BlackGEM Trigger Mode
When an external trigger is issued, BlackGEM can be triggered to cover the error box of the event, to identify an optical counterpart. This mode will primarily be used for gravitational wave triggers issued by the Advanced LIGO/Virgo collaboration. Error boxes need to be large (i.e. > 10 degrees) to make it efficient to use BlackGEM in this manner. Many astrophysical phenomena are now better localized than this, and then using the BlackGEM array is not an efficient use of resources.
After a trigger is issued, the error box will be tiled with BlackGEM fields, according to the ranked tiling algorithm described in Ghosh et al. (2016). After the tiling is made, the array will start observing these fields in the q and r bands. Known transients from the BG-Qscan survey or other projects will be noted and discarded as possible counterparts.
Data will be processed immediately to identify new transients.