Big Cat Hunting

February 26, 2015 by grahamrob in Deep Sky Objects, General Astronomy, Imaging and tagged DSO Imaging, Galaxies, Leo | 1 Comment

As we move closer to the Spring Equinox, the winter sky is already rapidly disappearing towards the western horizon and I have been left wondering what next? I was concerned that after successfully imaging the Orion constellation and all its spectacular parts over the past four months, it would be a difficult act to follow, I needn’t have worried. Already starting to appear from late-evening, a series of constellations are about to proceed across the night sky over the next few months which will provide an equally spectacular but different kind of show to Orion.

First of these is the constellation Leo, the celestial Lion, which it turns out is packed with galaxies and double stars. The asterism of Leo is in the shape of a lion which, being dominated by various groups of galaxies holds much imaging promise, with my 81mm telescope providing an ideal field of view.

Located behind Leo’s rear ‘leg’ is the best of these, known as the Leo Triplet or M66 Group, which consists of three galaxies: M66, M65 and NGC 3628. Evidence suggests that these are linked in a gravitational dance with each other which, in the case of NGC 3628, has created a disturbed, unbarred galaxy with a faint 300,000 light-year star to the east. M66 is an intermediate spiral galaxy, with a diameter of about 95,000 light-years and is the largest and brightest of the trio. M65 is a smaller, barred intermediate galaxy. The field of view has also captured other galaxies as well as the orange giant star 73 N Leonis. All-in-all a wonderful image which I hope to return to in order to achieve even better detail using longer exposures, guiding and hopefully a larger telescope one day.

Leo Triplet: M66, M65 & NGC 3628
WO GT81 + modded Canon 550D & FF | 10 x 180 secs + calibration @ ISO1,600 | 21st February 2015

To the west of the Leo Triplet, in the direction of Leo’s dominant star Regulus, is another triple collection of galaxies called the M96 Group. While a little fainter that the Leo Triplet, the M96 Group nonetheless makes a wonderful image accompanied, as it is, by numerous other galaxies and stars. Of the latter, the giant orange 52 K Leonis star dominates the scene.

M69 Group: M105, NGC 3373 & NGC 3371 + other galaxies and orange giant 52 K Leonis WO GT81 + modded Canin 550D & FF | 10 x 180 secs & calibration @ ISO 1,600 @ 21st February 2015

M96 Group: M95, M96, M105, NGC 3373 & NGC 3371 + other galaxies and orange giant 52 K Leonis
WO GT81 + modded Canon 550D & FF | 10 x 180 secs & calibration @ ISO 1,600 @ 21st February 2015

It’s fair to say that the results of my big cat hunting around the constellation Leo have been a pleasant and successful surprise, with further promise still to come as Spring develops. Watch this space!

Inverting the M96 Group image helps show better the galaxies and other significant features.

Two’s Company

February 24, 2015 by grahamrob in Solar system, Widefield Imaging and tagged Mars, Solar system, Uranus, Venus | Leave a comment

During the late 20th Century planetary relationships took on a new meaning as a metaphor for the difference between men and women, following the publication of John Gray’s book Men Are From Mars, Women Are From Venus. Making a beautiful view at the moment, Venus is currently flirting with Mars in the early evening sky, for a very brief period low on the western horizon just after sunset. Its appulse with Mars can be easily seen with the naked eye but the view from Fairvale Observatory lasts only about 20 minutes and therefore requires good seeing conditions and quick action to get a picture.

At the weekend the view was even better, with the crescent of the New Moon adjacent to the field of view of Venus and Mars at the same time but my camera was not ready. Ideally I would like to image its apparition with a telescope but having to act quickly, last night I managed to get a quick photograph of the two planets using a DSLR camera and a 600 mm telephoto lens; the International Space Station flew by shortly afterwards but unfortunately too late get a photograph combining all three, timing is everything.

Later in the month the apparition of Venus will also include Uranus, making an even better show but will definitely not be a case of two’s company, three’s a crowd!

