Cataclysmic Variable stars observations submitted to AAVSO


12011obs

So…with my personal satisfaction,today I exceeded  12.000 CCD observations in 4 years submitted to American Association Variable Star Observers http://www.aavso.org.

They are all of Cataclysmic Variables that I…love,mainly stars belonging to the ZCamPaign from CVnet  https://sites.google.com/site/aavsocvsection/  (thank you Mike!)

So…keep on rockin’!!!

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Categories sky

NGC224 Rosette nebula in Ha-SII-OIII narrowband filters,2012


ngc2244SIIHaOIIIdef1
©Stefano Padovan

The Rosette Nebula (also known as Caldwell 49) is a large, circular H II region located near one end of a giant molecular cloud in the Monoceros region of the Milky Way Galaxy. The open cluster NGC 2244 (Caldwell 50) is closely associated with the nebulosity, the stars of the cluster having been formed from the nebula’s matter.
The cluster and nebula lie at a distance of some 5,200 light-years from Earth (although estimates of the distance vary considerably, down to 4,900 light-years.[3]) and measure roughly 130 light years in diameter. The radiation from the young stars excite the atoms in the nebula, causing them to emit radiation themselves producing the emission nebula we see. The mass of the nebula is estimated to be around 10,000 solar masses.
It is believed that stellar winds from a group of O and B stars are exerting pressure on interstellar clouds to cause compression, followed by star formation in the nebula. This star formation is currently still ongoing.
A survey of the nebula with the Chandra X-ray Observatory in 2001 has revealed the presence of very hot, young stars at the core of the Rosette Nebula. These stars have heated the surrounding gas to a temperature in the order of 6 million kelvins causing them to emit copious amounts of X-rays.(Wikipedia)

I took this picture remotely using my telescope T5 at iTelescope in New Mexico from Hamburg.This kind of nebula fits perfectly for narrowband filters imaging.The normal set of filters RGB for color imaging is replaced with a SII Ha OII filters that enchances some parts of the nebula that otherwise are hidden to the human eye.The result is totally different from the colors that we usually see.
The total exposure was about 12 hours.
To compare this image with a normal RGB here is the same target that I took the year before with RGB filters.You can see the difference of details.Of course between the two pictures there is also a difference of exposure.The second one is about 6 hours LRGB.Enjoy

ngc2237Rosetta

©Stefano Padovan

Mammatus,Flaça – Catalunya,summer 2012 ©Padovan


mammatus

 

©Stefano Padovan

Mammatus clouds,something very strange but easy to see in summer.It  happens when there is cold air and small ice crystals from the top of huge cumulus coming vertically down to the ground,Close to the surface they find hot and humid conditions so from ice they change into vapour.A very heavy condition that usally brings heavy rain and winds.Airplane pilots totally avoid this kind of clouds.

Here some explanations: