The 2014 OPTICON school in Rozhen (Bulgaria)


                The 2014 edition took place at the Rozhen Observatory (Bulgaria), from Sept. 17h to 24th, for the observations,

                           and then in Sofia for the data reduction, until the final presentation of the results on Oct. 1st .  

20 students, from 11 different nationalities, gathered first in Sofia in the afternoon of Sept. 17th,  to go up to the Rozhen Observatory, where the first week of the school was taking place.
Although the arrivals were perturbed for some of the participants due to the AF strike,
finally everybody arrived in time to take the morning bus to the observatory
(although some of them  without their luggage...)
On the way up, a short stop to visit the Bachkovo Monastery, one of the oldest in Bulgaria,
and a typical meal on the shore of the river gave already an idea of the warm Bulgarian hospitality.
As usual, the school started with some lectures on fundamentals for observations.
This started with a lecture on telescope optics and imaging, given by Alessandro Pizzella (Padova), a long time collaborator of this program,  and organiser of the schools in Asiago.
The introduction to spectroscopic techniques was given by Michel Dennefeld (Paris), who described the
classical case of long-slit spectroscopy (to be used later-on during the school) but gave also an overview of all the other techniques, including the ones used at the VLT, such as the Multi-Object Spectroscopy and  Integral Field Spectroscopy.
Stefano Banuolo (Armagh) then described spectro-polarimetry, a powerful technique which sometimes appears difficult,
but is very simple if the principles are well understood, as was clearly shown during this lecture.
These first lectures were complemented by a presentation of the principles of stellar classification by Ilian Iliev (Sofia),
who also introduced the students to the intricacies of IRAF...

  To allow efficient work, the students were divided into five groups, under the leadership of their respective tutors,
to prepare the scientific program for the observations, and make the necessary technical choices for the instrument set-up. The available telescopes were the 2m Ritchey-Chretien telescope for spectroscopy, the 60cm Cassegrain one for photometry, and the 50/70cm Schmidt telescope for imaging. 

Each group had one night for spectroscopy, and could use the other telescopes at will, as needed for their program.
To avoid too many change-overs, the first two nights at the 2m were planned in Coude focus (for the stellar classification program), and than a change-over was programmed to install the focal-reducer to the RC focus, a change in which the students participated actively and where they could see all the detailed pieces of the instrument.

The group at
                    the telescopeMounting the Focal Reducer

                   The group at the 2m telescope                                Mounting the Focal Reducer                                                        

On Wednesday the 24th, everybody went down to Sofia, where the second week was taking, together with the Awareness Conference (see our corresponding page for details). On the way down, a guided visit of Plovdiv (the ancient Trimontium of the Roman empire) provided an interesting, and welcome break.
In Sofia, where everybody was assembled in the Hemus Hotel,  intensive data reduction was going on, interlaced with the various lectures given for the Awareness Conference. Practical work was also added, to write a (good) telescope time proposal: would the participants have obtained the time to do the observations for their science project in the school? The proposals submitted on the last day showed that, although some imperfections still remained, good progress had been made during all those days under careful supervision. And a Sunday break allowed all the participants to visit the city, and enjoy a barbecue organised by our hosts in the gardens of the Institute of Astronomy.


Finally, after hard and intensive work, the scientific results were presented on the last day of the school.
The group lead by Vania Stateva (Sofia), with Jana Bogdanoska (Macedonia), Sunay Ibryamov (Sofia), Tamas Kiss (Budapest) and Eyup Ulgen  (Istanbul) studied the peculiar star Iota Delphini in Coude spectroscopy, to determine its chemical composition. After removing the telluric lines, and observations of various  comparison stars, including the primary reference Vega, they found that indeed this star had peculiar abundances, [Fe/H] = +0.267 and [Ca/H]=-0.5, in accordance with results in the litterature. Its was planned to observe more stars of the same category, but the changing weather, and the needed change-over to Cassegrain focus for the other programs did not allow them to  do more.

The group lead by Galin Borisov (Varna), with Erdem Aytekin (Erzurum), Michalina Goreka (Torun), Knarik Khachatryan (Erevan) and Marc Magee (Belfast) put in practice the lessons on spectro-polarimetry to put a diagnosis on the type of various asteroids. Although the number of observation points were limited, they could, using the change of polarization with the phase-angle, establish that  12 Victoria was an L type, while 80 Saphho was of S type. They also realized how important it was to measure reliably the instrumental polarisation, which can be much larger than the value to be measured!

The group lead by Patrick Francois (Paris), with Charlotte Marshall (Nottingham), George Kleftogiannis (Patras), Alexander Kurtenkov (Sofia) and Nemanja Rakic (Belgrade) observed old stars in clusters in the halo of our galaxy to see if abundance differences  were to be found in those clusters were supposedly, all stars should have the same age. 
The two clusters NGC411 and M36 were selected for best observability, and the first important task was to select individual stars in them, and verify their belonging to the cluster with help of precise radial velocity measurements.
This being done,  Mg and Fe abundances were derived, bu no  differences were found within the measurementÅ› uncertainties. These clusters can be added to the targets used to measure a galactic disk abundance gradient.

The group led by Krisztian Vida (Budapest), with Ioakeim Chrysopoulos (Patras), Gancho Ganchev (Sofia), Will McLean (Armagh) and Monika Sitek (Warsaw) studied some late type stars hosting exoplanets, from the Kepler sample, to establish their photometric and spectroscopic characteristics. Although disfavoured by the weather, they could obtain excellent BVRI photometry for all their candidates, but establish the spectral type by spectroscopy for only one candidate, KIC 10063343 which was found to be a K7V star by comparison with series of stellar spectra for references. They could also observe the RCVn star HK Lac.             

Finally, the group led by Toma Tomov (Warsaw), which comprised Cristina Barbarino (Napoli), Ioannis Liodakis (Heraklion), Mirela Napetova (Sofia) and Clement Ranc (Paris), took spectra of two recent Novae, Nova Del 2013, and Nova Cygni 2014, to establish their evolution stage, and compare with spectra of earlier epoch.
Nova Del 2013 was found to be already in the nebular phase, which is not surprising in view of its age, as it is a fast Nova. But the spectrum of Nova Cygni 2014, which had been classified as a very slow, FeII type nova,  showed a very rapid change, with asymetric line profiles, and the appearance already of some nebular lines, in contradiction with its earlier classification. Here also the adverse weather did not allow more observations (spectral changes might have been seen over a few days only), but the group was able to derive the extinction, and hence the distance of the object through the Na and K absorption lines, and derived a distance of 4.7 kpc (with an uncertainty of 0.6 kpc)
Clearly this work needs to be followed, and will lead to an interesting collaboration.


Targets of Opportunity are novadays an important part of astronomer's lives...and the school was, as usual, keen to contribute to the classification of new objects.  As a result, two CBET telegrams could be published, confirming and classifying the Supernovae 2013 ed (CBET 3596) and 2013 ee in NGC 3079 (CBET 3597)