Installation

The code is written for Python 3.

The python libraries required are:

• numpy

• astropy

• scipy

• matplotlib

• mgefit

Install GALFIT if you haven’t done so.

Download the latest release, and install it via

cd ellipsect
pip install .

or

cd ellipsect
python setup.py install

Also, you can install it via pip:

pip install EllipSect

Run the automated tests:

tox

Note: EllipSect needs the GALFIT output files (GALFIT.XX) to work. Although GALFIT is not strictly required, it will require it to create the model components and sigma image. Make sure you can call GALFIT from the command line. Otherwise the automated tests will fail.

For Linux or Mac, just run ellipsect in the command line:

ellipsect

and that’s it!!

HOW TO USE

easy run:

Once installed, run ellipsect in the same directory that you run GALFIT. It only requires the latest GALFIT’s output file. The easiest way to run the program is:

ellipsect galfit.01

It will display images like the ones below:

for more options:

ellipsect --help

Full manual:

To see other options for EllipSect:

How to use

Script run:

If you want to use EllipSect inside your own python script, you can call it in the following way:

from ellipsect import ArgParsing
from ellipsect import SectorsGalfit

#put all the argument parsing in a list:
args=['galfit.01','--logx', '--phot','--noplot']


parser_args = ArgParsing(args)

photapi = SectorsGalfit(parser_args)

print("Akaike Criterion: ",photapi.AICrit)
print("Bulge to Total: ",photapi.BulgeToTotal)

To check all the output variables besides AICrit and BulgeToTotal, check:

Output variables

Questions?

Do you have any questions or suggestions? Please send an email to canorve [at] gmail [dot] com or open an issue

I’m open to new ideas that can benefit the software EllipSect and the GALFIT community

License

The code is under the license of GNU

Cite as

If you find this code useful, please cite as:

Añorve, C., Reyes-Amador, U., de Ramon Toledo, D., Ríos-López, E., & López-Cruz, O. (2026). EllipSect: A Surface Brightness Analysis Tool for GALFIT 3. Revista Mexicana de Astronomía y Astrofísica, 62(1). https://doi.org/10.22201/ia.30618649e.2026.62.01.7524

Zenodo repository: https://doi.org/10.5281/zenodo.14597845

References

Akaike, H. (1974). A New Look at the Statistical Model Identification. IEEE Transactions on Automatic Control, 19, 716–723.

Añorve, C. (2012, July). (PhD thesis). INAOE.

Barden, M., Häußler, B., Peng, C. Y., McIntosh, D. H., & Guo, Y. (2012). GALAPAGOS: from pixels to parameters, 422(1), 449–468. doi:10.1111/j.1365-2966.2012.20619.x

Blakeslee, J. P., Holden, B. P., Franx, M., Rosati, P., Bouwens, R. J., Demarco, R., Ford, H. C., et al. (2006). Clusters at Half Hubble Time: Galaxy Structure and Colors in RX J0152.7-1357 and MS 1054-03, 644(1), 30–53. doi:10.1086/503539

Cappellari, M. (2002). Efficient multi-Gaussian expansion of galaxies, 333(2), 400–410. doi:10.1046/j.1365-8711.2002.05412.x

de Vaucouleurs, G. (1948). d’Astrophysique, 11, 247. Recherches sur les Nebuleuses Extragalactiques.Annales

Häußler, B., Bamford, S. P., Vika, M., Rojas, A. L., Barden, M., Kelvin, L. S., Alpaslan, M., et al. (2013). MegaMorph - multiwavelength measurement of galaxy structure: complete Sérsic profile information from modern surveys, 430(1), 330–369. doi:10.1093/mnras/ sts633

Jedrzejewski, R. I. (1987). CCD surface photometry of elliptical galaxies - I. Observations, reduction and results., 226, 747–768. doi:10.1093/mnras/226.4.747

Peng, C. Y., Ho, L. C., Impey, C. D., & Rix, H.-W. (2002). Detailed Structural Decomposition of Galaxy Images, 124(1), 266–293. doi:10.1086/340952

Schwarz, G. (1978). Estimating the Dimension of a Model. Annals of Statistics, 6(2), 461– 464.

Sersic, J. L. (1968). Atlas de Galaxias Australes.

Tal, T., van Dokkum, P. G., Nelan, J., & Bezanson, R. (2009). The Frequency of Tidal Fea- tures Associated with Nearby Luminous Elliptical Galaxies From a Statistically Complete Sample, 138(5), 1417–1427. doi:10.1088/0004-6256/138/5/1417

Vikram, V., Wadadekar, Y., Kembhavi, A. K., & Vijayagovindan, G. V. (2010). PYMORPH: automated galaxy structural parameter estimation using PYTHON, 409(4), 1379–1392. doi:10.1111/j.1365-2966.2010.17426.x

Other Stuff

Check my other project GALFITtools here