System performance

• Gain [K/Jy], Tsys[K], SEFD[Jy/Tsys], and average beam width[Asecs]
• coma parameter, 1st sidelobe height, main beam efficiency,  and main beam + first sidelobe efficiency.
• Pointing errors [Asecs] vs az and za.

For the alfa receiver the data is first plotted with all pixels together. The color is used to code the pixel number. After the combined plot there are 7 more plots showing each pixel by itself. For these plots the color is used to distinguish the source used.

There are sections that show the cumulative system performance and the system performance by month.

---

Links to sections:

---

System modification history:  (top)

• 11dec17: added 05-07 model data offsets correctly for cb,xb,430. (mainly affected 430).
  
• 09dec17: updated model19 offsets for 430,cband,xband including 04-07dec17 data.
• (but did it wrong.. 05-07 data had model19 offsets. mainly affected 430).
  
• 04-07dec17. recheck other rcvr offsets with model19 installed.
  
• 01dec17: installed model19
• 21-25nov17: verify model19. use same offset as rcv had with sbn in model18
  
• 19nov17: svn with model19, but platform way out of position.
  
• 01-17nov17: td tracking. data for model19 .. taken with model18A installed
  
• 30oct17: no td tracking, 430lf ballast added to az arm
  
• 22,24,25,26oct17:  no td  tracking, pre 430lf ballast
• 20sep17: hurricane maria
• 01aug17: cband wide installed. cal values and optical alignment are provisional
  
• 13jun15: lbw changed 1295 freq -> 1310  to get away from punta salinas new freq, changed l175 -> 1150 to get away from gpsl5
• 18sep13->15jun13 (file .2). lbw low band was taken with circular rather than linear mode.
  
• 21may14: alfa reinstalled.
  
• 28mar14- alfa down to lab. weight change may affect pointing (za)
  
• 13jan13: updated pointing error offsets using jan12-dec12 data.
  
• 27feb12-04mar12 model 18 taken with sbn. The pointing error will be large since the tiedowns used a new position to remove the residual platform tilt.
  
• nov10: cband Tsys increased to about 40k on 13nov10 and then went back down around about 22nov10.
  
• Caused by the gortex horn cover coming off and moisture getting in the mouth of the horn.
  
• 03jun10: updated pointing model with 1,2,3 az fits to data mar10-jun10
  
• 24mar10: repaired broken beam, za limits 3.5 to 12 deg za
  
• 02mar09: switched the pointing errors to be from 01jul08.. last mod to pointing model.
  
• 01jul08: xband model subtracted 4 asecs from za constant term for bania. Did not modify any other recievers.
  
• 20jun08: updated pointing model with calibration data using fits to 1az and 3 az terms.
  
• 13jun08: cooled 327 receiver installed
  
• dec07: this included the pointing model made with sband narrow after the painting project completed. It will include the pointing errors after the painting and before the new model was installed.
  
