TRAPUM Survey Goals

Utilising the power of MeerKAT, TRAPUM will discover numerous new pulsars and transient events in order to expand our knowledge of the populations of sources which emit at radio wavelengths on timescales ranging from microseconds to seconds. The discovery and continued study of these objects provides a powerful tool to improve our understanding of physics in extreme environments.

Science Themes

The science case for TRAPUM covers a broad range of neutron-star, galactic and extra-galactic astrophysics as well as gravitational and high-energy physics. The primary science objectives are:

  • Increasing the sample size of all types of radio pulsars, constraining the birth rates and distribution of neutron stars in the Galaxy.
  • Exploring the properties and evolution of globular clusters by discovering and timing many new pulsars and transients associated with them.
  • Investigate the dependence of the pulsar and fast transient populations on host galaxy properties, by searching for them in external galaxies.
  • Improve our understanding of gravity, by discovering relativistic binaries and millisecond pulsars suitable for gravitational wave experiments.
  • Working with MeerTRAP Expand the searchable parameter space for fast transient radio sources, enabling study of the most energy-dense events in the Universe, and potentially identify electromagnetic counterparts to gravitational radiation events and Search for high red-shift radio bursts and use them to refine cosmology.

The Cassiopeia A supernova remnant.

This science-impact driven project plays to the strengths of the MeerKAT telescope in time-domain astrophysics, the excellent sensitivity allows for the detection of these very faint radio sources, and the high instantaneous spatial resolution enables localisation of events that last for a fraction of a second. This capability for localisation of radio transients is critical to the using and understanding the exotic and currently unknown origins of many of these events.

These science goals will be achieved through a series of targeted searches, capitalising on the sensitivity of MeerKAT to make significant new discoveries.

Read more about the survey plan below

Survey Plan

Targeted pulsar searches of SNRs, PWNe, and unidentified Fermi gamma-ray sources
Supernova remnants (SNRs), pulsar wind nebulae (PWNe) and Fermi gamma-ray sources host, arguably, some of the most interesting radio pulsars. The discovery of a radio pulsar coincident with a SNR/PWN/gamma-ray source is crucial for understanding the energy budget of such systems and, vice-versa, multi-wavelength counterparts provide substantially more context for understanding the nature of the radio pulsar itself. Discovering young pulsars associated with SNRs or PWNe is important for understanding the Galactic neutron star formation rate, the nature of the supernova explosion, and the injection of high-energy particles into the interstellar medium. Unidentified Fermi gamma-ray sources provide a treasure map for deep pulsar searches and, for example: the millisecond pulsars (MSPs) found can probe accretion physics (e.g. "transitional" MSPs), provide new precision timers for the International Pulsar Timing Array, as well as identify exotic binaries capable of testing gravity and/or constraining the neutron star equation of state.

Globular Cluster Searches
Globular clusters (GCs) harbor a very large number of MSPs per unit stellar mass compared with the Galactic plane. This is because the dense stellar environments in the cores (104 − 103 M pc−3) promote collisions and exchange interactions that create binaries capable of recycling old neutron stars to become MSPs. A total of 146 pulsars have been discovered in globular clusters to date, the majority of them MSPs. Some clusters are spectacularly prolific: Terzan 5 and 47 Tuc host 34 and 25 pulsars respectively. Surveying them with MeerKAT therefore has the potential for rich and rapid reward.

Approximate fraction of observation time spent on each survey component as granted in 2016.
Target Fraction
SNRs,PWNe,TeV & γ-ray 44%
Globular Clusters 33%
Nearby Galaxies 22%

Extragalactic pulsar and transient searches
MeerKAT has the sensitivity to reveal new pulsars and fast transients beyond the Milky Way. Studying extragalactic pulsars we can help us understand the relationship between the formation of neutron stars and their environement. Only 29 such extragalactic pulsars are known, and all are located in the Magellanic Clouds. Using MeerKAT we will reach a survey sensitivity beyond anything other survey performed before to study not only the Magellanic Clouds but also other galaxies of the local group and beyond. Detecting pulsars and fast transients outside the local group, and determining how much their signal was dispersed by the intergalactic medium will begin to provide us with the tools needed to probe the structure of the intergalact medium. Moreover, understanding the nearby population of giant pulse emitting, or radio-emitting magnetars, has gained even more importance given that they are proposed models for at least some of the fast radio bursts (FRBs) and this is further highlighted by the recent discovery of a repeating FRB.

