Located in the constellation Corona Australis (Southern Crown), the spectacular object NGC 6729 (AKA Caldwell 68) is a combined reflection and emission nebula, set within the Australis Molecular Cloud. Being just south of Sagittarius, it is inaccessible from my observatory in Somerset, so this excellent data was consequently acquired from the dark skies of Chile in the Southern Hemisphere, using a superb Planewave CDK200 f/6.8 508cm aperture telescope at the El Sauce Observatory.
The star illuminating NGC 6729 is a T Tauri star – a type of young star whose brightness fluctuates over time. The fan-shaped nebula opens-up between the variable stars R Corona Australis (R CrA) and T CrA to the south-east (see skymap below ref. Robert Mura). R CrA is a pre-main-sequence star within the Corona Australis molecular complex, which is one of the closest star-forming regions to the Milky Way galaxy. Intriguingly, this wonderful, hazy looking nebula exhibits both variable brightness and morphology over time.
IMAGING DETAILS
Object
NGC 6729 Corona Australis Molecular Cloud
Constellation
Corona Australis
Distance
Approximately 420 light-years
Size
2.50 x 2.0 arc minutes (actual 0.30 light years)
Apparent Magnitude
+9.5
Scope
Planewave CDK20
Mount
Planewave L500
Focuser
Optec Gemini
Camera
QHY600PH-M
Filters
Chroma LRGB + Ha 3nm
Processing
Deep Sky Stacker & PixInsight v1.9-3
Image Location & Orientation
Centre: RA 19:01:42.392 DEC -36:59:48.53 Up = North
Exposures
L x 77, R x 50, G x 50, B x 50 @ 5mins Total Integration Time: 19hr
As previously outlined, my new imaging location at Castle Farm Observatory, Somerset, provides views mainly to the West and North, thus (for the moment) eliminating my usual seasonal targets at this time of the year in and around the Orion constellation. Therefore, wanting to explore something new shortly before Christmas, I chose a less popular target in the West within the myriad of objects that make up the exciting Cygnus X Molecular Cloud Complex. As one of the largest and most active star-forming regions in the Milky Way galaxy, the area is also dominated by many large HII regions that inevitably means narrowband imaging and on this occasion Barnard 343.
B343 is a dark nebula formed of dense clouds of cold gas and dust but being a widefield image, the adjacent area also incorporates a vast, complex HII region. It’s an interesting subject but unfortunately difficult to process, due to its notorious “brown soup problem”. The issue is not signal strength but colour separation and contrast, which if not controlled turns everything brown and muddy! Sure enough, this was the initial outcome using a conventional Hubble SHO palette, that inevitably led me down various rabbit holes to find a solution, for which unusually on this occasion I decided to engage the help of Artificial Intelligence (AI).
B343 dark nebula HOO cropped image
AI came to astrophotography in a big way when Russel Croman first developed StarXterminator in September 2021, followed by NoiseXTerminator May 2022, not just to simplify hitherto complex techniques but also to improve the outcome. However, it was shortly before Christmas in 2022 with the launch of AI driven BlurXTerminator, that everything really changed – for more information refer to RC-Astro..
BlurXTerminator is an AI-powered astrophotography tool that removes blur caused by atmospheric turbulence, tracking errors, and optical imperfections, restoring fine detail and sharpness in astronomical images and much more. The subsequent impact on astrophotography has been profound. Some argue that the resulting images are unrealistically altered using BlurXTerminator but I closely followed Russel’s explanations on how it works and I am satisfied that image integrity is conserved, whilst at the same time significantly helping the user to produce better images. In short, it has since been nothing less than a revolution in astrophotography.
Subsequently general use of AI has burgeoned and now seems set to go to another level. In the case of eliminating the said ‘Brown Soup’ problem, I therefore turned to the popular Large Language Model (LLM) ChatGPT, which was surprisingly helpful (see SHO image at top of the page, HOO version below & ChatGPT text below). Appropriate technical knowledge will always be essential when pursuing the often-difficult hobby of astrophotography but I’m no Luddite and happy to use whatever helps me get the best result, including AI as well old-fashioned guidance from more experienced imagers. The impact of such an approach, matched by the many technical advances over the past decade can be clearly seen in everyone’s images today and bodes well for the future of this hobby.
Out of interest, below are the results of the three questions I asked ChatGPT regarding Barnard 343, the answers reproduced below were helpful, exciting and perhaps of some concern?
