gtk-redshift software package provides transitional dummy package, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gtk-redshift
gtk-redshift is installed in your system.
Make ensure the gtk-redshift package were installed using the commands given below,
$ sudo dpkg-query -l | grep gtk-redshift *
You will get with gtk-redshift package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | X Window System software |
| Package | gtk-redshift |
| Version | 1.11-1 |
| Description | transitional dummy package |
| Sub Section | x11 |