Shining brilliant white, magnitude -3.9 Venus – top left & the smaller, faint magnitude +1.3, red planet of Mars – bottom right

STOP PRESS!

Another good evening sky this evening and tonight I manged to set-up the telescope to take this beautiful picture of Venus and Mars:

Parting Shot

February 14, 2015 by grahamrob in Deep Sky Objects, Imaging, Software and tagged DSO Imaging, Nebulae, Orion | 6 Comments

I thought I was finished with Orion for this winter but a high pressure system and clear weather provided an unexpected opportunity on Sunday evening that I couldn’t resist. The good news: as Orion is passing the Meridian by 8.00 pm it provides an early start. The bad news: being near Gatwick Airport, at this time of the evening the sky is full of aeroplanes at Fairvale Observatory, most of them flying directly through the Orion field of view!

With such good weather, I also decided to try out computer control for the first time. I installed EQMOD before Christmas and have since been reading and watching tutorials on its use and experimented operating with it indoors. Frankly I am somewhat intimidated by the large collection of software that is required to go to the next level with imaging and EQMOD is just the first step. However, eventually I just have to do it and this would be the night to start!

EQMOD is a software project written and run by enthusiasts which provides computer control to the mount, thus dispensing with the SynScan handset. It also does much, much more and in general provides far superior control and flexibility, in particular linking control with a chosen planetarium programme – usually either the excellent Stellarium or Carte du Ciel, all of which is free!

Notwithstanding, I still have the major problem of polar alignment as my house completely obstructs all views of the northern sky. For the moment I adopted a belt-and-braces approach, first achieving polar alignment using the SynScan routine before switching to EQMOD control; once comfortable using EQMOD I plan to try out alignment software called Alignmaster, which I hope will allow me to completely dispel with SynScan. On this occasion EQMOD worked a treat. For alignment, just clicking on the object you want to see in the planetarium software (with which EQMOD is linked), the telescope slews and after accurately aligning the scope with the star you press a sync button. It’s so quick that it is easy to rapidly establish five or six (or more) star alignment points, thereby constructing a triangular matrix from which the mount can then track more accurately. There are many other features I have yet to use but so far I like what I see and am in awe of those who have written and maintain the system.

With EQMOD computer control thus established successfully, I set out to image some old ‘friends’ in Orion. Having only recently acquired a modded Canon 550D, it seemed only right to take another look at M42 the Great Orion Nebula and The Flame and Horsehead nebulae.

The impact of modification was immediately evident with M42, it now being much redder than before and with greater detail exhibited in the nebulosity. The tracking also looked OK, though a few stars looked a little bloated, suggesting there’s still work to do on another day i.e. autoguiding.

Orion’s Sword: M42 The Great Orion Nebula, Running Man Nebula & NGC 1981 Star Cluster
WO GT81 + modded Canon 550D & FF | 10 x 180 secs @ ISO 800 & darks calibration | 8th February 2015

The Flame and Horsehead nebulae also show similar improvements and, in the case of the Horsehead, the actual ‘head’ is much clearer than before.

NGC 2024 Flame Nebula & Horsehead Nebula WO GT81 + modded Canon 550D & FF | 10 x 180 secs @ ISO 800 & darks calibration | 8th February 2015

NGC 2024 Flame & Horsehead Nebula; NGS 2023 relection nebula just below/left of the Horsehead
WO GT81 + modded Canon 550D & FF | 10 x 180 secs @ ISO 800 & darks calibration | 8th February 2015

With Orion by now well past the Meridian and the weather holding up well I then decided to try my luck once again with Jupiter, which by now is well located high in the south east sky. Unfortunately like sport, astronomy is a game of two halves. Following the success using EQMOD my experience with Jupiter was a complete failure.

