Observational methods in astrophysics

Physics, Second Cycle
1. in 2. year
Course director:
Lecturer (contact person):
Hours per week – 1. semester:

Enrollment into the program. It is recommended that the student is familiar with the material which is part of the courses Astronomy I and Observational astrophysics within the Bologna I studies of Physics.
Completed written assignements are a prerequisite for the oral exam.

Content (Syllabus outline)

Detection: visual and infra-red light: modern digital detectors, modern telescope designs, sources of noise and their mitigation, detection of photons out of the visual range, detection of cosmic rays and neutrinos.
Methods of direct imaging: image formation, photometry, interferometry, radar imaging, presentation of electronic images and their formats.
Spectroscopy: types of spectrographs and their properties from the user point of view, spectroscopy outside the visual range, optimal signal extraction, calibrations and standard ways to present various types of observations, sources of noise and common systematic errors.
Other methods: astrometry, polarimetry, Solar observations, magnetometry, virtual telescopes, databases.
Interpretation of astrophysical spectra: minimum distance methods and their limitations, alternative methods, program packages to calculate stellar and nebular spectra, examples of interpretations of spectra of normal stars, binary stars, nebulae, stellar winds, galaxies, and active galactic nuclei.


• D. F. Gray: The Observation and Analysis of stellar atmospheres, Cambridge Univ. Press, 3rd edition, 2008
• H. Bradt: Astronomy Methods, Cambridge Univ. Press, 2004,
• P. Lena, et al.: Observational Astrophysics, Springer-Verlag, 3rd edition, 2012,
• C. R. Kitchin: Astrophysical Techniques, Taylor and Francis, 2003.

Objectives and competences


Student gets familiar with the latest observational methods in astrophysics and with their data processing. Experience is gained by studying a range of individual examples.


Understanding of the possibilities and limitations of determination of individual astrophysical parameters of an observed astronomical object

Intended learning outcomes

Knowledge and understanding:
Understanding of individual observational methods and their recent development. Critical understanding of reliability of results, problem of uniqueness of solutions. Knowledge of standard procedures to reduce (mostly) spectroscopic data.

Acquired knowledge allows for a critical evaluation of results in the literature and permits to start with research activities, mostly in the field of spectroscopy which is the source of most physical data about objects in the Universe.

Only measurements can decide between possible and real situations. Solid knowledge of observational methods and their limitations is the basis for a critical evaluation of the results.

Transferable skills:
Experience on solution degeneracy, which is frequently a problem in interpretation of spectroscopic results, is useful to treat the inverse problem in highly non-linear systems of other types. Familiarity with techniques of digital image and spectra processing and knowledge of their physics background has many diverse uses.

Learning and teaching methods

Lectures, exercises, seminars, homework, consultations


Final written exam and/or seminars during the course
Oral exam
grading: 5 (fail), 6-10 (pass) (according to the Statute of UL)

Lecturer's references

dr. Janez Kos:
1. KOS, Janez, ZWITTER, Tomaž, et al. Pseudo-three-dimensional maps of the diffuse interstellar band at 862 nm. Science, ISSN 1095-9203, 15. avgust 2014, vol. 345, no. 6198, str. 791-795. http://www.sciencemag.org/content/345/6198/791.full.pdf , [COBISS-SI-ID 473217]
2. KOS, Janez, ZWITTER, Tomaž, ČOTAR, Klemen, et al. Discovery of a 21 Myr old stellar population in the Orion complex. Astronomy & astrophysics, ISSN 1432-0746, let. 631, november 2019, a166, str. 1-7. https://www.aanda.org/articles/aa/pdf/2019/11/aa34710-18.pdf, doi: 10.1051/0004-6361/201834710. [COBISS-SI-ID 932993]
3. KOS, Janez, ZWITTER, Tomaž, et al. Holistic spectroscopy : complete reconstruction of a wide-field, multiobject spectroscopic image using a photonic comb. Monthly notices of the Royal Astronomical Society, ISSN 1365-2966, November 2018, vol. 480, issue 4, str. 5475-5494. https://academic.oup.com/mnras/article-pdf/480/4/5475/25636822/sty2175.pdf, doi: 10.1093/mnras/sty2175. [COBISS-SI-ID 890497]
4. KOS, Janez, TRAVEN, Gregor, ZWITTER, Tomaž, et al. The GALAH survey : chemical tagging of star clusters and new members in the Pleiades. Monthly notices of the Royal Astronomical Society, ISSN 1365-2966, February 2018, vol. 473, issue 4, str. 4612-4633. https://academic.oup.com/mnras/article-pdf/473/4/4612/21907260/stx2637.pdf, doi: 10.1093/mnras/stx2637. [COBISS-SI-ID 849281]
5. BUDER, Sven, KOS, Janez, ZWITTER, Tomaž, ČOTAR, Klemen, TRAVEN, Gregor, et al. The GALAH survey : an abundance, age, and kinematic inventoryof the solar neighbourhood made with TGAS. Astronomy & astrophysics, ISSN 1432-0746, let. 624, april 2019, a19, str. 1-30. https://www.aanda.org/articles/aa/pdf/2019/04/aa33218-18.pdf, doi: 10.1051/0004-6361/201833218. [COBISS-SI-ID 909185]