History File

02jun01 -- The plan now is to build the last 5 Q-band receivers and 7 K-band receivers by December 2002 as part of the EVLA project.

14sep00 -- Antenna gain curves for K and Q band added by Steve Myers.

05sep00 -- All new K band receiver feed horns appear to be contaminated by water during wet weather. The worst ones have been purged with dry air and had a passive desiccant system installed. This has not solved the problem. We are continuing to work on solving the problem. In the mean time, check your K-band observations carefully. If the weather is very wet, you could see system temperatures 50-200 K greater than normal for the new receivers. It is unlikely that any K-band observations in such high water column conditions would be recoverable. See K-band performance plots below for a demonstration of the problem (ANT 1 is a good example).

13jul00 -- ANTs 10 and 28 surfaces errors were significantly decreased using K band holography. They now provide reasonable responses at Q band.

29jun00 -- 21 Q band and 13 new K band receivers now available.

23may00 -- 20 Q band and 13 new K band receivers now available.

28mar00 -- K band receivers are currently a mix of new receivers with vastly improved system temperatures (To~40K) and old receivers with To~100-150K. A simple procedure is being developed that can be implemented in AIPS to properly weight calibrated uv data to take advantage of the power of the new receivers. If you follow this procedure, you will gain up to a factor of 2 improvement in the RMS (depending on the weighting scheme used in IMAGR) and you will decrease systematic errors caused by noisy baselines between two old receivers. Click HERE to obtain a copy of the step-by-step procedure being developed and to see how to calculate the theoretical RMS expected in your K-band map. For questions: contact Debra Shepherd (dshepher@aoc.nrao.edu).

27mar00 -- If delivery of parts is on schedule, expect the first 2000 Q band receiver to be installed around 15may00, with new Q receivers going onto the array every 1.5 months after this.

16mar00 -- Based on K-band holography run, ANTs with good surfaces at 1.3~cm are: 1, 3, 6, 7, 8, 9, 11, 12, 15, 16, 18, 19, 25, 27. ANTs with poorer surfaces are 2, 10, 13, 14, 21, 22, 23, 24, 26, 28. The BEST ANT surfaces are 7, 9, 15, 27. The WORST ANT surfaces are 10, 23, 24, 28 (aug 00 UPDATE: ANTs 10, 23, 24, & 28 have all had their panels readjusted based on K band holography. They should be OK now). ANTs 4, 5, 17, 20, 24 & 28 were not measured in this run.

16mar00 -- Y2000 plans are to install 6 new Q band receivers and 4 new K band receivers. Build and installation will take place gradually over the year as parts and amplifiers are made available.

01mar00 -- 19 Q band and 12 new K band receivers now available.

17dec99 -- Average Q-band receiver temperature is 50 - 55 K accross the 40 - 50 GHz band.

16dec99 -- RMS pointing error for all antennas at Q-band 5-6", the worst case pointing error is 10"-15".

16dec99 -- Focus looks good for all Q band receivers

30nov99 -- ANTs 10, 24, & 28 K band amps approx. 25% low. Panel readjustments required

22nov99 -- Sucessful 4 IF Fringes on VLA-Pie Town link at Q and K bands