Introduction
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 Ellen, Benjamin and OferLSST UK in-kind contribution: observational systematics for photometric redshift estimates
We have investigated how different observational effects such as sky brightness, seeing, and number of exposures can affect the photometric redshift (photo-z) distribution for LSST. The observation strategy for Rubin is to cover a large survey region before building up the depth. During the first few years of observation, therefore, it is expected that the inhomogeneity in depth due to e.g. varying weather condition is large. Effectively, one can regard each pointing as a ‘mini’ survey with different observational systematics and limiting magnitudes. This could potentially be a problem for weak lensing analysis because the signal is sensitive to the mean redshift of the tomographic bin, especially for the precision required by LSST.
In this investigation, we focus on the ‘gold’ sample from the first (Y1) and fifth year (Y5) data release, for which the simulated observation conditions for the Rubin Observatory (OpSim) as well as the DC2 DM catalogue are used. We split the sample into tomographic binning for lens sample between 0.1 in 0.2 ≤ z ≤ 1.2 according to Y1 and Y5 requirements respectively.
One of the main aims is to check whether the spatially varying observing conditions introduce fluctuations to the mean and scatter of each tomographic bins that are larger than the Rubin requirement. The photo-z is estimated using a template-fitting algorithm, BPZ_lite. We find that for the sample with reduced photo-z outliers, the shifts in the mean redshift and the scatter in each tomographic bin is consistent with the random noise of the sample, and comparable to the Rubin requirement.
Additionally, we also looked at the impact of spatially varying observational conditions in each band on the cModel magnitude, the magnitude error, colour, and galaxy over-density.
Plots: Variation of magnitude error, photo-z bias, and photo-z scatter with i-band 5σ depth using the coaddM5 MAF map from OpSim for Y1 and Y5 data in the DC2 simulation.
QianjunHang , Benjamin Joachimi , Ofer Lahav
Working with the Rubin Observatory SQuaRE team in Tucson
Dummy header for Dominic, Tom and Tim
Dominic Sloan-Murphy , Tom J Wilson , Tim Naylor
Dummy header for Dan
LINCC Tech Talks
To be written
Mention LINCC session at PCW
https://community.lsst.org/t/lincc-tech-talks-series-starting-october-13-2022/7108
Forthcoming meetings of interest
Meetings of potential interest for the coming months include:
27th February – 3rd March – DESC Collaboration Meeting (virtual). 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 Forthcoming LSST-related Meetings .
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.