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ARCHIVE 2011INTRODUCTIONImaging 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 3rd, 2011Satellite Galaxies of M31, NGC 147 & 185 These two satellite galaxies of M31 are not the most spectacular objects. However, with clouds about the shorter exposures I use with the Tak+Canon seemed a better option. Again the UHC filter was used - not sure the colours of the galaxies are too accurate with this filter though so I blended them with some archive data from 2002. Image details:
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NGC 147 & 185 |
NOVEMBER 27th, 2011Spiral Galaxy, M33 Another experimentation with the UHC filter. Obviously it is not ideal for galaxies but M33 has many nebula within it and the plan was that the UHC filter would highlight these. To produce the final image, the UHC data was toned down with archive data I had taken back in 2007. This mellowed the colours a tad so it would look a bit more natural. One surprising aspect the UHC filter revealed was 3 prominent blue/green nebulae which at first I thought must be artifacts but turned out to be real. The brighter two are IC132 and NGC 588 with the third southern one apparently not catalogued. Image details:
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M33 |
NOVEMBER 20th, 2011Little Dumbbell Nebula, M76 One of the faintest Messier objects and one to which I had not previously paid much attention. However with moonlight present, this was a suitable target for narrowband filters and its colours have responded well to a UHC filter. A tricky object visually and it looks more like a butterfly than a dumbbell to me. Image details: |
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Planetary Nebula M76 |
NOVEMBER 13th, 2011Planetary Nebula, Abell 74 (PK 72.7-17.1) Located in Vulpecula, this planetary nebula is a very old, very large, very round and very faint! If you select your objects by size then this one will pop up in your searches but it needs serious exposure times to drag it out of the sky background especially if you suffer from light pollution like myself. The red elliptical fuzzy above centre (half way from the centre to the top edge) is background galaxy PGC66471. Image details: |
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Planetary Nebula Abell 74 |
NOVEMBER 1st, 2011Emission Nebula, Sh2-135 Reasonably clear again on the 15th October but a 88% full Moon meant another narrowband target was the order of the day. This somewhat ignored nebula in Cepheus has responded well to H-alpha despite me not being able to shoot as long as planned due to computer problems - PCs don't survive long in our Lancashire climate. Image details: |
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Emission Nebula Sh2-135 |
OCTOBER 23rd, 2011The Phantom of the Opera Nebula, Sh2-173 At last back to imaging after the worst run of weather ever - no decent imaging nights from 17th August until 14th October! And then it was 94% full Moon so H-alpha it had to be. This object is a bit large for my field of view but I couldn't resist - if you lean your head 45 degrees to the right then the phantom becomes obvious. Image details: |
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Phantom of the Opera Nebula |
OCTOBER 1st, 2011Northern Cygnus from Kelling Heath After a shocking run of cloudy nights (35 in a row) we headed south and east to the Kelling Heath Star Party in an attempt to find clear skies. The weather was great and on the first night we had about 2 hours of clear skies before hazy clouds drifted in. Subsequent nights were not quite as good. The 20Da is about half-way between an un-modded and modded camera - the h-alpha sensitivity is better than standard but doesn't match a modded camera. Image details:
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Northern Cygnus from Kelling Heath |
AUGUST 28th, 2011Comet Garradd passing M71 The Takahashi was set-up with a UHC filter for other imaging but there were some gaps in the clouds around twilight on the 27th so I was able to grab 2 images of Comet Garradd as it was passing globular cluster M71 before it clouded in. I really didn't know what to expect but amazingly the comet has recorded despite the un-ideal filter. Image details:
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Comet Garradd passing M71 |
AUGUST 27th, 2011Emission Nebula Sharpless Sh2-97 (Narrowfield) Emission nebula in Cygnus. Rarely imaged and I now know why - it is extremely faint barely registering with the H-alpha filter in 20 minute sub-exposures. I always try to get the target pretty central but in this case I failed. The catalogue I was using for its location was in error and as the object was so faint I didn't realise I was aiming a bit too high. Image details: |
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NGC5907 |
AUGUST 25th, 2011Emission Nebula Sharpless Sh2-97 (Widefield) After experimenting earlier in the year with processing an image taken with a UHC filter, I decided to try one out for myself on the Takahashi. The subject was the very faint nebula Sh2-97 - well it needed a difficult target to test it out. It was taken with an 85% full moon present and yet the 10 minute sub-frames were not fogged out. The nebula was extremely faint and needed a boost from a "starless" image taken simultaneously with the RCOS. Overall I now believe the UHC filter is best the way to go with a DSLR under light polluted skies - at least for nebulae as I have yet to test it on a galaxy. Image details:
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Sh2-97 |
AUGUST 19th, 2011The Observatory Re-opens The observatory re-opened yesterday (17th August) after its summer break. Our summer nights don't get dark enough for imaging but it gives me a chance to carry out maintenance and upgrades. Only one major change this year - the Takahashi has been fitted with an off-axis guider. This was the prism/eyepiece holder from a second-hand Meade unit shoe-horned into the Takahashi camera connector tube. This machining was carried out by Brian and an excellent job he did. I hope to use it later this autumn. It should enable much longer exposures with the Canon 40D.
