On Wednesday the 29th of August 2018, the Dwingeloo Radio Telescope took part in a test VLBI observation and we managed to obtain fringes to Westerbork and Jodrell Bank (Mark II Radio Telescope) right away. This is more than 40 years after its first appearance as a VLBI telescope (see Schilizzi e.a., A&A 77, 1979).
The Dwingeloo Telescope, once the largest fully steerable dish in the world, is now operated by the CAMRAS volunteer organisation. They have, with great support from ASTRON, restored and rejuvenated the historical instrument. Its return to VLBI is a huge milestone and a testament to the great work by all these volunteers.
The image shows the fringes in one of the 8 subbands of each 16 MHz that were recorded. The background image depicts the ‘flowchart’ created in the open source GnuRadio program to convert the input from raw samples, into properly timestamped VDIF data for the JIVE correlator.
Just like the previous time that Dwingeloo did VLBI, the frequency reference is again a borrowed Rubidium clock. However, as part of the ASTERICS project, we are working to transport the H-maser frequency reference signal from Westerbork over fiber to the Dwingeloo Telescope. This still requires a bit of digging to bridge the last few hundred meters to the telescope, but expect even better fringes soon.