Category Archives: nebulae

Sadr and The Butterfly

Sadr (Gamma Cygni) sits at the centre of the large asterism known commonly as the Northern Cross that makes up the constellation of Cygnus. The region surrounding this F8 supergiant is rich in dust and hydrogen within the plane of our Milky Way as this view, taken in the light of hydrogen alpha (at 656.3nm) shows. 

Region around Sadr (Gamma Cygni) and IC1318 in Cygnus in Hydrogen AlphaNotably, just to the east (left) of Sadr, is the Butterfly Nebula, IC1318. This actually sits much further away from us than Sadr at ~5000 light years (Sadr is about 750 ly distant). The nebula appears split into two by a dark dust lane running E-W, catalogued as LDN 889. 

In the lower right of the image is the Crescent Nebula, NGC6888, powered by the Wolf-Rayet star HD 192163, while to just to its east, and only faintly visible is the small planetary nebula, PN G75.5+1.7, also known as the Soap Bubble – though really a bigger scale and [OIII] filter data would make this much more obvious!

Image taken on 17th Sept 2018 from West Oxfordshire. 

QHY163M (-15C, gain/offset=200/85), Canon 200mm 2.8L II (@f3.85), Baader 7nm HA filter, Losmandy GM8 with Gemini 1.

3h40m total exposure (5min subs) with HDR Composition for bright stars (25x30sec). 

Processing in Pixinsight. 

Image is centred at: (
RA: 20h20m25s
Dec: 40°20’31”



The Eagle and The Swan

The plane of the Milky Way is littered with areas of star formation; regions of the sky that glow in the light of hydrogen alpha, emitted by large clouds of excited hydrogen. Two such areas are the Eagle Nebula (M16), and the Swan or Omega Nebula (M17) as shown (north is approximately up in this image).

Eagle Nebula and Swan Nebula in Hydrogen AlphaBoth nebulae are regions of recent and ongoing star formation – and both have associated open clusters containing young, hot, luminous stars whose radiation helps to excite and illuminate the nebulae themselves.

M16 is thought to lie at a distance of approximately 7000 light years, with M17 between 5000 and 6000 light years. Also shown is the open cluster M18.

Image was taken from Domaine des Mathevies, Sainte-Nathalène, Nouvelle-Aquitaine, France on 14/15/16th Aug 2018. This is a region of sky that I can’t really image from home: the southerly declination means that it’s never particularly high above the horizon from Oxfordshire, and this pairing never makes it above the roofline of our house from my home observatory!

Image taken using a QHY163M at -15C (gain/offset 200/85), Canon 200mm f2.8L II lens with a Baader 7nm H-Alpha filter. Tracked on a Losmandy GM8.

2h50m total exposure (in 5min sub frames).

Field centred at:
RA: 18h 19m 51s
Dec: -15° 02′ 59″
Size: 3.76 x 5.12 degrees

Collinder 399 – The Coathanger

Collinder 399 - The Coathanger and nearby dark nebulaeWithin the constellation of Vulpecula is an asterism catalogued as Collinder 399 (Cr 399, from a catalogue of open clusters published by Swedish astronomer Per Collinder). More commonly, this asterism is called the Coathanger, owing to its appearance  Brocchi’s Cluster, or Al Sufi’s Cluster. 

Despite being considered as a true open cluster for much of the 20th century, this is in fact a random grouping of stars – data on parallaxes and proper motions from Hipparcos (…340..402B) shows these stars to be a chance alignment rather than any kind of bound cluster. 

To the north (and partly encompassing the Coathanger itself) is a reflection nebula with designation LBN130, while further to the north, located with a background of a larger dark nebula (LDN 767) are another two patches of reflection nebula VdB126/LBN134 and LBN 133. Surrounding the whole area are many members of the LDN (Lynds Catalog of Dark Nebulae) catalogue that block the light from the myriad background stars in the plane of the milky way – these are marked in the associated annotated image. 

Image was taken from Sainte-Nathalène, Perigord, France on evenings of 10th/11th Aug 2018. Camera was QHY163M running at -15C on a Canon 200mm f2.8/L II lens (@f3.85).  Mount was a Losmandy GM8, guided with a 160mm guidescope and ZWO ASI120MM.

Exposure was LRGB using Baader 36mm LRGB filters. Exposures were L=166 (1min sub-exposures); RGB=98:90:88 (2min subs) – totalling 7h22m. All taken at gain 75, offset 27. Image capture using Sequence Generator Pro; processing using Pixinsight. 

