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Students practice in Astronomy 2010

In the period March 26 to April 1, the astronomical practice for the undergraduate and graduate students from the Astrophysics program of the University of Sofia took place at the National Astronomical Observatory Rozhen of the Bulgarian Academy of Sciences. The 50/70 cm Schmidt telescope with FLI PL 16803 CCD was used as well as the computer network of the Observatory.

The main goals of the practice were performing professional observations and thorough processing of the astronomical images with the specialized software IRAF - from initial data reduction, through photometry and astrometry, to final results about given observational tasks. The students were taught in details how to handle problems of observational astronomy. They had the chance to plan and execute professional observations by themselves sticking to previously approved programs. Each of them passed through all steps of one observational task by him/herself and in groups. The steps involved pointing the telescope, obtaining dark, bias and flat field images, working with observational software (MaximDL, Astrobell, Guide 7.0), working in Linux environment, getting to know the basic packages and capabilities of IRAF, initial processing, matching and combining of images, aperture photometry, astrometry, work with tables (the package tables), exporting eps-figures from IRAF, etc.

Observatory staff astronomers and professors from the Department gave lectures and presentations familiarizing the students with the observational facilities of NAO - Ritchey-Chretien and Coude foci of the 2 m telescope, VersArray1300B, Versarray512B CCDs, Photometrics, the FoReRo 2 focal reducer, 60 cm Cassegrain telescope. 50/70 Schimdt telescope with FLI PL 16803 CCD and the Solar Coronograph.

During the practice, the students visited the Smolyan Planetarium and attended the star show "Short history of the Universe", prepared by Mariyana Hadzhigencheva. The students were also introduced in great details to the planetarium facilities by the physicist Leyla Chavdarova.


Dr. Haralmbi Markov - Institute of Astronomy, BAS

Dr. Nikola Petrov - Institute of Astronomy, BAS

Leila Chavdarova - Planetarium Smolyan

Hristina Kalaydzieva - Planetarium Smolyan, director

Nikifor Iliev - Institute of Astronomy, BAS

Results of the observational tasks sorted by groups:

Group I - Nikola Karavasilev, Blagovest Petrov, Georgi Latev, Veselina Dimitrova

NGC2126 (RA = 06 02 32.0, DEC = +49 52 00) - an open cluster in the constellation Auriga.

Result - BV photometry and determining cluster membership. Obtaining colour - magnitude diagram of the cluster.

Additional result: two stars with significant movement were found in the field. By comparing the results from the Schmidt telescope with the images from the Aladin Preview (, two comparatively bright stars not identified on earlier frames were noticed. The stars (15925, 15934 - Luyten, W.; Hughes, H. 1980, PMMin, 55, 1) turned out to have significant proper motions of 0.611 and 0.801 arcsec/yr, respectively. They have shifted by 35 and 46 arcsec, respectively, from their 1952 positions (shown in Aladin Preview).

Group II - Stanimir Kisyov, Vladimir Bozhilov

M13 (RA = 16 41 41.44, DEC = +36 27 36) - a giant globular cluster in the constellation Hercules.

Result: BV photometry and determining cluster membership. Obtaining colour - magnitude diagram of the cluster.

Group III - Nikolay Kacharov, Anna Lalova, Dinko Atanasov, Plamen Nikolov

GJ 1214 b - an exoplanet with mass of 0.0179 solar masses and orbital period of 1.58 days, orbiting around the star GJ 1214 (RA = 17 15 18.94, DEC = +04 57 49), distance 13pc. The exoplanet was observed during an eclipse.

Result: Light curve obtained. Expected beginning of the eclipse - 2:03 UT, mid transit - 2:47 UT, end - 3:31 UT.

Group IV - Gergana Beltcheva, Trifon Trifonov

V407 Cyg (RA = 21 02 09.85 DEC = +45 46 33.0) - a symbiotic binary in Cygnus, which erupted like a classical nova on March 10.813, 2010. Despite the photometric and spectral data available, the status of this object is still unclear which makes these observations very important.

Result: BVR photometry of the binary and obtaining of standard magnitudes, using standards in the field ( Light curves sent to AAVSO (

The images below show combined B,V, and R images, taken with the 50/70 cm Schmidt telescope of the NAO Rozhen and the CCD camera FLI PL 16803 by the students during the practice.

Department of Astronomy, Faculty of Physics, 5 "James Bourchier" Blvd., 1164 Sofia, Bulgaria