Wednesday, October 24, 2012

A far cry and hard by

NGC6946 Fireworks Galaxy
At the border of Cepheus and Cygnus the Swan constellations there is a place where quite remote deep sky objects meets quite close one. A far cry object is NGC6946 galaxy, called also Fireworks Galaxy. The galaxy is located about 18 million light years away from Earth and it is quite obscured with interstellar matter of our Milky Way. It was discovered by William Herschel in 1798. In Fireworks Galaxy  nine supernovae were discovered. 
The hard by object is NGC6939 star open cluster, which is about 6000 light years away, so 3000 times closer than Fireworks Galaxy. This region of the sky is quite close to our galaxy plane, so it is fairly easy to find here star cluster, but not so easy for distant galaxies light to go through the interstellar matter.
Photo was taken with GSO 150/750 newtonian with coma corrector and Canon 20D modded camera. Exposure was 40x5 minutes.

Monday, October 22, 2012

Indian summer

Indian summer, so the summer welcomes autumn in the sky. 
Probably the last sunny week before it will get cold, and autumn fogs will envelop my countryside and made observations quite hard for some time. 
The retiring summer sky objects are represented by Milky Way in the constellation of Swan. The brightest star in the photo is Sadr. Above it there is well known Butterfly Nebula (IC1318) that has three bright patches, each one about 50 light years large. At the bottom to the left shines small Crescent Nebula (NGC6888). Crescent nebula consists of some shells of gas energised by a very energetic Wolf-Rayet star. The whole photo is filled with star clusters, dark and light nebulas that are placed 3000-6000 light years away from us.
Photo was taken with 200mm telephoto lens at f/5.6. Exposure 40x5 minutes at ISO800, Canon 20D modded camera. 
The incoming autumn season is represented by well known Andromeda Galaxy (M31). This huge, spiral galaxy contains about one trillion stars (1012) - it is over three times more than our Milky Way, and it is the closest to us spiral galaxy. M31 is about 2.5 million light years away from Earth. It is visible with naked eye under good conditions, and spans about three degrees over the sky (which is six times more than apparent Moon diameter), but only central, bright part is visible without optical instrument.
Photo was taken with the same setup as above, exposure was 80x3 minutes.
Original size photos are available under links at the photo titles.

Monday, October 15, 2012

Autumn ionisations

Milky Way is shining high in the sky during the autumn - depending of the time you can see Cygnus, Cassiopeia or Perseus constellations above your head. In these ones you can find massive amount of gas and dust clouds that form different nebulosities. Many of them are deep red hydrogen alpha nebulas or dark dust clouds that covers objects placed behind them. One of the well known nebulas is IC1805 in the Cassiopeia. It is also known as Heart Nebula. It is placed about 7000 light years away and it is formed by the ionised hydrogen excited to light by nearby stars. 

The star cluster inside is known as Melotte 15. In the picture bottom you can see one of its separated part that has been discovered in the first place and it is also known as NGC896. Upper part of the picture is occupated by the Soul Nebula (IC1848) that is also 7000 light years away. In these both nebulaes you can find many star clusters, but in fact in this sky region it is hard to faind a place wihtout them.
A little bit to the left in the constellation of Cygnus (The Swan) nearby its brightest star Deneb there is more famous nebula North America (NGC7000). It occupies upper picture part. Below there is Pelican nebula (IC5070) separated from North America with the visible dust line. Both these nebulaes are in fact the same ionised gas cloud and its distance from Earth is not well defined. Also the star that illuminates this cloud is not yet determined for sure - if it is Deneb, the nebulaes are about 1800 light years away.

Both pictures have been taken using modded Canon 20D camera using 200mm telephoto lens at f/5.6. IC1805 is a stack of 35x5 minutes exposures. NGC700 is 60x5 minutes stack.

Clear skies!