Imaged by Jean-Yves Beninger from Singapore
on 14 July 2005
H-Alpha filter imaging
SKY90 - SBIG ST8 - AP600EQMD
Stack of 28 images, 3 minutes
H-Alpha Bin 1x1 : 84mn
NGC 6357 is
a large emission nebula in Scorpius.
When an electron
from an hydrogen atom falls from a higher to a lower energy
level, the energy difference is emitted as a photon.
This image is
taken through a filter that selects the Hydrogen Alpha photon,
the smallest fall in the Balmer series ( from level 3 to level
2 of the different levels allowed for an electrron).