Category Archives: galaxies

M31, NGC206 and the Bologna Catalogue

NGC206 Region in M31 - Lum ChannelPresented here is a bit of a “nonsense image” of the Andromeda Galaxy, M31, that I grabbed early in the evening of the 22nd Jan 2017. This was a quick run, mainly while I was waiting for another target to clear the tree near my observatory…!

However, even in an image like this, which only consists of 14x5min exposures through a luminance filter, there is lots to be explored – first it gives me a good idea about future plans for a mosaic (though this will have to wait until the autumn now, and may be a major undertaking…). It also gives a good view of NGC 206, which is a bright star cloud in M31, and I plan to image this alone at longer focal lengths later on. Also, it allows me to explore objects in the Bologna Catalogue 1.

NGC206 Region in M31, with Bologna Catalogue Globular Clusters AnnotatedThis catalogue  is not one that comes immediately to mind when talking about deep-sky objects – but it is a very specialised list describing globular clusters (GCs), candidate GCs and previous candidate GCs in M31. The up to date version of the catalogue is freely available on the Bologna Catalogue website and can be downloaded, manipulated and used as a source of information for the Annotate script in Pixinsight. Presented here in negative format is the south west region of M31, with overlaid markers for the confirmed GCs in the Bologna Catalogue v.5 (with associated V magnitudes) in red, as well as a few small PGC galaxies that loiter in the field marked in light blue. There are 181 marked objects alone in this field – most of which have been successfully captured using just a small 4 1/2″ refractor!

Image details:

ST2000XM, William Optics FLT110 + FLAT4 reducer
14x5min, L filter
Reduced and processed in Pixinsight

References

1. Galleti S., Federici L., Bellazzini M., Fusi Pecci F., Macrina S.: “2MASS NIR photometry for 693 candidate globular clusters in M31 and the Revised Bologna Catalogue (V.1.0)”, Astron.&Astrophys., 2004, 416, 917 (G04)

M33 – The Triangulum Galaxy

RA: 01h 33m 54.0s
Dec: +30° 40′ 15.8″
Up is -89.8°E of N
(Plate solve by nova.astrometry.net)
M33 - Triangulum GalaxyMessier 33 is a spiral galaxy in the constellation of Triangulum, and is sometimes called the Pinwheel  Galaxy, a name it shares with M101, It is the third largest member of the Local Group of galaxies with a diameter of about 60,000 light years; the two larger members being our Milky Way and the Andromeda Galaxy (M31). There is suggestion that M33 and Andromeda have experienced an encounter at some point in the past (and will do again in the future!).

M33 is one of the most distant objects visible to the naked eye, but it is a relatively diffuse galaxy, and so it’s visibility with the naked eye and through binoculars is strongly affected by light pollution and sky transparency – in this respect, M31 is far more visible to the naked eye. 

There are lots of H-II star forming regions within M33 that are visible as pinkish areas of hydrogen emission in the spiral arms. The largest of these is NGC604 which was catalogued independently of the galaxy core by William Herschel. This area is probably very similar to the Orion Nebula in many ways, and can be found to the north-east (upper-right) of the core of the galaxy (north is to the right in the images).

The images were all taken across several nights in November 2016 (7th, 28th, 29th) from West Oxfordshire with an SBIG ST-2000XM though a William Optics FLT110, all mounted on the Losmandy Titan. Exposures were as follows:

L:R:G:B
310 (31x10m) : 95 : 90 : 80 (RGB in 5m subs, 2×2 binned)
All exposures taken at -20°C.

Reduction and processing performed in Pixinsight and Photoshop. The processing of this object proved tricky. The galaxy largely fills the field and leaves relatively little background to work with in running DBE processes. This left several colour casts and gradients that I needed to manually remove within Photoshop – not an easy task…  

M33 HDR EnhancedAlso included here is a luminance only channel using the L channel data, that has been processed using HDR Multiscale Transform, Local Histogram Equalization and TGV Denoise to reveal to a greater extent the structure of the galaxy – in many ways this might be regarded as “over-processed”, but an interesting take on the galaxy nevertheless. 

M101 – Pinwheel Galaxy

Field centered at: RA: 14h 03m 12.6s, Dec: +54° 21′ 16.7″
Up: 178 E of N.