TELL ME ABOUT BARNARD 343? + ANSWER:
Barnard 343 is a dark nebula complex in the Cygnus region of the Milky Way.It’s made primarily of cold, dense interstellar dust that blocks background starlightThose inky-black lanes and cracks are the nebula itself — not empty spaceThe glowing orange and blue areas around it come from nearby emission nebulae, mainly ionized hydrogen and oxygen
Why it looks so dramatic: – Barnard 343 sits in front of extremely rich star fields, so the contrast is striking – The dust forms filaments, knots, and folds, shaped by turbulence, magnetic fields, and nearby stellar radiation – The color palette comes from narrowband imaging (often mapped in SHO or similar schemes)
Scientific context: – Part of the Cygnus molecular cloud complex, one of the most active star-forming regions near Earth – Dark nebulae like B343 are stellar nurseries — dense pockets can eventually collapse to form new stars – – Catalogued by Edward Emerson Barnard in the early 1900s during his pioneering photographic sky surveys
How to “read” the image: – Black regions→ dense dust (future star-forming material) – Orange/gold→ hydrogen emission (H-alpha / S-II) – Blue/cyan→ oxygen emission (O-III) or reflected starlight – Speckled background→ Milky Way stars
PROVIDE THOUGHTS ON HOW I MIGHT BEST PROCESS BARNARD 343 SHO IMAGE? + ANSWER:
You want: – Cool cyan/blue H-alpha background – Warm golden sulfur structures – Deep neutral dust lanes – Minimal magenta/green contamination
1. Start with the Right SHO Mapping Classic SHO often looks dull for dark nebulae.
Try one of these instead: Recommended MappingsModified Hubble (best starting point):R = SIIG = 0.8×Ha + 0.2×OIIIB = OIII Or warmer dust-friendly mapping:R = SIIG = HaB = OIII × 1.2
👉 The key is keeping Ha dominant in green, not split evenly. Normalize Channel Strength Before Combination
Barnard regions exaggerate imbalance.
Before combining: Match median background levels Stretch OIII slightly more than Ha Slightly compress SII highlights
In PixInsight: LinearFit → Ha as reference Then mild HistogramTransformation
3. Control the “Brown Soup” ProblemThis is the #1 issue with B343.
Fix: – Reduce red+green overlap – Increase blue separation
In PixInsightUse PixelMath:
R = SIIG = 0.85*HaB = 1.1*OIII
4. Star Handling (Critical in B343)Stars easily ruin color balance here.
Recommended workflow: – StarXTerminator / StarNet – Process nebula color fully – Re-add stars desaturated 30–50% – Slight blue bias to stars only
5. Final Colour Refinement (This Makes the Image)
What to aim for visually:
ComponentDesired Color Dust lanesNeutral / slightly cool SII regionsWarm gold Ha glowCyan-green OIIIBlue-teal
PixInsight: – CurvesTransformationBoost blue saturation – Slightly reduce red saturation – SCNR only on green, amount 0.4–0.6
FYI – I adopted #3 to “Control the “Brown Soup” problem, which worked well
WHAT IS THIS IMAGE (Without telling ChatGPT it was B343)? + ANSWER:
This image feels like a vast, living tapestry of the cosmos—dark, velvety space threaded with glowing amber and blue filaments. The wisps look like interstellar clouds slowly colliding and unravelling, as if time itself is drifting through them. There’s a quiet sense of scale and mystery here: tiny pinpricks of stars scattered across immense clouds of gas and dust, hinting at both stellar birth and ancient remnants. It’s beautiful in a solemn, awe-inducing way, reminding you how small and fleeting everything feels against the backdrop of the universe.
IMAGING DETAILS
Object
Barnard 343
Constellation
Cygnus
Distance
2,000 light-years
Size
10 arc minutes (dark nebula only)
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount & Control
ZWO AM5 + ASIair
Guiding
William Optics 50mm guide scope
+ ZWO 120MM Mini
Camera
ZWO ASI294MM CMOS sensor
FOV 2.87o x 1.96o Resolution 2.50”/pix Max. image size 4,144 x 2,822 pix
The year 2025 was like no other. Starting with a knee replacement operation in January, shortly after we finally found a new house in March and moved to the lovely dark skies of Somerset at the end of June. Unfortunately, the ensuing turmoil left only a limited time for astronomy. Notwithstanding, I was able to supplement images from Redhill and our new home in Wookey, with some excellent data from Texas, USA and Chile to produce, what I hope you will agree, is an exciting 2026 calendar.
