Overspill

October 27, 2016 by grahamrob in Deep Sky Objects, General Astronomy, Imaging, Solar system and tagged Andromeda, Aquila, Delphinus, Lyra, Messier Objects, Moon, Pegasus, Veil Nebula | 1 Comment

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After months of cloud followed by 3-months of lost imaging time due to a mysterious camera / mount control problem, I was on the verge of throwing in the towel by August. But then I sorted the problem, started guiding and as if by magic, with a prolonged spell of good weather managed 7-nights of astronomy between 23^rd August and 13^th September; such was the intensity I was able to work over consecutive nights and by the end quite exhausted but happy.

Under clear skies and warm nights I could operate in just shorts and a T-shirt, a hitherto unknown experience at Fairvale Observatory. In such comfort I was also able to experiment and optimize the equipment set-up further – oh, if it could only be like this always. Of course I did not miss the opportunity to chase some night sky objects as well, imaging 11 targets all-in-all, sometimes on more than one occasion. It was a glorious time which has since taken time to organise and process.

NGC 6905

NGC 6781

M57

M57

Top left – NGC 6905 Blue Flash Nebula in Delphinus constellation 42″ x 35″ mag +11 26th August; Bottom left – NGC 6781 planetary nebula in Aquila constellation 1.8′ +mag 11.8 23rd August; Middle M57 Ring Nebula Lyra constellation 1.4′ x 1.1′ mag +8.8 13th September; Right M57 23rd August

A number of these images have already been reviewed in Forbidden Fruit and The future is not what it used to be but, such was productivity that for the record I’ve collected the overspill here. Inevitably targets reflected what was about and in sight from this location at the time but were nonetheless diverse in nature, ranging from the Witch’s Broom to planetary nebulae, the Andromeda galaxy and, making use of the otherwise frustrating monthly occurrence, the Moon. Features such as M57 and NGC 6781 are intrinsically too small for the William Optics GT81 and Canon 550D, filling significantly less than 1% of the original image but after cropping both are evident in the final picture.

M15

NGC 6960

M31

Top Left – M15 Globular cluster Pegasus constellation 29th August; Top Right – Q1 Moon 23rd August; Middle Right – NGC 6960 Witch’s Broom Western Veil Nebula; Bottom – M31 Andromeda Galaxy 26th August

These images are not particularly memorable but it was a fun time and I will remember the enjoyable experience for a long while. Of course, the cloud has now returned and since passing the autumn equinox night temperatures have plunged into single figures. On the plus side, Orion is on its way together with all the other photogenic objects that characterize the winter night sky – can’t wait!

The future is not what it used to be

October 7, 2016 by grahamrob in Autoguiding, Deep Sky Objects, General Astronomy, Imaging, Processing, Software and tagged Andromeda, Photography, Veil Nebula | 3 Comments

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If I’m honest my astrophotography has so far often been – never mind the quality feel the width! That is to say, I have tended to chase objects – nebulae, galaxies, planets, solar – in order to learn about my equipment and the night sky as well as just have fun recording images of these distant worlds. Nothing wrong with that is there? It’s not that I don’t aspire to obtaining the best image possible and I have made good progress since starting out but I’ve often felt constrained by circumstances.

Although I’ve generally been happy with my images, it’s a fact that there are a number of factors that altogether make astrophotography difficult, especially here at Fairvale Observatory:

Poor weather & persistent cloud cover
The Moon
Buildings & trees obscure sightlines
Light pollution from Gatwick airport
Numerous aircraft passing overhead
Equipment problems
Software problems
Equipment and software failures
Equipment limitations
Need to assemble equipment each time

Bad weather, frequent cloud cover, limited sightlines, aircraft trails and the inevitable monthly occurrence of the Moon limit imaging opportunities here.

