Observation by David Arditti: Elephant Trunk Nebula in IC 1396

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David Arditti


David Arditti


2018 Oct 07 - 02:00


2018 Oct 29 - 15:21


The Elephant Trunk (IC1396)

Planetarium overlay



Field centre

RA: 21h37m
Dec: +57°44'
Position angle: +0°31'

Field size

1°22' × 1°04'

  • 81mm Apochromatic refractor
  • Field flattener
  • H alpha, OIII and CLS filters
  • Artemis 285 mono camera

Total 5 hours 35 mins


Edgware, Middlesex, UK

Target name

Elephant Trunk Nebula


Elephant Trunk Nebula in IC 1396

About this image

This was created using a similar method to the image of the Pelican Nebula that I recently posted: that is, with two narrow band filters and one broad band light-pollution filter. The H alpha signal was mapped to the red channel in the image, the OIII to the blue, and the green channel was created from a mixture of OIII and CLS. The CLS image was also used for the luminosity layer. It is thus a false-colour image that simulates true colour in a way that excludes the worst of my local light pollution.  The method, which might be my own invention, would be a lot easier if all manufacturers made their filters the same thickness, but they do not. Because the CLS and narrow-band filters are from different manufacturers, Astronomik and Astrodon, the focus points and image scales are changed slightly, necessitating careful correction at compositing stage.

IC 1396 is an area of emission nebulosity that is far larger than the field here. The 'Elephant Trunk' is an area of compression of the gas, where winds from stars newly-formed in the small dark dust clouds are pushing back the surrounding envelope.

The 81mm William Optics apochromatic triplet refractor I used was donated to the BAA, and is still for sale, with an undriven mount. Offers invited, see p303 of the October Journal.

The British-made Artemis 285 camera is 12 year old and still going strong.

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