UK Involvement in LSST: Phase B
Lead Research Organisation:
University of Hertfordshire
Department Name: School of Physics, Astronomy and Maths
Abstract
Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.
Planned Impact
Support for UK involvement in LSST, through funding the LSST:UK Science Centre (LUSC),
can generate societal and economic impact under the following five headings:
1. Enhancing the research capacity, knowledge and skills of enterprises working on "Big
Data" issues being incubated within the Higgs Centre for Innovation.
The Phase B LUSC Data Access Centre workpackage is co-located on the Royal Observatory
Edinburgh campus with the Higgs Centre for Innovation, which is being funded to improve
interaction between academia and industry in Space and Big Data, and to enhance
economic impact in those two domains. We shall exploit that co-location to ensure that Big
Data innovations within the LSST project in the US filter through to UK SMEs and that the
challenging requirements of LSST inspire the development of novel Big Data techniques
and technologies within the UK, as has been the case in the US.
2. Increasing public engagement with research through Citizen Science initiatives.
The LSST:UK Consortium will develop a Citizen Science platform based on the pioneering
Zooniverse project, which currently has more than one million users doing real science
online. Computational advances between now and the start of LSST operations will enable
Citizen Science activities that greatly exceed what is currently possible, and perhaps most
exciting is the prospect of involving Citizen Scientists in the classification of the million or
more transient alerts that LSST will generate per night, placing the public at the heart of
LSST's pioneering exploration of time-domain astronomy.
3. Enhancing cultural enrichment and quality of life through education & outreach activities.
The LSST:UK Consortium institutions have a wealth of experience in education and public
outreach (EPO) activities, from running Open Days and exhibitions to CPD courses for
school teachers to Massive Online Open Courses (MOOCs). During Phase B we will develop
an EPO programme, in conjunction with the very active LSST EPO team in the US.
4. Enhancing the research capacity, knowledge and skills of organisations through the
employment of researchers with high-level expertise derived from working on LSST.
Over the 18-year lifetime of the LUSC programme, many students (e.g. from the STFC dataintensive
science CDTs) and postdocs who have developed high-level expertise from
working on LSST will pass from astronomy to the commercial sector, taking their valuable
knowledge and skills with them. Particularly valuable will be the computational and
statistical skills that will be readily applicable to the Big Data challenges prevalent in the
public and private sector, and the expertise in thick CCDs developed through UK
involvement in the LSST camera team.
5. Wealth creation, through the placing of construction contracts with UK companies.
The detector characterisation work started during LUSC Phase A, and proposed for
continuation during Phase B, has included liaison with a UK company that has now signed a
large contract to supply roughly half of the LSST detectors.
can generate societal and economic impact under the following five headings:
1. Enhancing the research capacity, knowledge and skills of enterprises working on "Big
Data" issues being incubated within the Higgs Centre for Innovation.
The Phase B LUSC Data Access Centre workpackage is co-located on the Royal Observatory
Edinburgh campus with the Higgs Centre for Innovation, which is being funded to improve
interaction between academia and industry in Space and Big Data, and to enhance
economic impact in those two domains. We shall exploit that co-location to ensure that Big
Data innovations within the LSST project in the US filter through to UK SMEs and that the
challenging requirements of LSST inspire the development of novel Big Data techniques
and technologies within the UK, as has been the case in the US.
2. Increasing public engagement with research through Citizen Science initiatives.
The LSST:UK Consortium will develop a Citizen Science platform based on the pioneering
Zooniverse project, which currently has more than one million users doing real science
online. Computational advances between now and the start of LSST operations will enable
Citizen Science activities that greatly exceed what is currently possible, and perhaps most
exciting is the prospect of involving Citizen Scientists in the classification of the million or
more transient alerts that LSST will generate per night, placing the public at the heart of
LSST's pioneering exploration of time-domain astronomy.
3. Enhancing cultural enrichment and quality of life through education & outreach activities.
The LSST:UK Consortium institutions have a wealth of experience in education and public
outreach (EPO) activities, from running Open Days and exhibitions to CPD courses for
school teachers to Massive Online Open Courses (MOOCs). During Phase B we will develop
an EPO programme, in conjunction with the very active LSST EPO team in the US.
4. Enhancing the research capacity, knowledge and skills of organisations through the
employment of researchers with high-level expertise derived from working on LSST.
