Re: [APML] New Ha(Ha/R,GB) Images

["Paul M. Rybski" <rybskip@idcnet.com>]

Dear Brian,

      Concerning the NGC 6888 photo, I noticed only a few stars -- and 
not the brightest in the field -- sporting diffraction spikes.  In 
which channel did these stars exhibit diffraction spikes?  Is there 
any way to remove them in Photoshop?

Paul Rybski, Physics, UW-Whitewater

>Hi All,
>
>Hope you all are having a great holiday season!
>
>I'm kind of a season behind with these objects but with a few days 
>off I finally got
>to them. These 2 images are wide field (38 x 25 arc minutes) CCD images of the
>Bubble and Crescent Nebulas using HaRGB compositing techniques. The 
>Crescent is a
>rework that I posted a few months back but the star colors and 
>nebulosity are much better.
>The HaRGB technique was tricky to get good color results. Each image 
>is 120:30:30:30
>minute respective exposure using a 20" f/4 homemade Newt and a 
>Finger Lakes IMG6303E
>CCD camera. The Ha and R channels were combined 50/50 to make the R 
>component for
>the RGB color composite. The image scale is 1.5 arcsec/pixel.
>
>Following the thread of digital vs film......with the 1 & 1/2 hour 
>of download time ( parallel
>interface on my camera) for these series of images it now takes 5 
>hours of acquisition time
>to just get the raw data for one of these images. A few years back 
>short exposure times
>were touted as a main advantage for CCD imagers but as we have 
>gained experience
>exposures are now at or exceeding film length times to get optimum 
>results not to mention
>the post processing times involved.
>
>
>These new images are at:
>
>http://www.heavensgloryobservatory.com/Color_Jpegs/ngc6888HaRGB08-6303Eweb.jpg
>
>and
>
>http://www.heavensgloryobservatory.com/Color_Jpegs/ngc7635HaRGB03-6303Eweb.jpg
>
>
>
>Best regards, Brian Lula
>
>
>
>
>Brian Lula
>Polytec PI, Inc.
>(508) 832-3456
>
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