Light pollution study of Zielona Góra

Light pollution study of Zielona Góra

A quick recording of various street lamps was done in an effort to map the light pollution around the observatory .

Equipment used

The equipment was very simple .A diffraction grating with 300 lines per millimeter mounted in front of an 135mm telelens .
The camera used was a CANON EOS 10D DSLR . The ISO setting was set to 800.

East

To the East at azimuth 090 the public school Nr. 7 is placed . In its yard three strong High Pressure Sodium lamps exist .
On the streets around the church Mercury pressure sodium lamps are placed .
In fig.1 we can see a spectrum of these High Pressure Sodium lamps .The cocnlusion is that monochromatic imaging at 5007Å can be done almost unaffected by the pressence of these lamps .Also the light pollztion around the Ha line is not severely affected.

This is the scpectral response of the Orion Ulotrablock filter, the Observatory owns.No leakage of other wavelengths was found.

Southeast

Southeast seems the best area to photograph .Especially from azimuth 090 to azimuth 180 wich is the area beteween the Mercury lights of the nearby school and the Falubaz stadium .
Also the most usual spectral lines used for taking narrowband photos are left unaffected .
This is a spectrum form the lamps in this region.

South & Southwest
At South the Falubaz stadium exists .It uses the same lights as the school's yard, Mercury lamps, so the situation is the same like North .
Thus from azimuth 180 to azimuth 270 the same light pollution conditions apply .

West & Northwest
The center of the city is placed to the West .Moving further from the observatory towards the center we meet High Pressure Sodium lamps .
Some Mercury lamps exist at the center of the city ,probably from the hill . At the center all the street lamps are High Pressure Sodium lamps .
Such lamps are used in city centers because inside them there is also a small quantity of Mercury that helps the ignition of the lamp and they also provide a colour balance because colour vision is important while driving in the city .
Also the High Pressure Sodium Lamps near the Observatory are older than the same ones at the center .The ones near the observatory have lower blue intesity .
It is advisable to avoid photograhing to the west ,targets with an altitude less than 40 degrees .

North

To the North there is the main street Podgórna .There are also High Pressure lamps .
This is the spectrum of an HPS lamp just outsode the Observatory.We can see the self absorption effect.

Northeast

Northeast towards the UZ Univeristy the street light are also High Pressure Sodium lamps .
From azimuth 000 to azimuth 090 there is a mix of High Pressure Sodium and Mercury Spectra .Practically that means that in the whole region there is light pollution present at almost the whole optical spectrum .
The biggest problem are the School lights because they have a broader and continuum spectrum .This is their spectrum.

Conclusion

As expected towards the center we have the maximum light pollution.The best area seems to be from azimuth 090 to azimuth 180.This is also expected as there are much less lights.However this area is better for the extra reason that the spectrum of the lamps in this area does not affect the entire optical spectrum, but leaves interesting spectral lines such as at 5007Å and 6562.72Å slighlty affected.Between azimuth 090 and azimuth 180 the University's Orion Ultrablock filter can be safely used.