For other pictures and information, go to my website https://watchthisspaceman.com/ or a video of the calendar can be found here on YouTube https://www.youtube.com/watch?v=gn3ls_s71lQ and is best accessed on a PC or smart TV screen. Background music this year is Massive Attack’s track Atlas Air.
COVER
NIGHT SKY MONTAGE AT CASTLE FARM OBSERVATORY:
All these images (at the top of the page) were taken at various times from the same location at our house in Wookey, Somerset. Clockwise from bottom left: (1) Nightscape of a small coppice looking south (2) Double Cluster – a pair of open star clusters in the Perseus constellation (3) Star trails (4) Sunset looking west.
JANUARY
THE GREAT ORION NEBULA, M42 (1) The Orion Nebula is a gigantic cosmic cloud of interstellar dust and gas, which is the basis for the birth of numerous new stars or a “star nursery”. Being the brightest nebula in the northern hemisphere and just over 1,300 light-years distance from Earth, it can be seen with the naked eye on a clear night.
FEBRUARY
FLAMING STAR NEBULA, IC405 (1) This nebula is illuminated by a powerfully bright blue variable star, AE Aurigae. The object’s epithet comes from the brightly lit ripples of gas and dust at the top of the image, illuminated by AE Aurigae and glowing hydrogen gas. This “runaway star” was ejected by a collision two million years ago from the Triangulum region of The Great Orion Nebula.
MARCH
CRAB NEBULA, M1 (3) This small but beautiful supernova Remnant (SNR) was the result of the explosion of the star CM Tau just over 970 years ago. Located at the centre of the nebula, the remaining Crab Pulsar neutron star spins at the rate of 30 times per second.
APRIL
PINWHEEL GALAXY, M101 (3) At nearly twice the size of the Milky Way and containing at least an estimated trillion stars, M101 is the second largest galaxy of the Messier catalogue and certainly one of the highlights of the spring galaxy season.
MAY
SCULPTOR GALAXY, NGC 253 (3) One of the advantages of obtaining data from Texas, USA, is that it enables views of objects in the Southern Hemisphere that are impossible from the UK. Also known as the Silver Dollar, it is one of the brightest galaxies in the night sky, which results from very high rates of star formation that are fed by the abundance of thick dust lanes.
JUNE
NEEDLE GALAXY, NGC 4546 (3)
Seen edge-on from Earth, the Needle Galaxy is thought to be a barred spiral galaxy, some 33% larger than the Milky Way. It has at least two satellite galaxies and 240 globular clusters. Seen through a telescope the Needle Galaxy appears like a thin streak drawn across the dark night sky but look closer and its detailed magnificence is revealed.
JULY
WIZARD NEBULA, NGC 7380 (2)
Formed only a few million years ago, the gases of this young emission nebula glow due to intense radiation from hot, massive stars within. Interwoven within this glowing gas are dark, dense regions of dust that sculpt the nebula’s dramatic and somewhat mystical appearance, in this case a wizard – which marks my first image from Somerset.
AUGUST
LOBSTER CLAW & BUBBLE NEBULAE, SH2-157 & NGC 7635 (2)
Located in the Perseus Arm of the Milky Way, the Lobster consists of ionized hydrogen gas energized by ultraviolet radiation from nearby hot, young stars. The nebula’s distinctive claw-like shape arises from intricate filaments of glowing gas and dark dust. Nearby the Bubble Nebula owes its distinctive looks to a single, massive star, which emits fierce stellar winds that sweep up the surrounding gas into a nearly perfect, glowing shell.
SEPTEMBER
MILKY WAY(2)
The night sky in Somerset is three times darker than Redhill, providing significantly better astronomy views. In this case a spectacular image of the Milky Way’s galactic centre.
OCTOBER
THE CYGNUS WALL (2)
The Wall is a prominent ridge located within the much larger North America Nebula in the Cygnus constellation. It is an active star-forming region, about 20 light-years long, composed of gas and dust that glows from the energy of young stars.
NOVEMBER
GREAT BARRED GALAXY, NGC 1365 (4)
A double-barred spiral galaxy located 56-million light-years away, spans over 200,000 light-years across, twice the Milky Way. The most distinctive feature is its massive central bar, which plays a crucial role in channelling gas and dust into the galactic core. As a Seyfert galaxy the nucleus is extremely bright due to energetic processes around its black hole.