Under these circumstances I usually need to grab what I can, frankly it’s a miracle I’m able to achieve anything sometimes; Met office statistics for the six-months period from September 2105 showed cloud cover was a record 68% compared with an historical average of 32% for that time of year, as a result it was unusual to be able to undertake astrophotography more than once month, if that! Wherever possible I therefore have to target those items that I can improve easily, quickly and cheaply dealt with, which is mostly equipment. Buoyed by renewed enthusiasm from my recent autoguiding success, I now intend to concentrate on changing some key items that I hope will eventually bring about more noticeable improvements.

sign2 For a while I have been thinking about getting a larger telescope, in order to get to those faint fuzzies that are beyond the capabilities of the otherwise excellent William Optics GT81. As usual the choice is a minefield of possibilities, each with inevitable imaging pros and cons! I started thinking about a Ritchey Chrétien or Schmidt Cassegrain but I have really appreciated the qualities of the aforementioned WO GT81 and am now erring towards a larger refractor. However, after further consideration I am now considering a change of priorities.

In September I was fortunate to attend a presentation on image processing by Nik Szymanek who, it has to be said, really knows his onions when it comes to astrophotography; I was intrigued and impressed to find out he also hails from my neck of the woods when I was a teenager in Essex and is an accomplished rock drummer – something I also used to meddle with in the past – what a geezer, as he would say. The talk was very instructive and I am now ploughing my way through Nik’s fabulous book on the subject called Shooting Stars (published in magazine form by Astronomy Now). Such personal, first-hand and relevant guidance is difficult to find in astroimaging and the book has a wealth of really practical information and useful advice that I wished I’d known sooner. Good equipment is important but in the world of digital imaging the significance of processing cannot be overstated. It’s a dark art alright (no pun intended) but Nik’s work has strengthened my resolve to improve my processing knowledge and I’m even more determined to raise the bar during the forthcoming winter.

20160708-shooting-stars-for-store Following Nik’s talk and listening to others, the penny that has now dropped is that for the moment it’s not the telescope but the camera that needs changing. After careful thought it’s apparent that I already have very good set-up, yes a bigger aperture would be good for those smaller fuzzies but the 81mm apochromatic refractor I already own is an outstanding telescope that still has much potential when combined with the AZ-EQ6 mount and now autoguiding.

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The addition of a modded DSLR at the beginning of last year had a significant impact on my images, especially with Ha dominant DSOs which I literally saw in a new light using this camera. I have continued with the DSLR for a number of reasons but mainly because I am familiar with such cameras which are relatively easy to use and produce reasonable results when starting out with astrophotography. However, listening to Nik and reading the forums and elsewhere, I have come to accept that the best way forwards should now be a CCD-type camera. As a result I am deep in my research of CCD issues and possible cameras – this could take some time and won’t be cheap!

The operation of CCDs is quite different to a DSLR and I’m sure will involve a whole new period of pain but it’s clear that this is the best route for now if I am to significantly improve my astrophotography. Other than the technical challenges CCD imaging presents, I am however concerned about the greater number of frames needed for LRGB + calibration and how that’s going to work with the weather restrictions and other problems I have but it’s got to be worth a try.

However, before setting out on this daunting task I first slewed the camera towards a few familiar objects just to experiment with guiding and assess the benefits it might bring to my imaging in the interim. A spell of unusually good weather in late August – early September was too good to miss and with guiding I was able to achieve exposures of up to 8 minutes. However, for the moment I continued to limit the number of Subs and calibration frames just to ensure I could shoot more objects in the available time, plus you never know when the next bank of cloud will roll in – old habits die hard!

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Looking at the results below demonstrates my progress when compared with earlier images but the limited number of frames and calibration has probably restricted the full benefit of what might be gained from guiding and some shots remains quite noisy. Nonetheless, I now have high hopes that the potential is within my grasp to make real progress in achieving better image quality. I am not convinced I have yet reached a turning point but I am well positioned to navigate the tasks required to get there, which are now more clearly understood and in my sights or should that be RDF – watch this space!

