reflector adjustments jan01The observations used the standard 4 strip calibration technique described in the arecibo technical memo 2000-4 : "The Main beam and First Sidelobe parameters for Arecibo's receiver systems". The cband frequencies used were 4500, 4860, 5000, and 5400 Mhz. 8 sources were tracked (although only 2 or 3 were complete tracks) and the gain, SEFD, and pointing errors were computed. The source fluxes were taken from chris salter's most recent flux.cat catalog. The gain computation used the cal values measured in jan01. The 5400 Mhz cal value is probably not very reliable (see the above reference).
sband gain during and after surface adjusted (jan01)
Pitch, roll, focus correction at multiple frequencies on 3C48, CTA21 (feb01)
cband cals measured jan01 using sky and absorber)
sband focus curve after jan01 reflector adjustment.
cband focus curve after jan01 reflector adjustment.
The SEFD measurements only rely on the source flux. The best SEFD we were getting was 5 to 6 Jy. This occurred for two sources at similar za: B033+133 and B0017+154. This means the fluxes are probably not too far off.
The pointing errors have increased since the last model. the rms error is now:
When the cband cals were measured in jan01 there was a discrepancy in the cal values computed using the absorber or the sky for frequencies greater than 5000 Mhz. This could have been a problem with the cal measurement technique or possibly a loss in the OMT. If it was a loss, then the OMT will reemit at its temperature (70 K). This will throw off the estimation of the input power when the cal is measured relative to the sky (say 18K) and absorber (300K). Figure 3 SEFD plots shows that 5400 Mhz also has a funny SEFD. This lends support to the idea that the receiver is having problems above 5000 Mhz and that it is the system temperature that is increasing.