MOPTOP - prototyping a new approach to high time resolution, multi-wavelength optical polarimetry

Lead Research Organisation: Liverpool John Moores University
Department Name: Astrophysics Research Institute


Optical polarimetry is a probe of physical and magnetic field geometries in many otherwise spatially unresolved astronomical sources. Polarization is now taking a leading role as a key diagnostic of physical conditions (for example magnetic field strength/order/geometry and relativistic plasma dynamics) in time variable sources such as blazars, active galactic nuclei, x-ray binaries and gamma ray bursts (GRBs). In these high energy sources, polarization allows astronomers to probe the physical conditions at spatial scales that will never be accessible to direct imaging observations.

At LJMU we have led the application of polarization to time variable sources. Here we propose a programme to develop a new concept in multi-wavelength, optimized time resolved optical polarimetry (MOPTOP). The work builds on a 2012 (1 year) PRD programme which developed a multi-band optical polarimeter for time domain studies (RINGO3). MOPTOP combines novel concepts from that design with new, low-cost, high-sensitivity sCMOS detectors and a dual beam design to develop a concept that combines a wide, un-confused field of view with maximal sensitivity and low systematic errors.

MOPTOP is currently at TRL 3 (we have tested one key component of the design - namely the fast synchronization of two sCMOS cameras). In this proposal we request funding of ~£171k to increase the instrument TRL to 7 (a prototype tested and operational on a telescope). The increased sensitivity of the instrument will allow access to sources down to 19th magnitude (at 2% error) on a 2.0 metre class telescope. The design should also have much lower systematics (<0.1%) allowing greater utility for weakly polarized sources, and a 4 times wider field of view enabling rapid follow-up of poorly localized transient sources. The prototype will be tested on the 2.0m Liverpool Telescope (La Palma) and/or the 2.4 metre NARIT telescope (Thailand). We do not envisage protectable IP will arise from the project and consequently will make the instrument design fully public domain, with the aim of encouraging copies to be placed on other facilities around the world.

Planned Impact

ARI has a long tradition of strong industrial and PUS engagement. For this particular project we will:

* Continue our process of engagement with engineering companies (SMEs) who will receive advice and guidance on the technical requirements for high end engineering projects (through working with the LCR 4.0 ERDF delivery team and other reach out work). This will ensure SME(s) have the relevant experience and technology to tender for commissioned work, such as the structure of the prototype. As an example, we have worked in the past with a long established (70 years) SME on Merseyside employing around 20 staff. Initial contact with ARI was through the Liverpool Telescope project, where they were contracted to build several parts of the telescope via the university owned company Telescope Technologies Ltd. Because of this, the company has had to upgrade its skills and machinery to deliver the high precision needed for astronomical instrumentation, allowing it to received a grant from MAS (Manufacturing Institute, via the local council organization Wirral Direct) in order to upgrade their precision machining capability with a new, more accurate, CNC lathe and safeguarding a number of jobs at the time. Their ongoing work with LJMU ARI features as part of their adverting as an example of a high-profile/high-technology client. The reputation the company developed in terms of precision engineering for astronomical applications over the past 10 years has assisted them in gaining contacts with other international observatories (e.g. work on the new William Herschel Telescope Auxiliary camera) and recently with CERN where they produced the chain links that carry cooling pipes and electrical cables for LHC.

* Work with sCMOS supplier Andor to test and develop the capability of their Linux Software Development Kit (SDK) to ensure the API supports multiple cameras with simultaneous readout.

* Use MOPTOP as part of the new ARI distance learning courses being developed, which attract non-traditional students and delivers them experience of cutting edge research.

* Use MOPTOP as part of the National Schools Observatory. This major project has over 100,000 observations successfully delivered to over 2000 schools from the Liverpool Telescope already, and with over a million web pages served every year and an average of about 4,000 unique visitors each week, the NSO has established itself as a leading astronomy website for UK schools. Polarisation is traditionally a rather "dry" technique at school level. MOPTOP provides the opportunity to show its practical application in an exciting context (the most powerful explosions and jets in the universe!)

* Use MOPTOP as part of the material on Gamma Ray Bursts and robotic telescopes for a planned update to the Spaceport visitor attraction. Spaceport is a key component of Mersey Travel's tourist portfolio which has the aim of enhancing the regeneration of the Seacombe and Birkenhead areas on the banks of the Mersey (other parts of the portfolio include the Beatles Story). The attraction regularly exceeds visitor number predictions (currently at 100,000 per year) and brings considerable income into a regeneration area. Using the standard STEAM model for determining the economic benefits of tourism in the City Region for day visitors, this equates to a net gain of more than £2m per year and the creation of an estimated 50 new jobs.


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Copperwheat C (2020) Characterization of a dual-beam, dual-camera optical imaging polarimeter in Monthly Notices of the Royal Astronomical Society

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Maund J (2021) RINGO3 polarimetry of very young ZTF supernovae in Monthly Notices of the Royal Astronomical Society

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Shrestha Manisha (2019) MOPTOP: Polarimetry for time domain astrophysics in The Extragalactic Explosive Universe: the New Era of Transient Surveys and Data-Driven Discovery