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Nebulae in the SMC




These are a collection of gas nebulae in the Small Magellanic Cloud. Chadwick and Cooper, in their excellent book "Imaging the Southern Sky", have named the collection The Magnificent Seven (tilt your head to the right to see why). The photograph is an example of narrow-band imaging. The term narrow-band refers to the fact that the filters used during the data collection process allow light only from very specific regions of the visual spectrum in which electrons are jumping between energy levels. In this case, the image is a composite of the light from hydrogen (H-alpha @ 656.28 nm, reddish; H-beta @ 486.00 nm, blue) and oxygen (O-III @ 500.70 nm, greenish). Research astronomers will use these bands - and many others - to discover much about the nature of an object. Astrophotographers tend to use them like a palette of paint, although we often are quite interested in the same things as the pros but at an amateur level. The other benefit of narrow-band imaging for astrophotography is that it can be done in full moonlight. Because the moon does not emit light in these ranges, moonlight is, essentially, ignored by the camera sensor. The trade-off is that one needs an enormous (!) amount of exposure time to get even half-decent results.

Date: 26 July 2018
R.A.: 00h 47m 47s
Dec.: -73° 14' 04"
Photo stuff: 12 subs @ 300s ea. for each band; ISO 1600; Canon 60Da on Meade RCX400 16" f/8; 0.7 focal reducer.
















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