Radio astronomy observing and antenna repair at the Plishner observatory, February 15, 2020

Participants: Rich Russel, Bob Haggart, Glenn Davis, Lewis Putnam, Bill Miller, and Gary Agranat.

Photos by Bill Miller and Gary Agranat.

We worked at the Plishner antenna site in Haswell on Saturday February 15, 2020. We had three projects:

  1. Attempt at observing a circumpolar pulsar, utilizing the System 1 manual tracking system. (Rich Russel, Glenn Davis, Lewis Putnam).
  2. Complete building and installing shelf space in the Communications (Operations) Trailer (Bob Haggard).
  3. Repair of the 3-element Yagi ham radio antenna, to realign the three elements (Gary Agranat, Bill Miller, Bob Haggard).

1. The major task of the day was an attempt at a science observing run of a circumpolar pulsar. This is one of the brighter puslars in the sky. And being circumpolar, it is always above the horizon, though it can still get relatively low to the horizon. The observing technique required continually pointing a the celestial coordinates and integrating the signal for at least a half hour. By integrating over time, the random noise tends to cancel more, leaving the actual radio source signal the time to accumulate and sum to a higher level than the noise floor.

Science Lead Rich Russel (seated) and System 1 Lead Glenn Davis setting up the pulsar observations.
Bill Miller, Lewis Putnam, Rich Russel, and Glenn Davis in the Communications Operations Trailer during the observation runs.
The display for the System 1 manual tracking. The circles in the black field represent the antenna beam width for different frequencies. The large blue ring represents a 4 degree diameter beam width, and is for the 408 MHz feed currently being used for the pulsar observing. The inner yellow ring is 0.8 degrees in diameter, which is for our HI hydrogen observing at 1.4 GHz. The pink dot represents where the center of the beam is pointing. A star field map is projected on the background black field. The upper part of the display shows azimuth and elevation of the antenna, and its conversion to the celestial coordinates of Right Ascension and Declination at the current time.
The signal strength across the frequency spectrum being observed. For pulsar observing, we cannot detect the pulsar signal itself in real time. We must integrate the signal over at least a half hour of observing. Then we process the signal, with an expected pulsar timing. That process averages out the background noise while adding the actual pulsar signal enough to elevate above the noise floor — in theory.
The 60 foot dish antenna turning to aim at the pulsar.
The 408 MHz antenna feed. Ray Unberecken has designed a base for the antenna feeds so that these can be easily swiveled out for service and changeout. Ray designed and built this feed.

2. Bob Haggart worked on completing the building of desk and shelf space in the Communications Operations Trailer. The additional space is actually important, as that gives us a means to organize and better utilize our work space, and not instead have items pile up randomly.

Bob Haggart
New desk and shelf space in the Communications Operations Trailer.
New desk and shelf space in the Communications Operations Trailer. Note the addition of amenities, of microwave oven and coffee pots.

3. A third project was the repair of the front element of the 3-band Yagi ham radio antenna on the 40-foot tower. The front element had rotated slightly askew.

The front element of the 3-band Yagi ham radio antenna on the 40-foot tower rotated askew somehow. Fixing this was our third project undertaken this day.
The tower was rotated down for service.
Bill Miller aligning the front element. Also working on this were Gary and Bob. Bob utilized cable lengths to help ensure actual evenness. We also used squares and levels.
Gary working on the antenna. The ladder was used to access and retighten the center supports at the mast.
While the tower was down for the service, Bill reinforced the structural support for the 2-meter band vertical antenna on a side support from the tower.
Gary raised the tower back up.
The 50-foot tower almost at its vertical position.

After the tower was raised back to vertical position, Bill and Gary slightly rearranged the positioning of the 80 meter dipole that is supported from a pulley on the tower. The repositioning separated the dipole with better clearance from other nearby wires

We discovered that the Communications Trailer phone used for our 2-meter talk-in radio was transmitting but not receiving. Bill started to troubleshoot it.
Bill photographing the dish antenna. Pikes Peak is visible in the distance, over a hundred miles away.
Gary also photographed the dish antenna.
The 60 foot antenna rotating back to its parking position after the observing runs.

Rich Russel processed the observation data, but the processing did not bring out the pulsar. Troubleshooting is a topic at the February Science Meeting. Meanwhile, the System 1 antenna pointing system worked well.

The group finished up the work well before sunset, so that traveling back with the sun setting was not a significant issue. We had good weather for this trip, for a winter day in February. Our temperature was in the 40s F, which was actually midler than the 30s in Colorado Springs. And our wind was light.