Wednesday, April 20, 2016

M27 - The Dumbell Nebula 20-Apr-2016





Distance 1,360ly, in Vulpecula

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300. Exposures: 3 @ 5 min., Ambient temp 59f.
Image capture scale: 0.41 arc-sec/pixel (un-binned). Resized to 50% in ThumbsPlus. Final image scale/resolution 0.82 as/p. Field of view (horizontal) = 24.5 arc-min. Image capture using ImagesPlus Camera Control 6.0.
Mount: Orion HDX110 German equatorial mount. Autoguided with an SBIG Sti autoguider and a Celestron OAG (off-axis guider), with PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 5 bias frame master and 0 flat frames, Average combined. HDR Stretch, Curves and multiple enhancements in ImagesPlus. Cropped and resized to final dimensions, one pass unsharp mask, contrast, saturation, gamma in ThumbsPlus.

20160420_M27_CombAvg-IPddpadjnr-TPadj.jpg

Monday, April 18, 2016

A Marvelous Coincidence



The Sun and Moon have nearly the same angular size a seen from Earth and so make total solar eclipses possible.

Sunday, April 17, 2016

M16 - The Eagle Nebula 13-Apr-2016




Distance 7,000 ly, in Serpens

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300. Exposures: 3 @ 10 min., Ambient temp 56f.
Image capture scale: 0.41 arc-sec/pixel (un-binned). Field of view (horizontal) = 10.9 arc-min. Image capture using TSXPro Camera Add On (Software Bisque).
Mount: Orion HDX110 German equatorial mount. Autoguided with an SBIG Sti autoguider, a Celestron OAG (off-axis guider) and a Starlight Xpress SXV-AOLF (Adaptive Optics Large Format) device using PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 5 bias frame master and 7 flat frames, Min/Max Exluded Average combined. HDR Stretch, Curves and multiple enhancements in ImagesPlus. Cropped to final dimensions of 1600x1600. One pass unsharp mask, downsized 50% in ThumbsPlus. Final image scale/resolution 0.82 as/p).

20160413_M16_CombExcAvg-IPddpadj2-TPadj-IPnr-TP2.jpg

Galaxy M66 in Leo 12-Apr-2016




Distance 36 ± 5.0 Mly

Telescope configuration: Celestron EdgeHD 1100 with the Celestron 0.7x focal reducer (fl=1960mm, f/7.0).
Camera: Nikon D5300. Exposures: 4 @ 10 min., Ambient temp 55f.
Image capture scale: 0.41 arc-sec/pixel (un-binned). Field of view (horizontal) = 19.4 arc-min. Image capture using TSXPro Camera Add On (Software Bisque).
Mount: Orion HDX110 German equatorial mount. Autoguided with an SBIG Sti autoguider, a Celestron OAG (off-axis guider) and a Starlight Xpress SXV-AOLF (Adaptive Optics Large Format) device using PHD2 autoguiding software, not dithered.
Post processing: ImagesPlus 6.5: NEF conversion and calibration, alignment, stacking/combining using 0 dark frames, a 5 bias frame master and 7 flat frames, Min/Max Exluded Average combined. HDR Stretch, Curves and multiple enhancements in ImagesPlus. Cropped to final size. Two passes unsharp mask, downsized 50% in ThumbsPlus. Final image scale/resolution 0.82 as/p).

20160412_M66_CombExcAvg-IPddpadj-TPadj.jpg

NGC3628 - The northern galaxy in the Leo Triplet 02-Apr-2016

NGC3628 - The northern galaxy in the Leo Triplet 02-Apr-2016

For details see here
 



Sunspot AR2529 - 17-Apr-2017

Sunspot AR2529 - 17-Apr-2017

Didn't get a chance to take a shot at this until today. Still, pretty respectable size as far as sunspots go.
 
 
Taken with a Nikon D5300, 1/640th sec at ISO 100 through an Explore Scientific 127mmED refractor. Original 6000x4000 frame cropped to 3000x2000 and resized to 50pct.
 

Saturday, April 9, 2016

Recent Work - May, 2015

After a brief hiatus, I'm back to astrophotography.

Here is a sampling of photos taken with the Celestron 14 inch EdgeHD and the Canon 6D (full frame) camera: http://www.pbase.com/wjshaheen/apod_submissions

And, here is a gallery of cumulative work done over the years:
http://www.pbase.com/wjshaheen/astro_images_by_subject

William Shaheen
Gold Canyon, AZ
USA

Friday, April 8, 2016

Astrophoto Flat Field Illustration

This is to demonstrate the effect of taking "flat" frames to clean up errors in the optical system, such as due to dust-motes or vignetting. (Bias and dark frame subtraction are another matter.)

First up is an unprocessed single frame light image ....





Now, here is the flat frame, taken the next morning. (Note the dust mote just above and left of center and the more pronounced ones toward the bottom.) ...

 
And here is the resulting frame after applying the flat frame.  (Still needs a little work but I think you get the point. Another reason to crop) ...
 
 
No noise reduction or bias frames were applied, just to show only the effect of applying a flat frame.
 
Flat frames are worth the effort.
 
William Shaheen