Over the 18-year lifetime of the LUSC programme, many students (e.g. from the STFC dataintensive
science CDTs) and postdocs who have developed high-level expertise from
working on LSST will pass from astronomy to the commercial sector, taking their valuable
knowledge and skills with them. Particularly valuable will be the computational and
statistical skills that will be readily applicable to the Big Data challenges prevalent in the
public and private sector, and the expertise in thick CCDs developed through UK
involvement in the LSST camera team.
5. Wealth creation, through the placing of construction contracts with UK companies.
The detector characterisation work started during LUSC Phase A, and proposed for
continuation during Phase B, has included liaison with a UK company that has now signed a
large contract to supply roughly half of the LSST detectors.
Publications
Beckmann R
(2023)
Population statistics of intermediate-mass black holes in dwarf galaxies using the newhorizon simulation
in Monthly Notices of the Royal Astronomical Society
Bichang'a B
(2024)
The properties of AGN in dwarf galaxies identified via SED fitting
in Monthly Notices of the Royal Astronomical Society
Bichang'a B
(2024)
The properties of AGN in dwarf galaxies identified via SED fitting
Davis F
(2022)
Radio AGN in nearby dwarf galaxies: the important role of AGN in dwarf galaxy evolution
in Monthly Notices of the Royal Astronomical Society
DÃaz-GarcÃa S
(2022)
Linking star formation thresholds and truncations in the thin and thick disks of the low-mass galaxy UGC 7321
in Astronomy & Astrophysics
Garner R
(2022)
Deep Narrowband Photometry of the M101 Group: Strong-line Abundances of 720 H ii Regions
in The Astrophysical Journal
| Description | (A) Brief background Our understanding of the Universe is predicated on objects brighter than the surface-brightness limits of wide-area surveys. The 'low-surface-brightness' (LSB) Universe, defined as the regime that is largely invisible in past large surveys like the SDSS (which are shallow), contains objects that are essential for understanding cosmic structure. For example, virtually all dwarf galaxies outside the local neighbourhood lie in this regime, as do LSB structures such as merger-induced tidal features and intra-cluster light that offer fundamental constraints on our cosmological model. Under ideal conditions, LSST can reach surface brightnesses fainter than ~30 - 31 mag arcsec^-2, across ~18,000 square degrees. The LSB Universe therefore represents virtually all the extra-galactic discovery space of this transformational survey. However, LSB flux is extremely sensitive to sky over-subtraction. Preserving this flux is, therefore, a key requirement of the LSST pipeline, without which its discovery space will be severely limited. The aims of this project were to (1) test how well the LSST pipeline preserves LSB flux and (2) develop strategies to improve LSB flux preservation, based on what was found in (1). (B) Significant achievements (B1) We injected mock objects, based both on idealised profiles and realistic objects from the NewHorizon cosmological simulation, into survey images from the Hyper Suprime-Cam (which are like those from LSST). These were then processed using the LSST pipeline. We showed that, across a wide range of magnitudes, sizes, light profile shapes and axial ratios, the pipeline sky subtraction caused significant LSB flux loss below ~26 mag arcsec^-2. We quantitatively demonstrated, for the first time that, without amending the pipeline, most of LSST's discovery space will remain inaccessible. (B2) Measuring the LSB flux preservation in different versions of the LSST pipeline requires a metric that can be routinely evaluated as the pipeline evolves. We created such a metric - the average surface brightness at which any given model's radial surface brightness profile is over-subtracted by 0.1 mag arcsec^-2. We wrote new software to routinely calculate this metric for different versions of the pipeline. (B3) Detailed experiments on the pipeline demonstrated that the third step ('bgModel2') in the 'skyCorr' task, which drives the sky-subtraction, is the most impactful on LSB flux. Objects with sizes greater than or equal to the spatial bin size used to produce 'bgModel2' systematically lose flux to the sky subtraction. We showed that, to preserve LSB flux, 'bgModel2' should either not be implemented or the bin size should be tuned to ensure that LSB flux is preserved at the largest spatial scales possible. (B4) During this project we worked as external international contributors in close collaboration with the LSST Algorithm and Pipelines (A&P) Team based in Princeton. Given the utility of our work, the PDRA leading the effort was made a member of the A&P team, with full access to their internal resources. The project has since continued (see below) and created a noteworthy and permanent collaboration with the A&P team. All scientific objectives of this award were met by this project. |
