From discussion with Orel, @mlinhoff , @mieke.bouwhuis , @volodymyr.savchenko , Simulations can be indexed by 2 spatial and 1 NSB keyword (At least so far), but the spatial keywords should be specified in two coordinate systems: (zenith, azimuth), and (hourangle, declination). So the keywords should be: * **zenith**: float in deg * **azimuth**: float in deg * **hour_angle**: float in hourangle? or deg? * **declination**: float in deg * **nsb_factor**: float, multiplier from dark (e.g. 2.0 means 2x dark rate) Note that this works for three simulation methologies: 1. classic grid in zenith/az 2. grid along fixed dec lines 3. tailored sims, which are a special case of 2. Note the simnulated RA is not needed, and indeed HA is better, as it lets us choose "closest" in the case we want to avoid redoing tailor sims with similar conditions. Things to consider: a. Where is the PROD number stored? `activity.configuration` works for R0 sims, but for products derived from it, we need a simulation_context metadata perhaps with the prod number. b. for tailored sims, where do we link the OB and SOI? * For OB, there is already `instance.obs_id` * for the SOI, we need a keyword.