I had previously encountered significant problems with my webcam last year, that mostly stemmed from problems with the capture software and it was here that I was to stumble (fall more like it) once again. Initially Firecapture seemed to boot up OK and recognised the camera, though try as I may I could not see Jupiter on the screen; I knew it was there as I had previously centred and focussed it there. I therefore decided to reboot the software, which was a big mistake. This time Firecapture would not recognise the camera and on trying to de-bug the problem I ended up with the dreaded ‘black screen of death’. Here was the downside of computer control, with the black screen going nowhere I also lost all control of the mount! I therefore retreated to SynScan, parked the telescope and deliberately crashed the computer; I have not yet investigated the problem further since then – watch this space!

It was therefore something of an ignominious end to the evening. However, I was still buoyed by the earlier success of EQMOD and more than happy with what may be my parting shot of Orion for this winter. Au revoir.

Horsehead Nebula with the NGC 2023 reflection nebula, bottom left

Room With A View

February 12, 2015 by grahamrob in Comments, Imaging, Widefield Imaging | Leave a comment

The International Space Station is an amazing achievement and I consider the people who fly in the ISS to be very lucky.

From time to time the ISS flies over Fairvale Observatory and last Christmas Eve was such a moment when, travelling at just over 17,000 mph about 250 miles above Earth, I managed to get a picture of its trail in the sky.

ISS flies over Fairvale Observatory 24th December 2015

ISS flies over Fairvale Observatory
24th December 2014

Yesterday US astronaut Terry Virts currently onboard the ISS tweeted this fantastic picture of the British Isles from his vantage point above Earth, set-off by the Aurora Borealis to the north. Thanks Terry and good luck.

Orion in Perspective

February 6, 2015 by grahamrob in Deep Sky Objects, Equipment, General Astronomy, Imaging, Widefield Imaging and tagged Orion, Photography | Leave a comment

Perspective:

The appearance of objects relative to each other, as determined by their distance from the viewer, or the effects of this distance on their appearance – The Free Dictionary.

Noun: The art of representing three-dimensional objects on a two-dimensional surface so as to give the right impression on their height, width, depth and position in relation to each other – Oxford English Dictionary

I have just finished an Open University MOOC (Massive Open Online Course) on Orion, which it has to be said was mixed in its content and quality. Notwithstanding, the course provided a useful basic understanding of objects in the Universe, particularly Orion, how they related to each other and as a whole. Through my professional experience I am used to viewing and understanding objects in 3D, all the more so since computer modelling has provided a tool with which to visually illustrate such spatial shapes and relationships. Although it is obvious that such relationships also describe the astronomical space in which we exist i.e. the Universe, and commonly describe the location of stars and other heavenly bodies by their distance, RA and DEC, I have seen very few of these objects visually modelled for common asterisms or constellations.

The constellation of Orion is probably the main feature of the winter night sky and it is certainly my favourite, particularly when looking at its rich content: M42 the Great Orion Nebula, the Running Man Nebula, the Horsehead and Flame Nebulae, M78, Barnard’s Loop and many more. Sadly after more than 4-months imaging these objects for the first time, Orion is now starting to rise very early in the evening and by 11pm is well past the Meridian – it will not be long before this magnificent feature will be gone for another year, until on the very early mornings of next October it will reappear again, can’t wait!

With my new found interest in astroimaging I have almost exclusively used a DSLR camera and focused my attention on DSO features, using a telescope and GoTo mount, somewhat neglecting the use of the camera for basic widefield photography. Apart from the attraction of playing with my new toys, I was put off by the lack of a suitable camera attachment and a wide angle lens; because of the inherent crop factor associated with the cropped digital sensors employed in most DSLR cameras (except very expensive full frame cameras), the real focal length of a camera lens will be extended and hence the field-of-view narrowed – in my case with a x1.61 crop factor, a 50mm lens operates at an apparent focal length of 80mm! However, using the top off an old camera tripod I recently I managed to jerry rig the camera onto the GoTo mount, thus providing tracking and enabling longer exposures. It’s only a start but there is great promise in such photography, as seen on this excellent website, and I intend to pursue more of these images with a better way of attaching the camera and decent wide-angle lens when I can.

