I was following the install instructions at https://erosita.mpe.mpg.de/dr1/eSASS4DR ... tallation/ for the eRO-SDAS workshop.
Here are my notes on Ubuntu 24.04.1:
1) fftw3 is not a ubuntu package. "sudo apt-get install libfftw3-dev" is enough and works
2) for cfitsio, one needs to install "libcfitsio-dev" to get libcfitsio.a, standard cfitsio only gives the shared library (.so). Then the library is at /usr/lib/x86_64-linux-gnu/libcfitsio.a
3) I had heasoft already, but got the error that xanlib is missing. So not only heasoft needs to be installed, but it also needs to be built to include xanadu. By default (without configuring), this is the case, so should not be a problem, except for users who have a stripped-down version for sing xspec primarily.
Maybe these can be added to the documentation.