| Exploitation Route | The outcomes of this funding served two important purposes. First, it demonstrated the shortcomings of the LSST pipeline in terms of low surface brightness (LSB) flux preservation and second it offered a strategy to mitigate the sky over-subtraction generated by the pipeline so that LSB flux can be preserved (which is necessary for LSST to fulfil its scientific potential). We have been awarded further funding (ST/X001318/1) to continue this work. The outcomes of this award have already been taken forward by the LSST Algorithm and Pipelines (A&P) Team, in which the PDRA who led the effort during this award is now embedded as a full member. The PDRA has continued in the new project, which is now funded by ST/X001318/1. The aim of this new project is to implement the strategies produced by work funded by this award to preserve LSB flux in the LSST pipeline and ensure that the survey can access its discovery space. |
| Sectors | Education Other |
| URL | https://github.com/lsst-uk/sky-estimation-WP3.7 |
| Description | (A) Academic impact As noted in the Key Findings section, the findings from this award have established methodologies that can be used to preserve low-surface-brightness flux in surveys like the LSST. The methodologies are described in Watkins et al. 2024, MNRAS, 528, 4289. In particular, the findings have been taken forward in a new project (now funded by ST/X001318/1) which aims to implement these strategies in the LSST pipeline. (B) Non-academic impact The methodologies established during this award will enable the LSST pipeline to preserve low surface brightness flux. Images in which LSB features are visible are far more spectacular than those in which they have been removed. This is important for education and outreach, in terms of demonstrating the capabilities of the LSST to both the scientific community and the general public. |
| First Year Of Impact | 2024 |
| Sector | Education,Other |
| Description | UK involvement in LSST: Phase C (Herts component) |
| Amount | £414,347 (GBP) |
| Funding ID | ST/X001318/1 |
| Organisation | Science and Technologies Facilities Council (STFC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 03/2023 |
| End | 03/2027 |
| Title | Prototype sky subtraction method for the LSST pipeline that is optimised for low-surface-brightness science |
| Description | This method is a modification to the LSST pipeline which avoids the over-subtraction of flux from real astronomical objects due to an over-estimate of the night sky brightness in each exposure. This will be particularly important for low-surface-brightness (LSB) objects which are most affected by sky over-subtraction. Since most of the extra-galactic discovery space of LSST is in the LSB regime, this altered pipeline setup will be important for enabling LSST to fulfil its full scientific potential. The method is currently in the prototype stage and, in the coming years, will be fine-tuned and tested on real data (e.g. from the LSST commissioning surveys in 2024/25). |
| Type Of Material | Improvements to research infrastructure |
| Year Produced | 2024 |
| Provided To Others? | Yes |
| Impact | The method will allow LSST to produce images which can be more broadly utilised by the astronomical community than the survey's original key science goals, without hampering the survey's ability to achieve said goals. Additionally, the paper we have published describing the method will help provide a path for similar surveys to similarly broaden their scientific scopes. The paper can be found here: https://ui.adsabs.harvard.edu/abs/2024MNRAS.528.4289W/abstract A prototype of this method is currently being tested in the LSST pipeline. Initial tests show that several metrics improve when this setup is used compared to the default version of the pipeline. |
| URL | https://ui.adsabs.harvard.edu/abs/2024MNRAS.528.4289W/abstract |
| Title | Low surface brightness sky subtraction |
| Description | We are developing sky subtraction algorithms that preserve faint flux in deep survey images like those in the Legacy Survey of Space and Time (LSST) from the Rubin Observatory. |
| Type Of Material | Data analysis technique |
| Year Produced | 2022 |
| Provided To Others? | Yes |
| Impact | These algorithms will be transformative for LSST and enable it to fulfil its scientific potential as the premier discovery machine in the low surface brightness regime. |
| Title | Strategies for optimal sky subtraction in the low surface brightness regime |
| Description | Synthetic source master images and associated source property catalogues used in the study "Strategies for optimal sky subtraction in the low surface brightness regime" (Watkins et al.). |
| Type Of Material | Database/Collection of data |
| Year Produced | 2023 |
| Provided To Others? | Yes |