As a result, on Christmas Eve I obtained my first reasonable image of the whole Orion constellation, which with better exposure shows the detail, beauty and context of the numerous DSO items contained within and images previously noted.

The Orion Constellation Canon 700D | 27 x 10 secs @ ISO 1,600 & calibration | 24th December 2014

The Orion Constellation
Canon 700D & Telephoto 200 mm | 27 x 10 secs @ ISO 1,600 & calibration | 24th December 2014

In the early days of my astroimaging about 12 months ago, I found focussing something of a challenge but, with the assistance of the wonderful Bahtinov mask and Live View on-screen computer focusing, I thought that had become a thing of the past, unfortunately not! Guided by the infinity mark on the camera lens for focussing, I set out to image some of Orion’s more elusive nebulosity, in particular Barnard’s Loop, with which I am fascinated – its enormous size of some 10^oor 600 arcminutes and complete absence from ordinary view are both intriguing, exciting and challenging. I had tried to photograph this feature before, which completely envelops Orion’s Sword and extends up towards Betelgeuse, but to no avail. With my bodged but useable camera set-up I tried again two weeks ago. This time the problem was once again focussing; it turns out that with widefield astroimaging using a standard camera lens, infinity does not necessarily mean infinity, as there is some leeway either side. The out-of-focus images that resulted could therefore not be stacked but, using a single image, calibration and extensive post-process stretching in Photoshop, Barnard’s Loop was finally revealed and even Lambda Orionis above Betelgeuse and Bellatrix, albeit very noisy and out of focus. Notwithstanding, I am pleased with this enticing glimpse and will return another day to rectify the problems.

The Orion Constellation & Barnard's Loop (up / north is left) AZ-EQ6 Mount + Canon 550D & 200mm Telephoto | 180 secs @ ISO 1,600 & calibration | 22nd January 2015

The Orion Constellation & Barnard’s Loop (up / north is left)
AZ-EQ6 Mount + Canon 550D & Telephoto 200 mm | 180 secs @ ISO 1,600 & calibration | 22nd January 2015

Since my first decent image of the Great Orion Nebula on a very early morning at the beginning of last October, I have had hours of fun and some frustration imaging various parts of the Orion Constellation. But despite my new familiarity with the Orion constellation, 3D modelling and, I’d like to think, good spatial awareness, I was still pleasantly surprised and impressed by this wonderful 3D video of the constellation produced by the Space Telescope Science Institute for NASA and used during the aforementioned Open University course, which really does put it all into perspective: The True Shape of Orion.

Busy Bees

February 1, 2015 by grahamrob in AstroBin, Deep Sky Objects, Imaging and tagged Cancer, DSO Imaging, Star Clusters | 1 Comment

Cancer AKA the Crab, is the dimmest of the zodiacal constellations and generally lacking in notable objects except, at its centre, lying almost on the Ecliptic just 600 light-years from Earth, M44 is one of the closest star clusters to the Solar System. More engagingly, M44 derives its alternative name from its appearance as a swarm of stars dancing actively like bees i.e. the Beehive Cluster. Its Latin equivalent, Praesepe means hive, manger or crib.

At 600 million years old its dancing stars must be considered quite youthful compared to our Sun’s 4.5 billion years and are thought to have been created from the same, very large molecular cloud as Hyades in the constellation of Taurus. An open cluster of some 1,000 stars, M44 spans 15 light-years across or about 1.5^o. A few but distinctive yellow-orange tinted red giants stand out, scattered amongst the brighter hot blue stars, making an attractive image, one I expect to return to during the next three or more months as The Crab shuffles westwards across the night sky before giving way to views of a Spring and Summer nature.

M44 The Beehive Cluster
WO GT 81 + Canon 550D & FF | 20 x 120 secs & calibration @ ISO 1,600 | 24th January 2015

Flip Flop

January 29, 2015 by grahamrob in Deep Sky Objects, Imaging and tagged DSO Imaging, Gemini | 2 Comments

Another night, another lesson learned, the hard way.

