M. Arnaut, C. Wöhler, P. Halder, G. Ahuja, S. Ganesh, M. Bhatt. Wide-field Polarization Imaging and Numerical Modeling of the Coma and Tail of Comet C/2023 A3 (Tsuchinshan-ATLAS). Supplementary online material of the manuscript accepted by the journal "Astronomy and Astrophysics" on January 05, 2026.

M. Arnaut, C. Wöhler, P. Halder, G. Ahuja, S. Ganesh, and M. Bhatt.Wide-field Polarization Imaging and Numerical Modeling of the Coma and Tail of Comet C/2023 A3 (Tsuchinshan-ATLAS).Astronomy and Astrophysics 707, A150, 2026.https://doi.org/10.1051/0004-6361/202555905 Online Material C2023A3_Observations.zip======================== This archive contains our observational data in FITS format. The acquisition date and binning mode are encoded into the filename. Each FITS file contains an image cube with four channels, which correspond to 1. Intensity in DN. Between 0 and 65535.2. Degree of linear polarization (DoLP). Larger than 0, value may artificially exceed 1 for pixels with low intensity and low SNR (such pixels should be discarded by masking them out).3. Angle of linear polarisation in degrees relative to the direction of the image rows. Between -90° and +90°.4. RMSE of the sinusoidal fit to the pixel-wise intensity vs. polarizer angle data, in DN. Channel 1 divided by channel 4 approximately corresponds to 1.25 x SNR_F with SNR_F as the signal-to-noise ratio of the intensity. Further details about the data analysis can be found in Section 2 of the paper. C2023A3_Modeling.zip==================== This archive contains our MSTM5-based modeling results for a variety of parameter settings in Matlab (MAT) format. The composition, number of monomers, fractal dimension, fractal prefactor, mean (in nm) and logarithmic standard deviation of the monomer radius, and the scale factor applied to the model agglomerate are encoded into the filename, respectively. Furthermore, the archive contains several Matlab functions and scripts that allow for reading the result files and reproducing the modeling-related figures of the paper: readMSTM5Result.m: Read simulation result for a given combination of composition, number of monomers, fractal dimension and scale factor.computeWeightedSum.m: Average simulation results for a given composition and scale factor over a set of numbers of monomers and fractal dimensions, assuming an agglomerate size distribution following a power law with given exponent.showRg.m: Script that plots the gyration radius of the fractal agglomerate in dependence on the fractal dimension Df and number of monomers N for a given scale factor.showDoLP_PhaseCurves.m: Generates and displays the modeling-related figures of the paper. These Matlab functions and scripts can also be run in the free software Octave.