alan4908

LBN 438 is a dusty nebula located in the Lacerta constellation which is also known as the sand worm (from the Dune science fiction series) or the shark nebula. It doesn’t appear very often on SGL, probably because it is so faint ! It is illuminated by interstellar radiation known as Extended Red Emission (ERE). ERE is a relatively recent discovery (1975) and is a photo-luminescence process whereby hydrogenated amorphous carbon is illuminated by interstellar photons in the 500 to 1000nm spectral range. Although the nebula also contains ionized hydrogen, it only emits a relatively weak Ha signal, so I decided to only use broadband filters to acquire the target. The LRGB image shown below was captured with my Esprit 150 and represents just over 13 hours integration time. At the top of nebula is a reddish glow, which I presume is due to ERE. The nebula is surrounded by very bright blue stars which can detract from the relatively faint nebula, so these have been stretched much less than the rest of the image and then blended back into the main image. If you look closely at the background you will also be able to see various small background galaxies (eg middle left). I hope you like it. Alan LIGHTS: L:31, R:17, G:15, B:17 x 600s; DARKS:30; BIAS:100; FLATS:40 all at -20C.

Thanks Bryan

Thanks - I believe my imaging resolution of 0.7 arc seconds per pixel helps to bring out the details but it also makes imaging capture more challenging, particularly as I image unguided. Alan

Thanks Peter. Thanks for the comment Dave. Hmmmmm..... I had a look in Aladin but cannot see anything marked so I presume it must be a faint reflection nebula, although the shape suggests some form of shock wave. While I can see the object in other images, most scientific attention has been directed towards on the other side of Barnard 175 where the various remnants of the supernova explosion can be seen. Thanks Steve . Thanks - yes, the Esprit 150 is an excellent scope - if anyone is in the market for a large refactor, then it is definitely worth considering, particularly given the price compared to the competition.....

Thanks Adrian ! I'm glad you liked it Paul - and you are correct in that the wide dynamic range of this object makes it a challenge Thanks for the comment. Alan

In the constellation Cepheus, at 1400 light years from Earth, lies vdB 152, a small blue reflection nebula located at the tip of the dark Bok nebula Barnard 175. Embedded in the dark nebula is the Herbig Haro object HH 450. The faint red streak to the right of the reflection nebula is a supernova remnant known as SNR G110 + 11.3 which appears to be approaching vdB 152. Some of my notes for those that might be interested: Reflection nebulas are created when a nearby star illuminates the gas of at a nebula at an insufficient energy level to ionize the gas but strong enough to create light scattering that makes the dust visible. Reflection nebulas mostly appear blue because particles in the nebula scatter blue light more efficiently than other wavelengths. Bok nebulas are isolated and relatively small dark nebulas containing dense dust and gas from which star formation can occur. Herbig Haro objects are bright patches of nebulosity that form when fast moving narrow jets of partially ionised of gas, ejected from a newly formed star, collide with nearby gas and dust at several hundred km/s. The LRGB image below represents 12 hours integration time and was taken with my Esprit 150. An annotated image is also shown. Alan LIGHTS: L:28, R:13, G:14, B:17 x 600s, BIAS:100, DARKS:30, FLATS:40 all at -20C.

Thanks ! Many thanks for your comment Olly.

Thanks - I don't often reprocess but I'm pleased that this time. Thanks for the comment. Many thanks Dave.

I decided to reprocess my M100 data from last year. This time, I decided to present the image in a much wider field of view, which has the benefit of highlighting the various background galaxies. The other notable changes are that the blue spiral arms are emphasized more and the overall brightness of the central galaxy has been increased. At just over 12 hours integration time, this was taken with my Esprit 150. Alan The original version is here:

I use NoMachine https://www.nomachine.com/ and actually prefer it over TeamViewer. Alan

Thanks Yes, I really do like my Esprit 150 - given the quality, I think it represents excellent value for money. Alan

My second processing attempt at the dark nebula LDN981. This time, I decided to try a more traditional LRGB rendition and so excluded the Ha I had also acquired. The image below represents 15 hours integration time and was taken with my Esprit 150. Alan LIGHTS: L:29, R:20, G:18, B:23 x 600s;. DARKS:30, BIAS:100, FLATS:40 all at -20C.