A good, clear sky on Saturday meant the prospect of a long and productive imaging session before the frost came down. Whilst Orion has now moved to early evening, the light pollution from Gatwick airport to the south is bad at that time, so I’ll grab what I can but later is better when the light pollution starts to subside; from experience I presume they start to turn off the airport lights gradually from about 10pm, so that by midnight the sky is noticeably darker and much better for astronomy – though nothing like a true dark sky. I therefore look more to the south east at about 8pm to line up potential imaging targets for about one to two hours later when objects will be located at their best position, towards the Celestial Meridian and preferably high in the sky; such a location reduces the thickness of the atmosphere and improves tracking accuracy as the telescope’s angle with the object is less extreme. At the moment this means something in or around the constellation of Gemini and later at night Cancer; Canis Major, Pupis and Hydra also fit the bill except for one critical problem, they are too low in the sky and are mostly obscured by houses and trees, grrrrr!

Having imaged three, mostly easier objects earlier in the evening, at about 10pm I then turned my attention to something more challenging. Though large at some 100 light-years in diameter, the wonderfully named Jellyfish Nebula in the Gemini constellation (not far from the M35 open star cluster), with an apparent magnitude of +12 is quite faint and would be difficult to photograph. Notwithstanding, my first test image showed it was already in my field-of-view, though as anticipated faint, which I then set about adjusting to optimize its position within the frame before starting imaging. In this regard two bright, dominant stars flank the nebula – to the left or East, Tejat Posterior and to the right or West, Propus – thus assisting on screen identification and the approximate position of the nebula on the camera’s sensor.

At this time the nebula was very close to the aforementioned Celestial Meridian and it was clear that during a 1-hour imaging run would actually cross the Meridian, thus requiring a so called ‘Meridian Flip’. When setting-up the EQ-mount and telescope at the start, it is essential that they are aligned parallel with the Celestial Meridian in order that the mount and scope will then exactly track the movement of the night sky during subsequent viewing or imaging. However, due to the physical nature (internal gears) and resulting constraints of the mount and tripod, as tracking proceeds from east to west and eventually encounters the Celestial Meridian, it is necessary to carry out a Meridian Flip, manually or automatically. Such a flip requires that the mount and thus telescope and camera are swung from the west side of the tripod to the east, thereby ensuring that in continuing to track the object as it proceeds westwards they do not come into contact with the tripod.

Using the guide stars of Tejat Prosper and Propus to mark the East and West limits of the nebula and expecting the bulk of the other associated nebulosity to extend upwards, I positioned the stars towards the bottom of the frame. However, the nebula had by now crossed the Meridian and the telescope and camera was switched (flipped) to the other side of the mount before I completed framing. In-so-doing and, in my defence operating in the dark, I had overlooked that as a consequence of flipping across the Meridian, the camera had been inverted. Oblivious to this change of the camera’s attitude, I continued to frame the stars and thus hopefully placing the nebula towards the bottom of the image, when instead I should be moving them towards the top of the frame as the camera was now upside down. The result was that the final image unfortunately misses some of the associated nebulosity, though thankfully not the Jellyfish itself.

IC 443 The Jellyfish Nebula with Propus to the left and Tejat Prosper to the right after inverting the camera. As a result much of the considerable interstellar cloud illuminated by interaction with the nebula is outside the bottom of the image. WO GT81 + Canon 550D + FF | 20 x 180 secs @ ISO 1,600 + calibration | 24th January 2015

IC 443 The Jellyfish Nebula, with Propus to the left and Tejat Prosper to the right after a Meridian Flip inverted the camera before framing. As a result much of the interstellar cloud illuminated by interaction with the nebula is lost outside the bottom of the image.
WO GT81 + Canon 550D + FF | 20 x 180 secs @ ISO 1,600 + calibration | 24th January 2015

The Jellyfish Nebula is considered to be the remnant of a supernova that took place between 3,000 and 30,000 years ago and is now interacting with surrounding molecular clouds. Like similar supernovae such as M1 the Crab Nebula, the Jellyfish also harbours a neutron star within, indicating a collapsed stellar core. The main Jellyfish is some 100 light-years across and 5,000 light years away from Earth.