(plate solve from nova.astrometry.net)

The Pinwheel Galaxy, M101 is located in Ursa Major, and I found this a surprisingly tricky object to image – it has low surface brightness, with a lot of faint outlying regions. I also appeared to have some small issues with the flat fielding process here – there are a couple of very large dust bunnies in the raw data that haven’t quite been subtracted away and there’s a touch of clipping to deal with this. Add to this some faint colour gradients (attempted to sort out gradients!) and a couple of bright stars in the field and it became something very tricky to try and get right (and I’m still not 100% convinced that it’s truly there yet…).

The fainter galaxy to the right (east) of M101 is NGC5477, which is a dwarf galaxy at about the same distance (~20MLy). There are lots of fainter objects in the image as well: the brighter galaxy to the upper left of M101 for example is MCG+09-23-25, and there are also loads of other faint galaxies, galaxy groups and QSOs lurking in there. Using a solved fits file in Aladin is very instructive here!

I used fairly long exposure lengths (I was using the FLT110 at f7 here, a shorter focal length would be a major bonus in truth – at f4-5 this would be a much deeper image!). Exposure details are as follows:

WO FLT110 @ f7 on Losmandy Titan, ST2000XM cooled to -20C (images on 18 & 19-Apr-2015)
L: 4.5hrs (1×1)
R: 70min (2×2 binned)
G: 48min (2×2 binned)
B: 48min (2×2 binned)

The Luminance for the image was processed using a Lucy-Richardson deconvolution (3 iterations) using CCDSharp.

M101 - Pinwheel Galaxy in UMa (Luminance)

 

M101 - Pinwheel Galaxy in UMa (LLRGB)

M65, M66, NGC3628 – The Leo Triplet

RA: 11h 19m, Dec: 13°15′ (approx. centre)m65_m66_ngc3628_20061221.jpg
The famous Leo Triplet is a small group of three spiral galaxies (namely, M65 (NGC3623 – bottom-left), M66 (NGC3627 – top-left) and NGC3628 (right)) that is located about 35 million light years away between Theta and Iota Leonis. All three galaxies are readily visible in a small telescope, though NGC3628 tends to be the hardest of the three to spot. Additionally, the smaller galaxy NGC 3593 (not shown) may also be a member of this group.

This image was taken from the dark skies of Mid-Wales on December 21st, 2006 as a “quickie” before sunrise after a run on imaging the Cone Nebula (to follow in a later post) – it’s only about an hour of total exposure. A much longer imaging run would allow the faint surrounds of M66 and the “tidal tail” of NGC3628 to be brought out, but unfortunately, as is so often the case with imaging in the UK, the clouds came in for the next 5 nights leaving the telescope ready to go, but unable to actually take an image…

M81 & M82 – Bode’s Nebula and The Cigar Galaxy

Image centred at:  RA: 09h 55m 34.7s, Dec: +69°19′ 52″
Up is 89 degrees E of N
(Plate solve from nova.astrometry.net)

M81 and M82 in Ursa majorM81 and M82 in Ursa Major are two of the brightest members of the M81 group of galaxies. M81 (often called Bode’s Nebula after being discovered by Johann Elert Bode in 1774) is a large bright spiral approximately 12 million light-years distant, whilst M82 (the “Cigar Galaxy”) is an irregular starburst galaxy, highly disturbed by gravitational interaction with other members of the group.

This was taken from Kelling Heath at the 2007 Spring Star Party on an excellent night after we had been fogged out for the previous two nights! I’m hoping to go again this year to do some more imaging…

m81_m82_mandel_wilson_3-20070415.jpgIn the region of M81 and M82 (and across large parts of the northern sky), there is a large faint nebular complex associated with dust and gas expelled from the plane of the galaxy. The region here is part of MW3 (Mandel-Wilson Catalog of Unexplored Nebulae) and the faint dusty areas show up faintly in a strongly stretched image of the region. This has been refered to as an “Integrated Flux Nebula” since it reflects the galaxy’s light rather than that of a single star. Also visible is Holmberg IX (below M81) which is a small, faint blue irregular galaxy also in the M81 Group.