M31 Andromeda Galaxy

WO GT81 + unmodded Canon 700D & FF| 10 x 30 secs & ISO 800 | August 2014

WO GT 81 + modded Canon 550D + FF | 9 x 120 secs @ ISO 1,600 | 19th September 2015

WO GT81 + modded Canon 550D & FF & PHD guiding | 10 x 300 secs @ ISO 1,600 calibration | 8th September 2016

NGC 6905 Western Veil Nebula – The Witch’s Broom

NGC 6960multiplelevelsonecontrast FINAL(Medium)

Canon 700D | 20×90 sec + darks.bias/ flats @ ISO 800

WO GT81 + modded Canon 550D + FF & PHD guiding | 5 x 300 secs @ ISO 1,600 & calibration | 8th September 2016

NGC 6888 Crescent Nebula

WO GT81 + modded Canon 550D + FF | 19th October 2015

WO GT81 modded Canon 550D + FF & guiding | 10 x 300 secs @ ISO 1,600 & calibration | 11th September 2016

NGC 6992 Eastern Veil & Bat Nebula

Eastern Veil Nebula – NGC 6992 (right) & NGC 6995 (left). WO GT81 + Canon 700D & FF | 29 x 120 secs + darks/bias?flats @ ISO 1,600

Eastern Veil Nebula (NGC 6922 & 6995): WO GT81 & modded Canon 550D + FF & guiding | 10 x 300 sec @ ISO 1,600 + darks | 11th September 2016

Forbidden Fruit

September 21, 2016 by grahamrob in Autoguiding, Deep Sky Objects, General Astronomy, Imaging, Software and tagged DSO Imaging, Guiding, Messier Objects, Nebulae, Photography | 3 Comments

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Soon after embarking on my astrophotography adventure just over two years ago it became apparent that after getting the basics right – polar & star alignment, focus, image capture etc. – the Holy Grail of imaging is increased exposures times, thereby collecting more of those elusive photons that have travelled across the Universe. The first step to achieving this goal is tracking, which since purchasing my AZ-EQ6 mount in 2015 I have been successfully improving over time, on a good day achieving 180-second exposures and from time-to-time resulting in some decent images. However, the light from DSOs is often very feint and can require much longer times, which is easier said than done.

At the same time as acquiring the aforesaid mount and a William Optics GT81 telescope I also purchased a William Optics 50mm guide scope, with which I intended to start guiding and thus push exposures above my 3-minute barrier. Despite these aspirations, through a combination of events and my unease about the apparent difficulty of guiding, the guide scope has remained unused – until now. Having recently purchased a dedicated Starlight Express Lodestar X2 guide camera, I have finally been emboldened enough to give it a try.

Starlight Express Lodestar x2 Guide Camera can be used either via the mount’s ST4 port or via ASCOM and the computer for pulse guiding.

I initially struggled to set up the guide scope and get the guide camera working together. In particular obtaining focus proved very difficult; like the GT81 the guide scope focus turns out to be achieved within a very short distance that is measured in fractions of millimetres, which in this case required the insertion of an extension tube.

Reminiscent of the Space Shuttle on its Boeing 747 transport plane! The William Optics 50mm guide scope + Lodestar X2 guide camera neatly mounted atop the GT81 imaging scope using the integral rings.

Thereafter the big challenge, which I had previously avoided, was to start using the very popular PDH guiding software; Push Here Dummy (PHD) is named tongue-in-cheek by its original creator Craig Stark and is an amazing but somewhat intimidating piece of software.

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The principle is simple – find a star within the FOV and use it as a fixed reference point from which to assess and then correct small tracking errors in order to achieve better tracking, which thereby maintains pinpoint accuracy and enables longer exposure times, thus avoiding trailing of the sky and the objects being imaged. Its use is regarded as something of a dark art but I have finally grasped the nettle with some success. After months of clouded skies followed by an almost fatal equipment failure (see here for more), a period of exceptionally good weather and clear skies since late August provided the ideal opportunity to get to grips with this challenge that has so far eluded me.

