TITLE: GCN CIRCULAR NUMBER: 30949 SUBJECT: BepiColombo MGNS joins the IPN DATE: 21/10/20 12:08:08 GMT FROM: Kevin Hurley at UCBerkeley/SSL <kevin.hurley@comcast.net> K. Hurley on behalf of the IPN team, A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the MGNS/BepiColombo team, and J. Benkhoff on behalf of the BepiColombo team, report: The ESA/JAXA BepiColombo mission was launched on October 20, 2018 on a 7.2-year journey to Mercury. After arrival in late 2025, the mission will spend a nominal one year in Mercury orbit. The mission consists of two spacecraft: the JAXA-provided Mio spacecraft for the thorough exploration of the environment, and the ESA-led Mercury Planetary Orbiter, MPO, for a comprehensive exploration of the planet itself, the interior, and its magnetic field. The MPO contains the Mercury Gamma-Ray and Neutron Spectrometer (MGNS) experiment [1, 2] consisting of a 3” diameter x 3” long CeBr3 scintillator, which also has a gamma-ray burst detection capability. During the cruise phase so far, MGNS operated for about 23 months, and has detected 38 confirmed gamma-ray bursts, 21 of which have been localized to annuli using data from HEND/Mars Odyssey, which is also part of the IPN since 2002. The verification of the localization accuracy of this method was based on gamma-ray bursts for which optical afterglows were detected. Reference [3] presents 5 gamma-ray bursts as examples of these localizations. MGNS is now the 34th experiment to be integrated into the interplanetary network (IPN) since 1977, which currently consists of Konus-Wind, Mars Odyssey, BepiColombo, Swift, INTEGRAL and AGILE. In this configuration, the IPN now has two interplanetary spacecraft, which will lead to more precise GRB localizations. References: 1. Mitrofanov, I.G., Kozyrev, A.S., Lisov, D.I., Litvak, M. L., et al. (2021). Space Science Reviews. Volume 217, Issue 5, article id.67A. 2. https://np.cosmos.ru/index.php/en-us/instruments/mgns 3. The links below show maps with localization annuli from MGNS-HEND data for 5 gamma-ray bursts: GRB 190530A, GRB 200219C, GRB 200415A, GRB 200716C and GRB 210112A. http://l503.iki.rssi.ru/owncloud/index.php/s/bXsgMFb9afifHzz http://l503.iki.rssi.ru/owncloud/index.php/s/mPC5lrPy2pYLmbz http://l503.iki.rssi.ru/owncloud/index.php/s/FcbgOtcA5pEx3nD http://l503.iki.rssi.ru/owncloud/index.php/s/58JCvMJ6x5uzbbU http://l503.iki.rssi.ru/owncloud/index.php/s/g4miSw176EHU7bL