Cygnus Wall in NGC 7000. Shawn Nielsen, 2014This is 5 hours of H-alpha and Oxygen 3 data combined to produce a false colour image of the Cygnus Wall in NGC 7000. A variant of the Hubble palette colour profile was applied.

This image consists of three hours of hydrogen-alpha (Hα) images and two hours of OIII data. The Hα frames were captured last November (2013) using a modified Canon EOS Rebel T1i DSLR and the OIII data using an SBIG 8300M CCD camera in July 2014.

The Cygnus Wall resides within the North America Nebula which can be found in the constellation Cygnus. Cataloged as NGC 7000, it is an emission nebula that resembles the continent of North America. The Cygnus Wall region is the Gulf of Mexico area within the nebula.

Narrowband astrophotography is one of two types of imaging you can do inside a city with light pollution. The other being planetary astrophotography. The filters used in narrowband imaging notch out (cut off) the artificial light created by street lights and porch lights left on all night even though everyone is inside sleeping. It is similar to what a light pollution suppression filter would do but more specific wavelength is targeted, as example, H-alpha filter allows the 656.28 nm through.

A William Optics Zenithstar 71 APO Refractor with SBIG 8300M CCD and FLI filter wheel were used to take this image.

Filtered imaging though will be made difficult with LED street lighting which is a full spectrum white light consisting of all wavelengths. Optical filters will not be able to “filter out” this light. The best that can be hoped for with LED is that cities and towns choose lower colour temperature (3000K or less) which will help mitigate some of the blue wavelength (compared to 4000K and 5000K LED) that actually increases skyglow and light pollution.

NGC 7000 is sometimes incorrectly called the “North American Nebula”.

Skynews Photo of the Week August 2014This image from featured as Photo of the Week on Skynews Magazine.

 

 

Technical:

  • William Optics Zenithstar APO Refractor with WO Flat6 .8x reducer/flattener
  • Modified Canon T1i DSRL for H-alpha data (3 hours)
  • SBIG 8300M CCD with FLI filter wheel for Oxygen 3 data (2 hours)
  • Calibration, align, stack in Pixinsight.
  • Processed in Pixinsight and Photoshop.

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