At first I used a couple of sessions to overcome some past problems and ensure that everything was stable and worked well for basic tracking and imaging, in particular:

Repair and improve the imaging camera’s AC/DC adapter lead;

Where possible improve all other leads and connections – once bitten …..! In this respect I have significantly re-arranged and tidied up the many power, control and camera leads, which has included the addition of right-angle USB / mini-USB camera connectors that now makes plugging-in easier and produces less strain on the connections i.e. more secure. Simple, cheap and something I should have undertaken long ago;

Revisit EQMOD-ASCOM in order to achieve more robust tracking – especially reviewing the star alignment procedures;

Fit the guide scope using the rings incorporated onto the GT81 OTA, subsequently re-balancing the equipment and improve the mount’s feet positioning.

At this point I spent a couple of nights just playing with the equipment and in particular EQMOD-ASCOM, so as to obtain the best possible alignment; having suffered an enforced absence from imaging I just wanted to have some fun again too. At the end of this process, first using SynScan for polar alignment before switching to EQMOD-ASCOM + Cartes du Ciel for star alignment, I successfully produced a good 10-star alignment model which was then saved for future use. The resulting images already showed some improvement but I still had to tackle PHD. With unusually good weather I decided to leave the final set-up outside under cover, thus preserving the settings for a shot at the aforementioned task of guiding next time. In the interim I then needed to read the operating instructions and watch numerous videos on the use of PHD.

EQMOD-ASCOM 10-point alignment model. With an obstructed view of the northern sky by my house, all points are inevitably located in the southern quadrants.

Like so much of amateur astronomy, I will forever be grateful for the time and effort given by others to help those like me pursue our hobby. The material, videos and responses to my forum queries on guiding have as usual been nothing short of outstanding and very, very helpful. It’s still been difficult to get going but without the help and support of others it would be a complete non-starter. In this respect I’d like to pay credit to SGL and the Open PHD Guiding forums.

Armed with this knowledge I have since undertaken a few sessions using PHD2 with reasonable success, achieving exposure times of 5-minutes and more. Changing conditions and different objects make it necessary to continually finesse guide settings throughout the night and between nights and it’s already obvious that there’s much more to learn. Such adjustments are not always linear or empirical in nature and will often only come from gut feel (experience).

I have chosen to use ASCOM pulse guiding, though my equipment also has ST4-ports which I had initially intended to use due to its apparent simplicity. I am unable to argue the pros and cons of each method but there seems to be an overwhelming preference for pulse. What I do understand (I think) are the greater subtleties that can be obtained with the pulse guiding technique and in particular, the co-ordination it provides with ASCOM, thereby ensuring PHD and the mount communicate with each other to provide essential directional information as well as guiding. I am still investigating the impact of various BRAIN settings but through trial-and-error have progressed since my first guiding session.

First Pass: early guiding results 30th August 2016

Getting better: most recent guiding results 12th September 2016

Calibration of PHD is frustratingly slow and it seems that even after successfully completing the RA-procedure can still fail during the subsequent DEC / backlash clearance. After calibration use of the PHD Guide Assistant can then provide more help in achieving the best settings for the given set-up and conditions, though it is also very slow. However, once completed PHD is fantastic and so far has run well during the night, even when changing objects. Furthermore, I’ve also studied and experimented with the PHD Drift Align tool and am hopeful that by using this I may soon be able to both dispense with SynScan altogether and improve polar alignment, hitherto my imagining nemesis as I cannot see Polaris from my location – a very exciting prospect – what’s not to like?

Starting a sequence of experimentation I chose a familiar but hitherto difficult DSO object to image that should benefit from longer exposures. Having by now reached late-summer / early autumn, there were a few old favourites around such as the Veil and North America nebulae but for these trials I decided to go for the low hanging fruit of M27 or Apple Core nebula AKA Dumbbell nebula.

My previous image of M27 in August 2014!

