alan4908

Yet another reprocess after taking on board comments. Changes are: 1) Star halos were reduced or removed. I discovered that when I had imported the image from CCDstack into PS I hadn't paid attention to the pixel values of the stars. On the previous reprocessed image, the brighter stars turned out to have a pixel value of over 200, making them very difficult to colour. If you do attempt this you get halos. I also used the smudge tool set to colour and a brush set at 40% opacity to clean up some halos. 2) Reduced colour artifacts - on the previous image I discovered that I hadn't blurred the colour starless image sufficiently. As a consequence I produced many colour artifacts. This version incoporates an additional Gaussian Blur 4 and a Dust and Scratches radius 24 and threshold 16. 3) Allowed some green into the image which I think helps in the transition from the gold/red to the darker colours. 4) Slightly reduced the overall colour contrast. I noticed that one side benefit of the halo reduction was that I obtained increased resolution in the starfield, for example the very bright blue star was revealed to consist of several stars.

A crop of the main image

After watching several hours of video tutorials on how to process Hubble Palette images, I made this result which uses the same data as my original attempt. The basic steps were: 1) create a Hubble Palette via PS clipping masks; 2) Adjust colours; 3) Remove NB stars via Stratton. 4) Use the Ha as a Luminescence layer (the OIII and SII where a bit noisy) - sharpen and apply High Pass Filter, reduce noise 5) Remove stars from Luminosity layer via Stratton. 6) Blend Luminosity into colour image. 7) Blend RGB star layer via PS Screen into image (this seemed to give a more natural effect than the alternative PS Lighten).

A Hubble Palette of IC1396 with a RGB starfield.

This narrow band image with an RGB starfield was created by mapping Red to Ha, Green to SII and Blue to OIII and represents about 16 hours imaging time. Straton was used for removing the narrowband stars before replacing them with the RGB starfield. The starfield blending was achieved by using PS Screen since I found that this method gave a much improved starfield compared to my previous technique of simply replacing the NB starfield via a RGB field via a NB star mask. I'd like to have captured more SII data but got fed up waiting for a clear sky. H:8; O: 12; S: 5 x 1800s. R:7; G:6 B:6 x 600s. DARKS: 30; BIAS:100; FLATS:40

I decided to attempt to improve the star field of the image by mainly making the stars more circular at the edges of the frame (mainly top right and bottom left). This was done by two methods: 1. Radial blur on individual stars; 2.Creating a duplicate of the image which is then shifted by a one or two pixels in the horizontal and vertical directions pixels via the offset filter and then applying the Darken blending mode. I also used masks to limit the impacted area and the degree of the effect.

A crop of the wide field view of NGC6888.

My first bi-colour narrowband image of the Cresent Nebula, the total integration time is 14.5hours. Ha is mapped to red, OIII is mapped to blue and synthetic narrowband green was created from a combination of Ha and OIII via Noel's actions. I also decided to show a few subs of broadband data in order to create a more realistic starfield and decided to try out creating synthetic broadband green. The Ha, OIII and synthetic green where blended using the PS technique described by Don Goldman in Lessons from the Masters. Having created an RGB image I then created a synthetic narrowband luminance image on which I performed all sharpening and contrast enhancement. The star field was processed separately and blended into the narrowband image via a star mask. LIGHTS: L:5; B:12; x 600s; Ha:5; 16 x 1800s.; DARKS: 30; FLATS: 40; BIAS: 100 all at -20C.

I went for a reasonably long exposure (15.5 hours) mainly since this length of time appears to get optimal results. The image is a Red blend of Ha using PS Screen Blending, I did try the Lighten blending method but preferred the result with Screen. The Luminescence (L) layer was deconvoluted in CCDstack and then further sharpened with Smartsharpen and a High Pass Filter. The RGB layer was blended into the L layer after a linear stretch with Levels. Shadows/Highlights was then applied to the RGB layer before the image was combined into an LRGB. LAB colour applied to a and b channels and finally a gentle boost of Vibrance. The starfield was processed separately since some of the stars where getting too big, I also spent quite a long time correcting the star field for Chromatic Aberration errors.

I was originally attempting to construct a LRGB image of the California nebula (NGC1499) but it disappeared below my horizon before I had captured sufficient data. I therefore decided to create my first tone mapped image using the Ha I had acquired as the base. I decided to go for near(ish) representation of colour, after a little experimentation, I eventually settled on red for the nebula, a blue (ish) background and white (ish) stars. The Ha data which was the basis for the image is displayed in a separate image of this gallery.

My first Ha nebula image with my new 3nm Astrodon filter. Although the California Nebula disappeared below my horizon before I had captured all the data I wanted, I was quite impressed with the amount of detail revealed by stacking just four subs. The details where enhanced in PS with a High Pass Filter and HDR toning. LIGHTS: 4 x 1800s Ha. DARKS: 30; FLATS: 40; BIAS: 100 at -20C.

A crop of the image M106 bonus galaxies (reprocessed).

After watching a few more hours of PS tutorials, I decided to reprocess the M106 image. In an attempt to reduce the red in the image, I decided to more aggressively black clip the Ha data, prior to blending with the PS screen mode. To improve the image quality, I also used noise reduction on the Ha data. I then made a few slight changes to the colour - to reduce the red further I change the Hue slightly towards Blue. To increase the effect of the Ha regions, I reduced the amount of cyan. Finally, I decided to apply a PS cooling filter - totally non-scientific but I thought it improved the image. I also took the opportunity to correct a few star defects: non circular stars, where fixed by a radial blur and a few red star halos I'd missed from my previous attempt where eliminated.