• xxapr07: pointing off since painting program moving weights.
• 31mar07: painting project started moving weight on the platform.
• 10dec06: updated  pointing model 1az terms and az*sinza.
• 03/04dec06: x102 runs had offsets in model for testing. sin(za) az: -45.9*sin(za). 1az term for za: -6.7cos(az) - 6.8sin(az) . These values were added to model. To goback to old model, subtract these values.
• 16jun06: lbw polB Cal. found loose sma feed thru inside dewar. Probably causing the drifts in polB Tsys.
• 10apr06: sbn cal remeasured 15mar06. installed 10apr06. backdated to 14oct03. Need to recompute the sbn data to used these new cal values. the old ones were probably a little high.
• 04dec05: lbw polB cal value jumps 20%. remeaured cals on 23feb06.
• 23nov05: lbw diodes replaced
• 30sep05:   station clock off by 1 second midnite to 8:30am. lbw calibration data will have extra 15 asec pnterr.
• 18aug05: sbw cal cables changed. This changed the amount of cal getting into the dewar. Need to remeasure the cals.
• 08aug05:   new cband cals installed. backdated to 25may05 when new amps were installed. recomputed cband data from may05 with new cal values.
• 22jul05:    lbw diode 1 died.. used diode 2 for cals until new diodes arrive.
• 21jun05:   installed new lbw cals (had a bug in diode1->polb... fixed 09aug05).
• 01jun05 :    lbw: found bad polA connection to probe in dewar. found cracke polB cal cable in dewar..
• 25may05:   cband reinstalled with new amps, cal values need to be updated.
• 13mar05    Included 430ch data in system performance.
• 12mar05    oh filterbank installed for alfa.
• 29jan05     (check date) 430 filters to remove tv station intermods installed polb ch and pola,b dome.
• 23jan05    recomputed alfa system performance using the new cal values.
• 05jan05    added alfa data. Using old cal values from the lab.
• 27dec04    cbh . model offsets az,za incremented by (-.28,-3.82). data from x102 runs.
• 27oct04    the 327 data taken 27,28oct04 had a hybrid in front of the receiver. It was used to create circular polarizations for a vlbi observation.
• 09oct04    cband dewar brought down. found short in polA  cable inside dewar that was causing the tsys values to jump around.
• 12sep04    lbw cals measured 06aug04, installed 12sep04, backdated to 04jun04.
• 04jul04    cband polA cal value jumps back (after dewar warmed up and cooled down). note continues to jump around until 08oct04 when dewar brought down and short found in one of the cables in the dewar.
• 31may04    cband polA cal value jumps.
• 17may04    pointing model 15 installed after verify runs completed. (sbn installed a few days before).
• 14may04    sbw diodes replaced, horn lowered 2.4 inches.
• 10may04   during this week calib scans were done with some receivers with large pointing errors.
• 10may04  during week pointing model made sbn, verification other sources with calib scans.
• 01may04  tertiary resurveyed into position
• 29apr04    horns resurveyed and moved into "best" position. lbw,sbw,sbn not moved.
• 23apr04    lbw polB cal value jumps.
• 21apr04   alfa installed, kevlar cables installed week before.
• 15mar04    xb receiver back up. Was in lab for cals,amps, loose cables in dewar. remeasured cal values.
• 29feb04    pointing offsets cbh updated using calib runs feb04.
• 14feb04     horn survey, repositioned horns, updated pointing model. Larges move was lbw.
• 13feb04    sbh horn moved dow .8 inches to bring in focus. New cals installed
• 10feb04    cbh installed
• 26jan04    leaf springs on the dome changed to stiffer ones (approx. date)
• 14jan04    610 receiver moved on the turret floor.
• 07jan04    327,xband receivers moved on the turret floor.
• 10oct03    sbw cals remeasured. backdated to 15aug03. still drifting.
• 02nov03  lbw gain curve from data 01mar03 thru sep03. back dated to 01mar03.
• 14oct03    8am. az encoder jumped by 3 teeth (about 16 asecs). fixed on 16oct03.
• 05oct03    xband cals remeasured on antenna test rangei valid from 05oct03.
• 04sep03    I think the Cal values on xband have changed after new horn installed (see measurements).. They need to be remeasured.
• 03sep03    new xband horn installed.
• 21jul03    xband. updated pointing offsets from calib data.
• 21jul03    xband installed new cal values from sky,absorber.
• 30may03 recomputed xband cals. uncorcal,0cal definitions were wrong on measurement page.
• 18may03 loose cable cband cals. retightened cable and redid cals.
• 14may03 remeasured sbh cal values. diodes have been drifting.
• 22apr03: cband new cal noise diodes installed.
• 10mar03: corrected feeds offsets installed 07mar03.
• 07mar03: model 14 installed with feeds offsets (but offsets were backwards)
• xxfeb03: dome lifted, elevation rails shimmed, model 14 installed.
• 21nov02: lbw horn focus changed
• 30aug03: 610 antenna switched from fat dipole back to skinny dipole
• 28aug02: cband horn focus changed
• 21aug02: lbn horn focus changed.
• 31jul02:   327 room temperature receiver installed.
• 02apr02: update xband turret position from theodolite survey.
• 23may01: 610 receiver switched to fat dipole.
• 06feb02: reshimmed xband horn position.
• xxsep01: major adjustments to reflector surface completed.

Misc, multi-freq:   (top)

 home_~phil