• 1 Introduction
• 2 Commissioning update: on-sky observations begin!
• 3 Report on ComCam commissioning run
• 4 Rubin alerts and broker workshop – meeting report
• 5 Upcoming open call for members of LSST:UK Science Working Group
• 6 LSST:UK in the news
• 7 NSF DOE Vera C. Rubin naming convention
• 8 National Astronomy Week
• 9 Recent LSST:UK Science Centre outputs
• 10 Forthcoming meetings of interest

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Introduction

2024 ended on a high note, with a very successful on-sky observing campaign with the commissioning camera, ComCam.

@Graham Smith and @Will Sutherland both write about that at greater length below, while a technical summary can be found in the interim report by Keith Bechtol et al (SITCOMTN-149). The focus of the next few months on the summer will be getting LSSTCam fully installed, prior to its on-sky commissioning campaign.

In late November, members of the LSST:UK leadership undertook a pair of training sessions on EDI issues for academic leaders, delivered by Hannah Ravenswood and @Matt Jarvis, who run such sessions for a variety of groups at Oxford. The attendees found the sessions very thought-provoking, so we intend to run them again for the Project Delivery Group (i.e., the Working Package Leaders for our in-kind contribution programme). We are also considering how we might provide EDI training for the Consortium as a whole, possibly as part of an All Hands Meeting later this year.

The Rubin User Committee has published the report from its most recent meeting, and the Community Science Team has added its response; both can be found here.

Finally, 17 February sees the next deadline for stage-one proposals to the LINCC Incubators scheme. As previously noted, this programme can provide a very useful source of software engineering expertise and LSST:UK members have fared well so far, with @Meg Schwamb and @Tom J Wilson among the first awardees.

 

 

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Comet C/2023 A3 (Tsuchinshan–ATLAS) is seen over the Rubin summit facility, with Venus to the left. (Credit: Hernan Stockebrand)

 

Commissioning update: on-sky observations begin!

Late 2024 was hugely significant and exciting for the Rubin Construction Project and the global LSST scientific community, as the first photons were detected with ComCam in the focal plane of the Simonyi Survey Telescope.

As @Will Sutherland reports below, the ComCam commissioning observations were successful, and included seven fields that are suitable for scientific verification and early science. Other members of the LSST:UK commissioning team (notably, @Dan Ryczanowski and @Tom J Wilson) and our international collaborators are now engaged in the early stages of scientific verification of ComCam data within the Rubin commissioning team (SITCom). The existence of on-sky data is also stimulating closer coordination between the LSST:UK DEV, DAC, and commissioning teams.

Looking ahead, the recent ComCam success is increasing confidence in the project timeline, and has brought forward the timescale for the first wave of early science results from the community. In particular, release of data products from the ComCam observations is envisaged for mid-2025 (Data Preview 1), i.e. adjacent to NAM2025 in Durham. Full details of the fields that were observed with ComCam and initial tests of the data quality, can be found in a publicly available SITCom Technical Note (SITCOMTN-149). In summary, the seven ‘ComCam deep fields’ span solar system, stellar, galactic, extragalactic and cosmology interests, with the deepest data reaching AB=27 in the r-band. The timescale for the start of survey operations is currently unchanged at the end of 2025.

The latest commissioning news, including more detail on what is reported here, can always be found on the Community Forum. While this forum was updated regularly during the ComCam run, the posts will likely be less frequent until LSSTCam on-sky commissioning begins. This is planned for spring 2025.

In summary, 2025 promises to be a very exciting year… so stay tuned for more news in the months ahead, and start getting ready for early science!

@Graham Smith

Report on ComCam commissioning run

As reported elsewhere, Rubin Observatory had its first on-sky observing run from October to December 2024 using ComCam (a smaller 9-chip version of the actual LSSTCam).

I travelled to the summit from 20 November to 9 December to assist mainly with the Active Optics commissioning, spending 12 nights on the mountain and 5 at the Recinto (campus) in La Serena; weather was cloudless throughout.

During the run, roughly one quarter of the on-sky time was used for active optics testing, another quarter for various other technical tests (e.g. M1 support loops, exposure timing, stray light tests, fast-readout modes, etc) and about half for ‘early science’ observations on selected targets; the E-CDFS field was observed close to 10-year main survey depth in gri filters (shallower in u/z/y), while a number of other fields including 47 Tuc, Fornax dSph, a Euclid deep field and an ecliptic field were observed less intensively.

Unlike LSSTCam which has dedicated defocused wavefront sensor chips in 4 corners, ComCam does not: so, active optics ‘donut’ images were taken as ‘triples’, a sequence of three exposures with ComCam pistoned by -1.5mm, +1.5mm and 0mm from current focus position. (Here, the in-focus 0mm image is just a cross-check and does not enter the correction loop).

Similar to LSSTCam, the defocused donuts for selected stars, typically five per chip, are then analysed for wavefront aberrations, then these are input to a singular-value decomposition to derive a vector of corrections (hexapod offsets and mirror force patterns) which are sent to the telescope (see Megias et al, arXiv/2406.04656 for details).

Generally the active optics worked well, with all the image processing and coordinate rotations now sorted out; as long as the initial aberrations are not very large, the system generally converges to AO residual errors near 0.2 arcsec in two or three iterations. Some speed enhancements and robustifying against overlapping donuts or other glitches are still required, plus the wider field of LSSTCam will add new challenges.

For the telescope in general, the tracking is very precise, and slewing is quick even at the current 20% of full speed. Images with ISR-removed were available via USDF at about 30-second delay (obviously these are only 5% of full-size). There are various moderate issues including occasional TCS freezes, degraded rotator performance near the zenith, M1M3 force actuators faulting, and some suspected dome-seeing issues.

