Historical



How the Moscow Observatory was lost



70-cm reflector of SAI Moscow Observatory located in the Vorobyev Hills is a third in Russia if arranged by the mirror area. Since the end of 1950-s when it was installed here, it was used to take about 10000 sky photos, and additionally large amount of multicolor photometric CCD observations (the observations of X-ray transients and novae taking with the 70-cm reflector are presented in this site ). There were performed numerous observations of Galactic Cepheids' radial velocities using CORAVEL type spectrometer constructed by Tokovinin what represented about 40 per cent of the whole the world observational matherial (this spectrometer was installed at the moment of taking the photography).


Yu.M.Luzhkov, the Mayor of Moscow: 'Moscow WILL BE the most illuminated sity in the world'. 'Well! We approve', probably that was the reply of V.S.Sadovnichy, the Rector of Moscow University. And the design illumination of the University building was restored and switched on. The building was illuminated by seachlights from the ground, so, the general amount of illumination was simply lost in the sky.

The commercial advertizing firms reduced the situation to the end. In the billboard construction, they used the same method as that one used by University: illumination from the bottom upwards. This choice was preferential, as the flashes of polished surface are absent, so people may distinguish it better from different directions. With Luzhkov's help, Sternberg Institute forced these firms to reconstruct the billboards with the illumination directed from top to bottom, and in such a way to pass IDSA standards. These measures reduced the rise of light pollution in the vicinity of the observatory and prolonged the agony of Moscow Observatory for 7 years. During these 7 years since 1999 till 2006, the sky brightness increased on average from 15m.2 to 14m.0 per squire arcsecond. But the illumination of University building stayed a 'sacred cow', improved and strengthened, inspite it does not pass IDSA standards.


Rusty dome of 70-cm reflector in 2007. The observations are not carried out there now. Nobody plans to bring this telescope out of the city. I am afraid that the water leaks through the rust dome on the telescope.

Certainly, the solar telescopes of Moscow Observatory were not suffered of the night sky pollution.

In addition to the Moscow Observatory, Sternberg Institute lost all other observatories through nationalization, as Tien-Shan Observatory in Kazakhstan, Maydanak Observatory in Uzbekistan, and Crimean Station was nationalyzed in 2007 by Ukraine. For the present time, the university observational astronomy is destroyed.

Characteristics of interference due to light pollution at the SAO observational sight.


Well, as a result of increasing city lights in the villages located in the vicinity of the Special Astrophysical Observatory, we see in the spectra of night sky increasing line emission of mercury HgI at the wavelengths of 4046, 4358, 5460, 5769 and 5790A, and sodium at NaI D2D1 5890 and 5896. This effect is especially strong in the winter time when the snow cover is set in this villages. What problems meet the astronomers in their investigations due to strengthening of these emission lines? Some astronomers think that these emissions are even useful to be additional reference lines usable to check wavelength calibrations and radial velocities based on dispersion curves made with calibration lamp spectra. But this does not correspond with the reality for the stellar spectra. The light of sky, and the light of star are destributed unequally inside the slit of spectrograph, what gives rise to systematical errors in the wavelength masurements.

As a result of sky background subtraction in the long-slit spectra, the defects of the sky emissions remain, which distort the spectra of objects, line profiles, and estimates of equivalent widths and intensities of star lines. For instance, "the 4358-A Hg line can be a hazard for observers wanting to compare the intensities of the 4363 and 5007-A OIII lines (for measuring the temperature of astrophysical plasmas)", and "the 5460-A Hg line lies in the centre of the y band of the ubvy system" - note Benn and Ellison in their Internet resource. The strongest forbidden [FeII] emission line in the blue range of the spectrum at the wavelength of 4359A coincides with the same mercury 4358A line, [FeII] emission being a blend of several components.

Figure 8. HgI 4358A line masks strengthening [FeII] 4359A forbidden line in the spectra of red nova V838 Mon. The defects of sky spectrum subtraction are seen in the bottom spectrum. BTA/SCORPIO.