With limited success I imaged this planetary nebula in my early days of astrophotography but with its 8.0’ x 5.6’ size and apparent magnitude of +7.5, I found it difficult to obtain good detail and colour. However, even without guiding the improved set-up and alignment produced better results at 3-minutes and with +5-minute guided exposures the images immediately showed very noticeable improvement.

The images were taken on four different nights starting on 23rd August and finished on 8th September, during which time the sky was clear and the weather warm with very low humidity, though by the end seeing conditions had started to deteriorate due to the impact of the emerging 1st quarter Moon. All images have been cropped to the same size of 700 x 500 pixels or 2% of the original FOV i.e. an object size of about 0.20%! Given this very small size M27 really is at the limit of the GT81 telescope.

m27-comps-paintfile-cropped

Strictly speaking the images are not fully comparable as the aggregate exposure times are not equal but nonetheless I think the results demonstrate the positive impact of guiding. The final two images are guided but do show greater star distortion, particularly at 8-minutes. I suspect this may be due to the period over which the mount was left outside and would probably have benefited from some alignment tweaking before imaging re-commenced – lesson learned; the severe cropping ratio has also magnified any problems that would probably be less obvious in a larger widefield image. There’s obviously room for improvement but I’m very happy with these early results which I can hopefully now build on.

M27 Apple Core Nebula – my first and favourite guided image | William Optics GT81 + 50mm guide scope & 10-point EQMOD-ASCOM star alignment model | modded Canon 550D + field flattener & Starlight Express Lodestar X2 guide camera | 3 x 300 secs @ ISO 1,600 & full calibration, 3.3% cropped image| 30th August 2016

Unfortunately there is some downside to the longer exposures obtained from Fairvale Observatory: potentially more aircraft tracks and cloud plus more extended imaging time is unavoidable but overall it is, as expected, a major leap forwards for my astrophotography. There’s still much to learn and improve with the technique but for now I am delighted to say that after nearly two years I am at last successfully guiding – would you Adam & Eve it?

Summertime Blues

June 15, 2016 by grahamrob in Deep Sky Objects, General Astronomy, Imaging, Software and tagged DSO Imaging, Jupiter, Mars, Saturn, Star Clusters, Sun | Leave a comment

This year the Summer Solstice falls on 20th June at 23.34 BST, meaning the Sun will have reached its furthest point north; as a result from 22nd of May to 19th July 2014 there is a state of permanent Astronomical Twilight AKA Nautical Darkness at Fairvale Observatory. This means there is a complete lack of Astronomical Darkness for imaging, which when combined with short nights poses various problems for astronomy in general. Notwithstanding, there are benefits and other opportunities which are worth exploiting.

Annual darkness at Fairvale Observatory 2016

To turn the problem around an obvious solution at this time is viewing and imaging the Sun. However, following the initial success of testing my equipment in preparation for Mercury’s transit of the Sun on 9^th May, the actual event proved disastrous for solar imaging. I have subsequently re-checked the equipment and software set-up and the problem has continued but without any obvious reason. Popular opinion on the EQMOD Forum is that it is a software issue – drivers, EQMOD, EOS Utilities – so when time allows over the summer I will reinstall and test everything, hopefully ready for the return of astronomical darkness on 20^th July. Murphy’s Law will likely mean it’s something else but for the moment this seems to be the only way forwards, or is it backwards? Having just managed to get guiding to work, I had been looking forwards to a new imaging era but that’s astrophotography!

Although the nights are now short the temperatures have been pleasantly warm; after the long dark but cold nights of winter (and spring this year) it’s been a real pleasure to be outside in summer clothing and without the threat of condensation on the equipment. Notwithstanding, ever present cloud and inevitably the Moon has continued to thwart my efforts until recently, as I have at last just managed a couple of very enjoyable evenings.

At the moment the three major planets of Jupiter, Mars and Saturn can all be seen at various times between 10.00 pm to nearly 3.00 am, when the early morning light then becomes evident. After putting on a great show during May, Jupiter still remains high in the sky just after sunset. Mars and Saturn are at a much lower declination of between 10^oand 17^o but provide very good views in the right seeing conditions, especially Mars which with an apparent dimension of 18.6^ohas recently looked excellent, even to the naked eye.

