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ARCHIVE 2010INTRODUCTIONImaging from the worst place on Earth? Possibly! Welcome to my image blog from Lancashire, UK. Living in Lancashire does make imaging a challenge. Our incessant damp cloudy weather is legendary and coupled with light pollution probably as bright as can be found anywhere (I am 15 miles NW of the centre of Manchester) makes for testing times! Add to that flight path one with constant aeroplanes, which is why it has been suggested as possibly the worst place on Earth for imaging. Now the good news. With modern light pollution filters we can still produce excellent results - at least when the clouds clear - but of course we cannot match dark sites - I avoid looking at images from such sites as they are very depressing and un-representative of what the rest of us have to suffer! So if you too live in cloudy suburbia then I hope the following images offer some encouragement. I often shoot the luminance and the colour simultaneously - there are not enough clear spells to alow the luxury of shooting separately. Having two telescopes and two cameras is obviously essential for this - as is having a dome slot wide enough for both to have a clear line of sight. The luminance is usually taken with the RCOS + Apogee Alta and the colour Takahashi + Canon 40D. Despite their disparate focal lengths this works reasonably well as the Canon has 5 micron pixels (plate scale 2 arcsecs/pixel) and the Apogee 18 micron ones when binned 2x2 (plate scale 1.3 arcsecs/pixel). I find binning essential to maximise signal and improve the signal-to-noise ratio. The images are all taken from my back garden and appear in order of me processing them - we have plenty of cloudy nights for that. I use a combination of IRIS and Maxim for processing with final tweaks in Photoshop CS2. To get rid of the light pollution takes much trial and error. IRIS scores here with several options but processing often comprises many nights work - certainly always longer than the actual taking. The exception are images taken with an h-alpha filter which is a superb light pollution filter. It also permits imaging with strong Moonlight present - isn't it funny how it always seems to be clear at full Moon! |
DECEMBER 19th, 2010Planetary Nebula, Jones 1 (PK 104-29.1) Jones 1 was discovered in the 1940s by Rebecca Jones of Harvard University. Although quite large it is extremely faint. Its age of 35,000 years makes it one of the oldest planetary nebula known so it has had plenty of time to fade away. Its central star, strong blue in my image, is a rare example of a very hot hydrogen-deficient star. Long OIII exposures (13 x 1200 seconds) were required to get this faint object to register above the background noise. H-alpha was surprisingly quick to register but my CCD camera is 50% more sensitive to Ha than OIII. A back illuminated CCD with their high blue sensitivity would be better for this object. I've put one on my wish list! Image details:
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Jones 1 |
DECEMBER 12th, 2010Barred Spiral Galaxy, NGC 7479 (Caldwell 44) We don't have a really prominent barred spiral in the northern hemisphere and NGC 7479 is probably as good as it gets. Discovered by William Herschel, this galaxy is to be found just below the Square of Pegasus. Rather than using the Takahashi for the colour information, I shot a set of red and blue images using 3x3 binning to maximise signal in the time available. Image details:
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NGC 7479 |
DECEMBER 5th, 2010Emission Nebula NGC 7538 (Sharpless Sh2-158) NGC 7538, a stellar nursery for massive stars. Located around 9000 light-years away making it one of th closest regions of massive-star formation. Star factories like NGC 7538 consist mainly of hydrogen gas, but they also contain small amounts of cosmic dust. It has a total mass of almost 400 000 Suns. NGC 7538 is an active factory where stars come to life – especially huge ones that are over eight times more massive than the Sun. Hundreds of seeds of future stellar generations nestle in the mixture of surrounding gas and dust scattered across the image. Once they reach a critical mass, they will ignite as stars. Thirteen of these proto-stars have masses greater than 40 Suns, and are also extremely cold, less than –250ºC. Image details:
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NGC 7538 |
DECEMBER 2nd, 2010Planetary Nebula, PN G128.0-04.1 (Sh2-188, Simeiz 22) Located in Cassiopeia near NGC 457, this unusual planetary nebula has a very asymmetrical appearance. The explanation is that its central star is travelling at 125 kilometres per second across the sky which causes a pronounced build up of material in the direction in which the star is moving and a corresponding spreading-out in the opposite direction. Note also the faint edge-on galaxy towards the bottom right, left of the two bright stars. Because it is a planetary nebula, I returned to using an OIII filter for this object and the nebula did record with this, albeit faintly. I combined it with the usual Ha. Image details:
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Sh2-188 Nebula |
NOVEMBER 17th, 2010Gamma Cas Nebula, IC 63 Located in Cassiopeia close to Gamma Cas, this emission nebula is part of the larger Sh2-185 nebula. Because there is little OIII in this object, I combined the usual Ha with a standard blue filter. I also made sure Gamma Cas was out of the picture to avoid its light flooding out the nebula. Image details:
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IC 63 |
NOVEMBER 7th, 2010The Iris Nebula, NGC 7023 Located in Cepheus, this blue reflection nebula is dominated by a 7th magnitude star (SAO 19158) at its centre. Not surprisingly, it is this star that illuminates the nebula. Because it is predominately a reflection nebula, an OIII filter was not appropriate so instead I combined the usual Ha with a standard blue filter. Image details:
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Iris Nebula |
OCTOBER 31st, 2010The Wizard Nebula, Sh2-142 Sometimes erroneously referred to as NGC 7380 but the nebula is actually Sharpless Sh2-142 whilst NGC 7380 refers to just the cluster. The latter was discovered by Caroline Herschel on 7th August 1787. Shot through poorish seeing conditions during what I later learned was temperature inversion turbulence. The radio ham guys got excellent reception this week but it didn't do much for astronomical seeing! Image details:
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Nebula Sh2-142 |
OCTOBER 17th, 2010The Cave Nebula, Sh2-155 (Caldwell 9) Totally unsuitable as a visual object for the Caldwell catalogue (far too faint), it nevertheless makes a great object for imaging. In fact it has it all - an extensive emission nebula (red), a reflection nebula (blue) and dark nebulosity (the Cave). I tried a new technique for this object imaging with an H-alpha filter in combination with a blue one instead of what I would previously have used, an OIII filter. Image details:
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The Cave Nebula |
OCTOBER 3rd, 2010The Elephant's Trunk, IC1396A This dark nebula, known as the Elephant's Trunk, is believed to be the site of ongoing star formation, containing many infant (less than 100,000 years) stars only discovered in 2003 infrared images. Located in Cepheus it is part of the larger IC1396 complex, although strictly IC1396 refers to just the star cluster not the nebula. I took the colour image 3 years ago when I was testing a Celestron x0.63 focal reducer and this year finally got around to taking an H-alpha image which I used for the luminance. Image details:
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Elephant's Trunk Nebula |
SEPTEMBER 19th, 2010The Ring Nebula, M57 Popular planetary nebula in Lyra - one of the few deep-sky objects easily visible from light polluted Lancashire. After recording the faint outer halo of M27 I thought I would have a go to do the same with M57. In fact it has two outer halos - the furthest out being very faint. I have not over-brightened the outer halos in an attempt to keep some realism. Image details:
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Ring Nebula |
SEPTEMBER 5th, 2010The Soap Bubble, Planetary Nebula PN G75.5+1.7 Located in Cygnus, this planetary nebula was recently discovered by amateur astronomer Dave Jurasevich on July 6th, 2008. My image was taken through H-alpha and OIII (with green synthesized). The nebula is clear with the H-alpha filter but virtually nonexistent with the OIII filter. However, some published images record the nebula with their OIII filter but this is not the case for me using Baader narrowband ones. Perhaps those recording the nebula with their OIII filter are picking up the adjacent H-beta line? Image details:
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Soap Bubble |
AUGUST 30th, 2010Emission Nebula, NGC 6820, and Open Cluster, NGC 6823 Located in Cygnus this seldom imaged object features one of those "pillars of creation". Image details:
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NGC6820/6823 |
AUGUST 21st, 2010The Dumbbell Nebula, M27 Three years in the making! Data from 2007 and 2010 combined to produce this image. One of the brightest planetary nebula in the northern sky so normally short exposures are sufficient. However, to record the faint outer reaches much longer exposures are required.
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M27 |
AUGUST 16th, 2010Collimation Test Image First job for the Autumn season was to collimate the RCOS. Preliminary collimation was done with a Takahashi collimator (but see later) with final adjustment carried out on an out-of-focus real star image. The tak had got quite close but it did need a fair bit of tweaking with the primary mirror adjusters. It took about 30 minutes to get this close. The bottom edge of the image is slightly fuzzy due to tube currents. I had only just switched the fans on and initially it was much worse but was beginning to settle down when I took this image. Note: for collimation of an R-C telescope, the secondary should be marked with a central spot.