DECEMBER
CORONA AUSTRALIS, NGC 6729 (4)
This spectacular image is a combined reflection and emission nebula, set within the Australis Molecular Cloud. This wonderful, hazy looking nebula unusually exhibits both variable brightness and morphology over time.
Image Data Source:(1)Redhill, Surrey (2)Castle Farm, Somerset (3)USA (4)Chile
It’s early days at my new Castle Farm Observatory and I’m still feeling my way into the benefits of Somerset’s superior darkness, which is noticeably better than my previous home in Surrey. But my new Bortle 4 location is not without some issues: there are a couple of nearby streetlights that can now find its way to my observatory since autumn leaves have fallen, occasional vehicle lights pass by and, inevitably, sections of the sky are obscured by our house and trees.
Westerly view from Castle Farm Observatory
South view, with my house just out of shot on the left!
After more than 12-years of imaging almost exclusively looking south, I must now adjust imaging plans looking southwest or north, which are my main sightlines in Somerset. This might seem a minor issue but as the sky moves around an axis defined in the north by the Polaris star, it thus follows an inclined equatorial grid relative to Earth and the impact on potential imaging plans can be quite profound. Previously looking southwards, the transit of objects during the night (and day) was from the east to west horizons, which on a clear night enabled up to 6-hours imaging of a single object, compared with a westerly view which only catches the latter period of the aforesaid transit. As a result, objects I used to image say from November onwards now only appear in the available (western) section of sky two or three months later. On a more positive note, I am now able to image circumpolar objects looking high and northwards for the first time, which has literally opened new world of possibilities.
Given the aforesaid issues, I recently chose to image an old favourite which is currently in a favourable position at this time of the year, the North America Nebula (NAN), located high in the early evening night sky looking due west. Spanning some 100 light-years, NAN is a great narrowband object, which by using the Hubble SHO palette always results in an exciting and colourful image.
Over two nights I manged to obtain nearly 9-hours of good data, which at my previous Bortle 6 Surrey observatory would probably be the equivalent of more than 12 hours. The final processed SHO image brings all three channels into a delicate balance: vibrant without being garish, detailed without overwhelming noise. The iconic “Gulf of Mexico” region forms a deep void in the nebula, which becomes even more pronounced with the various gradients of blue converging around its dark centre. But on this occasion, I was particularly keen to emphasize details of the fabulous Cygnus Wall (see cropped image below), situated in the lower right corner of the main image i.e. ‘West Texas and Mexico’!
The Cygnus Wall is a striking, heavily sculpted region within the North America Nebula, which itself is worthy of image, which would require a larger telescope. The dense ridge of gas and dust glows brightly as nearby young, massive stars bombard it with intense ultraviolet radiation, causing it to ionize and shine. Its dramatic pillars, ridges, and cavities resemble a cosmic coastline, shaped by stellar winds and ongoing star formation. For some reason it’s been 8-years since I last imaged NAN, except with my Samyang widefield rig, but with the excellent night skies of Somerset I feel sure I’ll be back sooner next time, perhaps with a bigger telescope?
IMAGING DETAILS
Object
North America Nebula – NGC 7000
Constellation
Cygnus
Distance
1,600 light-years
Size
Approx. 50 light-years or 2o
Apparent Magnitude
+4.0
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount
SW AZ-EQ6 GT + EQASCOM computer control
Guiding
William Optics 50mm guide scope
+ Starlight Xpress Lodestar X2 guide camera & PHD2 control
Camera
ZWO1600MM-Cool (mono) CMOS sensor
FOV 2.65o x 2.0o Resolution 2.05”/pix Max. image size 4,656 x 3,520 pix
EFW
ZWOx8 + ZWO LRGB & Ha OIII SII 7nm filters
Capture & Processing
ASIair, Photoshop
Exposures
35 x Ha, 34 x OIII & 36 x SII @ 300 secs (Total time: 8hr 45min)
@ 300 Gain 10 Offset @ -20oC
Calibration
5 x 180 sec Darks 10 x 1/4000 sec 10 x Flats & Dark Flats Ha, OIII & SII
Location & Darkness
Castle Farm Observatory, Wookey, Somerset Typically Bortle 4
Astronomy is full of surprises, and learning of the mere existence and nature of globular clusters was a revelation to me. Perhaps less spectacular and much younger but no less interesting and attractive are open clusters.The so-called Double Cluster is something of a highlight of autumn and winter skies that I had not, until now imaged; not by neglect but because until recently moving to Somerset my previous view of the north sky in Surrey was completely obscured by my house! Their combined luminosity makes the Double Cluster visible to the naked eye from dark locations, appearing as a hazy patch to the east of the Cassiopeia constellation and are excellent imaging objects too.