With such opportunities I decided to try out the Skywatcher 150PL and the ZWO ASI120MC once again. It is almost two years since I used this telescope, preferring instead the superior William Optics GT81 for viewing and imaging. However, with a focal length of 1,200mm and 150mm aperture (f8) the Newtonian scope is better suited to planetary objects; this was also the first time I rigged the scope for use on the AZ-EQ6 GT mount, thus providing better control than the EQ3-2 I have previously used.

Sure enough the views of each planet were very good but also being unaccustomed to the ZWO webcam through lack of use, I failed to obtain any images! Pity but the lesson learned is that I cannot just dabble with this equipment and need to dedicate more time in the future if I am to learn how to use properly again. Nonetheless, it was fun re-acquainting myself with these planets. As an unexpected bonus the ISS also flew right over Fairvale Observatory for over 7 minutes. This time the station was noticeably brighter than previously observed, which I put down to Nautical Darkness and the relative position of the Sun that results, thus producing greater reflection and therefore better illumination of the ISS when viewed from the ground?

All-in-all after months of difficulties and inactivity it was a good night and at midnight I therefore decided to swap to the William Optics GT81 for some DSO imaging. After setting-up the scope I looked up and, as if from nowhere, broken cloud had rolled in obscuring much of the sky and putting an end to any DSO imaging. Oh well, I had had a good time before and was at least able to get to bed at a civilised time – one of the other drawbacks of summer astronomy. As luck would have it the weather was also good on the following night, probably even better than before and this time I concentrated on bagging some DSO images as the planets again marched across the sky from east to west.

As a result of the aforementioned equipment and software problems I have resorted to the trusty SynScan handset again for alignment and mount control. Impressive though EQMOD and all the other paraphernalia are, so far I have found it all to be somewhat fickle and from my personal experience often unreliable. However, after last year’s enforced astronomy hiatus following my operation and the almost farcical lack of observing conditions over winter and now spring, I’ve become a little rusty with the set-up and as a result, on this occasion encountered my old nemesis – polar alignment – to be something of a problem once again.

Amongst the types of DSO objects, I find globular star clusters to be particularly intriguing; I had not even heard of such features until taking up astronomy in 2013. Some 158 of these ancient star clusters are known to orbit around the main disc of the Milky Way. At about 11bn to 13bn years old they are very old and despite what so-called experts might say, it seems to me their origin remains something of a mystery; it’s interesting that such clusters are also associated with other galaxies.

At this time of the year a number of globular and open clusters feature across the night sky and form excellent imaging targets. First up at about 11.00pm was M5 and immediately I discovered the shortcomings of my polar alignment, further aggravated by the decision to try 4.00 minute exposures = big mistake; ironically prior test shots turned about better!

M5 globular cluster + excess trailing! WO GT81 Canon 700D + FF | 9 x 240 secs @ ISO 800 + darks | 6th June 2016

M5 test shot: 10 sec @ ISO 6,400

M5 test shot: 15 sec @ ISO 6,400

Following on from M5 shortly after midnight, M13 appears at a much higher altitude, thus helping to reduce the impact of star trails. Furthermore, as I was by now fully aware of the polar alignment error, I reduced the exposure time from 4.00 to 2.00 minutes; it helped but nonetheless could not hide the impact on the resulting images. Note to self: always ensure good polar alignment. An EQMOD – ASCOM – CdC alignment model would be much better but until I can correct the aforesaid problem it’s down to SynScan and hopefully in the interim I can return to globular clusters once more during summer.

M13 with less but still noticeable trails! | WO GT81 & Canon 700D + FF | 19 x 120 secs @ ISO 800 + darks | 7th June 2016

Before going to bed I couldn’t resist a few quick shots of an old summer favourite, M57 or the Ring Nebula, itself also very high above Fairvale Observatory by this time of night. Considering the alignment problems the image wasn’t too bad, however, the first half of 2016 has really been a case of one step forwards, two back. I hope the next 6-months will be more positive, they will inevitably be darker and colder.

