Users Committee Report (2026A; April 27)

Science
#1

The Rubin Users Committee (UC) thanks the Rubin Project members for their continued efforts in serving the user community during the early science optimization phase of the LSST. The committee congratulates the Observatory on the start of alert production in the Deep Drilling Fields and on the discovery of over thousands of new asteroids. The committee also wishes to report feedback on the outstanding support provided by the Rubin science team and Data Management liaison to the Solar System Science Collaboration (SSSC) during the Solar System sprint in February, as well as the prompt release of 3I/ATLAS observations with cutouts and an example notebook. These were not planned deliverables given the current state of operations, and the community deeply appreciates the effort.

Finding 1: Solar System Data Access and the Prompt Products Database

The SSSC and the broader Solar System community face significant challenges in accessing Rubin Solar System data products during the current early science optimization phase, resulting in potential lost scientific opportunities. Rubin has discovered over 11,000 new asteroids and detected more than 80,000 known Solar System small bodies, but this data is not currently served through any alert broker, nor is it accessible on the RSP. The relevant astrometry and photometry has been submitted to the Minor Planet Center (MPC), but crucial metadata are missing. The alert structure has also changed: Solar System object association in alerts now relies on MPC confirmation rather than direct pipeline association, meaning the community must await MPC verification before objects are reliably identified. This leads to duplicated effort and inconsistent approaches across groups. The current Solar System processing pipeline computes orbital and geometric quantities, including heliocentric and topocentric distances and phase angles, that are not yet publicly accessible through the RSP, even though they are already being produced. In the interim, the SSSC has been constructing a community database augmented with these quantities with support from the B612 Foundation, but this workaround is unsustainable as data rates increase and places an undue burden on a small number of groups who are effectively providing a service to the entire community.

The committee recognizes the complexity of the current situation, including the fact that some of this processing occurs outside the standard documented pipeline. The committee encourages the Observatory to explore mechanisms to make Solar System processing pipeline outputs more accessible to the RSP user community as a stopgap measure until the Prompt Products Database (PPDB) is delivered. Rubin Solar System data products are small relative to the full astrophysical transient data volume, and bridging this gap would substantially expand scientific return during the early science optimization phase.

Finding 2: Access to Pointing History and Survey Footprint Information

Community access to the pointing history of the telescope and associated metadata would significantly benefit a broad range of science cases. The scientific motivation spans multiple collaborations that rely on time-domain data. The committee notes that the Rubin scheduler now provides observation timing information in the nightly summaries, in addition to field identifiers, which was a much needed feature. It would be desired to have further information available, such as limiting magnitudes and seeing, and an easy way to grab the information.

The committee is aware that a file covering December through April is expected to be released through the RSP around July 2026. The committee recommends that the Observatory communicate clearly to the community the planned timeline, content, and format of this release, and considers additional columns to be of high scientific value across multiple communities. The committee encourages the Observatory to provide this information at regular intervals consistent with the approach used during Science Validation.

Finding 3: Discoverability of In-Kind Contributions

The committee continues to hear from users who have difficulty identifying, locating, and accessing resources contributed through Rubin’s in-kind partner programs. While a dedicated webpage exists at https://in-kind-program.lsst.io/ and platforms such as IDACs are intended to host contributed datasets, users report that it is not straightforward to determine what has been delivered, what is still forthcoming, or how to access specific tools and data.

The committee understands that an improved website is in progress and acknowledges the work underway by the in-kind program team. The committee gently encourages the Observatory to continue prioritizing discoverability improvements, and suggests that a brief community-facing communication highlighting what is currently available and how to access it would be of immediate benefit.

Finding 4: Template Generation: Transparency and Community Engagement

The community has expressed ongoing confusion about the current plans for template generation, particularly for sky regions outside the Deep Drilling Fields. This uncertainty significantly hinders science cases that depend on image differencing, including transient, variable star, and Solar System science, and makes it difficult for community members to plan follow-up programs or assess the suitability of Rubin data for their ongoing programs. The committee is aware of ongoing discussions with Rubin leadership on this topic and acknowledges that Eric Bellm recently provided new information via Community Forum, which was well received.

The committee encourages the Observatory to be more transparent and proactive in communicating the template generation strategy and timeline to the community. There is substantial expertise within the Science Collaborations that could inform decisions about template quality and generation processes, and the committee encourages the Observatory to engage the community in this discussion. A technical note documenting how image subtraction quality depends on the number of input template images, along with the metrics used to evaluate that quality, would be of significant value to the community in understanding what science is currently feasible and what will become possible as operations mature.