IC-443 Jellyfish Nebula, correctly orientated Propus is now to the right.

The denser, though still delicate nebulosity of the main ‘Jellyfish’ feature, is located immediately east of Prospus but most of the entire field between the two aforementioned stars and an equal area above is also occupied by extensive, though more faint nebulosity – it was this which was lost in my final image due to the framing error noted above. Even with the new modded camera and 180 second exposures at ISO 1,600, the sensor has struggled to capture all the light but I am fascinated and pleased nonetheless with the result. A better image of IC-443 AKA the Jellyfish Nebula will have to wait until I am able to undertake much longer exposures, which I hope to do one of these days soon. In the meantime, I will be more aware of the Meridian Flip and its associated problems.

Seeing Red

January 24, 2015 by grahamrob in Deep Sky Objects, Equipment, Imaging and tagged DSO Imaging, Orion, Photography | 2 Comments

It was towards the end of last year I realised what I was missing in my images. Hydrogen alpha (Ha) is a deep-red spectral line created by energised hydrogen gas, with a wavelength of 656.28nm, such light is a dominant feature of emission nebulae. However, terrestrial cameras are made with an infra-red (IR) filter placed over the sensor in order to achieve the red-green-blue colours that typify what the human eye see as life on Earth. Unfortunately by filtering out some of the red wavelengths this has a negative impact on DSO astroimaging, as it will block the aforementioned Ha light. The result is that imaging such Ha features with a DSLR camera, as I have been doing with a Canon 700D, can significantly reduce the colour and even detail – in some cases where Ha is the principal light source the camera sensor may almost completely fail to register the object at all.

I had been aware of this problem from the outset when I purchased the Canon 700D but decided to make-do in order to see, (a) how I got on, and (b) if I even liked astrophotography. Nearly one year on and maybe I made a mistake then but I also enjoy using the camera for terrestrial photography. Here’s the catch: to improve the camera’s sensitivity to Ha it is necessary to remove the IR filter, to become what is then known colloquially as a modded camera, however, in doing so the camera becomes useless for terrestrial photography. Removing the IR filter allows more red light wavelengths to reach the sensor and, as a result, terrestrial pictures then acquire an overall pink-red hue! There are some ways round this but, as always with implications – but it was now clear I needed a modded camera.

There are three basic ways to ‘restore’ a modded camera for terrestrial use:

Adjust the custom white balance – each time the white balance needs to be set manually, depending on the type of prevailing light and subject. It will work but, in my opinion, makes the process of day-to-day photography something of a chore and certainly reduces the scope for spontaneity, something I like when I am out-and-about photographing.

Restore the colour balance during post-processing – basically this requires adjusting each photograph individually using processing software, such as Photoshop, to remove excess red that is reaching the sensor without the IR filter.

Use an OWB (Original White Balance) filter – like the CLS light pollution filter I already use, this filter fits snuggly in front of the mirror / behind the camera lens (if fitted) and essentially acts like the original IR filter that has now been removed for astrophotography. Although quite expensive, this is by far the most convenient solution but there’s a problem: the back-focus section of the standard Canon EF-S lens I use is too long to accommodate the filter. An EF or other manufacture’s lens would overcome this problem (at further expense) and I was about to go down this route when serendipity paid a visit.

