Pulsar Observations

The detection of pulsars is viewed as a major achievement by many in Citizen Scientist Radio Astronomy circles. The difficulty of this activity has produced some optimistic claims - fortunately there are many examples of successful pulsar detections by citizen scientists which comply with the scientific method and, as such, are good sources of information.

These webpages document the activities at the Hawkesbury Radio Astronomy Observatory (HawkRAO) centred around the Vela Pulsar.

After more than 4.5 years of daily Vela observations and detection of two 'glitches' further observations have ceased.

The initial aim of the project (to observe and detect Vela glitches) has been achieved - twice.

Considering the expense of powering an automatic observation system 24/7 there is now not sufficient motivation to continue observations.

Some statistics:

  • Daily cadence observations covering 1st May 2017 to 1st October 2021 - 4 years and 5 months with >95% up-time.

  • Two Vela glitches detected - February 2019 and July 2021.

  • The February 2019 glitch result was the first ever detection of a glitch by a radio astronomy amateur in any pulsar.

  • Over 8 TB of voltage data archived.

  • All observations done with $20 RTL_SDR 'dongle' bought through eBay and Amateur Radio antennas.

  • Custom observational software written in C# WIndows application.

Detection of Two Vela Glitches in HawkRAO Observation Data

Glitch #1: After 20 months of daily observations, on the 1st February, 2019, the HawkRAO system detected a 'glitch' in the Vela Pulsar.

ATel #12466: Notification of 2019 Vela Glitch on 'Astronomers Telegram'

On the 1st February 2019 at 14:09 (UTC) Vela 'glitched' (refer to ATel #12466 above).

The glitch (~ 2.5 ppm jump) was clearly seen in HawkRAO data in the MJD 58516 observation as shown by the jump in the spin frequency trace (light blue line) in the archived 'Glitch Monitor Panel' on the right.

This is the first time that a glitch has been recorded and notified by an amateur radio astronomy observatory - in any pulsar.

Glitch #2: A second Vela glitch has been detected in HawkRAO observation data (23rd July, 2021 UTC).

ATel #14808: 2021 Vela Glitch seen in HawkRAO Data on 'Astronomers Telegram'

On the 22rd July 202021 at 15:04 (UTC) Vela 'glitched' again (refer to ATel #14808 above).

The glitch (~ 1.25 ppm jump) was clearly seen in HawkRAO data again as shown in the plot below of the offset (in ppm) from the predicted spin frequency.


  1. The value of the glitch magnitude (ΔF/F = 1.26 ppm) is calculated by doing a linear fit of post-glitch measurements and solving for the epoch of the glitch.

  2. The results published via ATel are as follows...

    ATel #14806: 1.26 ppm (no limits specified) - IAR
    ATel #14807: 1.26 +/-0.03 ppm - UTMOST
    ATel #14808: 1.25+/-0.1 ppm (HawkRAO initial estimate - now updated)
    ATel #14812: 1.238+/-0.07 ppm - ORT

    Therefore - the latest HawkRAO analysis as shown below is consistent with ATels #14806 and #14807.

    The post-glitch 'speedup of slowdown' is clearly shown in the following graph and at 10.2 e-3 is within past glitch values for Vela.

  3. The post-glitch plot is done using the pre-glitch value of F1 and so shows that post-glitch the rate of slowdown has increased (i.e., slowing down faster than predicted by the pre-glitch ephemeris). This post-glitch 'speedup of slowdown' is clearly shown in the following graph and at 10.2 e-3 is within past glitch values for Vela.


The target pulsar was selected as B0833-45 (J0835-4510) as it is the strongest pulsar (5 Jy @ 400 MHz) and also happens to pass almost directly overhead at the HawkRAO location (34°S). Use the 'Vela Pulsar' tab to view more details about the pulsar.

The antenna and low noise amplifiers are commercial products and data acquisition is achieved via a relatively inexpensive USB SDR - the RTL-SDR dongle.

The analysis software - Virtual Control Panel (VCP) - was written specifically for the HawkRAO hardware setup.