Users June 2026

users@lists.einsteintoolkit.org

13 participants
22 discussions

Agenda for Thursday's Meeting
by users＠einsteintoolkit.org 29 Jun '26

29 Jun '26

Please update the Wiki with agenda items for Thursday's meeting. Thanks! https://docs.einsteintoolkit.org/et-docs/meeting_agenda --The Maintainers

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Collaboration / Peer-learning on Einstein Toolkit & GRMHD Simulations
by Abderrahim El Khou 28 Jun '26

28 Jun '26

Hi everyone, I hope this email finds you well. I am a PhD student working on computational astrophysics, specifically focusing on General Relativistic Magnetohydrodynamics (GRMHD) simulations using the Einstein Toolkit. As I am currently advancing through my research and setting up my simulation pipelines, I am looking to connect with a fellow PhD student or researcher working in the same field. My goal is to find a peer with whom I can collaborate closely—sharing insights, troubleshooting code, analyzing HDF5 outputs, and optimizing simulation setups. Ideally, we can combine our efforts to speed up the learning curve, solve technical challenges together, and work toward co-authoring and publishing joint papers. If you are working on GRMHD within the Einstein Toolkit ecosystem and are interested in learning together and collaborating on research outcomes, please feel free to reach out to me directly at " abderrahimelkhou00(a)gmail.com". Looking forward to connecting with the community! Best regards, *Abderrahim El Khou* PhD Student in Physics High Energy Physics Laboratory, Rabat, Morocco

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Meeting minutes for 06/25/26
by Lucas Timotheo Sanches 25 Jun '26

25 Jun '26

Attendees: Lucas (minutes), Yosef, Roland, Noora, Peter, Steve (chair),Beyhan, Nikolai, Johnny Tsao. # Review of the ET 2026 Summer School. - It was held last week at UIUC. - Helvi thanks all local organizers and members of the scientific and organized comite. - 40 people in person, 30-40 people online. - Mix of invited talks and lectures, about 30 minutes each. - Tutorials on CarpetX and the ETK. - Tutorial on Spectre. - Tutorial server was at capacity, which is good, this means good engagement. - We had sessions on different NR codes, - We had talks on career paths outside of academia. - The UIUC organizers will send out emails to presenters asking for permissions for publishing the talk videos. - Next summer school: Organized by Zach Etienne, University of Idaho, summer 2027 - Helvi suggests we have more discussion on using LLMs for NR. - Helvi suggests we distribute short talks by early career scientists better throughout the day. - Lucas comments he likes having tutorials on different codes and how to use them. - Helvi and Roland emphasize for the seniors to reach out to the younglings and talk to them. They suggest we spread out the seniors and the younglings to go out to lunch, for instance, so there can be networking and conversations. - Noora said there was good feedback on having different code presentations. - Beyhan says that presenters should probably have the data ready when presenting. Roland says we could give users complete notebooks, with the notebook output (not final data output) so that users can read them off as presentations are going. - Helvi suggests that we recommend presenters to have backup data, with complete results. Steve agrees. - Roland suggests we give the presenter some special slurm powers, so that they can actually run their demos and not get blocked by the students on the queue. - Beyhan suggests including some of the features that we don't have on the ETK from other codes. # ET_2026_05 release - There is now a release announcement. - Steve remarked that the list may be incomplete because he forgot to treat the NRpy repo differently, possibly excluding contributors from there. - Roland pointed out that it is not clear what some of the names have contributed. Steve says he will review his Claude procedure for including names. - Beyhan points out DIRAC/Cosma 8 is missing among supported machines. ## Gallery runs - Deborah is seeing some issues when running the GW150914 gallery example. The black holes shot to the side, instead of orbiting. Steve believes he knows the cause, which is related to the way that TwoPunctures handles and updates its parameters. His unification of TwoPunctures and TwoPuncturesX have introduced this issue. Yosef suggests adding a regression testing to the suite to make sure it is caught. Steve agrees. - Noora says her example is running. ## Test suite results -`advanced_features` failing on Anvil and Sunrise - Peter says he will rerun on sunrise. - Zach says he has identified an issue in Nrpy elliptic and Leo is already on it. - Noora says that she will provide the testsuite results for Frontera shortly. She reports two failing tests, `SBH_AxiDilHairID_test (from AxiDil_Evol)` and `sphere_pugh_ppm (from Hydro_InitExcision)` ## Inclusion votes - CanudaX voted YES for inclusion. - Cottonmouth voted YES for inclusion. ## Unanswered questions on the mailing list - None that need responses