Not to be taken literally, but sometimes I would rather be lucky than smart. Whilst researching the aforementioned issues and seeking out other possible solutions, such as purchasing an already modded camera, I registered on the excellent Astronomy Shed forum and posted a question on how to deal with my problem. By the next morning, together with other advice on how to proceed, my attention was drawn to a Canon 550D for sale that had just been posted on the forum that very moment. Furthermore, the price was good and the seller would modify the camera for a small charge; it requires a degree of expertise to carry this out but, as a professional photographer with an interest in astronomy, the seller had undertaken this successfully many times before, though I obtained references to be sure. Therefore, after a few online exchanges, I became the new owner of a modified Canon 550d camera, together with some other bits and pieces – leads, intervalometer and a Canon battery grip.

Apart from the fact that this was a good camera, at a good price, it had one other very useful attraction – it is a close relation of my other camera, the Canon 700D (about three years older in development terms) and thus I immediately knew my way around and, furthermore, all my existing accessories would fit. Like I said, I had just got lucky – in more than one way. It’s early days but, with a clear sky last Friday and plenty to image at the moment, I just had to try it out and was not disappointed.

Rosette Nebula
WO GT81 + Canon 550d (modded) + FF | 15 x 120secs @ ISO1,600 + darks/bias/flats | 16th January 2015

The evening’s targets were Comet Lovejoy, The Rosette Nebula and the Great Orion Nebula, of which the latter two showed off the camera’s new capabilities best. The difference was there to see immediately with the images straight out the camera and stacked, with a noticeable increase of red colour present. The benefit after post processing is perhaps more subtle but, I suspect, will become more apparent when I move on to objects where Ha is more abundant, such as NGC 2264 AKA The Christmas Tree Cluster & Cone Nebula, which when imaged just before Christmas showed just what I was missing – a shortage of red light and thereby significant detail of these beguiling astronomical objects. Hopefully this issue will now become a thing of the past and in the future I will be literally seeing red, for all the right reasons.

M42 & NGC 1977 After DSS stacking only
WO GT81 + Canon 700D (unmodded) + FF | 15 x 120secs @ ISO800 darks/bias/flats

M42 + NGC 1977 After DSS stacking
WO GT81 + Canon 550D (modded) + FF | 5 x 120secs @ISO1,600 + darks

The above stacked, pre-post processing images are the same objects shot with unmodded (Canon 700D) and modded (Canon 550D) cameras, showing a marked increased in red light using the modded camera following the removal of the IR filter. Below, the same images after post-processing.

Final, post-processing image from unmodded camera

Final, post-processing image using modified camera

Lovejoy Part-2

January 18, 2015 by grahamrob in General Astronomy, Solar system, Viewing and tagged Comet, Solar system | 1 Comment

I first became acquainted with C/2014 Q2 Comet Lovejoy just before Christmas and have since been keen to obtain my own image of the object from Fairvale Observatory; at the time I was fortunate to obtain a photograph of the comet from a fellow astronomer in La Palma. Despite the comet reaching its best positon on January 7^th, some 44 million miles from Earth and with the apparent magnitude (brightness) improving throughout January to less than +4.0, unfortunately nature and life prohibited me from attempting this task: Christmas, New Year, travel, bad weather, full Moon etc. A couple of clear skies did present a good visual sighting through binoculars but no image.

Last week, on Thursday evening, I eventually got my first opportunity but due to very strong winds (hence the clear sky) was unable to even set-up the equipment. The following evening a cold but clear sky again occurred and this time I took my chance.

Photographing and processing a comet is not straightforward. Since my last post, Comet Lovejoy has tracked west (to the right) of the Orion constellation and at the time of imaging was located just above the western end of Taurus, before it passes west of Pleiades on 19^th January. The first problem is therefore obvious – it’s travelling very fast, about 82,000 mph. Fortunately Livecometdata.com provides real time information on the comet’s journey, which is both impressive (how does it do this?) and very useful. Inputting the real time RA and DEC location data into the SynScan handset, the mount slewed straight to the comet, which was just off-centre of the field of view. And thus I had my first, proper live view of a comet – fantastic! Now for the tricky part: how to get an image?