Finding 5: Timestamps in Observation Logs and Documentation

The committee reiterates its recommendation, supported broadly across the community, that timestamps and version indicators be added to all documentation pages and observation logs. Users continue to report difficulty determining when documentation was last updated and which data release it corresponds to, and the absence of observation timestamps limits the utility of pointing history data for time-sensitive science. The committee strongly encourages the Project to treat this as a priority.

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#2

Hello,

Could you please clarify this statement?

You don’t mean that Solar System objects are not being served through alert brokers at all, right? When working with Rubin alerts through the Fink broker, I see large numbers of asteroids every day, and occasionally comets. Some of these objects already have an ssObjectId and an MPC designation.

Am I correct in understanding that you are referring instead to additional Solar System data products (such as orbital parameters, distances, phase angles, and other derived quantities) that are not currently exposed through brokers? In other words, are you saying that the detections themselves are available, but the full Solar System data package is not yet accessible through brokers?

Or do you mean something else?

Thank you.

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#3

Hello,

Just to clarify, brokers receive all alerts generated by the alert pipeline. In addition, from Feb 23rd 2026 (when the Solar System object association pipeline was deployed on the Rubin side), brokers receive extra information if an alert has been associated to a known Solar System object (mpc_orbits and ssSource sections – see Alert Production Database).

My understanding is that @iandreoni is reporting the Solar System data extracted independently from the period prior to alert generation (Rubin’s early optimization surveys).

Best,
Julien

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#4

Association is spatial identifying the closest Solar System object. That doesn’t mean it’s correct especially with uncertainty. Although not quite worded correctly. The point is that an object not seen for 5 years is associated positionally because it’s predicted to be the closest doesn’t guarantee that object is the transient source, orbit fit is what will tell you that and that’s what the prompt products database would include is the feedback loop with the MPC including those associations in the orbit fit so any false associations would get filtered. This is important for many wanting to do science with Rubin.

The aim was to highlight there’s a need to get the Rubin prompt products database contents to the community. The alerts are telling us this is the closest predicted Solar System sources so if the community saw an associated asteroid do something odd, we would want to wait to submit the paper until the MPC has confirmed those observations are of that object if it hadn’t been observed in years.

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#5

Thanks to the Users Committee for their 2026A report. Responses from Rubin Observatory are compiled below – looking forward to seeing the UC at the Rubin Community Workshop at the end of July.

Finding 1: Solar System Data Access and the Prompt Products Database

The SSSC and the broader Solar System community face significant challenges in accessing Rubin Solar System data products during the current early science optimization phase, resulting in potential lost scientific opportunities. Rubin has discovered over 11,000 new asteroids and detected more than 80,000 known Solar System small bodies, but this data is not currently served through any alert broker, nor is it accessible on the RSP. The relevant astrometry and photometry has been submitted to the Minor Planet Center (MPC), but crucial metadata are missing. The alert structure has also changed: Solar System object association in alerts now relies on MPC confirmation rather than direct pipeline association, meaning the community must await MPC verification before objects are reliably identified. This leads to duplicated effort and inconsistent approaches across groups. The current Solar System processing pipeline computes orbital and geometric quantities, including heliocentric and topocentric distances and phase angles, that are not yet publicly accessible through the RSP, even though they are already being produced. In the interim, the SSSC has been constructing a community database augmented with these quantities with support from the B612 Foundation, but this workaround is unsustainable as data rates increase and places an undue burden on a small number of groups who are effectively providing a service to the entire community. The committee recognizes the complexity of the current situation, including the fact that some of this processing occurs outside the standard documented pipeline. The committee encourages the Observatory to explore mechanisms to make Solar System processing pipeline outputs more accessible to the RSP user community as a stopgap measure until the Prompt Products Database (PPDB) is delivered. Rubin Solar System data products are small relative to the full astrophysical transient data volume, and bridging this gap would substantially expand scientific return during the early science optimization phase.

Response 1: The desire to have an alternative data access mechanism for Rubin detections of Solar System small bodies is understood. However, no interim workaround is planned because the optimal way for Rubin to make Solar System data accessible remains pushing forward on the planned Early Data Preview 2 (EDP2; release date 27 July 2026) and Prompt Products Database (release anticipated Sep-Oct; RTN-011).

Finding 2: Access to Pointing History and Survey Footprint Information

Community access to the pointing history of the telescope and associated metadata would significantly benefit a broad range of science cases. The scientific motivation spans multiple collaborations that rely on time-domain data. The committee notes that the Rubin scheduler now provides observation timing information in the nightly summaries, in addition to field identifiers, which was a much needed feature. It would be desired to have further information available, such as limiting magnitudes and seeing, and an easy way to grab the information. The committee is aware that a file covering December through April is expected to be released through the RSP around July 2026. The committee recommends that the Observatory communicate clearly to the community the planned timeline, content, and format of this release, and considers additional columns to be of high scientific value across multiple communities. The committee encourages the Observatory to provide this information at regular intervals consistent with the approach used during Science Validation.