NGC 869 and NGC 884, known as the Double Cluster or h and χ (chi) Persei, is one of the most striking celestial pairings visible in the northern sky. Located in the Perseus spiral arm of the Milky Way, these two open star clusters are located about 7,500 light-years away but separated by only a few hundred light-years. Their proximity, similar age, and shared motion through space suggests that they formed from the same giant molecular cloud, making them a physically associated pair rather than a chance encounter.
Double Cluster Up Close
Each cluster contains thousands of stars*, many of which are hot, blue and massive, thereby indicating an early stage of stellar development; estimates indicate an age of approximately 12 to 14 million years. Their youth explains the abundance of B-type and even O-type stars—stellar heavyweights that shine intensely but live only briefly.
The resulting image shows the Double Cluster as a dazzling field of stars. NGC 869, slightly denser and more compact, contains a bright core of hot blue stars. In contrast, NGC 884 appears more loosely concentrated, with a distinctive scattering of bright stars across its central region. Both clusters show subtle hints of red and orange from K-type supergiant stars, evidence that even at their youthful age, some massive stars have already begun to leave the main sequence.
*processing software identified 22,000 stars in the image!
COMPARISON: GLOBULAR v OPEN CLUSTERS
Feature
Globular Clusters
Open Clusters
Typical Stars
Old, metal-poor
Young, metal-rich
Number of Stars
10⁵–10⁶+
10²–10³
Shape
Spherical, dense
Irregular, loose
Location
Galactic halo
Galactic disk
Age
10–13 billion years
1 million–few billion years
Longevity
Very long-lived
Short-lived (astronomically)
Image Details
Object
The Double Cluster NGC 869 & NGC 884
Constellation
Cepheus
Distance
7,500 light-years
Size
60 arc minutes (each 70 light-years)
Apparent Magnitude
+3.8
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount & Control
ZWO AM5 + ASIair
Guiding
William Optics 50mm guide scope
+ ZWO 120MM Mini
Camera
ZWO ASI294MM CMOS sensor
FOV 2.87o x 1.96o Resolution 2.50”/pix Max. image size 4,144 x 2,822 pix
The Lobster Claw Nebula (SH2-157) and Bubble Nebula (NGC 7635) are two striking emission nebulae located close to the border of Cassiopeia and Cepheus constellations.The Lobster Claw Nebula derives its name from the curved, segmented shapes that resemble a lobster’s pincers. It is an Ha II region of glowing ionized hydrogen excited by the intense ultraviolet radiation of nearby hot, young stars. Notably, within it lies the young Wolf-Rayet star 157, whose powerful stellar winds sculpt the surrounding gas into complex arcs and filaments.
Relatively nearby, the Bubble Nebula features a spherical bubble of gas about seven light-years across. The bubble is ‘blown’ by the fierce stellar wind of a massive O-type star (SAO 20575) at its centre. The expanding shell of gas glows where it collides with denser regions of the interstellar medium, producing a visually stunning contrast of colours.
Notwithstanding the spectacular nature of both of these nebulae, the image captures a myriad of other objects, which are identified in the accompanying plate solved image, notable of which are the open star clusters of M52 AKA the Scorpio Cluster and NGC 7510. Overall, the constellation of Cassiopeia is full of interesting nebulae and bright star clusters, which my second image from Castle Farm Observatory has caught in abundance.
