B0833-45 Daily Observations

Primary Purpose of Observations

The primary aim of the daily observations is to measure the spin frequency of the Vela pulsar and attempt to detect a 'glitch', a sudden increase in spin frequency (usually in the 1-3 ppm range) which interrupts the normal slow decrease in spin frequency. The time between Vela glitches averages 2-3 years. Two such glitches have been detected in HawkRAO data as of June 2022.

Daily Observation Results

For each daily observation (nominally a 2-hour transit observation) the raw IQ data from the RTL-SDR dongle receiver is converted into archive format (via DSPSR), RFI-zapped by PAZ and period-searched by PDMP.

The results of the analysis are presented via a PDMP output image plus GNUPLOT graphs of a processed PDMP output text file ('pdmp.per' parsed then predicted barycentric period added and then saved as 'pdmpeph.per').

To view the latest daily result upload navigate to 'Latest Observation Results'.

Example Verification Plots of HawkRAO Data using Professional Software

While the daily HawkRAO observations are analysed by HawkRAO home-made software, the results so obtained have been verified against professional analysis software and long-term plots of measured spin frequency (where the 2019 Vela glitch is clearly visible @ MJD 58515 - circled in green).

PRESTO: Prepfold


Long Term Barycentric Spin Frequency:>800 days

Observation Setups

Two observation setups have been utilised over the years...

  1. The original Windows C# software (VCP) from May 2017 until end-of-2021. (See below for further details).

  2. A Linux-based system run on a Raspberry Pi 400 as of early 2022.

Current Linux/RPI400 Observation Setup

To reduce power consumption the Windows C# observation acquisition and analysis software was rewritten into two C# console applications running under Ubuntu Mate on a Raspberry PI (RPI400). The console applications and their functions are:

  • A robotic scheduler which reads observation parameter files and initiates observations at the transit times of the target pulsar (C# console application)

  • Acquisition, analysis and display C# console application which 'pipelines' the RTL-SDR acquisition program, a modified professional analysis program (DSPSR - with the RTL-SDR added as a valid backend), RFI-zapping via PAZ and period search and result display by PDMP. Output data files from PDMP are further processed and plotted via GNUPLOT.

A short video of the setup can be viewed via this Youtube link...

RPI400 Linux-based Observation System

Ongoing results can be viewed in 'Latest Observation Results '.

A low-res gallery of past PDMP results can be viewed in 'PDMP Results Gallery '.

Original Windows Virtual Control Panel (now retired)

Initially daily observations were automated by a scheduling robot, a function of the Virtual Control Panel (VCP - a custom C# Windows application), followed by automatic analysis and website upload.

The automated daily observations commenced May, 2017 and completed 4.5 years of daily observations (>98 % up-time). Two glitches were detected in this period by this system.

VCP Observation Examples

Below is an example of typical HawkRAO observatory VCP results of reception of Vela pulsar signals showing the Observatory Status, the Period Search Panel, the Glitch Monitor Panel, a Vela Information Panel and an Aggregate Pulse Profile using the original C# Windows VCP application.

End of May 2021 saw a start of a new run (MJD 59347). The ephemeris used was updated to reflect Vela's spin down post-2019 glitch. The aggregate pulse profile as well as spin statistics displayed in the 'Glitch Monitor Panel' have been restarted from MJD 59347.

Also - due to instability of external online topocentric Doppler resources - calculations for Doppler have reverted back to ancient FORTRAN code ('DOP') ported to C.


  1. As can be seen in the graphic below a second glitch has been detected in HawkRAO data of magnitude ~1.25 ppm.

  2. Daily observations are no longer carried out by this system. The latest observations and sample results from the current system can be seen in 'Latest Observation Results ' and 'PDMP Results Gallery ' respectively.


Comments and suggestions are always welcome. Please use the following email address.