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evolving flat boundary conditions
by Ryn Grutkoski 25 Jun '26

25 Jun '26

Hello, I am trying to do a cosmology simulation project using Cactus. For this project, I'm evolving an expanding homogeneous fluid in a box (FLRW spacetime), and I would like to use flat boundary conditions. I've attached the par file I am currently using. However, when I run this, the boundary cells do not seem to update at each time step to match the current value of the grid cells on the edge, as seen in this plot of the second time step output: [image: image.png] Is there a way to make the the boundary cells be updated at each time step according to the evolution of the edge of the grid? Thank you, Ryn -- Ryn Grutkoski *they/them/theirs*

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Question about error of CCTKi_SetParameter
by MAKINO Taiki 25 Jun '26

25 Jun '26

Dear Einstein Toolkit Team I am a new Einstein Toolkit user and have a simulation error. I encountered an error related to activating Multipole. Its error message is following: WARNING level 0 from host hubble process 22 in thorn Cactus, file /data/usr/Cactus/configs/sim/build/Cactus/main/SetParams.c:93: -> CCTKi_SetParameter: Error at line 41 in parameter file /data/usr/sim_Result/test_BNS_GW6/output-0000/test_BNS_GW.par while activating thorns I compared the parameters of Multipole in my par file with those of the example file: https://einsteintoolkit.org/gallery/bhns/bhns_gw230529.par However, I could not find any significant difference. In addition, I also previously encountered same errors related to activating Trigger and TerminationTrigger and dealt with these by commenting out. But I’m not sure why these errors occurred. I have attached my .par file to this email. I would appreciate any advice. Thank you for your time and assistance. Best regards, Taiki Makino Graduate School of Science, Nagoya University makino.taiki.g6(a)s.mail.nagoya-u.ac.jp<mailto:makino.taiki.g6@s.mail.nagoya-u.ac.jp> 取得 Outlook for Mac<https://aka.ms/GetOutlookForMac>

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Einstein Toolkit Meeting Reminder
by users＠einsteintoolkit.org 24 Jun '26

24 Jun '26

Hello, Please consider joining the weekly Einstein Toolkit phone call at 9:00 am US central time on Thursdays. For details on how to connect and what agenda items are to be discussed, use the link below. https://docs.einsteintoolkit.org/et-docs/Main_Page#Weekly_Users_Call --The Maintainers

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Agenda for Thursday's Meeting
by users＠einsteintoolkit.org 22 Jun '26

22 Jun '26

Please update the Wiki with agenda items for Thursday's meeting. Thanks! https://docs.einsteintoolkit.org/et-docs/meeting_agenda --The Maintainers

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Slides of 2026 North American Einstein Toolkit Workshop and School
by Helvi Witek 22 Jun '26

22 Jun '26

Dear all, thank you to all of you who attended the 2026 North American Einstein Toolkit Workshop and School last week, and helped making the meeting a success. The slides of the talks are now available on our workshop website: https://etksummerschool2026.illinois.edu/program-2/ The 2027 North American Einstein Toolkit Workshop and School will be hosted by Zach Etienne at the University of Idaho; with dates TBA. Best wishes Helvi (on behalf of the organizers Noora Ghadiri, Jay Kalinani, Maxwell Rizzo, Helvi Witek) --------------------------------------------- Dr. Helvi Witek Associate Professor Department of Physics University of Illinois at Urbana-Champaign 247 Loomis Lab 1110 W Green St Urbana, IL 61801 ---------------------------------------------

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No Einstein Toolkit Meeting Reminder
by Roland Haas 17 Jun '26

17 Jun '26

Hello all, Due to the 2026 US ET summer school and workshop there will not be an Einstein Toolkit phone call on Thursday. Yours, Roland -- My email is as private as my paper mail. I therefore support encrypting and signing email messages. Get my PGP key from http://pgp.mit.edu .

