Hi, I was taking a closer look at DP0.3 diaSources in visits with large numbers of SSO detections (i.e. near the ecliptic) and the spatial distrubution looks unusual to me. Is the star-like distribution in this figure to be expected? I would have expected the detections to fill the whole footrpint. Is this related to the known issue “The camera footprint was slightly inaccurate”?
Interestingly, in the above figure I have plotted the footprint outline and the detections are contained within the overlap of a footprint with rotSkyPos = theta and rotSkyPos = -theta.
Hi James,
Thanks for the plot. Yes, I would have said that this must be a manifestation of the known issue that you’ve linked to within the DP0.3 documentation. I believe that the relevant DP0.3 data set creators who might have more insight are at institutions currently on holiday until Monday 11/27, but I can ping them once they’re back for any further input they’d like to provide here.
Great thanks Aaron. I only came across this by accident and was mostly just wanting to check that this was a known effect. So not urgent at all while people are on holiday (I forgot it was Thanksgiving for USA folk)!
@Gerenjie – might you have any further insight/commentary on this? For instance, is the “overlap of a footprint with rotSkyPos = theta and rotSkyPos = -theta” behavior mentioned by James universal across visits simulated for DP0.3? I was hoping to tag Pedro as well, but I can’t find a corresponding forum account. Thanks!
Woah, thanks @jrob93 !! The strange camera footprint was known and we have a new version of the simulator which generates a correct footprint, but we hadn’t managed understood what the strange shape was or pinned down the issue in our old software. This explaination makes a lot of sense to me, and that’s a very striking plot – I’m fully convinced that it’s a theta-and-negative-theta overlap bug.
@jrob93 This is the most impressive piece of sleuthing I’ve seen in a while! We knew we had an incorrect footprint issue, but the old code was convoluted enough that we never figured out exactly how it was getting messed up.
Again, fabulous job!
Neat, glad to be of service 
I only noticed this because I realised there was a theta/-theta issue when plotting the footprint in healpy gnomview (with RA increasing to the left) vs a regular cartesian plot (with RA increasing to the right). So maybe this arises for the old DP0.3 code as a similar clockwise/anti-clockwise rotation depending on the reference frame.