| Impact | This paper discusses the merits and pitfalls of different kinds of sky subtraction techniques. It describes experiments using fully synthetic images to investigate three different techniques, two commonly used in low surface brightness surveys, another experimental. The study's results quantify the impact of undetected flux on sky models, which tends to bias estimated sky brightnesses high, risking over-subtraction of flux. If the sky is modelled with a complex function (for example, a high-order polynomial, or a spline interpolation), that over-subtraction can occur locally, leading to artificial divots surrounding extended objects like galaxies, or even objects which are simply located close together on the sky. However, the results demonstrate that when a simple model is used, and when proper care is taken to mask detected astronomical objects to low surface brightness levels, this bias can be reduced to negligible amounts. Even for a survey as deep as LSST, any sky subtraction technique traditionally used in low surface brightness surveys can still be applied safely, so long as empirical corrections are made for scattered light and undetected faint sources. The paper justifies the recommendations Watkins and collaborators have proposed to LSST's data management (DM) team regarding the survey's pipeline sky subtraction. Working alongside DM, Watkins et al. found that the existing algorithm suffers from two problems: insufficient masking of low surface brightness flux, and too complex a sky model. Following the paper's results, the team found that adjusting the algorithm to use a much simpler model, even without an improvement to the masking, proves very successful at minimising the impact of the sky subtraction on the flux of extended or clustered objects. In fact, a preliminary investigation suggests that the proposed revised algorithm might benefit more than just low surface brightness science: a number of DM's photometric quality metrics appear to improve slightly when the revised algorithm is used, compared to the default pipeline. However, the full impact of the proposed change is still being investigated. |
| URL | https://zenodo.org/record/8192051 |
| Description | Collaboration with LSST Data Management Team on low-surface-brightness science pipelines |
| Organisation | Princeton University |
| Country | United States |
| Sector | Academic/University |
| PI Contribution | We are collaborating with the LSST Data Management team (principally Lee Kelvin, Robert Lupton and Yusra Al-Sayyad at Princeton) to develop pipelines for low-surface-brightness (LSB) science for LSST. The default pipelines produced by the Data Management team are not optimised for low-surface-brightness science, which represents a significant discovery space for LSST. Probing this space therefore requires developing bespoke pipelines that preserve LSB structures in the LSST images. Our team will develop these pipelines in collaboration with the Data Management Team, who will help us with incorporating our code into the LSST software stack and performing tests of the software using the HSC and LSST commissioning surveys. |
| Collaborator Contribution | Robert Lupton and Yusra Al-Sayyad are acting as consultants on this project. Their team will help us incorporate the software we will produce into the LSST software stack. Since their team is also reducing the HSC survey (which is the precursor to LSST) they will provide assistance in testing our pipeline software using HSC data before the main LSST survey starts. |
| Impact | LSST:UK deliverables D3.7.1 30 Nov 2020 Report on optimal metrics for preserving low-surface-brightness flux at different spatial scales https://lsst-uk.atlassian.net/wiki/download/attachments/1146928/LUSC-B-10-D3.7.1-OptimalMetrics-LSB.pdf?api=v2 D3.7.2 28 Feb 2021 Report on mock testing results - quantification of depth improvements made over existing datasets https://lsst-uk.atlassian.net/wiki/download/attachments/1146928/LUSC-B-14-D3.7.2-MockTesting.pdf?api=v2 D3.7.3 31 Aug 2021 Software to output metrics that keep track of improvements to the pipeline sky subtraction https://lsst-uk.atlassian.net/wiki/download/attachments/1146928/LUSC-B19-D3.7.3-Improvement-Metrics-Software.pdf?api=v2 |
| Start Year | 2020 |
| Title | Software to do photometry on model galaxies and output sky-subtraction metrics in the LSST pipeline |
| Description | # sky-estimation-WP3.7/measureMetrics Repository for software used to do photometry on model images and output sky subtraction metrics. ## PYTHON CODE \_\_init\_\_.py : blank file to turn directory into Python module image_retrieval.py : functions for retrieving image cutouts at specific coordinates using the Butler plot_metrics.py : functions for reading in and parsing photometry output tables and measuring/plotting metrics surface_photometry.py : functions for doing surface photometry on images utility.py : miscellaneous useful functions ## JUPYTER NOTEBOOKS CataloguePhotometry.ipynb : demonstration of how to make photometry pickle tables for the full catalogues Overview.ipynb : broad overview of injected models and analysis thereof ## TABLES mags*.p : output from CataloguePhotometry.ipynb, photometry tables of models pre-sky-subtraction coadd_mags*.p : output from CataloguePhotometry.ipynb, photometry tables of models post-sky-subtraction lsstuk_icl_dwarfs.fits : table of parameters for the ICL + New Horizon dwarf model input catalogue lsstuk_lsb_sersic.fits : table of parameters for the single-Sersic profile model input catalogue |
| Type Of Technology | Software |
| Year Produced | 2021 |
| Impact | This software has enabled us to quantify oversubtraction of low-surface-brightness structures in the LSST pipeline. |
