------------------------------------------------------------------------ Introductory remarks by S. Kulkarni on the occasion of the viewing of "Gehrels Maniac Lecture, September 29, 2015" (an event organized by Kasliwal). ------------------------------------------------------------------------ https://www.youtube.com/watch?v=lG08SL8fDDk ------------------------------------------------------------------------ 7 Feb 2017, Hameetman Auditorium, Caltech campus ------------------------------------------------------------------------ Neil Gehrels passed away yesterday. Until his untimely death Neil was the Chief of Astro-particle Physics Laboratory at GSFC and College Park Professor at the University of Maryland until his untimely death yesterday. He grew up in an astronomical family. His father was Tom Gehrels who worked with Gerard Kuiper and transformed University of Arizona into a powerhouse of astronomy and planetary astronomy. [I recommend the interested student to read the book "Under Desert Skies" to get a glimpse of Neil's upbringing]. Neil attended the University of Arizona and graduated with a degree in music and physics in 1976. He then came to Caltech and worked with Rochus ("Robbie") Vogt . When Robbie became the Provost Neil switched to Stone at the Space Radiation Laboratory. The title of his PhD thesis was "Energetic oxygen and sulfur ions in the Jovian magnetosphere". His key thesis paper was the discovery of oxygen and sulfur Jupiter's magnetosphere, which given that Jupiter is a gas giant and so the expected dominant elements is Hydrogen and Heliuma, was a surprise. Gehrels & Stone attributed this anomaly to the volcanos on Io. Following graduation he went to GSFC and stayed there until his death. At GSFC his interests switched to gamma-ray astronomy and hard X-ray astronomy. His early achievement was the detection of a strong gamma-ray line (847 keV arising from decay of Cobalt 56) from SN 1987A. Neil had an amazing career in space astrophysics in two distinct capacities. First, he was an incredibly productive astronomer: 53,535 citations, 749 refereed papers and an h-index of 116 (on the day of his death). Next, most astronomers aspiring to be leaders in space astronomy would be happy if they got to lead or play a prominent role in one mission in their life. One may think that his claim to fame is being the Principal Investigator of the Swift Gamma-Ray Burst Mission. However, he was much more than that. He was the Project Scientist for the Compton Gamma Ray Observatory (one of the four Great Observatories), the US Mission Scientist of the ESA-Russian Integral, Deputy Project Scientist for the Fermi Gamma-ray Space Telescope and Project Scientist for the WFIRST mission. The latter came about because of his early involvement in proposing the SANP Dark Energy mission (led by Perlmutter & Levi). Neil's work was recognized by the Rossi Prize of the AAS and the Draper medal of the National Academy of Scinces (amongst other awards). Neil was a core member of the LIGO Science Team. Clearly, Neil was an exceptional leader. He lead but in a harmonious fashion. He was everyone's friend and yet at the same time saw missions go from concept to very productive facilities. I saw this in action when Swift Gamma-ray Burst mission was proposed. I was on the opposing team. Swift won. Immediately, Neil called me up and asked me to join the Swift Science Team. I event went to Cape Canaveral to see the launch (but came back empty handed; the flight was canceled four times owing to hurricanes). The move to invite me to the science team was certainly strategic: after all I was a very active player in GRB astronomy especially in radio and almost unique access to optical followup (in that era). However, his gesture also led to a lifelong friendship. Neil managed to inspire loyalty and I cannot recall ever saying no to any request that Neil made. This combination of being a genuine friend whilst making strategic moves is rare. In fact I know no other such person in my life. I would like to end by summarizing three notable papers. A. Gehrels et al. (2004) The Swift Gamma-ray burst mission (1930 citations). The large number of citations is no surprise. Swift had remarkable success across many branches of astronomy: SNe, GRBs, TDEs, flare stars, AGN, magnetars, etc. B. Atwood et al. (2009). Fermi GLAST (1702). Fermi had a big impact in the field of quasars, Galactic gamma-ray sources, gamma-ray bursts and unexpectedly in the field of millisecond pulsars. C. Gehrels (1986). Confidence limits for Poisson statistics (1325). Neil was most proud of this paper. We all will miss Neill. However, I take comfort that Neil led a vigorous life of research and discovery. Neil built missions that made it possible for many astronomers such as myself to make stunning discoveries about our Universe and at the same time was a most effective leader who accomplished big missions with a gentle style. [Note added after the event: About ten days prior to this event the President of the Tel Aviv University called me and informed me that the Dan David Foundation was recognizing Gehrels, Udalski and me for our contributions to the development of Time Domain Astronomy (TDA). The Foundation has three themes: past, present and future. TDA is seen (and correctly so) as the future area of inquiry in Astronomy. The recognition not only comes with cash (always welcome) but also festivities (colloquia, talks) in Israeli Universities during the third week of May. I was looking forward to meeting Neil in May when on Monday I learnt of Neil's untimely death.]