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JULY 11th, 2010The Black-Eye Galaxy, M64 Last of my spring images - the observatory is currently shut for 3 months during the summer light nights. A collision of two galaxies has created this unusual galaxy with a spectacular dark band of absorbing dust in front of the galaxy's bright nucleus, giving rise to its popular name of the "Black Eye" galaxy. A famous HST image reveals the dark band in all its glory but we get a hint of its turbulent motion here. Detailed studies in the 1990's led to the remarkable discovery that the interstellar gas in the outer regions of M64 rotates in the opposite direction from the gas and stars in the inner regions. Active formation of new stars is occurring in the shear region where the oppositely rotating gases interact.
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M64 |
JULY 1st, 2010Mosaic of the Whale and the Hockey Stick, NGC 4631 & NGC 4656 I've got a bit behind with my processing - blame the World Cup but now that it is finished (for England) I can get back to business! Four panel mosaic of the NGC 4631 Group. The two main galaxies are highly disturbed and have long been known to be linked by a "bridge" of neutral hydrogen (Roberts 1968). Presumably they must have passed close by each other in the past causing their present disturbed morphology. NGC 4631 (left) also has faint extensions - if you look carefully. The combined mosaic is 20Mb so it is much reduced here.
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NGC 4631 |
JUNE 10th, 2010The Whale Galaxy, NGC 4631 Two years in the making! Data from 2009 and 2010 combined to produce this image. Starburst galaxy without the normal smoothness of a typical edge-on galaxy. Its turbulent form is thought to be due to a previous interaction with nearby galaxy NGC 4656 (out of picture) rather than the smaller adjacent galaxy NGC 4627. The mosaic with NGC 4631 is work in progress!
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NGC 4631 |
JUNE 6th, 2010Seyfert Galaxy, NGC 4151 Although the observatory is now enjoying its summer break there is still a backlog of images to process. NGC 4151 was one of the first Seyfert Galaxies to be discovered. It appeared in Seyfert's original list of 12 published in 1943 and subsequently has been the most extensively studied of this type. The Seyferts are characterised by active galactic nuclei (AGN) which are conspicuous both in the optical and X-ray bands together with broad emission lines. They are powered by black holes at their centres and are believed to be similar to quasars but of somewhat lower energy.
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NGC 4151 |
MAY 25th, 2010Sunflower Galaxy, M63 Bright spiral galaxy located in Canes Venatici. It is a classic flocculent type of spiral, ie one where its visual appearance has short dis-jointed spiral structure. However, studies of molecular gas in the galaxy reveal long symmetrical spiral arms - a case of split personality! The galaxy is also classified as a "UV-bright LINER'' type. It was discovered by Pierre Méchain on June 14, 1779.
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M63 |
MAY 17th, 2010Spiral Galaxy, M94 Spiral galaxy with very bright core situated in the constellation Canes Venatici. It was discovered by Pierre Méchain, Messier's colleague, on March 22, 1781. Until recently it was believed that the galaxy’s inner spiral region was surrounded by a faint, broad ring of stars in an oval shape. However, recent deep multi-wavelength images (Jan 2010) clearly show the outer ring is not a ring at all but a faint spiral arm sweeping far out. My image gives a hint of this spiral structure.
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M94 |
MAY 1st, 2010Spiral Galaxies, M65 & 66 Pair of bright 9th magnitudes galaxies in the tail of Leo discovered by Messier in 1780. Just by their general appearance, I had always assumed these galaxies were located together in space but most current distance estimates put M65 (right) as the nearer galaxy at 22 million light-years with M66 (left) further away at 36 Mly ie 14 Mly apart!
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M65 M66 |
APRIL 19th, 2010Spiral Galaxy, M106 Discovered by Pierre Méchain in 1781, M106 is a large bright galaxy located in Canes Venatici. It is one of the closest Seyfert galaxies to us at around 25 million light-years away. Seyfert galaxies have active galactic nuclei thought to powered by supermassive black holes at their center - sort of tame quasars! The companion galaxy is NGC 4217.
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M106 |
APRIL 16th, 2010Moon, Venus and Mercury, Lancashire Beautiful conjunction on the 16th April with the crescent Moon plus Venus and Mercury (just!). Mercury was somewhat obscured by the Icelandic volcanic ash blowing over the UK. Mercury is low down, just left of centre. The Icelandic volcanic dust might have hindered seeing Mercury but with all aircraft grounded at least there were no aeroplane trails to spoil the spectacle!
