|
|
EVLA updates appearing in issues of NRAO eNews. |
|
|
The following table lists retrofitted EVLA antennas currently in the array, and the availability of their receivers. Antennas in red are not taking part in regular observing yet, but will be included shortly. Numbers in parentheses indicate antennas that temporarily have been taken out of the array because of hardware restrictions; once the WIDAR correlator is deployed these antennas will take part in the array again. |
|
|
The planned availability of the various bands on the EVLA is shown in Figure 1. No EVLA antennas have the VLA Ku (U) band (15 GHz) frequency available; installation of those on EVLA antennas will begin in 2010. Note that until the VLA correlator is turned off, due to hardware constraints the maximum number of available antennas will gradually drop to 22. |
|
|
In two VLA proposals with Snezana Stanimirovic (Univ Wisconsin), Carl Heiles (UC-Berkeley), and Ayesha Begum (Univ Wisconsin), we have investigated weak galactic HI lines in the direction of the extragalactic sources AS931 and AB1325. These lines have opacities of several times 0.001. In the direction of 3C286 we confirmed the weak lines detected by Stanimirovic and Heiles at Arecibo with opacities of 0.005 to 0.006. |
|
|
One of the goals of the EVLA upgrade is to be able to produce polarimetric images that are limited by noise rather than systematics. This can be achieved through stable polarizers and software that accurately handles polarimetric calibration and modeling, including the off-axis EVLA antenna response. The design of the polarizers in the antenna feed varies between the different EVLA observing bands. This note focuses on some early characterization of the polarizers at C and K bands and the measurement of the stability of the so-called polarimetric leakage terms. The C and K bands use orthomode transducer and waveguide designs respectively, being representative of the L/S/C and Ku/K/Ka band polarizers. |
|
|
Currently on time and on budget for completion at the end of FY2012, the first phase of the Expanded Very Large Array Project (EVLA) will offer the astronomical community an order of magnitude increase in sensitivity above the original VLA, contiguous frequency coverage between 1 and 50 GHz, and incomparable flexibility in the set up of the new WIDAR correlator. We propose a trio of relatively low-cost (< $12M total cost, FY09 dollars) enhancements to the EVLA. |