Towards a Galactic census
The known pulsar population has increased by nearly 50% sources, since 2010 when TRAPUM was first envisioned. This increase has been achieved by improving techniques and methods on existing telescopes, and new telescopes like LOFAR. Still, the task of finding even more pulsars could not be more timely. With new pulsars, new science is enabled, resulting from the bulk properties of the discovered population, from discovered pulsars being probes of the surrounding medium, or by being exceptional laboratories for testing theories of gravity. With MeerKAT being many times more sensitive than Parkes, the previous largest dish used for pulsar searches in the South, the search for pulsars in the Galactic plane - the birth place of pulsars - provides a significant and rare sharp increase in sensitivity for exploring the dynamic radio sky. The hundreds of beams combined with much increased sensitivity mean a significant increase in search capability, making a large-scale survey with MeerKAT not only possible, but in fact mandatory. With time provided by MPIfR’s “S-Band Project”, TRAPUM will conduct a L-Band survey along parts of the inner Galaxy. This TRAPUM survey will be the most sensitive survey of the inner Galactic plane ever conducted, being the benchmark and testbed for the later SKA surveys.

Using pulsars to probe gravity, dark matter & stellar populations in the Galactic Centre
The discovery of a pulsar closely orbiting the super-massive black hole at the centre of our Galaxy, Sgr A*, would not only supersede all previous tests of General Relativity (GR) in\ the strong-field regime, it would also enable the space-time around a rotating black hole to be probed with high precision and in a model independent fashion; for example, allowing tests of the cosmic censorship conjecture and the no hair theorem. Such a "laboratory" for precision tests of GR and black hole physics would be unrivalled by any future astrometric measurements of the S-Stars. Furthermore, mass-segregation in the central parsec may also lead to the presence of additional gravitational testbeds in the form of stellar-mass pulsar black hole binaries. As part of the MPIfR “S-Band Project”, the Max-Planck receivers will be used to conduct a sensitive survey of the innermost region of the Galaxy in the vicinity of the black hole. The MPIfR will share the results with TRAPUM as input for further studies.

Fast transients – working with MeerTRAP to discovering and understand source populations
The fast transient landscape has changed dramatically since 2010 with the discovery of the population of FRBs, including the revelation that some repeat, which are exciting in themselves but also highlighted that the dynamic radio sky is still largely unexplored and with potentially more rich rewards. MeerKAT’s unique combination of wide FoV, high sensitivity, and wide bandwidth will provide supreme sensitivity per unit time and frequency making it a prime instrument to study the transient sky. We will carry out commensal observing for fast transients on all of the TRAPUM observations proposed here: High energy point sources and SNRs, globular clusters and external galaxies.

Although not yet granted observing time we also consider here the exciting possibility of the detectability of Lorimer-burst brightness (30 Jy and >400-σ) FRBs with a MeerKAT Fly’s Eye experiment (i.e. single-dish observing). In Fly’s Eye mode, MeerKAT will instantaneously cover 0.8 × 64 = 51.2 deg2, and will therefore be able to detect rare, bright transient events. Finally, alongside the sheer increase in the number of FRBs detected the other major development is that FRB 121102 has exhibited repeated bursts seen both at Arecibo and with the GBT (Scholz et al. 2016). These bursts are characterised by a range of flux density and strongly varying spectral indices and a wide range of modulation indices that have so far prevented the detection of any possible underlying periodicity. The repeating nature indicates that they are not from a cataclysmic event and suggest that at least some FRBs are possibly associated with neutron star origins, like magnetars or giant pulses from radio pulsars. Crucial to understanding what this means for the FRB population as a whole is determining if all FRBs repeat or whether there are multiple classes.

