Whole Night Perseid Mosaic
It took almost 2 years of work, almost 450 hours of postprocessing and many hours of other hard work, but it was worth it. Here comes final result of Perseid meteor shower 2018 observed in Poloniny Dark Sky Park (more info on dark sky preservation on International Dark Sky Association) by Kolonica Observatory, Slovakia, during moonless nights around maximum of the annual meteor shower 2018. In this full-night-whole-sky mosaic you can count 407 meteors from comet 109P/Swift-Tuttle, captured from 6 to 14 August 2018 along with some nice sky phenomena. For better understanding, cardinal directions on right are related to start of photographic night(s)/after dusk and on left to end of it/before dawn. Thus (and with knowing one night was partially cloudy) you can easily count how many hours it total exposure is represented by the multiexposure. It is 51 hours. The mosaic can serve as subject for visual investigation of the Perseids since there are some facts to be considered:
- Images of meteors were taken with same equipment as mosaic and processed very precisely to preserve correct brightness, thus the result can help with photometric investigation of the meteors (about 70 percents of them; rest was low over horizon or behind thin clouds which made them fainter than in reality). Meteors are between +4.5 and -13 magnitude, mostly +1 and +2 magnitude. Of course, this “peak” in distribution of Perseids’ magnitudes is partially effected by selection effect as dimmer meteors were under resolution of the camera’s sensor, when using wide angle 12mm lens.
- Images of meteors were precisely colour-corrected (as well as the mosaic in background) to preserve correct colours of meteors given by the cameras as their spectral charasteristics allowed. Thanks to that fact it is possible to investigate the source of emissions along the meteoroids shining in the atmosphere as they ionise the air. More can be found in this paper.
- Distribution of meteors can be investigated as well and from several points of view. One of them is where (and when) appear meteors ending with bursts or explosion in the atmosphere. This is defined by two aspect: size of meteoroid and angle of its penetration in the atmosphere. Of course, velocity is important and very high in case of Perseids – about 60 km/s.
- Many of meteors are located between radiant and northern horizon. The reason is selection effect since this part of the sky is mostly circumpolar so most of the meteors appear above horizon, unlike the southern part of sky. There can be, however, found similar “cluster” of meteors cause by same effect (that part over south doesn’t set below horizon during the night)
- More bright meteors appear in second half of night(s) due to superposition of velocities of meteors and Earth’s movement a bit more towards the stream of meteoroids.
- You might notice not all meteors fly directly from same spot in the sky. Two reasons have to be considered: 1) Radiant is not a small spot in the sky (it is angulary larger area), 2) due to Earth’s movement on its orbit the radiant moves in the sky during so many days. As seen in annotated version, it made movement in the sky about 7.5 degrees from first to last photographic night. Maximum night is marked by orange colour. Most of meteors, however, come from one directions as most of them appeared during the maximum of the shower. In fact, by looking at the directions and positions of the meteors in the sky, you can estimate when (which night, even its part) a particular meteor appeared.
- Using modified camera, I have also captured many deep sky objects like HII regions (M8 Lagoon Nebula, NGC 7000 North America Nebula, NGC 1499 California Nebula, even M42 Great Orion Nebula–rising) and other prominent objects, such as galaxies (Milky Way, Andromeda Galaxy, Triangulum Galaxy) or star clusters (Pleiades). Two large constellations in opposite parts in the sky – Orion and Scorpius – can be found on evening and morning parts of the mosaic, respectively.
- Three planets which appeared in oppositions with the Sun during summer 2018, can be seen. Jupiter (setting), Saturn (in front of Milky Way’s bulge) and Mars (just few days before its closest opposition for next 15 years). On top-right part of horizon you can find dome of the Kolonica Observatory.
Whole Night Perseid Mosaic – annotated
For sky mosaic used Canon 6D BCF modified, Samyang 12 mm, f3.5, ISO 2000, 7 images (each 22x120s stacked, darkframes applied) stitched together, tracked on Vixen GP2 mount. Meteors were captured with 2 Canon 6D cameras, both with 12mm lens (to cover whole sky), f2.8, ISO 10000, 30s exposures, timelapsing from tripods. I would like to deeply thank to workers of Vihorlat Observatory (and Kolonica Observatory especially), Pavol Rapavy from Observatory Rimavska Sobota, Slovakia, and Mahdi Zamani from Garching, Germany, for great support with making this project possible.
Dark Sky Perseids