| URL | https://github.com/lsst-uk/sky-estimation-WP3.7/commit/4092ae6285051f2a1e54a63c09057ddd7703ad3a |
| Description | Low Surface Brightness Science, Session at the LSST Project and Community Workshop 2020 |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Low Surface Brightness Science, Session at the LSST Project and Community Workshop 2020 |
| Year(s) Of Engagement Activity | 2020 |
| Description | Talk at Symposium 12 at the EAS meeting 2021: Renaissance of the Low Surface Brightness Universe |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Invited talk by team member Dr Aaron Watkins. |
| Year(s) Of Engagement Activity | 2021 |
| URL | https://herts365-my.sharepoint.com/:p:/g/personal/aw21abf_herts_ac_uk/EftaGkhTTm5EpCuUp_DxB58BQDKk4g... |
| Description | Talk in session 'Low Surface Brightness Astronomy with LSST' at the Rubin Project and Community Workshop 2021 |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Talk by team member Dr Aaron Watkins. |
| Year(s) Of Engagement Activity | 2021 |
| URL | https://project.lsst.org/meetings/rubin2021/sites/lsst.org.meetings.rubin2021/files/watkins_pcw2021.... |
| Description | The low surface brightness Universe as seen by LSST |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | The Large Synoptic Survey Telescope (LSST) is a wide-field, ground-based observatory designed to image a substantial fraction of the southern hemisphere in six optical bands every few nights. The observatory will operate for at least a decade, allowing stacked images to detect light down to very faint surface brightnesses. Low surface brightness astronomy is a key area of research that will be uniquely expanded upon by LSST's combination of depth and area. For instance, galaxy clusters contain vast numbers of stars in diffuse light between the galaxies. The definitive LSST sample can capture enough of these systems to quantify the amount and spatial extent of this intracluster light in a more systematic fashion than ever previously possible. We will be able to characterize the stellar halos that surround nearby galaxies and unveil structures therein, such as tidal features and density inhomogeneities produced by galaxy mergers and interactions. These features, originated from the hierarchical formation processes, will provide critical clues to the formation history on a galaxy-by-galaxy basis. LSST will also enable the most complete census of low surface brightness or ultra-diffuse galaxies to date. In order to best detect and analyse the low surface brightness light in LSST there are a number of key preparatory tasks, specified in the published LSST Galaxy Roadmap. These are not part of the funded LSST infrastructure effort and need to be undertaken by Science Collaborations. LSST commissioning will start in 2020 and so this is the ideal time to ramp up the Science Collaboration's contribution. In this workshop we discussed the efforts made towards these preparatory tasks, discuss strategies adopted on common problems and determine what tasks still need to be done and who will undertake those, to ensure that the team are prepared for data arriving from 2022 onwards. |
| Year(s) Of Engagement Activity | 2020 |
| Description | The morphological mix of dwarf galaxies in the nearby Universe |
| Form Of Engagement Activity | A magazine, newsletter or online publication |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | Contribution to LSST:UK newsletter based on an article published in MNRAS by Sugata Kaviraj, Aaron Watkins and collaborators. It describes the morphological mix of dwarf galaxies using deep HSC images in the COSMOS which are a precursor to what will be available from the LSST in the near future. |
| Year(s) Of Engagement Activity | 2024 |
| URL | https://lsst-uk.atlassian.net/wiki/spaces/HOME/pages/3466297345/LSST+UK+Newsletter+43+April+2024#New... |
| Description | The risk to LSST's potential discovery space posed by night-sky subtraction |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Professional Practitioners |
| Results and Impact | Invited talk in the Low surface brightness session at the LSST@Europe 4 conference. |
| Year(s) Of Engagement Activity | 2022 |
| URL | https://sites.google.com/inaf.it/lssteurope4/home |
| Description | The role of AGN in the evolution of dwarf galaxies |
| Form Of Engagement Activity | A magazine, newsletter or online publication |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | Contribution to LSST:UK newsletter based on an article published in MNRAS by Sugata Kaviraj, Aaron Watkins and collaborators. It discusses the the role of AGN in the evolution of dwarf galaxies using deep multi-wavelength survey data. The data used offers a preview of what will be possible using LSST in conjunction with ancillary datasets in the near future. The newsletter is sent to the entire LSST:UK community and reaches hundreds of astrophysicists at all career stages who are actively working on LSST science. |
| Year(s) Of Engagement Activity | 2024 |
| URL | https://lsst-uk.atlassian.net/wiki/spaces/HOME/pages/3641573377/LSST+UK+Newsletter+47+August+2024#Ne... |