Field centred at:
RA: 19h 25m 37s
Dec: +21° 42′ 27″
Up is 358 degrees E of N, field size: 3.98 x 5.3 deg

This image was published in the Gallery section of Astronomy Now, October 2018. 

North America and Pelican Nebulae

North America Nebula (NGC7000) and Pelican Nebula (IC5070)The North America nebula is a remarkably shaped area of emission nebula in the constellation of Cyngus, just to the west of the blue-white supergiant Deneb (α Cyg – just out of shot to the right) – it’s name coming from the clear resemblance to the continent – even down to the gulf of Mexico. It is accompanied by the Pelican Nebula (IC5070), another emission region located between NGC7000 and Deneb.

"The Wall" in NGC7000The whole nebula is formed out of one cloud of gas, with a dark band of dust between the two blocking light from behind and giving the resultant shapes.

There are several areas of star formation in the nebulae – particularly along the region known as “The Wall” in NGC7000, and in the Pelican (and just visible on this image) a Herbig-Haro object (HH555) which shows two jets associated with a newly born star. 

The Pelican Nebula (IC5070)This can been seen in the 100% scale close up of IC5070, just to the right of the “eye” – the Herbig Haro object is at the end of the dark dust protrusion.

Just to the south of both the larger areas of nebulosity is a fainter region of gas which has a really interesting pattern of overlaid dust which forms streaks of darkness across the bright nebula, almost appearing to cross at right angles. 

IC5067/5068 in Cygnus

There are no definitive distances for this region of nebulosity on the sky, though if the gas is largely excited by Deneb, it would place the region at around 1600 light years distant with a size of about 100 light years. From earth, the total field of view is over 10 full moons across on the longest side. 

The image was taken using a new camera and lens combination – a QHY163M camera at -15C with a Canon 200mm f2.8L II lens (stepped down to f3.85 with a 52mm step ring). Mount was a Losmandy GM8, and total 5h56m in 2min sub exposures through a Baader 7nm H-Alpha filter. The camera was run at gain 200, offset 104, and all image capture used Sequence Generator Pro. Images were processed using Pixinsight. 

Data captured between 3rd and 8th Aug 2018 from Cassagnabère-Tournas, France.

Field centred at:
RA: 20h 54m 56s
Dec: +44° 14′ 42″
Field size (overall image) 3.96 x 5.26 deg, Up is 355 degrees E of N




Merope & Tempel’s Nebula (NGC1435)

Image centred at:
RA: 03° 46′ 18″
Dec: +23° 56′ 04″
Field of view: 25.46′ x 18.82′

Merope & NGC1435 (Tempel's Nebula)The Pleiades open cluster in Taurus is one of the brightest and most recognisable objects int he winter sky. As a first LRGB image using the 14″ Newtonian, and to test the setup of the off-axis guider, I imaged the area around Merope (23 Tau). This was also the first use of a Bahtinov mask that I got laser cut by Oxford Hackspace. The focusing mask works excellently – this should be a real plus, especially for any planetary/lunar work.

The particular area of nebulosity imaged here around Merope was discovered by Wilhelm Tempel on October 19th, 1859, and is catalogued as NGC1435. The dust isn’t in fact the nebula from which the cluster formed, rather that the Pleiades happen to be travelling through a particularly dense part of interstellar medium. This dust scatters blue light from the cluster members, resulting in the reflection nebula visible to us.

The image shows strong diffraction spikes from the secondary spider, as would be expected. There’s also further diffraction visible around the brightest stars dark shadowing present at 60 degree angles, which is the result of the mirror retaining “clips” (they are not actually clips – they are part of the cell in the case of the 9 point Orion Optics mirror cell). To remedy this would require a mask to be added over the outer edge of the mirror to cover these over – this is maybe something I’ll think about making in the future to help deal with tricky situations like this! 

The additional dark shadow pointing to the right appears to be the focuser drawtube intruding on the internal light path inside the scope – that’s probably something that can only be cured by either a shorter drawtube, or shortening the truss tubes. Again. Maybe I’ll wait in case I decide to change coma corrector at some point, in which case it’ll probably need a change to the focal plane position anyway.

The image was taken on the evening of the 7th Jan 2018 through the 14″ (350mm) Newtonian, with an ST2000XM and an MPCC v1 coma corrector. Total exposure was “only” 2h 32m (L: 59m (20x1m, 13x3m), RGB: 31m (10x1m, 7x3m) each channel). Processing in Pixinsight and Photoshop CS4.