Follow Up Timing (To be proposed for)
After the initial discovery of a pulsar, we want to extract as much science as possible by follow-up timing. Therefore, it is an absolutely crucial aspect of characterising the new TRAPUM pulsars to get a timing solution. In its most basic form this means getting an accurate position, period and period derivative so that one can compare the pulsar properties with the known pulsar population, and in particular for those sources that are found in our targeted searches we are interested in knowing their characteristic ages and their spin-down energies to compare with the SNRs and high energy emission, for example. We are also interested in determining whether or not the sources are potentially high precision timers and so useful for gravitational wave searches, and/or members of binary systems and so potentially useful for mass determinations or tests of gravity.


First Nearby Galaxies publication and first LMC observations!

Oct 2022

The Nearby Galaxies working group has now published its first paper! It can be found in the "Publications" section of this website. Remarkably, the first two observations of the Large Magellanic Cloud already revealed 6 new pulsars! The Small Magellanic Cloud survey is also well under way with 7 pulsar discoveries, doubling the currently known population. In addition, nearby galaxies Sextans A and B have been surveyed and a Fast Radio Burst has been found serendipitously. A survey of NGC 253 is currently being processed. Details of our discoveries can be found on the DISCOVERIES page.

TRAPUM/MGPS Reaches 100 Discoveries!

Jan 2022

We are proud to announce that TRAPUM together with its sister project the MPIfR Galactic Plane Survey (MGPS) have surpassed 100 pulsar discovieries. Given the source classes that TRAPUM has targeted, more than 60 of these new pulsars have periods below 30 milliseconds with 37 confirmed to be in binary systems. This represents more than a 10% increase in the total number of millisecond pulsars known. With the majority of the discovieres coming since the start of 2021 we are optimistic that we can continue our fantastic discovery rate into 2022 and beyond. Details of our discoveries can be found on the DISCOVERIES page.

TRAPUM First Year Review

Jan 2022

Towards the end of 2021 the TRAPUM collaboration submitted its first report on operations to SARAO. The report detailed how the addition of instrumentation from TRAPUM has enabled MeerKAT to become a premium pulsar and fast transient discovery machine, with TRAPUM discovering 36 pulsars in 11 globulsar clusters, 3 pulsars in the Small Magellanic Cloud and 15 pulsars (of which 14 are millisecond pulsars) in Fermi-LAT sources. The collaboration received positive feedback from the review committee with the reviewers noting that "The TRAPUM team has demonstrated, through their hard work in collaboration with SARAO teams, that MeerKAT (and by extension SKA1-MID) can be a prolific pulsar search instrument. This required the development of novel instrumentation, and they are to be commended for their achievements. Their transparency in making discovery details public is also welcome. Given their activities and results so far, it would appear that the team is well poised to make major impacts in pulsar astrophysics."

First Extragalactic Pulsar Discoveries!


We have started our observations of the Small Magellanic Cloud with TRAPUM in 2021. We have nearly completed four out of eight pointings in this L-band survey, which uses 769 coherent beams and the core dishes of MeerKAT. The survey is partially targeted to supernova remnants and pulsar wind nebulae. We have discovered several new extragalactic pulsars in the SMC, which you can read about on the DISCOVERIES webpage. We are also observing other nearby galaxies with the full array.

First Fermi Unidentified Sources Search Observations!

20 June 2020

We have made our first observations of a set of Fermi Unidentified Sources with TRAPUM. We observed about a dozen sources using all the available telescopes and about 250 beams arranged to sample the entire gamma-ray error circle of the sources. This forms the first set of sources in our sample prepared for our initial shallow survey which is using the L-band receiver and will include a two-pass approach. News on DISCOVERIES soon.

First Globular Cluster Observations!

April & May 2020

TRAPUM has made its first observations! Using all the available telescopes 288 beams were formed and used to observe the clusters Terzan 5, 47 Tucanae and NGC 6624 for about 4 hours each. Data analysis is ongoing. Stand by for announcements of discoveries which will appear on our DISCOVERIES webpage.

