clear sky chart

Job 9:9

Job 9:9-10
9 He is the Maker of the Bear and Orion,
the Pleiades and the constellations of the south.
10 He performs wonders that cannot be fathomed,
miracles that cannot be counted.

Sunday, July 28, 2013

M16, Hα & Oiii

I've imaged M16, the Eagle Nebula last year with the dslr.  This time, I used the CCD with Hα and Oiii.  If I had a Sii, I could have dome a hubble palette.  There was very little Oiii signal in this object.

Scope:    Celestron C6N
Mount    Celestron CG5
Camera  Orion Starshoot G3
Filters    Celestron Oiii, Orion Hα 7nm
Exposures  5 X 5 minute Ha, 6 X 5 min Oiii
Processing  Deep Sky Stacker, color combining and post processing in Photoshop CS5

This is the original size of the image put out by this camera.

If  I were to image this again, I think I would do an RGB with an Hα luminance.

Although this is a low resolution camera, I like imaging with this over the DSLR, as the exposure time is much less.  The sensitivity is much better than the DSLR.  The vignetting is almost nil, and with the exception of about a dozen hot pixels, the noise is way better.  I could never have taken a picture this clean with a total of 10 frames with the DSLR's, let alone get the fainter nebulosity on the bottom of the image. 

The following is the monochrome Hα image.

No brightening of this image was performed.  Noise reduction in the dimmer areas was done, and the star sizes were made slightly smaller, but generally, this is what I ended up with coming out of DSS.

Sunday, July 21, 2013

M82 with the CCD

I imaged M82 the other day, when it was rather low in the northern sky.  It was cloudy to the south, where I wanted to image.  Ursa Major was totally in the clear, so I thought I'd give it a try.

I imaged this using Ha for the red channel, and wideband green and blue to fill in the other colors.  The Ha was unaffected by the light pollution, as I was able to easily pick up the starburst region which I have never gotten before. The star spikes are artificially added using Carboni's astro tools.

What is interesting with the CCD is that very little post processing is required after these images are taken.  Very little histogram stretching is required.  The hardest part is combining the colors properly, but the detail appears pretty much as you see it here, after the channels are combined.  With the dslr, I'd have to stretch the histogram massively to get this, and even then, the starburst area does not show up.

I really need to take notes on the next DSO I image and write down the post processing workflow.  You wouldnt believe how simple it is, once the colors are combined and corrected, however, because the color levels are never correct when theyre taken, its difficult to know when they're right. 

To summarize, when Iprocessed this, I combined the colors, got rid of the nasty gradient on the green and blue, because of the light pollution, got the color balance close.  Did some very minor histogram stretching, a little bit of noise reduction.  Reduced the star size... sharpened, and here it is....

This is the unprocessed Ha stack with the only modification being done was to set the black point.  This is a stack of 5 frames.  No noise reduction, no histogram stretching...This is just as you see it coming out of DSS, except the black point was set in photoshop.  This was used as my red channel in the above image.

Wednesday, July 3, 2013

M27 Narrowband

If I ever needed proof of the difference in image quality one gets with a dedicated CCD vs a dslr, this has to be it.  I imaged in 2 colors, 8 3 minute frames per color (Ha and Oiii), mapped the Ha to red and the Oiii to green and blue.  The amount of stretching in photoshop was nil - just a wee bit to bring out the edges, but for the most part, this is how bright this appeared on the capture screen.

If that werent enough, I didnt stop there.  I re-mapped this into a Hubble Palette version.  Even more detail is visible!

Not bad for a 2-color image.  This narrowband stuff is turning out to be too much fun!  I still cant get over the fact that I did this with about 45 minutes worth of camera time.

This is a picture of last year's M27 taken with the dslr. 

Although not a BAD image, there was a lot of image stretch to bring out the fine detail, and lots more imaging and processing time.  Of course, this is a standard RGB using the dslr.