I had already posed this question on Stargazers Lounge and had a number of useful suggestions. Of course, whilst the mount tracks the celestial sphere, the comet is making its own way through the sky, which is not the same path as the stars seen from Earth; I believe it is possible to track the actual comet but that’s too difficult for me. Therefore, it is necessary to err towards lots of shorter exposures to avoid blurring; the longer the exposure the more likely it is the comet’s tail can also be captured in the image but it is a fine line between achieving this and blurring. In the end I took two sets of images at 20 seconds and 60 seconds – probably too cautious but I was happy with the result and will be better prepared for my next comet, whenever that is.

Then came the next obstacle – stacking and processing. I had not thought about this before but in the world of stacking, the software is unable to distinguish the comet from stars. As a result it is necessary to identify the comet in each light frame by manually tagging it; at this point I regretted taking x40 exposures! Deep Sky Stacker will then stack using one of three procedures which basically prioritises either the comet or the stars or a combination of both – I chose the latter. As usual post processing in Photoshop is then used to improve the final image.

C/2014 Q2 Comet Lovejoy WO GT81 + Canon 550D (modded) & FF | 40 x 20secs @ ISO1,600 + darks | 16th January 2014

C/2014 Q2 Comet Lovejoy
WO GT81 + Canon 550D (modded) & FF | 40 x 20secs @ ISO1,600 + darks | Fairvale Observatory 16th January 2015

Whilst I am very excited to have successfully photographed Comet Lovejoy, I was less than impressed by the stacked image and actually prefer the original. Processing comet images takes the dark art of processing to a new level and I feel I’ve only reached the learning foothills so far.

Lovejoy will be in the sky for some weeks to come as it tracks across Andromeda and Perseus during February and into Cassiopeia in March. Whilst the best may be almost past, I certainly hope to follow its progress and, subject to conditions, might even attempt to image it once again before it continues its 8,000 year orbit into deep space. However, for now I’ve got my comet and am well satisfied – I will spend the intervening winter days practicing my comet stacking.

Comet Lovejoy WO GT81 + Canon 550D & FF | 15 x 60 secs @ ISO1,600 + darks| 16th January 2015

Comet Lovejoy
WO GT81 + Canon 550D (modded) & FF | 15 x 60 secs @ ISO1,600 + darks| Fairvale Observatory 16th January 2015

The Eyes Have It

January 17, 2015 by grahamrob in Deep Sky Objects, Imaging and tagged DSO, Orion | 1 Comment

Before the cloud rolled in the other night and already successfully imaged the Rosette Nebula in Monoceros and M35 in Gemini, I decided to turn my attention once again towards Orion – it’s addictive! Having previously imaged M42 the Great Orion Nebula and other features of Orion’s Sword, the Flame and Horeshead Nebula, Orions belt and a basic widefield image of the constellation – alas without Barnard’s Loop and the Anglefish Nebula – it was time to tackle some of the more elusive objects.

This time the challenge was size – less than 6 arc-minutes overall and located nearby to Alnitak – the reflection nebula M78 would be difficult for my telescope. Whilst the mount was well aligned and I was confident the GoTo software would accurately point towards the chosen target, as is often the case, the original image was not promising. However, after stacking and some delicate post-processing, the nebula became apparent. Peering out of a hole in a misty patch of interstellar dust were two ‘eyes’ formed of 10^th magnitude stars, thus illuminating the nebula.

Section of sky located just above Alnitak – not promising but look closer.

At this magnification further detail is not possible but nonetheless, the image is intriguing. M78 (NGC 2068) is the brightest (+8.3 magnitude) portion of the dust cloud which also includes NGC 2071, NGC 2067 and NGC 2064, all (just) visible in the image. Together with the Flame Nebula, all these nebulae are associated with the LDN 1630 molecular cloud, part of the larger Orion complex. I’ll need something like a 10” or bigger scope to reveal better detail but at the end of an already successful night, the image was pleasing – I look forwards to looking into those eyes again one day.