My first attempt at LDN981, a dark cloud nebula located in Cygnus. I decided to try to make the image a little more colourful than the conventional rendition by capturing 10 hours of Ha data which I subsequently blended into the Red and Lum channels. This significantly increased the red parts of the image and the definition of the dark dust lanes, see below. At the bottom left on the image, an interesting object can be seen (Herbig Haro 389). This is revealed as a blue/red angular shock wave which has been created by a fast moving jet of partially ionised gas, which has been ejected by the central star, colliding with nearby gas. The image below represents 25 hours integration time and was taken with my Esprit 150. Alan LIGHTS: L:29, R:20, G:18, B:23 x 600s; Ha: 20 x 1800s. DARKS:30, BIAS:100, FLATS:40 all at -20C.

If you end up with an integrated image that you are not happy with, you could also try realigning all the subs again but this time with the frame adaption option checked in the Star Alignment process. This option makes PI perform a linear fit of individual sub frame with respect to the reference frame. This option is recommended if you have large intensity variations from the different data sets. These intensity variations might come from a different camera, different camera angle etc.

Thanks - yes, I agree about the appearance, it does look odd. In fact, everything about this galaxy seems a little strange and mysterious. Alan

Thanks - yes, I was very happy with the detail on this one, helped by the superlum + deconvolution approach mentioned above. Thanks - Yes, I did find this difficult to process. An Adam Block PI technique that I found of use when processing this: given the very high dynamic range of the object, after HT stretching it so that you can see the halo, use HDMRT but only via selecting a preview with the preview encompassing the "blown out" parts. Then apply HDMRT to the preview. Use the script substitute with preview to obtain the result. You may need to blend in the result with the original image, so that you don't see the join. You may also need to repeat this technique twice, for example, once to the very bright areas and once to the bright areas. Alan

Thanks for the comment Alan. The faint halo rendition was helped by application of a so called superluminance (constructed from the noised weighted L, R, G, B stacks), deconvoluting this also helped in extracting the detail. Thanks - yes - I found it interesting to read up and understand a little more about this mysterious object. Thanks Alan

For some reason, I've never imaged M94, so here's my attempt at this very unusual galaxy. M94 is approximately 17 million light years distant and contains both inner and outer rings. Star formation occurs in both rings but is mainly concentrated in the inner ring which is also known as a starburst ring, within this region, the rate of star formation is occurring so fast that it will exhaust the available interstellar gas supply well before the death of the galaxy. The extensive outer ring contains about 20% of the galaxies mass and consists of spiral arms when viewed in IR/UV, however, in visible light it appears as a halo. Exactly how the outer ring formed is subject to debate. Past theories include gravitation interaction with a nearby star system or accretion of a satellite galaxy, however, problems have been identified with each of these theories. It is also strange that in 2008 a study indicated that M94 also seems to have little or no dark matter, which is very odd since it is inconsistent with current galaxy formation models. So, all in all, a very mysterious object. The LRGB image below represents just over 13 hours and was taken with my Esprit 150. LIGHTS: L:26, R:19, G:18. B:17 x 600s; DARKS:30, FLATS:40, BIAS:100 all at -20C.

Thanks for the comment. Agree on your HH comment - these are quite unusual objects. Thanks. VdB1 is close to the star Beta Cassiopeiae (or Caph) one of the main stars on the W (see below). Although it was out of the field of view for the above image, I was getting a bit of stray light contamination from this star which I eliminated via Pixinsight's DBE routine. Thanks. I must have a look at that book - it looks quite interesting. Alan

Here's an image that you don't see often - vdB1 which is the first entry in the van den Bergh catalogue. VdB1 is a small reflection nebula in the Cassiopeia constellation. It's approximately 1600 light years distant and about 5 light years across. It consists of dust and gas which are illuminated by bright nearby stars. The scattered light from these stars appears blue since scattering is greater at shorter wavelengths. Another interesting object within the field of view, is a somewhat strange looking looped nebula. This is an example of star formation and several herbig-haro (HH) objects are also located in this vicinity. HH objects are bright patches of nebulosity which are created when high speed partially ionised gases ejected by stars collide with nearby gas and dust. I've marked the location of these objects on the annotated version below. The image below represents just under 13 hours integration time and was taken with my Esprit 150. Alan LIGHTS: 27, R:19, G:17, B: 14 x 600s, DARKS:30, BIAS:100, FLATS:40 all at -20C.