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Moon, Venus and Mercury |
APRIL 4th, 2010Spiral Galaxy NGC 2683 Image details: Located in Lynx, this almost edge-on galaxy was discovered by William Herschel in 1788. A feature of this galaxy is the mottled dust markings on the near side to us. Distances for it vary from 16 to 25 million light years. The image was taken with my two telescopes and cameras operating simultaneously - one recording luminance, the other colour.
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NGC2683 |
MARCH 28th, 2010Planetary Nebula Jones-Emberson 1 Large but very faint planetary nebula in Lynx discovered in 1939 by Rebecca Jones and Richard Emberson. Their discovery report mis-identified it as NGC 2474/5. Unfortunately this error has been oft repeated resulting in some planetarium programs, eg SkyMap, not including this object. It is in fact about 1 degree north of the galaxy pair NGC 2474/5. Coincidently there are two background galaxies present in the image. Image details:
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Jones-Emberson 1 |
MARCH 20th, 2010Supernova 2010af in NGC 3172 Discovered by Tom Boles on 4th March, this supernova must be one of the most northerly ever discovered as NGC 3172 is only 55 arcminutes from the north celestial pole. NGC 3172 is also known as Polarissima Borealis. Intriguingly the supernova appeared a long way from its parent galaxy so I was determined to take a deep exposure to see what was going on. Because of its proximity to the pole my exposures were virtually manually guided as equatorial telescopes struggle to autoguide here. What was revealed was a large face-on spiral galaxy with the supernova just off the west (right) edge. Catalogue sizes for this galaxy (typically given as 1 arcminute) are totally erroneous and its true diameter appears to almost 4 arcminutes. Given its large distance of 277 million light years, simple maths implies a diameter of 300,000 light years - a whopper! Two smaller galaxies overlay NGC3172. Image details:
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NGC 3172 and Supernova 2010af |
MARCH 18th, 2010Galaxay IC2574 (Coddington's Nebula) Discovered by Edwin Coddington in 1898 and classified as a nebula as this was the era before galaxies. It is actually a dwarf irregular galaxy in the constellation Ursa Major and is part of the M81 group of galaxies. Image details:
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IC2574 |
MARCH 18th, 2010Thor's Helmet, NGC 2259 Located close to Sirius, this nebula is really too low for me to image but I couldn't resist. This helmet-shaped nebula with wing-like appendages is popularly called Thor's Helmet. Stellar winds from the brightest star in the image is producing the nebula. It is a Wolf-Rayet type and will probably end its days as a supernova. Image details:
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NGC 2259 |
MARCH 12th, 2010Barred Spiral Galaxy, NGC 2903 Discovered by William Herschel in 1784, this galaxy is another that was surprisingly missed by Messier despite its size and brightness. Classed as a"hot-spot" galaxy, its nucleus is of an intermediate type between a normal one such as the Milky Way and that of a Seyfert galaxy. It is about 20 million light years away and located in Leo. Image details:
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NGC 2903 |
FEBRUARY 23rd, 2010The Seahorse and the Jellyfish, IC443 IC 443 is the bright nebula to the west (right) and is known as the Jellyfish Nebula. To the east (left) is a dark nebula silhouetted in front of a faint emission nebula - this takes the form of a seahorse. Image details:
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IC443 |
FEBRUARY 21st, 2010Remote Globular Cluster, NGC 2419 One of the most remote globular clusters known being even further away than our satellite galaxies, the Magellan ic Clouds - and yet, despite the distance, it is still recognizably a globular. Formerly known as the "intergalactic wanderer" this name is now known to be inaccurate as the globular is gravitationally bound to our galaxy taking several billion years to complete an orbit Image details:
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NGC 2419 |
FEBRUARY 14th, 2010Spiral Galaxy, NGC 2403 Large bright spiral galaxy in the constellation Camelopardalis surprisingly missed by Messier. Discovered by William Herschel in 1788. NGC 2403 is an outlying member of the M81 Group and is around 8 million light-years distant Image details:
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NGC 2403 |
FEBRUARY 7th, 2010Orion Nebula, M42 I couldn't resist a return to this old favourite but this time I wanted to combine RGB with H-alpha for a deeper image. Processing required 4 image masks to preserve detail from the brightest areas to the faintest. Image details:
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Orion Nebula |
JANUARY 20th, 2010The Foxfur Nebula Located just north of the Cone Nebula near to the variable star S Mon (S MONOCEROTIS), which is part of the young open cluster, NGC 2264. Image details:
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Foxfur Nebula |
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Please remember these images are copyright David Ratledge. Contact me before any use is made of them. |