I've recently started to increase my average imaging time per object, so this time I went for just over 15 hours. I also decided to compose the image by emphasizing the additional galaxies within the image since they also quite detailed. I was happy with the result. On the processing front: To bring out the details, on the Luminescence layer I used HDR toning and the High Pass filter at a range of pixel widths. Deconvolution (within CCD stack) and Smartsharpen were also applied to the main image. On the RGB layer, Shadows Highlights, LAB colour and Vibrance were applied. Given the small size of some of the galaxies, I decided to minimize the impact of the stars by processing the star layer separately. The Ha data was blended into the red channel via the Screen blending mode. Finally, I corrected some stars for Chromatic Aberration by selectively shrinking the red channel around some of the halos.

After watching several hours of PS tutorials, I decided to have another attempt at processing my recent image of M101. In this version I've changed several aspects: the blue colour has been reduced, the field of view has increased, I've also corrected some red star halos around blue stars. This last aspect is caused by Chromatic Aberration. To correct this I aggressively shrunk all the stars in the red channel and then applied a black layer mask. I then painted the layer mask with 15% white on the problem areas and then applied a mild Gaussian blur to the layer mask.

As a bit of an experiment, I put the ABELL 1656 image through the plate solving programme astrometry.net, which identifies quite a few of galaxies but as you would expect, the annotation gets a little crowded.....

Perhaps not the most visually stunning image in my gallery but perhaps the most interesting..... The Coma cluster (ABELL 1656) contains over 1000 galaxies and is dominated by two elliptical galaxies NGC 4874 and NGC 4889. It was also one of the first places where gravitational anomalies were observed by Fritz Zwicky in the 1930s’s, today it is thought that 90% of the cluster mass is formed of Dark Matter. A strange looking object is the star HD 112886 (top, middle). Is this an optical illusion created by a much nearer star and a “needle” type distant galaxy which appear to be overlaid on top of one another ? Taken with a Trius SX 26C. LIGHTS: 25 x 600s; DARKS: 40; BIAS:100; FLATS:40 all at -20C.

Since my telescope can hit the roof, I incorporated two safety switches on the RA and DEC axis, these switches are closed when the telescope is in the "telescope safe" position. I've also incorporated a third safety switch on the drop down wall. So for the roof to open or close all three switches must be in the closed positions. My second safety feature are design to minimize the chance of rain from entering the obsey when the roof is open. I've went for a total of three rain sensors, all of which are independent of each another. The main rain sensor is integrated into the cloud sensor and so far this has never failed. However, it is dependent on my obsey PC working correctly. I therefore decided that I needed a back up sensor that would trigger an alarm in my house if it detected rain when the roof when open- so I went for a battery powered wireless weather station approach - whilst this works, on testing it I was concerned that it requires quite a bit of rain before the sensor is triggered. I therefore decided on a more sensitive rain alarm sensor which sits on my warm room roof. This sensor also incorporates a heater, so needs to mains powered, it is interfaced it to a battery powered wireless alarm via a battery powered wireless link to my house. For the time being, I've decided not to install a UPS but I do have a mains power detector alarmed in the house. So, when I'm observing it's normally from a PC screen in the house. I recently decided to purchase CCDNavigator which has recently been upgraded to be ACP Compatible which makes programming an observing session very easy. Overall, I've been impressed by not only the physical build but also of the quality of the controlling software, which has proved very reliable.

In 2015 I decided that I wanted to move to automated observing (basically due to the UK weather and the fact that I like my sleep) - so, after a bit of research, I decided to go for a Ian King Roll Off Off Observatory - mainly due to Ian's excellent reputation and the fact that it came with various options such as an electric roof and a cloud sensor/electric roof controller that where Ascom and ACP weather alerts compatible. I decided on the smallest size available since I wanted it to blend into my garden as much as possible. Since I was interested in automation, I decided on a very small warm room, basically just large enough for someone to get inside. My design philosophy was that main power and ancillary equipment would, as far as practical, go in the warm room and low voltage equipment would go in the main obsey.

I went for a relatively long exposure with M101, mainly because of its faint spiral arms - I ended up with just over 17 hours. From a processing perspective, the image was sharpened by deconvolution (CCDstack2) and smartsharpen, HDR toning (PS). The Ha was incorporated into the LRGB image by blending the Ha data into the red channel via the PS screen blending mode. LIGHTS: L26; R:31: G:11: B:12 x 600s + Ha: 12 x 1200s, DARKS: 30; FLATS:40; BIAS: 100 at -20C.

My second image with my new camera (Trius 814) and my first attempt at M51. Since the galaxy is relatively small in the field of view and stars can get relatively large when stretched, I decided to process the star layer separately from the galaxy. The Luminescence layer was sharped by a combination of deconvolution (CCDstack) and smart sharpen/HDR toning (PS). LIGHTS: L:11; R:10:G:9:B:8 at 600s + Ha: 3 x 1200s. BIAS:100; DARKS: 30; FLATS: 40.