It is hoped that most of these can be improved before the real LSSTCam goes on-sky in April, so the coming year looks very exciting for Rubin.

@Will Sutherland

Rubin alerts and broker workshop – meeting report

The week of 13 January brought together scientists and software engineers from the UK and Europe for an alerts and broker workshop at the University of Oxford. The meeting included topics such as lensed supernovae, kilonova search, citizen science, real-bogus classification, solar system objects and technosignatures.

This year is due to see the installation of the 3.2 gigapxiel camera LSSTCam on the Simonyi Telescope and the start of commissioning and science verification. Much of the exciting early science will come from the nightly processing of the survey images, which will have a reference frame subtracted to reveal everything that moves, varies and explodes in the sky.

The sensitivity of these difference images is unprecedented and objects which are typically 100 times fainter than we see now in wide-surveys will be detected. We were delighted to host Eric Bellm, the lead for the Rubin alerts team, at our LSST:UK meeting in Oxford. With fortuitous timing, Eric was able to share the information from the report on the first astronomical images from Rubin and the Commissioning Camera  (SITCOMTN-149).  Eric showed the extremely promising early results, indicating that this first on-sky campaign delivered images that met the required optical quality and the system throughout was consistent with expectations.

The telescope acquires and tracks efficiently and effectively and the end-to-end workflows were executed for data processing. Eric was answered innumerable questions and highlighted how pleased the Rubin Project team were with the ComCam on-sky campaign. They learned a lot, but were slightly concerned that the data collected over the six-week observing period is merely 10% of one night of LSSTCam data ! 

Other discussions paved the way for further collaboration with other European brokers, and considered the prospect for a ‘super broker’ – bringing together multiple transient surveys. For the Lasair broker, the meeting will improve the learning curve for users and the documentation, and it sharpened the choice of light-curve features – to enable effective alert filters.

This year, the Lasair team will be getting ready for a 3-day rehearsal at full LSST rates at the end of February; the release of real astronomical data from the commissioning camera, in summer 2025; and the ramp-up to the full alert stream at the end of the year.

We are delighted to thank our colleagues from the BreakThrough Listen project for their generous financial support for the meeting. 

@Stephen Smartt @Roy Williams

Upcoming open call for members of LSST:UK Science Working Group

With on-sky data from ComCam now on disk at the US Data Facility and being verified, and Data Preview 1 slated to occur in mid-2025, it is now time to restart the LSST:UK Science Working Group (SWG). This body has understandably been dormant for some years, as the community waited for the construction project to progress and we all endured the covid pandemic and its aftermath.

As a baseline, the roles of the SWG are envisaged to be: (1) to help members of the UK community to get involved in LSST, including to accelerate the learning curve for new data rights holders; (2) to be a link between the eight international LSST Science Collaborations (SCs) and members of the UK community; (3) to assist the Project Scientist in providing scientific advice to the LSST:UK Consortium Board and Executive Group.

Membership of the SWG will likely number around 16, i.e. two members per SC, and will be open to all career stages. Early Career Researchers are strongly encouraged to step forward. An open call for nominations, including self-nominations, will be published (all going well) in February.

@Graham Smith

LSST:UK in the news

The new year brought a spate of media interest in LSST:UK, with the UK’s involvement in Rubin highlighted on several major UK and global news outlets.

On 3 January, Catherine Heymans, the Scottish Astronomer Royal, was interviewed on Today, BBC Radio 4’s flagship news programme, about her perspective on Rubin. You can listen to the interview Today - 03/01/2025 - BBC Sounds ; go to 1.43:20

Catherine subsequently appeared on Sky News and BBC Scotland to talk about Rubin and LSST:UK, while the Today interview was featured on the BBC World Service Global News Podcast (go to 20.10).

@Eleanor O'Kane

NSF DOE Vera C. Rubin naming convention

You may have noticed the use of the full name for Rubin – NSF DOE Vera C. Rubin Observatory – in official communications. The moniker reflects the funders, the U.S. National Science Foundation and the U.S. Department of Energy’s Office of Science.

When communicating about Rubin to an external audience, especially in text, please use the full name – NSF DOE Vera C. Rubin Observatory – in the first instance. After this, you can revert to a briefer style, e.g. Rubin or the Vera C. Rubin Observatory.

National Astronomy Week

National Astronomy Week (NAW) takes place on 1-9 February 2025. Drawing together the UK scientific, educational and astronomical communities, more than 250 events across the UK have been planned.

This year, the theme is Chasing the Moon, with telescope livestreams on the NAW YouTube channel, talks and stargazing events set to take place. A special show will screen at planetariums across the UK. Introduced by Catherine Heymans, the Scottish Astronomer Royal, the show will offer an immersive journey through the cosmos. @Chris Lintott has also recorded a video to highlight some of the activities.

The event is supported by the Royal Astronomical Society, British Astronomical Association, Federation of Astronomical Societies, and Society for Popular Astronomy.  Previous NAWs have marked the return of Halley’s Comet, the close approach of Mars in 2003 and the 400th anniversary of the invention of the telescope.

@Eleanor O'Kane

Recent LSST:UK Science Centre outputs

The LSST:UK Science Centre has recently produced the following technical reports.

@Terry Sloan

Forthcoming meetings of interest

Dates, locations and links… The current list of forthcoming meetings is always available on the Relevant Meetings page. You may also wish to check information held on the LSST organisation website LSST-organised events and the LSST Corporation website.