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JULY 6th, 2011The Splinter Galaxy, NGC 5907 Only 3 degrees from exactly edge-on, this Sc spiral galaxy has an interesting retinue of globular clusters. These were discovered by Kissler-Patig et al using the Hubble Space Telescope WFPC-2. In all they detected 25 - no mean achievement as current estimates place this galaxy at 54 Mly distant. By far the easiest for amateurs to detect is KAZF 5907-2. This globular is relatively well away from the disk and is one of the brightest (least faint) at mag (B) 21.89. It shows clearest in the luminance image (inset). Image details: |
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NGC5907 |
JUNE 27th, 2011The Whirpool Galaxy, M51 Taken just a few days before the supernova exploded - just my luck! Image details: |
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M51 |
JUNE 17th, 2011Spiral Galaxy, M96 Although the observatory is shut for its summer break, processing of this spring's images continues with still 2 more to do after this one. M96 is the largest galaxy in the Leo 1 Cluster (also known as the M96 Group) comprising around 9 main members. However, close inspection of this image reveals an additional 10 small copmanions to M96 although most could well be background objects. M96 is about 38 million light years away Image details: |
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M96 |
JUNE 5th, 2011Barred Spiral Galaxy, M95 A classic barred spiral but with a highly unusual nucleus. The nucleus comprises a gas ring orbiting around the centre. The centre contains around one million solar masses whilst the gas ring has several 'hotspots'. These 'hotspots' are thought to be the sites of intense star formation. Image details: |
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M95 |
MAY 25th, 2011The Needle Galaxy, NGC 4565 The classic edge-on galaxy - hence its common name, the Needle Galaxy. Over the years there has been much speculation as to whether NGC 4565's large bugle is a bar seen end-on. The issue seems to have been settled by Kormendy and Barentine (2010) who found that "from a formation point of view, NGC 4565 is a giant, pure-disk galaxy. This presents a challenge to our picture of galaxy formation by hierarchical clustering: it is difficult to grow galaxies as big as NGC 4565 without also making big classical bulges". Image details: |
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NGC 4565 |
MAY 15th, 2011The Hamburger Galaxy, NGC 3628 The faintest but largest member of the Leo Triplet, comprising the galaxies M65, M66, and NGC 3628. This group has been much studied since Zwicky drew attention to it in 1956. Zwicky reported a long optical plume (tidal tail) extending eastwards from NGC 3628. The beginnng of which is visible on the full frame version of my image (click here). Rots (1978) constructed restricted three-body orbital models for the tidal interactions between NGC 3628 and M66, which reproduced the formation of a long plume. You would have thought the tail would have been more in the direction of M66 but it is away from it. Image details: |
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NGC 3628 |
MAY 5th, 2011Planetary Nebula Abell 31 (Sharpless 2-290) Is this the largest planetary nebula? It has a larger apparent size than the Helix Nebula which is often claimed to be the biggest. However, Benedict at al. (2009) using the HST found it to be 3 times further away than the Helix at a distance of around 621 parsecs (approx 2000 light years). They used trigonometric parallax to determine its distance. Biggest or not, this ancient planetary nebula is seriously faint!!!!! Image details: |
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Abell 31 |
APRIL 18th, 2011Interacting Galaxies, NGC3718 + NGC3729 and Hickson Compact Galaxy Group 56 In the foreground is the galaxy pair NGC 3718 and 3729. These distorted spiral galaxies are believed to be a gravitationally bound pair and part of the Ursa Major Galaxy Group. They are around 40 million light years distant whereas Compact Galaxy Group Hickson 56 is 10 times further away at 400 million light years. Hickson 56 is also known as Arp 322 and comprises a chain of 5 galaxies (from left: edge-on spiral a (PGC 35631), an interacting trio b,c and d (PGC 35620, PGC 35618 and PGC 35615), and finally connected by a faint bridge galaxy e (PGC 35609). Image details: |
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NGC 3718 and 3729 plus Hickson 56 |
APRIL 3rd, 2011Spiral Galaxy, NGC2841 In 2001, this inclined spiral galaxy had its distance determined precisely (at 46 mly) by the Hubble Space telescope measuring Cepheid variable stars within it. Recently (Feb 2011), Hubble has released a highly detailed image of the galaxy's central regions. This galaxy is located in Ursa Major. We cannot rival the Hubble view but amateur images can give some indication of the galaxy's splendour. Image details: |
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NGC 2841 |