Globular Cluster Pulsars Discovered

Update May 2020

Working with the MeerTIME team we have searched 10 Globular clusters using search mode data recorded using the PTUSE backends for a beam pointed at one of the known pulsars in the cluster. So far we have discovered 10 new pulsars and you can find a summary of the details of these pulsars at our DISCOVERIES webpage. The TRAPUM surveys will use between 250 and 400 beams to allow for covering the entire cluster and will be able to use all 64 dishes to give greater sensitivity.

Proposal Submitted


A proposal describing the updated science case and observing request for TRAPUM has been submitted.

Website created


The TRAPUM website,, has been launched. Publications, data releases and survey status updates will appear here once the survey is underway.

Team members


  • Ben Stappers (UK)
  • Michael Kramer (DE)

Project Scientist

  • Ewan Barr (DE)

Working Group Chairs

  • Lina Levin-Preston (UK, Nearby Galaxies)
  • Ben Stappers (UK, PWNe/SNR/TeV WG)
  • Rene Breton (UK, Fermi WG Co-chair)
  • Colin Clark (DE, Fermi WG Co-chair)
  • Alessandro Ridolfi (IT, Globular Clusters WG)
  • Marta Burgay (IT, Follow-up WG)


  • Federico Abbate (IT)
  • Anjana Ashok (DE)*
  • Matthew Bailes (AU)
  • Vishnu Balakrishnan (DE)
  • Werner Becker (DE)
  • Miquel Colom I Bernadich (DE)*
  • Mechiel Bezuidenhout (UK)*
  • Markus Böttcher (SA)
  • Sarah Buchner (SA)
  • Francesca Calore (NL)
  • Emma Carli (UK)*
  • David Champion (DE)
  • Weiwei Chen (DE)
  • Ismaël Cognard (FR)
  • Oliver Dodge (UK)*
  • Andrew Douglas (USA)*
  • Liam Dunn (AUS)*
  • Arunima Dutta (DE)*
  • Ralph Eatough (CH)
  • Elisabeth Ferrara (USA)
  • Paulo Freire (DE)
  • Tasha Gautam (DE)*
  • Lucía Gebauer Werner(UK)*
  • Marisa Geyer (SA)
  • Heinrich Hurter (SA)*
  • Jean-Mathias Griessmeier (FR)
  • Tana Joseph (NL)
  • Ramesh Karuppusamy (DE)
  • Evan Keane (IRL)
  • Lars Künkel (DE)*
  • Yunpeng Men (DE)
  • Vanessa McBride (SA)
  • Lars Nieder (DE)
  • Prajwal Voraganti Padmanabh (DE)
  • Adipol Phosrisom (UK)*
  • Denisha Pillay (DE)*
  • Andrea Possenti (IT)
  • Venu Prayag (SA)*
  • Harry Qui (UK)
  • Shilpa Ranchod (DE)*
  • Scott Ransom (US)
  • Shalini Sengupta (DE)*
  • Maciej Serylak (UK)
  • Tinn Thongmeearkom (UK)*
  • Naomi Titus (SA)
  • James Turner (UK)*
  • Vivek Venkatraman Krishnan (DE)
  • Laila Vleeschower Calas (UK)*
  • Stefan Wagner (DE)
  • Patrick Weltevrede (UK)
  • Christoph Weniger (NL)
  • Norbert Wex (DE)

* Student

Project Organisation:

The management of the TRAPUM project will build upon experience gained from our membership in other large international collaborations such as LOFAR, the EPTA and SUPERB. An executive committee composed of the two PIs (Stappers and Kramer) and a further five members will be the decision making body responsible for organisation, membership, resolution, funding and planning. These five additional members correspond to approximately 10% of the total membership and will be drawn from each of the science working groups (see below), respecting diversity in nationality and gender, and will serve a limited term of no more than two years. The PIs will have the casting vote if required. While the science working groups will have significant overlap in membership and science topics they will have clear and distinct goals. In addition there will be two technology working groups which will work with and across all the science groups to provide the hardware, software and practical development necessary to meet the scientific goals. It is expected that the technology group members will have strong overlap with all the scientific groups, with at least one member from each present.