M57 Ring Nebula (left of centre) + Sulafat (left) & Sheliak (right) | WO GT81 & Canon 700D + FF | 13 x 120 secs @ ISO 800 | 7th June 2016

M57 – Ring Nebula, cropped.

Talk The Talk

May 25, 2016 by grahamrob in Equipment, General Astronomy, Imaging, Software, Widefield Imaging and tagged DSO Imaging, Moon, Nebulae, Photography | Leave a comment

“He who can, does. He who cannot, teaches.” 1903, George Bernard Shaw

At the end of last year I was contacted by a member of the Aperture Club, a photography group based in Purely – Surrey, who had come across this website and asked if I could give a presentation to the club’s members on astrophotography. Ordinarily I might have rejected the request – after all what do I know about astrophotography after only 18-months – but then again why not? Once I sat down and compiled some initial thoughts it was surprising just how far I had come and learnt already, albeit with still a long way to go. In the end I agreed and decided to take a two-fold approach to the talk: (i) a basic overview of astrophotography, and (ii) in this context my personal journey so far.

TTT Cover

The final structure adopted was like this, which I hoped would be both technically and aesthetically engaging and provide some insight into the challenges for astrophotography when compared to their day-to-day terrestrial pursuits:

Types of astrophotography
Astrophotography Methods
Light
Telescopes
Imaging
Cameras
Image Capture
Processing
Post Processing

I gave my talk to the club at the end of March, which lasted about 1-hour and I believe was well received; there was a good turn-out and subsequent Q&A session – which is always a good sign. I had also been asked to compile some related tasks for the members to undertake afterwards and after a break presented a second, shorter talk on some possible assignments. Copies of the talks can be accessed via the links here:

Astro Lecture PDF

Astro Assignments PDF

I would not be so arrogant to undertake such a presentation to other astrophotographers, at least not yet, but enjoyed introducing members of the Aperture Club to my hobby. Furthermore, through compiling the presentations I benefited from the process, which required me to think and understand the subjects more thoroughly than I might otherwise have done, making me think that Shaw was wrong. Good teaching requires a good understanding of the subject, the skill to impart that knowledge to the audience and the ability to apply the knowledge. I’ve previously walked the walk and in this instance I’d like to think I was able to talk the talk – I found the experience rewarding and I hope members of The Aperture Club did too?

Transit

May 9, 2016 by grahamrob in General Astronomy, Solar system, Viewing and tagged Mercury, Sun | Leave a comment

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Unfortunately not my image: Mercury starting its transit across the Sun today, photo by NASA.

The transit of Mercury across the face of the Sun takes place about thirteen times each century and today was one of those occasions; the next is on 11^th November 2019. With months of bad weather I’ve been unable to undertake very little astronomy for some time but albeit late, spring actually arrived last week and I took the opportunity to shake-down my equipment and experiment with settings for solar imaging in the hope of capturing Mercury’s transit. Using a Baader solar filter and both the William Optics GT 81 and Skywatcher 150PL, I have successfully imaged the Sun before. Of course, inevitably I aspire to a dedicated Lunt or Coronado solar telescope one day in order to image details of the chromosphere and prominences, which are not visible using a white-light solar filter.

Sun spot activity is limited at the moment but the Baader filter and WO GT81 do a reasonable job, although I find achieving focus of the Sun quite difficult. Using the DSLR I experimented with the field flattener and an alternative basic 1/ 1.25” nosepiece, which produced a preferable result of a slightly larger and sharper image. I also tried the ZWO ASI 120MC webcam but as I don’t use this very often struggled to get the settings right for any sort of image – I’ll experiment more with that over the summer. I also put EQMOD-ASCOM and the newly acquired gamepad control through their paces which both worked well, so I was ready for the transit – weather permitting.

