University of Oulu

An automated pipeline for photometric calibration and measurements

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Author: Mattila, Aleksi1
Organizations: 1University of Oulu, Faculty of Science, Physics
Format: ebook
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.9 MB)
Erratum: Erratum (PDF)
Pages: 54
Persistent link:
Language: English
Published: Oulu : A. Mattila, 2022
Publish Date: 2022-10-21
Thesis type: Master's thesis
Tutor: Neustroev, Vitaly
Reviewer: Salo, Heikki
Neustroev, Vitaly


Measuring magnitudes from astronomical images can be slow and difficult when done by hand, especially if there’s a large amount of targets or images that need to be analysed. To aid in this effort, Autophotometer, an automatic pipeline for photometric measurements and calibrations was developed. Autophotometer was made with Python, and it uses Source Extractor and SCAMP from Astromatic. The photometric calibrations are performed using data from Pan-STARRS1 and 2MASS surveys.

This master’s thesis describes the technical details of the pipeline and how it was used to study cataclysmic variables. Over 350 images of cataclysmic variables in multiple filters taken with the Nordic Optical Telescope were processed with the program to evaluate its performance and accuracy.

Most of the resulting magnitudes had errors comparable to those in Pan-STARRS1 and 2MASS catalogues. The accuracies were sufficient to analyse the spectral energy distributions of the targets and identify different types of cataclysmic variables. Some issues were encountered, mostly caused by bad image quality or very dim targets. In few cases the astrometric calibration of the coordinates of the objects failed. In general the program is reliable and easy to use.

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Copyright information: © Aleksi Mattila, 2022. Except otherwise noted, the reuse of this document is authorised under a Creative Commons Attribution 4.0 International (CC-BY 4.0) licence ( This means that reuse is allowed provided appropriate credit is given and any changes are indicated. For any use or reproduction of elements that are not owned by the author(s), permission may need to be directly from the respective right holders.