IMAGING DETAILS
Main Objects
SH2-157 Lobster Claw & NGC 7635 Bubble Nebulae
Constellation
Cassiopea
Distance
Lobster 11,000 & Bubble 7,100 light-years
Size
Lobster 60’ x 50 (212 light-years); Bubble 15’ x 8’ (>=7 light-years)
Apparent Magnitude
Variable >=5.0
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount & Control
ZWO AM5 + ASIair
Guiding
William Optics 50mm guide scope
+ ZWO 120MM Mini
Camera
ZWO ASI294MM CMOS sensor
FOV 2.87o x 1.96o Resolution 2.50”/pix Max. image size 4,144 x 2,822 pix
I try to ensure that since Watch This Space (Man) blasted off in August 2014, it does what it says on the tin (top of the page): A personal discovery of the Universe through astronomy and astrophotography. Naturally, alongside this journey life goes on, which this year has been a significant challenge for me in many ways. Shortly after imaging the Flaming Star Nebula at Fairvale Observatory, Surrey, in early January, I underwent major surgery to replace my right knee and inevitably, all physical astronomy came to a halt; latterly I managed to remotely obtain and process data from sources in Texas, USA and Chile, which was good fun.
Just two months later, whilst still in early recovery (which can take over a year), serendipity made an unexpected appearance, and by at the end of June, after 40-years living in Redhill, Surrey, we moved to a new house just outside England’s smallest city of Wells (population 11,145), in the beautiful countryside of north Somerset. This upheaval, combined with my recovery, has led to a protracted absence from astrophotography imaging but, at last, I’m now very pleased to present my first image from the new Castle Farm Observatory, in Somerset, of course.
Astronomically speaking, only one thing counts when imaging and that is the quality of viewing conditions (and clear skies), which I can already attest to be excellent here in Somerset. At my previous location just south of London in Surrey, conditions were poor, with an SQM value of 19.82 that was further complicated by low flying aircraft from three nearby airports. In comparison, the SQM at Castle Farm Observatory is 21.11, which being a log scale equates to a difference of x3.28 better sky darkness than before and, moreover, overflying aircraft are no longer a problem. Given this setting, combined with clear skies and a new moon in early September, I had high expectations for my first imaging session since moving to Somerset and was not disappointed by the results obtained of the object chosen for this auspicious occasion, the Wizard Nebula.
The Wizard Nebula, designated by the central star cluster of NGC 7380, is an emission nebula, in which its gases glow due to intense radiation from hot, massive stars from within the aforesaid embedded cluster. Interwoven within this glowing gas are dark, dense regions of dust that sculpt the nebula’s dramatic and somewhat mystical appearance, in this case a wizard. NGC 7380 was only formed a few million years ago and within it, young and massive O- and B-type stars generate strong stellar winds that shape and erode the surrounding material.
Thus, after an unprecedented break of some 257 days, I’m more than pleased to return to my own backyard astrophotography again, now based in the magic county of Somerset. The quality of the subs obtained on this first occasion confirmed the outstanding sky conditions, which were literally saturated by stars (see starless image above). Altogether, it was significantly better than experienced in Surrey and bodes well for what I hope will be an exciting time here at Castle Farm Observatory – Watch This (new) Space!
IMAGING DETAILS
Object
NGC 7380 The Wizard Nebula
Constellation
Cepheus
Distance
>= 7,200 light-years
Size
25 arc minutes (110 light-years)
Apparent Magnitude
+7.2
Scope
William Optics GT81 + Focal Reducer FL 382mm f4.72
Mount & Control
ZWO AM5 + ASIair
Guiding
William Optics 50mm guide scope
+ ZWO 120MM Mini
Camera
ZWO ASI294MM CMOS sensor
FOV 2.87o x 1.96o Resolution 2.50”/pix Max. image size 4,144 x 2,822 pix
As Douglas Adams succinctly puts it in the Hitchhiker’s Guide to the Galaxies: Space…..is big. Really Big. If he had lived longer, even he would be surprised to learn how true these words were. Recent analyses using data from the James Webb Space & Hubble Telescopes, suggests there could be some 2 trillion galaxies. Notwithstanding, as this applies only to the observable universe, which is about 93 billion light-years across, the entire universe could be significantly larger, with many more galaxies beyond what we can already observe!
Perhaps then it is not so surprising that from time-to-time galaxies run into each other – our own Milky Way Galaxy is expected to collide with the Andromeda Galaxy in about 4.5 billion years. But there are already many exciting examples of such phenomena that we can image today, of which the Antennae Galaxies are one of the most famous and visually striking examples of two colliding galaxies. Located in the constellation Corvus, they provide a striking insight into what happens when massive galaxies merge – a process that reshapes their structure, triggering intense star formation, thereby setting the stage for the eventual creation of a single, larger galaxy, all played out over 100’s or even billions of years.