The working groups are broken down into the following:

  • Galactic plane survey: Planning and executing the Galactic plane and Fermi excess survey. This is the largest single observing project and will require strong coordination of resources to ensure the most ecient observing. It will liase strongly with the targeted surveys group to ensure no overlap of targets.
  • Targeted surveys: Planning and executing the surveys of the Galactic centre, globular clusters, exter- nal galaxies and high-energy sources. These surveys are grouped together as they all require similar approaches, but they will be broken down further into specific teams which may not include all members.
  • Pulsar follow-up: Extracting maximum information from newly discovered pulsars eciently. Liaise with MeerKAT and worldwide pulsar timing projects for follow up radio timing. Organise observations at high energies, optical and perhaps non-photonic windows.
  • Transient survey and follow-up: Detection of transient signals and triggering of multi-wavelength follow- up observations. Have agreements in place with a variety observatories to follow-up transients at short notice. Liase with ThunderKAT for follow up as well.
  • Commensal observing survey: This task will involve liaising with the different working groups to determine what resources can be used and when and also to optimise the observing strategies of the targeted surveys described above to ensure optimal transient detection capabilities. Overlap with the follow up component of the Transients working group.
  • Beamforming: Development of scheme for phasing up array and polarisation and flux calibration. Includes experts who have performed similar work with other arrays like WSRT,VLA and LOFAR. Majority of the work will be in the initial phases of roll out of beamforming, but then will have a continuing reduced role to assess problems if/when they arise with calibration and related issues.
  • Processing: Particular focus on searching multiple data streams for periodic and transient signals. Also responsible for the organisation of data types, storage and transfer. Includes experts in machine learning approaches to transient and pulsar candidate identification.
  • Outreach working group: This is an important aspect of the proposal which all members will contribute to. It will be led by people with significant experience in professional and public outreach and educators.

Publications (8)

1) Wide field beamformed observation with MeerKAT

(Chen et al. 2021): ADS, ArXiv, DOI

We describe a wide-field beamformer for the MeerKAT radio telescope and outline strategies to optimally design pulsar and fast transient surveys.

2) Eight new millisecond pulsars from the first MeerKAT globular cluster census

(Ridolfi et al. 2021): ADS, ArXiv, DOI

We present the first eight pulsar discoveries made by MeerKAT. The eight pulsars are found in six different globular clusters and are all millisecond pulsars.

Pulsars: J1748-2446an, J1701-3006G, J1803-3002D, J1823-3021G, J0024-7204ac, J0024-7204ad, J1910-5959F, J1823-3021H

3) Two New Black Widow Millisecond Pulsars In M28

(Douglas et al. 2022): ADS, ArXiv, DOI

We report the discovery of two Black Widow millisecond pulsars in the globular cluster M28 with the MeerKAT telescope.

Pulsars: J1824−2452M, J1824−2452N

4) TRAPUM discovery of 13 new pulsars in NGC 1851 using MeerKAT

(Ridolfi et al. 2022): ADS, ArXiv, DOI

We report the discovery of 13 new pulsars in the globular cluster NGC 1851 with the MeerKAT telescope.

Pulsars: J0514-4002B, J0514-4002C, J0514-4002D, J0514-4002E, J0514-4002F, J0514-4002G, J0514-4002H, J0514-4002I, J0514-4002J, J0514-4002K, J0514-4002L, J0514-4002M, J0514-4002N

5) Discoveries and Timing of Pulsars in NGC 6440

(Vleeschower et al. 2022): ADS, ArXiv, DOI

We report the MeerKAT discovery of two pulsars in the globular cluster NGC 6440, as well as long-term timing solutions of the previously known pulsars NGC 6440C and NGC 6440D from multi-telescope data.

Pulsars: J1748−2021G, J1748−2021H

6) Four pulsar discoveries in NGC 6624 by TRAPUM using MeerKAT

(Abbate et al. 2022): ADS, ArXiv, DOI

We report the discovery of four new pulsars in the globular cluster NGC 6624 with the MeerKAT telescope. One of these (J1823-3022) shows a large offset in its position and dispersion measure when compared to all the other pulsars in NGC 6624, making its association with the cluster uncertain.

