...PULSAR RADIO ASTRONOMY AT 424 MHz

Most of the pulsar data and K5SO observatory information on this site is from activity in the 2006-2008 time frame. After a period of relative inactivity with regard to pulsar observations I have now returned to the pulsar observation effort and have revitalized the K5SO observatory. Current efforts are in developing an off-line data analysis technique in which a spectrum at 424 MHz is digitized and written to disk continuously as a single large data file over the entire observation period then analysed off-line later. Initially a single fixed-angle of polarization will be used. Eeventually polarziation diversity using the dual polarization feedhorn will be implemented.

K5SO radio telescope configuration

K5SO 8.6m dish and feedhorn for 424MHz operations

Operating position and 424 MHz in-shack receiver components (coming)

Radio telescope sensitivity measurements

PULSAR OBSERVATIONS

B0329+54: May 26, 2015 Collected at 424 MHz at 384KHz bandwidth over a 2.5 hour observation period; single V-polarization data displayed..

B0329+54_scintillation_effects Effects of scintillation in the interstellar medium are illustrated @424MHz using 384KHz BW with the 8.6 meter diameter dish.

AUXILIARY PROGRAMS

I have prepared a Windows utility to keep track of the apparent pulse repetition rate of the pulsar of interest for the time/date and location of the radio telescope and, if desired, to automatically update an external frequency synthesizer to synchronize the time-domain data acquisitions to the pulsar pulses arriving at the radio telescope in real time. It should be noted that the atuomatic-updating feature is not always required in order to detect many pulsars; simply setting the synchronization generator/synthesizer to the frequency specified at the begining of the observation and leaving it at that value during the entire observation is usually sufficiently accurate for most amateur observations of many pulsars (i.e., several hours of continuous observation/signal averaging). The utility makes use of a subset program of the TEMPO program used by many professional pulsar astronomers. This is the same subset program used in my earlier observations but the utility making use of the data files in the subset program is new. I have called the utility program TEMPO_calc. It may be downloaded here:

TEMPO_calc_files.zip (24.4 MB)

The zip folder includes three items, two folders and a setup instruction document:

i) TEMPO folder

ii) TEMPO_calc_Release folder

iii) Setup instructions (preliminary version)

The zip folder contains everything that you need to run TEMPO_calc, which uses the polyco.dat file produced by the subset TEMPO program. As an example, the front panel display of TEMPO_calc is shown below displaying the calculated local synchronization frequency for pulsar PSR 0329+54 on July 9, 2014 in New Mexico. Although, as mentioned above that it may not actually be needed for many pulsar observations, the program includes an option, lower left hand corner of the display, for automatically controlling an external signal generator or synthsizer. In the example shown below the program is set up to control, via a GPIB connection, an HP3325B synthesizer running at 40,960 times the fundamental sync freq. A corresponding 40,960 TTL divider chain is used to convert the synthesizer output signal to a new signal with the original pulsar sync freq, to be used to synchronize the receiver chain with dramatically improved stability and accuracy over what would be obtained if the synthesizer were generating the very low frequency synchronization signal directly:

TEMPO_calc runs on most Windows machines and provides current pulsar sync frequency information, update rate is under user control ranging from 1 second to 1000 seconds between updates as the user specifies, although as previously mentioned it is not always necessary to update the sync freq over the observation time for many amateur pulsar observations. Simply setting the sync generator/synthesizer manually to the calculated sync freq at the beginning of the observation is sometimes sufficiently accurate for a several-hour-long observation of many pulsars. Nevetheless, the automatic update feature is included in the program in case the user wishes to update his generator/synthesizer output frequency automatically. Diagrams of the new system configuration and additional related information will be posted as it is generated. Nevertheless, it is understood that the TEMPO_calc utility as it currently exists can prove valuable to other amateur radio astronomers seeking to detect pulsars, thus I have posted the download link above to provide access to the necessary files for such parties in the hope that it can be useful to them.