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Friday, February 12, 2016

NGC 1499, the California Nebula, project continues



It has been very cloudy up here for about several months now. At January 4. I was able to shoot some lights for the NGC 1499, the California Nebula. We had few hours of clear sky at February 1. I shot three hours of H-alpha light next to previous image to build a two frame mosaic. Colors are partly from an older wide field photo of the california Nebula.

Detail of the NGC 1499 as a two frame mosaic
Please, click for a large image

Image area spans about two degrees of sky horizontally. The photo is in mapped colors from the light emitted by an ionized elements, red=sulfur, green=hydrogen and blue=oxygen.


An older wide field photo of the NGC 1499
Please, click for a large image

A wide field image of the NGC 1499 from January 2012 was shot with a Tokina AT-X 200mm f2.8 lens, QHY9 astrocamera and Baader narrowband filter set. The white circle at lower right corner shows an apparent size of the full Moon at the same scale. (Moon has an apparent diameter of 0.5 degrees = 30 arc minutes.) This is a large target with a lowish surface brightness, total exposure time is around 30h.

INFO

The California Nebula is an emission area located in constellation Perseus. It appears to resemble outlines of State of California on long exposure photographs, like this one. It has a very low surface brightness and it's very difficult to observe visually. Distance from my hometown Oulu, Finland, is about 1000 light years.
this image spans around five degrees horizontally. The Wikipedia article states, that the angular size is about 2,5 degrees (Five full Moons side by side) but as can be seen in this image, the actual size, with a dim outer parts, is much large.

Detail of the NGC 1499
Please, click for a large image

The left side of the two frame mosaic at top of the page was shot at At January 4. 2016. 

Technical details

Processing work flow

Image acquisition, MaxiDL v5.07.
Stacked and calibrated in CCDStack2.
Deconvolution with a CCDStack2 Positive Constraint, 21 iterations, added at 25% weight
Color combine in PS CS3
Levels and curves in PS CS3.

Imaging optics
Celestron Edge HD 1100 @ f7 with 0,7 focal reducer for Edge HD 1100 telescope

Mount
10-micron 1000

Cameras and filters
Imaging camera Apogee Alta U16 and Apogee seven slot filter wheel
Guider camera, Lodestar x2 and SXV-AOL

Astrodon filter, 5nm H-alpha
Astrodon filter, 3nm O-III
Astrodon filter, 3nm S-II

Exposure times
H-alpha, 24 x 1200s =8h
O-III, 3 x 1200s binned = 1h
S-II,  3 x 1200s binned = 1h
Total 10h
Part of the S-II and O-III signals are borrowed from the older wide field photo.





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