The Fermi GBM Team was recently notified by the LIGO/Virgo/KAGRA (LVK) science consortium that there will be a slight delay before beginning the pending “O4” observation run…until 5/24/23. This observing run will also be extended from 12 months to 18 months, increasing the probability of a joint gamma-ray/gravitational wave detection. LVK cooperatively operates highly sensitive instruments that are designed to detect/locate/document gravitational waves. The LVK “engineering run”, which serves as their test and verification period prior to primary “O4” observation run, will begin around 4/24/23. The announced LVK delay is potentially beneficial to the Fermi Mission, as the change provides a few extra weeks of buffer between the planned Fermi orbit raise maneuver and the pending LVK operational run. The last burn of the Fermi orbit raise maneuver is currently set for March 3/23/23.
The GBM Sodium Iodide detectors are critical to multi-messenger science because they can confirm the presence of electromagnetic gamma-ray counterparts coincident with gravitational waves. Gamma-ray bursts are the first electromagnetic counterparts seen from neutron star mergers, so GBM is crucial in alerting the entire astrophysical community to the need to follow-up these exciting events like GW170817/GRB 170817A. Therefore, it is the desire of all involved that Fermi is settled into its new orbit before LVK begins new science operations.
