NGC925 - Spiral Galaxy in Triangulum
with 10" f/3.9 Astrograph
Uploaded 11/5/16
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This bright 10.7
magnitude inclined spiral has quite low surface brightness, and
is a challenge to image. About 11 arc minutes long, this is the
second best galaxy in Triangulum to grab some detail on after
M33. I have shot this many times with the 12 inch, but this image
is equal to those past shots in magnitude limit and exceeds in
revealing the faint outer details due its much faster primary
mirror.
The galaxy sports
some superb pink HII regions and many knots in the spiral arms.
Two images are posted here from the same data set, which took
one hour and a half. The top image is the normal shot, showing
the full field of the 10 inch and many colorful foreground stars.
The second image is a negative photo key, showing not only many
very faint background galaxies - all circled in red ranging in
brightness from 17.8 to 19.0 or so. The faintest stars in this
image are 20.0. Also, three asteroids are indicated with ovals
on their trails (they all move about the same amount in an hour),
the designation for the object - none have been named yet - and
the magnitude according to the latest orbital elements for each
object. Surprisingly, the faintest asteroid is mag 19.4 and only
seen as a very dim streak on the largest images. If I can figure
out how to track them and combine their light, the magnitude
limit would certainly be near 20.
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Select an image size for a larger view:
1290 x 960
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Instrument: 10" f/3.9 Orion Astrograph Newtonian with Baader MPCC
Mount: Astrophysics 1200 QMD
CCD Camera: SBIG 10XME NABG with Enhanced Water Cooling
Guider: Meade DSI Pro w/80mm piggyback refractor
Exposure: LRGB = 60:10:10:10
AstroDon RGB Combine Ratio: 1: 1.05: 1.2
Location: Payson, Arizona, Elevation: 5150 ft.
Sky: Seeing FWHM = 3 arcsec , Transparency 9/10
Outside Temperature: 45 F
CCD Temperature: -20 C
Image Processing Tools:
Maxim DL6: Calibration, deblooming (Starizona Debloomer), aligning, stacking
PixInsight: Curves, Deconvolution
Photoshop CS2: Curves, Color Correction, Gradient removal (Grad Xterminator), Cleanup
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