Summary: Delegate Assembly, Fri Dec. 3

The most recent DP0.1 Delegate Assembly took place on Friday, December 3rd (it was rescheduled from the original planned date of October 22nd). The presentation focused on the steps which are taken to convert the raw Rubin camera data to calibrated images. The presentation titled “From photons to photographs and back again” was delivered by Dr. Andrew Bradshaw, a member of the Rubin Camera team, currently working on assembling and calibrating the camera’s sensors. The presentation highlighted various instrumental effects which have to be taken into consideration towards producing accurate, reliable celestial images and catalogs of astrophysical sources. To the first order, one needs to know the sensor efficiency to light, and its dark current - but there is a number of additional subtle effects that need to be accounted for to produce data calibrated to the final Rubin requirements. All those steps are included in the standard processing, and do not need to be applied by the users of Rubin data: the presentation was aimed to illustrate “how the sausage is made.”

Dr. Bradshaw walked us through the process, which is illustrated on the slides shown by him, available here.

As one example, Dr. Bradshaw showcased one interesting systematic effect of the CCD detectors - the so-called “fatter when brighter” correlation, where the image of a point source is more extended (in relative terms) for brighter sources, and this is illustrated in a rendered notebook located here.

One of the breakout sessions (with the largest number of attendees) highlighted a discussion how to inject (or learn to inject) sources into DC2 images.

The recording of this Assembly can be found at this link [ DP0 Delegate Assembly: Image Processing - YouTube]

We will pause for a while with the Delegate Assemblies - none will take place in the remainder of 2021. We also will cancel the Assembly on January 14, since this is during the Winter AAS meeting. We will restart on January 28, where we plan to have a special session, entitled “DP0.1 - a half-year in review.” We also hope to continue with presentation of the delegate profiles.