Inside-out Doppler tomography was introduced by Kotze, Potter & McBride (2015) - Paper I. It is a complementary extension to the standard Doppler tomographic technique. The inside-out projection technique reverses the velocity axis to create an inside-out Doppler coordinate frame. Inside-out tomograms are constructed independently of the corresponding standard tomograms. This is achieved by directly projecting phase-resolved spectra onto the inside-out framework. The objective of using an inside-out framework was to explore a more intuitive velocity layout for Doppler tomograms. The results obtained with the inside-out projection technique in the Doppler tomography of non-magnetic cataclysmic variables also showed that it can enhance high-velocity emission details which are washed out in the standard projection. Similarly, it can expose low-velocity emission details which are overly compacted.

Kotze, Potter & McBride (2016) - Paper II expanded on the results presented in Paper I by applying the inside-out projection technique to the Doppler tomography of magnetic cataclysmic variables. Again, it better exposed low-velocity emission details which are overly compacted in the standard projection. This is especially apparent in the case of a mid-inclination polar with an almost blob-like blended lower velocity emission in the standard tomogram which is more exposed in the inside-out tomogram, making it easier to distinguish between the ballistic and magnetically confined accretion flows. The ability of the inside-out projection technique to enhance high-velocity emission details which are washed out in the standard projection is particularly effective in revealing the high velocity magnetic accretion flows in the case of polars.

Paper II also introduced flux modulation mapping, a variant form of modulation Doppler tomography (Steeghs 2003). The new flux modulation mapping technique produces Doppler maps that represent the amplitude and average of the modulated emission, as well as the phase of maximum flux. It extracts any phased modulation in the observed flux from a series of consecutive half-phase tomograms thereby making it is possible to map how the flux from a specific emission component modulates over a complete phase.

The doptomog code

Our doptomog code is based on the fast maximum entropy Doppler tomography code presented by Spruit (1998). The doptomog code can construct tomograms independently in the standard and the inside-out velocity coordinate frames.

In the spirit of open access, we are making our code publicly accessible:

NOTE: The code was developed for a Linux operating system.

1. Make a download folder for the code.

Open a terminal and run:

mkdir ~/doptomog-2.0

cd ~/doptomog-2.0

2. Download the compressed code.

In the open terminal, run:


OR just click on


and save in your created folder.

3. Uncompress the downloaded code.

In the open terminal, run:

tar -xf doptomog-2.0.tar.gz

4. Peruse the LICENSE and README files.

5. Follow the instructions in the README file and start tomogramming.

If you have any difficulties, please contact Enrico Kotze.