Dark Cloud outside of Barnard's Loop (LDN1622)

Dark Cloud
All Images Copyright Steve Cannistra

Please click here or on image for a higher resolution view.

Magnitude:  ?.
FOV shown here is approximately 1 degree.
Distance: ?
RA: 5h 52m 17s
Dec: +01 degrees 46' 09"

The Orion region is full of dark clouds and emission nebulae.  Although the most famous dark cloud is B33, the above image shows a less frequently photographed target.  This dark cloud is referred to as LDN1622 (Lynds Dark Nebula catalog) located just outside of Barnard's Loop and is shown in this widefield view by Loke Tan in the central left edge of this field.  I did not anticipate how faint the surrounding emission nebulosity would be, and even 4 hours cumulative exposure is not enough to do it justice.  Still, there is good detail within the dark cloud region itself, and the dark shading of the image gives it a mysterious and somewhat foreboding quality.

Photographic Details:

Date:  January 1 and 21
, 2005.
Scope:  Takahashi Sky 90 at f4.5 with field flattener/focal reducer, on a Losmandy G11 mount.
Autoguider:  STV with e-finder.
Camera:  SXV-H9.
Filters:  Ha (13nm bandpass) from Astronomik.
Exposures:  12 x 10', unbinned (1/1/05), plus
15 x 8', unbinned (1/21/05).  Total exposure time 4 hours.
Conditions:  1/1/05- Temperature 36 degrees F, below average transparency in part due to several thin clouds passing through, average seeing, no wind.  1/21/05- Temperature 0 degrees F, clear, average transparency and seeing.

Post-processing:  No darks, flats, or bias frames used.  Autoaligned in MaximDL, and sigma combined using the RC Sigma Reject Plugin for Maxim.   DDP done in ImagesPlus, followed by levels and curves adjustments in Photoshop CS.  Sharpening was performed using a combination of unsharp masking and Lucy-Richardson deconvolution (PSF 5x5, 3 iterations, ImagesPlus) in selected areas.  I also used Neat Image to smooth out certain regions, since the signal to noise ratio in the dark areas was suboptimal due to the relatively short exposure time for this faint object, even at f4.5.

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