alan4908

I've begun to capture star clusters when it's inadvisable to image fainter objects due to moon light pollution. I also quite like them since they provide a very good basis for practicing star field processing, which I find quite challenging. For this open cluster I used 600s subs which caused my camera to enter its non-linear, whilst this did not create saturated stars it can distort colours. I therefore decided to use the Pixinsight script Repaired HSV separation which may be used to repair non-linear data - it attempts to put the correct colour back into the star cores by examination of the surrounding pixels. I also shot sum Lum data in order to create the "glowing" star effect that I like which to me also looks more natural. LIGHTS: L:5, R:10, G:9, B:8 x 600s. DARKS:30, FLATS:40, BIAS:100 all at -20C.

An LRGB image and my first attempt at this galaxy with my Esprit 150. I decided to capture more than my usual amount of Lum subs with the objective of boosting detail. I was very happy with the resultant galaxy details and colours. LIGHTS: L: 34, R:11, G:20, B:21 x 600s. DARKS:30, BIAS:100, FLATS:40 all at -20C.

The Medusa Nebula is a faint planetary nebula that was only discovered in 1955, presumably due to faint nature of the object ! The image is an LRGB with an Ha blend into both the L and Red channels. To get a reasonable looking deep red colour, I only blended a small percentage of the Ha into the L channel. The faintness of this object, makes this a very difficult to process. While the Ha yielded some details but I think it would be improved by adding some OIII narrowband data. I will therefore attempt a bi-colour (Ha/OIII) at some point. LIGHTS: L:6, R:8; G:12;B:8 x 600s, Ha:14 x 1800s. DARKS:30, BIAS:100, FLATS:40 all at -20C.

A reprocessed attempt on NGC891. The starfield was processed separately from the main galaxy in an attempt to reduce the impact of the bright red/yellow stars. I was very happy with the amount of detail displayed in the main galaxy. LIGHTS: L:21, R:17, G: 15, B: 17 x 600s. BIAS:100, DARKS:30, FLATS:40 all at -20C.

An RGB image with a synthetic Lum layer. I decided to try taking a close up of M45 since I was interested in revealing the details of the nebula. I like the details and the star colours, however, I think I prefer a wider field of view. LIGHTS: R:25, G:14,B:49 x 120s, DARKS:30, FLATS:40, BIAS:100

A LRGB image with an Ha blend into both the L and Red channels. The image represents about 27 hours integration time. I was pleased with the result. The Ha data, which represents about half the integration time, contained less than perfect subs, however, since I had quite a lot of them (33) and the Ha was quite faint, I decided to go for an aggressive data rejection approach using the Poisson algorithm, the alternative would to have retained only the best quality subs. I decided to configure CCDstack to allow up to 26 rejections in a 33 pixel stack - which gave a good result. LIGHTS: L: 19, R:12, G:18, B:16 x 600s, Ha: 33 x 1800s. DARKS:30, FLATS:40, BIAS:100 all at -20C.

I was pleased how this LRGB image turned out, the most difficult part was obtaining the colours that I wanted on the galaxy arms (I went for a slightly purple blue). I was surprised by the clarity of the Ha regions, particularly as I did not use a Ha filter. I also went for a very bright core, I experimented with HDR processing but this simply made it dimmer and did not reveal any further detail.

My first attempt at the Crab Nebula (M1). The cropped image is a LRGB with Ha blended into the Lum and Red channels and represents about 14 hours integration. I was quite pleased with the amount of detail revealed. LIGHTS: L:14,R:16, G:8, B:14 x 600s, H:11 x 1800s. DARKS:30, BIAS:100, FLATS: 40.

A crop of the NGC2903 image showing the details of the galaxy.

A 10hour LRGB image of NGC2903 - an interesting core, showing structure. LIGHTS: L:13, R: 19, G:13, B: 13. DARKS:30; FLATS:40, BIAS:100 all at -20C.

My Ian King Roll Off Roof Observatory

A crop of the M31 data showing the enhanced detailed obtained with the Esprit 150, for a similar view with the ED 80 look in my Deep Sky II folder.

I was interested to see if I could get more detail from my M31 4 panel mosaic acquired with my SW ED80 by applying new lum data acquired from my Esprit 150. With the same camera, the FoV of the Esprit is only about 1/4 that of the ED80, so I decided just to enhance only the core with the higher resolution data. I used RegiStar to overlay the existing mosaic with the Esprit 150 lum data and then blended the two images together using PS and PI. The details of the subs are below: ED 80 1 2 3 4 L 16 16 18 12 600 s R 19 12 15 13 600 s G 16 18 9 10 600 s B 18 19 13 16 600 s H 5 8 6 6 1800 s Esprit 150 (M31 core) L 27 300 s

I decided to take this image of the open star cluster NGC884 with the goal of practicing my star field processing technique Basically, I think my star field images can be improved mainly in the sense of getting better colour into the core of the stars. For this image I tried several different approaches before settling on a DDP stretch of the Lum and RGB data which I then blended via PS Screen with some slightly stretched linear RGB data to get colour into the star cores. I set the exposure at 120s which gave a result such that the pixel level was just below my cameras non-linear region for the bright stars. LIGHTS: R:20,G:20;B:12 x 120s, FLATS:30, BIAS:100, DARKS:40 all at -20C.

An LRGB image of IC63 with Ha blend into the Lum and Red channels with a total integration time of 14.5 hours. This object is also known as the the Ghost of Cassiopeia. I like the outer glow of the nebula, which is caused by interaction of the nearby bright star Gamma Cass, which is just out of view, towards the top of image. I was also pleased that I was able to capture some nebula detail. I decided not to reduce the stars too much, since I like their variety of colours and sizes.

An LRGB image of a 70% illuminated moon. Taken with my Esprit 150 and Trius 814. At this level of illumination the image just fitted my field of view. After calibration in CCDstack, I selected the clearest images and aligned these in RegiStar. After stacking/error rejection in CCDstack, I then followed my normal DSO post processing (a mixture of PI and PS) with the exception that I used PS autocolor for the initial colour balance.

An LRGB image with Ha blended into the red and lum channels. The Ha is quite intense in this region so I only blended a small fraction into the red channel in order not to overwhelm the other colours. The image is cropped and rotated in order to highlight a "blue dove" that I saw when processing the image. I was also experimenting with a lower exposure time of 20min Ha subs. These didn't appear to make any difference to efficiency of gathering data, so in future I will stick with my default of 30mins. LIGHTS: L:16,R:10,G:14,B:18 x 600s; Ha:34 x 1200s, DARKS:30, FLATS:40, BIAS:100 all at -20C.

An LRGB +Ha image of the Wizard nebula. The Ha was blended into the Lum and Red channels. I had quite a processing battle to get (what I hope) are the correct star colours. I found it particularly difficult to get the blue in the blue stars that are embedded in the red nebulosity.

A bi-colour (HOO) image of the Wizard Nebula. 13.5hours integration time.