| Here is another urban
image taken from my driveway in the light polluted skies of Bedford. This started as a bit of a test shot for my new Zwo ASI2600MC-Pro, but turned out well enough that I'm adding time to the shot.
The raw stack background SNR is 33.6 dB and I usually target 42 dB or
better.
This would require 6.8 times the exposure or 15 hours. I now have most
of the calibration files I need, still waiting on a good cloudy day to
grab some reasonable flats. The tight crop was due to me taking the
camera off the scope and then not matching the rotation very well
with my previous subs when I put it back on the scope. As a result I
had to crop out the stacking artifacts. According to Wikipedia - The California Nebula (NGC 1499) is an emission nebula located in the constellation Perseus. It is so named because it appears to resemble the outline of the US State of California on long exposure photographs. It is almost 2.5° long on the sky and, because of its very low surface brightness, it is extremely difficult to observe visually. It can be observed with a Hα filter (isolates the Hα line at 656 nm) or Hβ filter (isolates the Hβ line at 486 nm) in a rich-field telescope under dark skies. It lies at a distance of about 1,000 light years from Earth. Its fluorescence is due to excitation of the Hβ line in the nebula by the nearby prodigiously energetic O7 star, Xi Persei (also known as Menkib). The California Nebula was discovered by E. E. Barnard in 1884. Click on the image to see a higher resolution version, then click again on the image to return to this page. The lower image is a previous processing attempt with less data requiring more noise reduction. |
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