The late summer – early autumn period marks a return of astronomical darkness and therefore for many a return to astronomy.  Naturally the iconic objects passing overhead at this time within Cygnus, Cepheus, Pegasus and Andromeda get most attention, so it’s easy to overlook other possibilities such as the less well-known Lacerta (Latin for Lizard) constellation situated between the aforementioned constellations (see skymap below).

Located along the western edge of Milky Way in the southern section of Lacerta, is the large but faint emission nebula SH2-126 AKA the Great Lacerta Nebula (GLN). Consisting of a reddish filament structure with a size of over 3 degrees, the nebula forms a “stellar funnel” at the centre and snaking away to the right is LBN 437 or the Gecko Nebula, a molecular cloud whose denser part is associated with bright young stars; the fascinating structure of the nebula is best seen in the starless Ha image below. The source of ionization is intense ultraviolet radiation from the stars including 10 Lacertae, a blue main sequence star. 

This somewhat elusive object requires significant integration time to bring out the detail and colours, which at over 21-hours over 10 nights is the longest I’ve been able to achieve from Fairvale Observatory so far and even that was not without its problems.  Moreover, despite this I also found processing to be very difficult, though I’m pleased with the outcome which I believe does justice to this magnificent astrophotography object.  Notwithstanding, I hope to return at another time with a bigger FL telescope to take a closer look at the Gecko, which here can just be seen on the right hand side of the GLN.

August marks the return of astronomical darkness and that also means a return to astrophotography, which inevitably draws us to objects within the Sagittarius Arm of the Milky Way that traverses the night sky at this time of the year.  As such there’s no shortage of targets but close to the zenith, high in the sky, it is difficult to avoid the wealth of possibilities that abound within Cygnus – the Swan.  I have often imaged favourites such as the North America Nebula and Veil Nebula but there is much, much more to Cygnus, in particular the vast area of nebulosity the stretches across the region centred around Deneb and Sadar (see red areas bekow).

Here I framed the image around the emission nebula SH2-115 but was unprepared and surprised by the richness of objects that the wider FOV captured.  Not far from Deneb, the large blue SH2-115 is energised by the open star cluster Berkley-90.  Numerous emission nebula from Lynds’ Catalogue of Bright Nebulae (LBN) can be seen adjacent to SH2-115 across much of the northern section of the image (see below).  Using the SHO Hubble palette format, here the nebulosity forms a rich golden-brown ribbon, which is exquisitely sculpted by the prevailing interstellar forces. 

South (right) of SH2-115 is SH2-112, a circular emission nebula thought to be energised by a blue double star BD + 45 3216 at the centre, with dark clouds and filaments contorted around the periphery.  Finally, just north-west of SH2-115 is the small but enigmatic SH2-116, AKA Abell 71.  This faint, blue disc was originally thought to be a planetary nebula, but this is now in doubt and awaits further research.

All-in-all there’s much to see in this busy image, which is an astrophotographer’s treasure trove of exciting objects, many of which are worthy of imaging in their own right; maybe I will return here again with a larger focal length one day? 

As previously reported (see Flame & Frogs), there’s a lot going on around the Auriga constellation at the beginning of the year, which I was able to capture well using the Samyang 135 rig in January.  For some reason and assisted by an unusually long period of clear skies, I then spent the rest of the month imaging the same area of sky and beyond again but with the William Optics GT 81 rig, with the aim of getting better resolution of the myriad objects that are found in this busy region – which would mean the need for a mosaic.

I generally avoid mosaics, (a) because they take too long and suitable weather windows in the UK are usually short, (b) because I find them a lot of hassle and (c) I now have the Samyang 135 rig to take care of such widefield framing.  Notwithstanding, 15-hours imaging time later, I completed 3-panels which incorporated Alnath, IC 405, IC 410, M36, M38 and more and I had the basis for my mosaic.  Unfortunately, the most southern panel including Alnath turned out to devoid of anything of interest, so in the end I decided to use only two panels for the final HOO image (see top of the page), which then broadly approximated to the aforesaid Samyang image i.e. why bother?

I have previously used Microsoft’s built-in mosaic software but this time decided to try out PixInsight’s inevitably complicated but excellent Photometric Mosaic script; earlier this year I set-up the new PI Gaia catalogues which provide the basis for identifying all stars in an image and furthermore, provide their individual photometric data, which can then be used for accurate colour calibration and exact mosaic matching!  Put simply, using the said database each mosaic panel is plate solved so that the image then contains the underlying detailed spatial and colour information.  Finally, using PI’s Gradient Merger Mosaic script this information is used to match and combine each panel with pixel accuracy to produce a seamless mosaic image.

Whilst I’m pleased with the final outcome and even enjoyed using the PI mosaic scripts, in this case I’m not convinced that the image is much better than the previous Samying 1135 version.  However, should the day come again when I get the mosaic urge, I’m now well prepared!