Let me show in my own instance, what a serious errors may be done as a result of such a coincidence (Fig. 8). We observed peculiar red nova V838 Mon using BTA. It belongs to a new class of astrophysical objects. This is a wide binary system, containing two hot B3V type stars. The brightest companion exploded, and the remnant of this explosion evolved as a unique very cool star, brown supergiant with the surface temperature 900 - 1500K. In the late 2004, four weak emission lines appeared in the blue part of its spectrum where the radiation of such a cool star was very weak. Three of them coincided by wavelength with the molecular emissions AlH and FeH, no molecular radiation was located at 4358A. We had an alternative identification of all these emissions with [FeII], but reject this solution because the star being so cool can not ionize iron atoms in principle. Moreover, we identified surely the molecular bands of AlO, TiO, and other molecules in the remnant spectrum. Therefore we accepted the first identification in our article to the Russian Astronomicheskij Zhurnal, and supposed that the HgI 4358A line was artifact, the reminder of subtraction. This was quite natural assumption because this line of parasitic pollution was strong in our spectrum. We understood that this was a real [FeII] line only in the late 2005 when the 'reminder of subtraction' strengthened noticeably along with the other tree lines. The ionization source became the neighbour hot star of V838 Mon system because the expanding surface of cool giant approached to it. And finally, the expanding explosion remnant had covered it, so that hot star disappeared from the total spectrum of the star. We had to talk with the journal editor board to correct this error, we made the supplement to the article with special explanation, and published alert in Astronomer's Telegram. But in the La Palma Conference (Spain) in 2006 specially devoted to this star and related objects, all the emissions we identified were considered as 'an instrumental effect' because nobody had detected them with the smaller telescopes and then had not confirmed. Fortunately later they were confirmed with the big South-African telescope SALT .

Increasing pollution of the sky with the sodium emission NaI D2D1 5890 and 5896A turns out by the bigger lost for BTA astrophysics. There are Galactic interstellar absorption NaI lines, which are unique well calibrated source to determine distance for the majority astrophysical objects, and then the source of additional information on the luminosities and other physical data.

All the details in the spectra, even the weakest ones are of interest for investigations of active galactic nuclei and quasars, optical aftergow of extragalactic gamma bursters. In the specra of objects located at the cosmological distances, there are systems of absorption lines. Sources of exteragalactic absorption are located at the different distances, and have different red shifts. It is very hard problem to identify these absorption lines and what is more to find the lines of a studied object between them. Light pollution causes multiple defects in the spectra, what results in increasing difficulty in the interpretation of spectra of cosmological objects. But cosmological studies are one of the foreground tasks delivered for BTA.

Additionally, the light pollution causes the essential degradation of the observational matherial taken in winter time or at nonideal weather conditions, - with the worse air transparency, cirri or through clouds. But these abilities are important for russian astronomers due to lack of telescopes with medium mirror sizes in Russia.

The conclusion is the following. We must undertake all possible efforts to save the starry heavens, the main SAO resource from light pollution. This is because the problems which use to solve with BTA can never be solved with other telescopes or with other methods. Moreover, the problems delivered for BTA do not have ready solutions as a rule, and therefore the probability of errors caused due to different casual interferences is high. And these errors can not be corrected without any larger telescope. 6-meter telescope is one of the largest in the world, and so the Russian astronomers, and the astronomers of other countries are working at the leading front of science, with the operative freedom. And just for this purpose, the huge financial means and resources of all Soviet Union were put in the BTA project, these resources are thousands times larger than those ones spending for city lights in the villages and communities located in the observatory protected area.

Continued:
Night sky spectrum of the Special Astrophysical Observatory.
Observations of relative intensities of HgI and NaI emission lines
Characteristics of interference due to light pollution at the SAO observational sight.
Light pollution sources-1.
Light pollution sources-2.
Results and conclusions.
Continued. Monitoring the situation.
THE WATER-BOTTLING PLANT IS STARTED-UP IN THE CENTER OF LIGHT-PROTECTED ZONE OF 6-METER TELESCOPE.