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Re: [Users] ET Simulation Error
by Beyhan Karakaş 16 Jun '26

16 Jun '26

Date: Tue, 16 Jun 2026 00:00:00 +0000 > From: MAKINO Taiki <makino.taiki.g6(a)s.mail.nagoya-u.ac.jp> > To: "users(a)einsteintoolkit.org" <users(a)einsteintoolkit.org> > Subject: [Users] ET Simulation Error > > > Dear Einstein Toolkit Team > > I am a new Einstein Toolkit user and have a simulation error. > > I can run DNSdata_test.par with GRHydro, but I cannot run it when I switch > GRHydro to IllinoisGRMHD. In detail, I changed the activethorns from > GRHydro to IllinoisGRMHD, and added some activethorns such as GRHayLib, > GRHayL and GRHayLHD. > > In addition, I commented out parameters of GRHydro like > ?GRHydro::sources_spatial_order?. And, I wrote HydroBase::evolution_method > = "IllinoisGRMHD?. The error message is as follows: > > ?WARNING level 0 from host hubble process 22 > in thorn Cactus, file > /data/usr/Cactus/configs/sim/build/Cactus/main/SetParams.c:93: > -> CCTKi_SetParameter: Error at line 36 in parameter file > /data/usr/sim_Result/test_BNS_GW_Piecewise4_Cactus_Illinois8/output-0000/DNSdata_test.par > while activating thorns? > > Also, one of participants of the Einstein Toolkit workshop advised that I > had to activate DNSdata which I had commented out and to comment out > parameters of thorns which I did not activate. After making these changes, > a different error appeared. It is the following: > > WARNING level 0 from host hubble process 0 > in thorn Cactus, file > /data/usr/Cactus/configs/sim/build/Cactus/main/SetParams.c:93: > -> CCTKi_SetParameter: Error at line 37 in parameter file > /data/makino/test_BNS_GW_Piecewise4_Cactus_Illinois9/output-0000/DNSdata_test_copy.par > while activating thorns. > > The list of activated thorns is provided below for reference: > > ActiveThorns = "Boundary CartGrid3D CoordBase Fortran InitBase IOUtil > LocalReduce SymBase Time" > ActiveThorns = "AEILocalInterp" > ActiveThorns = "MoL Slab SpaceMask SphericalSurface" > ActiveThorns = "Carpet CarpetInterp CarpetInterp2 CarpetIOASCII > CarpetIOHDF5 CarpetIOScalar CarpetLib CarpetIOBasic CarpetReduce > CarpetRegrid2 CarpetSlab CarpetTracker CarpetMask LoopControl" > ActiveThorns = "Formaline" > ActiveThorns = "HTTPD Socket" > ActiveThorns = "NaNChecker TerminationTrigger TimerReport" > ActiveThorns = "ADMbase ADMcoupling ADMmacros CoordGauge StaticConformal" > ActiveThorns = "RotatingSymmetry180 ReflectionSymmetry" > ActiveThorns = "Constants TmunuBase HydroBase " > ActiveThorns = "QuasiLocalMeasures" > ActiveThorns = "EOS_Omni" > ActiveThorns = "GRHayLib" > ActiveThorns = "GRHayL" > ActiveThorns = "IllinoisGRMHD" > ActiveThorns = "SummationByParts" > ActiveThorns = "GenericFD NewRad" > ActiveThorns = "ML_BSSN ML_BSSN_Helper ML_ADMConstraints" > ActiveThorns = "Hydro_Analysis" > ActiveThorns = "Dissipation" > ActiveThorns = "DNSdata" > ActiveThorns = "GRHayLHD? > > > The line reported in the second error (line 37) corresponds to: > > ActiveThorns = "GRHayLHD" > > Am I missing any required thorns, parameter settings, or something else > for using IllinoisGRMHD with DNSdata_test.par? > > Thank you very much for your time and assistance. > > I have attached the parameter file for reference. If any additional > information would be helpful, I would be happy to provide it. > > Best regards, > > Taiki Makino > Graduate School of Science, Nagoya University > makino.taiki.g6(a)s.mail.nagoya-u.ac.jp > > Dear Taiki, You should remove the GRHayL from the active thorns as the thorn name is GRHayLib for that. And you don't need HydroBase::evolution_method = "IllinoisGRMHD" for IGM. You activate both IGM and GrHaylHD you should choose one. Please have a look at the example parfiles: Cactus/arrangements/GRHayLET/IllinoisGRMHD and also in Cactus/arrangements/GRHayLET/GRHayLHD. Best regards, Beyhan.

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