overlapping each sbc by 2.5 Mhz. The band was measured in 80Mhz junks from 2950 Mhz to 4000Mhz. It took 13 measurements to cover the range. The VirgoA plots show:

Fig 1 PolA and Fig 2 PolB are on/off -1 normalized to the median value in each sbc. The 13 different measurements are over plotted. The 4 frames are the 4 sbc. The band passes look similar except for the bottom plot where the (blue?) line has a dip at -8 Mhz.

Fig 3 plots the sbc centered at 3550 Mhz. The dip is at 3545. The two green lines are the band passes for sbc4 in the two adjacent frequency bands (3350+/- 80Mhz).

10jan03: on/offs with J1609+266 (top)

On off position switching was done on J1609+266 (2.6 Jy at 3500Mhz). The correlator was run with 4*25Mhz bandwidths overlapping each sbc by 2.5 mhz. 13 steps were used to cover 2950 to 4000. Three passes through the frequency range were done with the last two offset by 5 and 10 Mhz (to cover the bandpasses edges). (PosOn/PosOff-1) - median(tsys) is plotted. The colors are: Red-0 offset, Green 5Mhz offset, Blue 10Mhz offset. The 10jan03 plots show:

Fig 1,2 polA,polB covering 2950 to 3490. There is a dip at 3323 Mhz in both polA and polB.
Fig 3,4 polA,poB covering 3480 to 3970. There is a large dip at 3545 in polA and polB. polA has a dip at 3620. polB has a dip at 3580 and possibly 3620.

processing: x101/030110/sbhresonance.pro

09may03: stepping the frequency on the absorber. (top)

The cals were measured on 09may03. The program stepped from 3 to 4 Ghz on absorber and then on the sky. The was repeated six times. The computations were spcAbs/spcSky after averaging the 6 sweeps. The 09may03 plots have polA in black and polB in Red. The Green dashed lines are the edges of the 25Mhz bands.

Fig 1: 3000 to 3500 .
Fig 2: 3500 to 4000.

There is a clear dip at 3545 Mhz. 3323 has a negative bump in PolA but it is at the edge of the bandpass.

processing: x101/030509/hcorcal/sbhresonance.pro

Possible resonances in sbh
3345 yes	Stronger in polA than polB. Seen in all 3 measurements
3323 maybe	10jan03 both pol. 09may03 dip, but at edge of the band.
3620 maybe	10jan03 dip polA (maybe also b). 09may03 dip polA and B
3580 maybe	10jan03 polB

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