Installing the base packages for development is required: autoconf, automake, libtool, pkg-tools, make, gcc.
Siril is developed with Arch Linux, which has all latest packages versions, and Linux Mint 15, and slightly old distribution. This allows us to verify a large range of package versions. Debian 6 doesn't have GTK+ version 3, so you need at least version 7, codename Wheezy. For a desktop system, the next stable is probably a better choice, called Debian testing, currently version 8 with codename Jessie.
Installing on Debian 7
You will need those packages to have a proper build system:
autoconf automake make gcc libtool pkg-config
Then you can generate the configure script:
$ aclocal && autoconf && autoheader && automake --add-missing
And install mandatory dependencies:
libfftw3-dev libgsl0-dev libcfitsio3-dev libgtk-3-dev
Finally you can install optional dependencies you want:
dcraw (can be installed later), libpng-dev libjpeg8-dev libtiff5-dev, and for film (AVI and others) support: libavutil-dev libavformat-dev libswscale-dev libavcodec-dev.
And run the configure and make.