Response 2: The Rubin scheduler data can be obtained from the browser-based all-sky map interface or the static table interface, or obtained and manipulated programmatically as demonstrated in the current notebook tutorial “Commissioning - 102. Rubin Schedule Viewer”. Limiting magnitude and seeing will not be added to the Scheduler’s outputs, and the “execution status” will remain the only post-observation column altered in the scheduler database, because image quality assessments belong (and will be included) in an observatory metadata database which will be available alongside the Prompt Products Database. A new file of LSSTCam visits metadata that covers April 2025 through the start of June 2026 is now available in the RSP as demonstrated in the updated notebook tutorial “Commissioning - 101. LSSTCam visits database”. The goal is to update this file on a monthly basis until the Prompt Products Database is available.

Finding 3: Discoverability of In-Kind Contributions

The committee continues to hear from users who have difficulty identifying, locating, and accessing resources contributed through Rubin’s in-kind partner programs. While a dedicated webpage exists at https://in-kind-program.lsst.io/ 2 and platforms such as IDACs are intended to host contributed datasets, users report that it is not straightforward to determine what has been delivered, what is still forthcoming, or how to access specific tools and data. The committee understands that an improved website is in progress and acknowledges the work underway by the in-kind program team. The committee gently encourages the Observatory to continue prioritizing discoverability improvements, and suggests that a brief community-facing communication highlighting what is currently available and how to access it would be of immediate benefit.

Response 3: The In-Kind Program team is working on a new set of resource tables and dashboards to provide improved access to the resources being delivered across contribution types. The plan is to present preliminary versions of these at the RCW and circulate a community posting with further information at the same time. Feedback from the community (both contributors and the wider community) is always welcome so that the In-Kind Program team can improve the visibility and accessibility of the resources. The information on resources will be available in a specific In-kind contributed resources section under in-kind-program.lsst.io. The UC and Rubin community members are encouraged to forward any concerns or questions on In-kind Program matters to the In-kind team using rubin-inkind@noirlab.edu.

Finding 4: Template Generation: Transparency and Community Engagement

The community has expressed ongoing confusion about the current plans for template generation, particularly for sky regions outside the Deep Drilling Fields. This uncertainty significantly hinders science cases that depend on image differencing, including transient, variable star, and Solar System science, and makes it difficult for community members to plan follow-up programs or assess the suitability of Rubin data for their ongoing programs. The committee is aware of ongoing discussions with Rubin leadership on this topic and acknowledges that Eric Bellm recently provided new information via Community Forum, which was well received. The committee encourages the Observatory to be more transparent and proactive in communicating the template generation strategy and timeline to the community. There is substantial expertise within the Science Collaborations that could inform decisions about template quality and generation processes, and the committee encourages the Observatory to engage the community in this discussion. A technical note documenting how image subtraction quality depends on the number of input template images, along with the metrics used to evaluate that quality, would be of significant value to the community in understanding what science is currently feasible and what will become possible as operations mature.

Response 4: For all readers, the Forum topic by Eric Bellm mentioned in the UC report details how a set of templates based on the forthcoming Data Preview 2 release has been deployed, and covers regions outside of the Deep Drilling Fields (see also template coverage in the Prompt documentation). To increase transparency, information about template generation has been updated in v9 of the Rubin Tech Note on the Early Science Program (RTN-011) and was covered during the Rubin Science Assembly on Early Science on Jun 18 (slides and recording). The current strategy for incremental template generation is to generate and deploy them where the input images are sufficient to avoid introducing large gaps and the templates pass quality validation (do not create excess false positives). Alert production in year 1 will remain opportunistic, with calibration stability, survey quality, and executing the LSST survey strategy remaining the overriding priorities. The ability to forecast template availability will improve as the input selection criteria are refined, and as production pipelines also move into sustained survey observations. A technical note is in preparation.

Finding 5: Timestamps in Observation Logs and Documentation

The committee reiterates its recommendation, supported broadly across the community, that timestamps and version indicators be added to all documentation pages and observation logs. Users continue to report difficulty determining when documentation was last updated and which data release it corresponds to, and the absence of observation timestamps limits the utility of pointing history data for time-sensitive science. The committee strongly encourages the Project to treat this as a priority.

Response 5: Work on this started after the 2025B report. It was implemented in the rubinobservatory.org/for-scientists pages in April (shown at the top of the page), and implementation in the technical documentation completed in June (e.g., dp1.lsst.io, bottom of the pages). These timestamp updates are automatically generated and can be trusted to accurately reflect the last time a document, a sub-section of a documentation site, or an individual webpage, was modified.

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