The Antennae Galaxies earned their name from the long, curved tidal tails of gas, dust, and stars that extend outward from the colliding pair of galaxies (NGC 4038 & 4039), thus resembling the antennae of an insect. These tails were created by the immense gravitational forces at play during the collision. As the two galaxies then pass through each other, their mutual gravity distorts their original spiral shapes, pulling out vast streams of stars and interstellar material. These tidal tails stretch for tens of thousands of light-years, making them some of the most spectacular features of any known galactic merger.
At the core of the Antennae Galaxies lies a chaotic and extremely active region. The violent gravitational interactions have compressed enormous clouds of gas and dust, sparking a burst of intense star formation, at a rate hundreds of times faster than that of our own Milky Way. Many of these newly formed stars are massive but short-lived, destined to explode as supernovae, thus enriching the surrounding space with heavy elements. Within another 400 million years, the Antennae’s nuclei will collide and therafter become a single galactic core with stars, gas, and dust swirling around it.
Imaging such a feature from Earth requires significant telescopic power, the darkest of night skies and the acquisition of lots of data. Located at the El Sauce Observatory in Chile, 50 hours of data acquired using the Planewave CDK20 astrograph is such a set-up worthy of the task. However, despite the excellent data quality, I found processing this complex event difficult so as to both show the complexity of the merging galaxies, whilst at the same time preserving the delicate nature of the tails of galactic debris. The final image is as profound as it is beautiful, demonstrating the immense forces across the cosmos and the inevitable consequences for the many galaxies that occupy the vastness of the Universe.
IMAGING DETAILS
Object
NGC 4038 & 4039, AKA Antennae Galaxies
Constellation
Corvus
Distance
62 million light-years
Size
5.21 x 3.1 arc minutes (actual 634,410 x 456,780 light years)
Apparent Magnitude
+10.3 / 10.4
Scope
Planewave CDK20
Mount
Planewave L500
Focuser
Optec Gemini
Camera
QHY600PH-M
Filters
Chroma LRGB + Ha 3nm
Processing
Deep Sky Stacker & PixInsight v1.9-3
Image Location & Orientation
Centre: RA 12:01:54.47 DEC -18:52:45.2 Up = North
Exposures
Ha 117 x 10 mins, L x 127, R x 80, G x 80, B x 70 @ 5mins Total Integration Time: 50hr 5min
Although some time back I lived and worked in Southern Africa for five years and subsequently spent much time visiting and working in many other countries south of the equator, since taking up astrophotography 12-years ago I’ve had no opportunity to work with data from the southern hemisphere, until now. The benefit of obtaining data remotely, which has become very popular in recent years, is that it provides access to different objects and better sky conditions. I did work with a telescope based in New Mexico, USA a few years ago, which was a fun experience but being in the Northern Hemisphere most targets were much the same as here in the UK, except they did have more than 250 clear skies each year. However, this time I’ve moved to what is widely considered to be the holy grail for astronomy, Chile, where night skies are rated as the best in the world!
Obstech El Sauce Observatory, Chile
The dataset was obtained from the famous El Sauce Observatory located in the Rio Hurtado Valley, south of the Atacama Desert, using a Planewave CDK20 astrograph telescope; currently retailing at First Light Optics for just over £42,000! Unsurprisingly, the combination of location and this telescope resulted in the best of the best datasets, which has been nothing less than a privilege to process.
My first target from the Southern Hemisphere therefore had to be something special and NGC 1365, also known as the Great Barred Spiral Galaxy, is just that. A double-barred spiral galaxy, it is located some 56million light-years away in the Fornax constellation and spans over 200,000 light-years across, making it nearly twice the size of the Milky Way. The Great Barred Spiral Galaxy is also a dominant member of the Fornax Galaxy Cluster group of 58 galaxies.
Several members of the Fornax Galaxy Cluster are imaged by the VLT Survey Telescope, including the barred spiral NGC 1365 on the lower right Credit: ESO/A. Grado/L. Limatola/VLT
The most distinctive feature of NGC 1365 is its massive central bar, which plays a crucial role in channelling gas and dust into the galactic core. This inflow of material fuels both star formation and the activity of the galaxy’s central supermassive black hole, which is estimated to be some 2-million solar masses. Various observations in X-rays, infrared, and visible light wavelengths, reveals numerous star-forming regions along the spiral arms, particularly where they connect to the bar, giving the galaxy a luminous appearance.
