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The "Pelican Nebula"

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About this observation
Observer
David Arditti
Time of observation
02/09/2018 - 23:00
Object
Pelican Nebula
Equipment
81mm f/5.9 William Optics triplet refractor
Artemis 285 mono camera
Exposure
124 mins
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David comments that this is not a true-colour image, but a combination of frames taken through a CLS filter and a Hydrogen alpha filter (6nm bandpass) on the nights of 2018 September 1/2 and 2/3. Total exposure was  2 hours 4 min. The CLS was used as luminosity on a red H alpha image. He comments that he might add some more data taken through other filters on future nights.

The telescope was an 81mm f/5.9 William Optics triplet refractor that he was testing and it was combined with a focal reducer giving f/4.7. It was mounted on an AP1200GTO, with no guiding.

Conditions were poor, with moonlight, and high cloud in addition on the 3rd. It's interesting how effective the 6nm filter is in countering even these conditions, in which the naked-eye limiting magnitude was perhaps 3.0. The CLS filter is probably of little effect now against the local light pollution, which is primarily white. David notes that a problem he has found is that filters from different manufacturers have quite different focus points. Of course one can re-focus, but that also changes the image scale slightly, because of the focal reducer, which means much adjustment is needed in processing. The camera used was an Artemis 285 mono camera.
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