Visit to the Jansky Very Large Array

(click on images within grids for a bigger image)

When you’re building the world’s largest radio telescope, then you need to go and see how other observatories have done the same and learn what lessons you can – which are the good operational practices and what are the mistakes you should try to avoid.

Early in September, we went to visit the Karl G. Jansky Very Large Array, in New Mexico, USA. The JVLA is an iconic radio telescope with its distinctive ‘Y’ shaped configuration and featuring in various film and TV shows, most notably perhaps in the movie Contact.

At the time of our visit, the 25-metre dishes were being moved out to their very widest configuration where the furthest distance between two individual dishes reaches over 22.6 miles. They are moved, individually, by a transporter along the train tracks you can see in many of the images here.

Altogether, there are 28 dishes at the JVLA, of which 27 are out in the field and operational and one is in “the barn” undergoing maintenance and other engineering work. Dish No. 11 was being pampered at the time of our visit.


In this way there is a continual maintenance cycle for all the dishes in the array. We had the opportunity to climb up the dish structure and to walk on the dish surface.

On the site, there is also the Bracewell Radio Sundial. Sundials traditionally use the changing position of the shadow of an object to sunlight to give an idea of the time of day. As the Sun moves from East to West, an upright object will cast a shadow that moves during the course of the day as the Sun makes this track across the sky.

This Radio Sundial does the same thing except that the central post casts a shadow on certain square markers on the ground which indicate either important dates in the history of radio astronomy, or important astronomical objects in the radio sky. The markers are spread out in distance from the central post so that different astronomical objects can be indicated at different times of the year, taking advantage of the fact that the Sun is lower in the winter than in the summer, and so casts a longer shadow. All very clever, but as you can see from the pictures in this post, it was a cloudy day on our visit and so we couldn’t get the full experience.

The concrete pillars were brought over from Stanford University where Ron Bracewell mounted the dish antennas for his radio telescope. Each time a visitor would come to his observatory, he would invite them to chisel their “signature” into one of the pillars. There are some famous names on there, including Nobel laureates, observatory directors and many of the early pioneers of radio astronomy. Of particular interest to me was the signature of Bernard Lovell, the first director of the Jodrell Bank Observatory.

It was a great experience to visit the JVLA – yes, it was my first visit! – and we came away with with a positive experience and lots of good lessons learned from an observatory that has been operating for almost 40 years.


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