MARCH 21st, 2011NGC 3190 Group, Hickson 44 Weather at the beginning of March was much better for imaging, ending a long frustrating run of cloudy nights. Located in Leo, NGC 3190 is the near edge-on spiral galaxy at the centre of galaxy group Hickson 44. Estimated to be around 80 million light years away, the other 3 main group members are the featureless elliptical, NGC 3193, a faint but striking spiral galaxy NGC 3187 and at the bottom (south) is NGC 3185, a barred spiral with an outer ring. Many background galaxies complete the scene. Supernova are relatively rare events but within 2 months in 2002, Galaxy NGC 3190 had 2 (2002bo and 2002cv). Image details: |
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NGC 3190 Group |
MARCH 11th, 2011The Medusa Nebula, Abell 21 At last some recent clear nights enabled me to complete imaging this object - in all it took 6 nights between clouds! Located in Gemini, this large but faint planetary nebula was initially thought to be a supernova remnant. However, measurement of expansion velocities and the thermal character of the radio emission confirmed it to be a planetary nebula. Image details: |
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Medusa Nebula |
FEBRUARY 20th, 2011The Horsehead Nebula, B33 The abysmal weather continues so I was forced to image only 27 degrees away from an 86% full Moon in order to get this shot. Desperate times call for desperate measures! I managed 3 hours split either side of the meridian. Colour was from previous year's images. Image details: |
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Horsehead Nebula |
FEBRUARY 13th, 2011Distorted Barred Spiral Galaxy, NGC 2146 Located in Camelopardalis, this galaxy is associated with radio source 4C 78.06 and is believed to be around 50 million light years distant. It is currently undergoing a major burst of star formation probably as a result of either a recent merger or strong interaction. Image details: |
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NGC 2146 |
FEBRUARY 5th, 2011Spiral Galaxy, NGC 925 After a shocking run of weather, even by Lancashire standards, I was finally able to complete the imaging this galaxy in Triangulum on the 28th January. Despite being in the same general direction as M31 and M33 this galaxy is not part of the local group and is in fact much further away at around 32 million light years. A study published in 2000 by Pisano, Wilcots and Elmegreen found NGC 925 to be a prototypical late-type spiral galaxy, with some properties similar to our Magellanic spirals, such as an off-center bar and having one of its spiral arms (the southern one) very dominant. Image details: |
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NGC 925 |
JANUARY 25th, 2011Rosette Nebula (South-East) Not one of my images but after a terrible run of weather I was asked to see if I could process this image for a colleague. He was struggling with it and as I had suggested experimenting with the filter he had used, I felt it only right I should try to see if a usable image could be extracted. The image was a trial with a Baader UHC filter on a modded DSLR camera (Canon 350D). The idea we had resulted from using a H-alpha filter with a DSLR when only 1 in 4 pixels (the red ones) were recording - the other 3 were doing nothing. Why not instead use a UHC filter which would pass the H-alpha and OIII (+ H-beta) at the same time - maximising imaging time. To process it I spilt the image into its RGB components. First I processed the R to get it as good as possible. I then added the G + B to make what I called B and processed it the best I could. Now the tricky bit. To synthesise a G layer I tried using the B as both B and G. Then I tried multiplying R x B to make G but that wasn't right. I tried averaging R and B but that wasn't right either. In the end I used an average of R x B and R + B. The result is what you see here which is hopefully close to natural colours for the nebula and the stars. Image details:
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Rosette |
JANUARY 10th, 2011Perseus Galaxy Cluster, Abell 426 Part of the Perseus-Pisces Supercluster, Abell 426 is a very large cluster, containing perhaps over one thousand galaxies. The central dominant galaxy is the cD type galaxy NGC 1275 (centre left). It is both a radio source (Perseus A) and a type 1.5 Seyfert galaxy. It is also believed to have a second system, known as the "high velocity system" (HVS), directly in front of it. The cluster is about 250 million light years from Earth. Image details:
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Abell 426 with NGC 1275 |
JANUARY 3rd, 2011Polar Ring Galaxy, NGC 660 NGC 660 is a highly distorted galaxy made up of two systems: a nearly edge-on disk plus an inclined polar ring or strongly warped outer disk. The likely explanation is a head-on collision/merger of two spiral galaxies, each with their own dust lanes. Located in eastern Pisces not far from M74. My last attempt on this object in 2008 just wasn't long enough so I returned for more signal and less noise! Image details:
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NGC 660 |
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Please remember these images are copyright David Ratledge. Contact me before any use is made of them. |