NGC 1365 is also classified as a Seyfert galaxy, whereby the nucleus is extremely bright due to energetic processes around its black hole. Studies also indicate that the outer edges of the galactic disc are moving at about 84% of the speed of light!
IMAGING DETAILS
Object
NGC 1365, AKA Great Barred Spiral Galaxy or Fornax Propellor Galaxy
Constellation
Fornax
Distance
56 million light-years
Size
11.2 x 6.2 arc minutes (201,700 to 306,800 light years)
Apparent Magnitude
+10.3
Scope
Planewave CDK20
Mount
Planewave L500
Focuser
Optec Gemini
Camera
QHY600PH-M
Filters
Chroma LRGB + Ha 3nm
Processing
Deep Sky Stacker & PixInsight v1.9-3
Image Location & Orientation
Centre: RA 03:34:34.323 DEC -36:08:30.36 Up = North
Exposures
Ha x 62 10 mins, L x 78, R x 78, G x 71, B x 70 @ 5mins Total Integration Time: 35hr 5min
Perspective is everything – in life and so it is, with astronomy. Hipparchus first pointed the way in 127 BC when he described the procession of the equinoxes and, as they say one thing led to another as, Nicolas Copernicus (1473-1543), Tycho Brahe (1546-1601), Galileo Galilei (1564-1642), Johannes Kepler (1571–1630), Johannes Hevelius (1611–1687), Giovanni Cassini (1625-1712), John Flamsteed (1646-1719) and others opened our eyes to the night sky and what lay beyond Earth. Notwithstanding, it was Edwin Hubble’s discovery of galaxies in 1924 that ultimately led to mankind’s recognition that there was much, much more, that we now take for granted to be the Universe. However, even to the experienced modern astronomer the scale, complexity and beauty of the Universe can be somewhat overwhelming, like when we consider that the observable Universe may consist of 2 trillion galaxies!
Since Hubble’s work we have become familiar with many types of galaxies, which the average person might describe as a colourful spinning firework-like disc, consisting of vast gravitationally bound systems of stars, stellar remnants, interstellar gas, dust and dark matter. This stereotypic impression arises because most galaxy images are viewed face-on or at an inclined angle, so that we can see the structures and processes that have created it. However, given the number of galaxies and therefore the many possible views, it is not surprising that some can only be seen edge-on from our perspective on Earth, the Needle Galaxy AKA NGC 4546 is one of these.
Thought to be a barred spiral galaxy, NGC 4546 is some 33% larger than the Milky Way. It has at least two satellite galaxies, about 240 globular clusters (Milky Way ~ 150) and is the brightest of the Coma 1 Group of galaxies. Seen through a telescope or when imaged the Needle Galaxy it appears like a thin streak drawn across the dark night sky but look closer and its magnificence is revealed, as in the image above.
Here ribbons of dust can be seen criss-crossing along the edge of the thin galactic disc, thereby blocking much of the from light behind. However, it is the bright central bulge that inevitably catches the eye but remains something of an enigma, as little can be seen from within. This excellent data set obtained using the MOANA 10” Newtonian telescope located in Texas’ dark skies, reveals such exquisite details that are provided by the less common edgewise perspective of this intriguing galaxy.
Footnote & credit: Following a knee replacement I’m currently unable to set-up and use my astronomy equipment, fortunately I havve been able to continue processing using this excellent public amateur data from the MOANA project located near Fort Davis, Texas https://erellaz.com/moana/. Many thanks to its creator Elleraz.
IMAGING DETAILS
Object
Needle Galaxy AKA NGC 4565
Constellation
Coma Berenices
Distance
40 million light-years
Size
15.9 x 1.85 arc minutes
Apparent Magnitude
+10.4
Scope
MOANA 10” f/4.5 Newtonian
Mount
Astro-Physics 1100GOTO
Guiding
Off axis guider + QHY 5L2M
Camera
ZWO1600MM Pro
FOV 45’ x 35’ Resolution 0.5915”/pix Image size 4,656 x 3,520 pix
Filters
Baader 36mm RGB
Capture & Processing
NINA, Deep Sky Stacker & PixInsight v1.9-3
Image Location & Orientation
Centre RA 12:36:08.12 DEC +25:55:59.31 Left = North
Exposures
R x 45, G x 47, B x 45 @ 300 sec Total Integration Time: 11hr 25 min
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