Katja Pottschmidt

The HEASARC and NuSTAR teams are greatly saddened by the sudden passing of Katja Pottschmidt. Most recently Katja was the lead scientist for the NuSTAR Guest Observer Facility (GOF), a role she had supported for many years. During her science career she worked on many other high energy astrophysics missions and played an integral role in advancing our knowledge of the universe. She was a wonderful colleague and friend and will be keenly missed by all who knew her.

The following tribute is adapted from a message from CRESST management and is a wonderful testatment to the impact Katja had.

Born May 31, 1971, in Aurich, Germany, into a military family (her father was in the German air force), Katja grew up in Aurich and Freising, Germany, in Norfolk, VA, and in Mons, Belgium. The family then settled in Balingen, Germany, where Katja finished high school. Following her lifelong interest in astrophysics - and an affinity for Star Trek - Katja studied physics at Tuebingen University, Germany, where she received her undergraduate and PhD degrees in physics. Her undergraduate focus was on linear state-space modeling of variability of black holes with Exosat. Her 2003 PhD, under dissertation advisor Ruediger Staubert, focused on the X-ray variability of Cyg X-1 using data from the Rossi X-ray Timing Explorer (RXTE). During her PhD, Katja discovered the strong changes in the X-ray lag spectra during state transitions in black holes, which she attributed to changes in the accretion flow geometry, a paradigm that has since become well-accepted in the field. Her passion for the study of black holes and neutron stars led her to positions in Geneva, Switzerland, where she became the archive scientist for INTEGRAL (employed by MPE) from March 2002 to December 2004. This was followed by a postdoc at the University of California, San Diego, in Rick Rothschild's RXTE-HEXTE group, where she especially worked on its background model. During this time, spectroscopy and variability studies of strongly magnetized accreting neutron stars caught her interest. In October 2007, Katja joined CRESST and UMBC to begin her position at NASA Goddard. She continued pursuing her research on neutron stars and black holes, and over the years was a member of the Guest Observer Facilities for INTEGRAL, Suzaku, Hitomi, NICER, XRISM, and NuSTAR (in the last years as the science lead). She was also informally involved with setting up the IXPE GOF.

Katja enjoyed working with students, including interns at GSFC; a PhD student at UMBC; and many students in Joern Wilms' group in Bamberg, Germany, where she often served as a second mentor. She also enjoyed working as a mentor to MICA animation studies students. During and after the pandemic, she was very active in welcoming and integrating new postdocs at Goddard, despite the challenges of COVID and having had open-heart surgery just before the pandemic. In recent years, she also started an informal group at GSFC on X-ray timing analysis and served as the driving force behind the international "XMAG collaboration," coordinating multi-mission observations of accreting neutron stars and shepherding the group into writing an extensive review of neutron star pulse profile studies. Unfortunately, she will not be able to see the final version of this document.

In Greenbelt, Katja first lived in the Lerner apartments before joining GHI. She loved Greenbelt, embracing its coop culture and the free spirit of the town. She was a regular at the New Deal Cafe, almost exclusively shopped at the COOP, frequently went to the movie theater, and every Sunday bought a crepe for breakfast and apples at the farmers' market. Her love of reading (especially fantasy and science fiction) led her to be one of the founding members of Greenbelt's book club. She fed the birds and squirrels in her garden, which was a great source of joy for her, and knew the Greenbelt woods and Greenbelt's history by heart. Young postdocs moving to the area could always rely on her showing them the hidden gems of the city that was her home.

Katja is survived by her loving partner of more than 20 years, Joern Wilms, of Bamberg, Germany, who came to Goddard every 4-6 weeks during the whole time she worked at GSFC; her parents Juergen and Inge, of Balingen, Germany; her sister Antje with partner Wolfgang and niece and nephew Mika and Ronja; her family of scientists at Goddard and everywhere in the world; and all of her friends.

We will carry her memory forward and she will continue to inspire us.