Introduction
A major construction milestone was reached at the end of August, with the successful installation of ComCam, the commissioning camera, in the Telescope Mount Assembly (TMA) in the dome. The Rubin team have also released a video of the installation process, which had been practiced many time over the past few months, using a camera mass surrogate in place of ComCam itself.
ComCam will now be subjected to a battery of tests to check that its behaviour in the TMA matches that recorded in the lab prior to this installation.
Credit: Rubin Obs/NSF/AURA
Congratulations to our very own Stephen Smartt on his appointment as the second holder of the Philip Wetton Chair of Astrophysics at Oxford. Stephen will be starting in Oxford in early October, but his LSST:UK roles will continue as they are.
Those with ideas for future newsletter items should contact the LSST:UK Project Managers (George Beckett and Terry Sloanlusc_pm@mlist.is.ed.ac.uk), while everyone is encouraged to subscribe to the Rubin Observatory Digest for more general news from the US observatory team.
Dummy header for Graham
Graham Smith
News from the SAC
A reminder that all minutes from the Rubin Observatory Scientific Advisory Committee (SAC) are available publicly on https://project.lsst.org/groups/sac/meetings . The last meeting was at the Project and Community Workshop on 7th August 2022 and the minutes are available. The major recommendations from the SAC :
For the Project to implement improved structure and content links for the community webpages, including a functioning search capability
More clarity on the decision making process for Survey Cadence Optimisation Committee (SCOC) and a clear set of tasks and goals for 2023
The Project should explore ways to generate alerts during early science operations, even if the templates are not perfect.
DPO has been successful in allowing users to gain experience of the Rubin Science Platform. But a method of releasing simulated solar system data products should be considered for inclusion in DP0
The project is considering how to implement pre-defined alert filters such that users can get a small number fraction of the alerts directly from the alert stream (as opposed to the full stream which is restricted to community brokers). A possibility is to partner with ANTARES to do this, and the SAC requested a more complete description of how this would work.
There was some discussion on the international contributions and community contributions to commissioning, and more details are available in the link above.
Lasair Meeting on Tiny Lightcurves
The Lasair broker relies on 'features' for lightcurves so that astronomers can build filters separating what is wanted from what is not. The LSST project will provide a large number of such features, mainly focused on periodic and stochastic variability. However, there is not much in the LSST alert packet concerning new sources, the possible explosive transients like supernovae, kilonovae, tidal disruption events, GRB afterglows etc. In this case, there may or may not be a galaxy association, and the distance of that galaxy may or may not be known. The LSST observations will utilise six light filters, ugrizy, and there may be just a handful of flux measurements spread over these. We call these 'tiny lightcurves'.
One objective for a community broker is to add values to the LSST alert stream, and the Lasair project has decided to add value by building useful features from tiny lightcurves. Therefore there was a brainstorming workshop Sept 12-13 at Edinburgh. Several algorithms were considered: fitting a straight line in magnitude -- i.e. power law in flux -- or fitting other simple curves, or the Bazin 5-parameter model. We also considered the non-parametric Gaussian Process to fit the lightcurve. In addition to working with detections of the new transient, we will take account of previous non-detection (upper limit measurements) to refine our understanding of the new transient.
We also asked how to make a useful feature; for example the parameters of a quadratic fit are features, but perhaps not useful to an astronomer building a query. The most relevant features for astrophysical explosions (as opposed to variables) with tiny lightcurves are the peak magnitude (combined with absolute magnitude if distance known) and the rate of increase and decrease of magnitude. Absolute magnitudes can be made only with a strong association with a galaxy plus knowledge of the distance of that galaxy. The rate of increase, we decided, would be done with a combination of methods, depending on the sparsity of the lightcurve. Work is beginning on formulating, coding, and testing suitable algorithms. Further details of the workshop can be found /wiki/spaces/LUSC/pages/2990505985.
Recent LSST:UK Science Centre outputs
The LSST:UK Science Centre has recently produced the following technical reports.
Title | Author | Description |
|---|---|---|
Forthcoming meetings of interest
Meetings of potential interest for the coming months include:
24–28 October 2022 – Rubin Observatory LSST@Europe4, at Accademia dei Lincei, Rome, Italy. The will be a hybrid meeting with a limited number of in-person spaces. Registration for virtual participation is open until 15th September.
17–22 October 2022 – DESC Sprint Week, at University of Michigen, Ann Arbor. Details to be published on DESC members website (login required).
Members of the Consortium (not in receipt of travel funding through one of the Science Centre grants) may apply for travel support for meetings of this kind via the the LSST:UK Pool Travel Fund. Details are available at https://lsst-uk.atlassian.net/wiki/spaces/HOME/pages/25853997/LSST+UK+Pool+Travel+Fund .
Note that the current list of forthcoming meeting 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.
Announcements
If you have significant announcements that are directly relevant to LSST:UK and would like to share the announcement in a future newsletter, please contact the LSST:UK project managers.