Tour of MRAO (Part 2): HERA, MERLIN, AMI Small Array, COAST and SKA
All trips at this location:
- Tour of MRAO (Part 1): Lord's Bridge station and AMI Large Array
- Tour of MRAO (Part 2): HERA, MERLIN, AMI Small Array, COAST and SKA
- Tour of MRAO (Part 3): 4C Array, Flora & Fauna, and One-Mile Telescope
- Tour of MRAO (Part 4): One-Mile Telescope Control Room
Map §
Leaving the AMI Large Array (at the furthest east of MRAO), we drove west back along the road that follows the old east-west railway line, under the bridge, and then turned left at the fork. This gentle curve follows the line of the former railway sidings, for when this site used to be a munitions storage facility.
We carried on southwest, taking a slight right at the point of a teardrop shaped road, then pulled in just after the next road loop, where HERA is visible about 60m away to the northwest.
HERA §
HERA (Hydrogen Epoch of Re-ionization Array) is not mentioned on the MRAO Wikipedia page. Perhaps this is because it is technically a HERA prototype. Here is an article by Cavendish Astrophysics (who operate the MRAO) about the “3-dish HERA prototype” at MRAO, which can clearly be seen in the photos below:
There is much more information about HERA and the receiver in this paper, titled Design of the New Wideband Vivaldi Feed for the HERA Radio-Telescope Phase II.
The actual HERA radio telescope is in South Africa.
Cambridge MERLIN §
From the same spot, but turning east, is a great view of the Cambridge MERLIN radio telescope with its 32m dish. It forms part of the e-MERLIN array, which consists of seven radio telescopes across England.
The e-MERLIN array consists of:
- Cambridge MERLIN telescope
- Defford telescope
- Darnhall telescope
- Knockin telescope
- Pickmere telescope
- Lovell Telescope
- Mark II
Wikipedia omits the Darnhall telescope from its list of MERLIN telescopes for some unknown reason?
See this Wikipedia page for many more radio telescopes.
The Cambridge MERLIN telescope, with its 32m diameter dish, is the second biggest dish in England. First place goes to the Lovell Telescope, which is also part of e-MERLIN, with its whopping 76.2m diameter!
Map §
Moving on, from HERA we turned left heading southeast down the main road, then turned left after Long Brook to park outside the front of the AMI Small Array.
According to the old map, this used to be the location of the BOMB STORES!
Plaques §
The AMI Small Array is completely enclosed within some angled walls. The only way to get in is through the adjacent building, which has a couple of interesting plaques out front:
Inside §
Inside, there is a server room that contains a couple of RF signal racks:
Back through the main hallway, a lab space leads to an angled door, that leans inwards at about 45 degrees. As will become clearer in the next picture, that’s because this door emerges from the sloping wall that encircles the AMI Small Array.
AMI Small Array §
As the name implies, the AMI Small Array is indeed smaller than the AMI Large Array!
Each receiver is approximately 4m high from ground level, and the dishes are 3.7m wide.
There are 10 receivers in total, arranged in the following formation:
x x
x x
x
x x
x x
x
COAST §
Just southeast of the AMI Small Array is COAST (Cambridge Optical Aperture Synthesis Telescope). Much of COAST is inside a bunker, but some of the equipment is also contained in this white boxes on the grass outside.
SKA §
Directly in front of COAST is an individual prototype SKA antenna. Specifically, I believe this is a SKALA-2 antenna for SKA-Low. See the paper titled Evolution of SKALA (SKALA-2), the log-periodic array antenna for the SKA-low instrument.
While researching SKA, I found this post from Cavendish Astrophysics, which links to this YouTube video, which provides aerial drone footage of SKA!
The tour guide told us that this SKA antenna was called “the final design”, but afterwards there were two more!
Next part §
To carry on with the tour, see here for part 3.
All trips at this location:
- Tour of MRAO (Part 1): Lord's Bridge station and AMI Large Array
- Tour of MRAO (Part 2): HERA, MERLIN, AMI Small Array, COAST and SKA
- Tour of MRAO (Part 3): 4C Array, Flora & Fauna, and One-Mile Telescope
- Tour of MRAO (Part 4): One-Mile Telescope Control Room