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



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:     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:
    processing: x101/030110/

    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. 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/

    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