Pulsars: J1823-3021I, J1823-3021J, J1823-3021K, J1823-3022

7) Radio Detection of an Elusive Millisecond Pulsar in the Globular Cluster NGC 6397

(Zhang et al. 2022): ADS, ArXiv, DOI

We report the discovery of a new pulsars (PSR J1740-5340B) in the globular cluster NGC 6397. The pulsar was found with the Parkes radio telecope and confirmed with the MeerKAT telescope in two TRAPUM observations. PSR J1740-5340B is an eclipsing redback in a 1.97-day orbit, the longest among all redbacks known.

Pulsars: PSR J1740-5340B

8) TRAPUM upper limits on pulsed radio emission for SMC X-ray pulsar J0058−7218

(Carli et al. 2022): ADS, ArXiv, DOI

As part of our survey of the Small Magellanic Cloud, we have published an upper limit on radio pulsations from X-ray pulsar J0058−7218. This limit is 7 times deeper than previous radio searches. This suggests that the radio emission of PSR J0058−7218 is not beamed towards Earth or that PSR J0058−7218 is similar to a handful of Pulsar Wind Nebulae systems that have a very low radio efficiency, such as PSR B0540−6919, the Large Magellanic Cloud Crab pulsar analogue.

Pulsar: PSR J0058-7218

9) The TRAPUM L-band survey for pulsars in Fermi-LAT gamma-ray sources

(Clark et al. 2023): ADS, ArXiv, DOI

We present the discovery of 9 new millisecond pulsars, the first results from our targeted survey of unidentified Fermi-LAT gamma-ray sources. All but one of these new pulsars are in binary systems, of which two are eclipsing redbacks with optical counterparts.

Pulsars: J1036-4353, J1526-2744, J1623-6936, J1709-0333, J1757-6032, J1803-6707, J1823-3543, J1858-5422, J1906-1754

10) Missing for 20 yr: MeerKAT Redetects the Elusive Binary Pulsar M30B

(Balakrishnan et al. 2023): ADS, ArXiv, DOI

We report the re-discovery of PSR J2140−2311B located in the globular cluster M30 and detected using the MeerKAT telescope. This pulsar has eluded detections for the past 20 years and its orbital parameters have been a mystery until now. PSR J2140−2311B has an orbital period of 6.2 days and is in a highly eccentric orbit (e = 0.879) around either a WD/NS. We also measured wdot from pulsar timing and assuming GR, we present here the total mass of the system. This pulsar is located 1.2(1)' from the cluster center and likely formed as a result of a secondary exchange encounter.

Pulsars: PSR J2140−2311B

Public Engagement

Our public engagement programme focuses on the distinct areas: the public at large, and school children in particular. The school-focused thrust engages children in South Africa and other SKA-node-bearing countries as a first priority, but with a global component as well. The content of the various components listed below relates to the TRAPUM mission, which focuses on radio transients and pulsars. Below are the main components planned in our public engagement programme for TRAPUM:

  • Produce a monthly newsletter to appear in a selection of South African print media, as well as online news portals. Existing contacts with independent science writers in South Africa to be followed up.
  • Perform hands-on, real observing and data analysis, engagements with schools building on the extensive experience of our team members but tailoring it to the specific needs.
  • Engage with the IAU’s OAD office and the SKA Communication and Outreach Team to see if mutually beneficial programmes can be launched as part of the TRAPUM public engagement programme.
  • Establish a TRAPUM citizen science component that will evolve from the Zooniverse project Pulsar Hunters and use it as a mean for public engagement but also to enable science in its own right.
  • Design, set up and maintain a well-structured webpage as well as both Twitter and Facebook profiles.
  • Develop simple pulsar-related materials that can be used in schools in a variety of modalities.
  • TRAPUM members will get involved in speaking at local schools during their visits to South Africa.
  • Involve current SKA bursary holders at universities to participate and contribute to this programme.