Last week’s test image of the Sun, with sun spot top left: WO GT81 + 1.25″ nosepiece | 1 / 2,500 sec @ ISO 100

After days of sunshine, albeit with high cloud that has continued to prohibit astrophotography at night, I was nonetheless hopeful of seeing at least some of the transit today. Notwithstanding, Sods law arrived in the form of a belt of cloud over south east England last night! Not to be defeated I watched the sky and cloud forecasts which suggested a glimpse of the transit might still be possible.

In hopeful anticipation I set up the equipment just before contact at 12.12 pm BST and shortly afterwards obtained a good view of Mercury as it started its transit across the face of the Sun. For the next three hours I managed glimpses of the planet as it continued its journey. It is very, very small but forms a distinct, sharp black dot against the background of the Sun when compared to the more diffuse, grey nature of the sunspots. It was an exciting experience and despite the drawbacks – cloud has now completely covered the sky for the rest of the transit – it was very enjoyable; so what’s the problem?

Despite all my preparation for imaging everything that could go wrong did and I was unable to obtain even a single photograph:

On setting up the camera and starting to focus the EQMOD-ASCOM tracking stopped and Carte du Ciel froze. Despite re-starting the set-up numerous times the tracking would not work!

Finally after resorting to the Synscan handset for tracking control, for some completely inexplicable reason I could not get any sort of image on the camera, that otherwise was working OK!

As I have learned many times before, the art of astronomy is patience and persistence but I am very disappointed not to have imaged Mercury during its transit today. Ironically once the cloud put an end to further activity, I tested the EQMOD-ASCOM tracking once again and it worked fine. Perplexed does not describe my feelings – oh well, 3-years to prepare for the next transit!

How I felt after today’s imaging!!! The transit view was still very good and I’m grateful for the breaks in the cloud.

The Sky’s The Limit

April 22, 2016 by grahamrob in Astronomy holidays, General Astronomy, Imaging, Widefield Imaging and tagged Arizona, Moon, Orion, Photography, Utah | 2 Comments

IMG_6235 (Large)

Imaging the Milky Way is a popular objective that has so far eluded me, mainly as I suffer from bad light pollution here at Fairvale Observatory. Embarking on a trip to the Southwestern USA recently where dark skies abound, I therefore had high hopes of at last achieving this goal but alas it was not to be and will have to wait for another day.

The trip of a lifetime

As a geologist I have often visited parts of Nevada, Colorado, Utah and California but never the famous sites of the Grand Canyon, Monument Valley, Glen Canyon (Lake Powell), Bryce Canyon and Zion National Park, which this time formed the trip of a lifetime.

Alvan Clark & Sons 24″ refractor telescope at Lowell Observatory, Flagstaff, Arizona

First stop was after flying into Las Vegas was Flagstaff, home of the Lowell Observatory, where Pluto was first discovered and amongst others houses a magnificent 24-inch Alvan Clark & Sons refractor telescope built in 1895, which I hoped to use for viewing at the observatory’s nightly public sessions. Unfortunately this was not to be as the sky remained resolutely overcast throughout the evening, despite good conditions earlier in the day. Notwithstanding, the observatory is a fascinating place and still remains an important centre of modern astronomy studies; the adjacent town of Flagstaff is also home to the Department of Physics and Astronomy at the Northern Arizona University.

Final notes and paper published by Percival Lowell postulating the existence of a Planet X beyond Neptune, later confirmed by Clyde Tombaugh at Lowell Observatory in 1930 and named Pluto

About 40-miles east of Flagstaff is the site of Meteor Crater, the best preserved meteorite impact crater on Earth. Nearly one mile in diameter and over 500 feet deep, the 50,000 year old crater is very big and very impressive. There’s a lot to like about Flagstaff if you’re into astronomy!

Meteor Crater, Arizona, USA

The Holsinger Meteorite: the largest remaining fragment of the 45 metre meteorite that created Meteor Crater

Moving on to the next stop at the Grand Canyon did not disappoint but staying just outside the park the location suffered some light pollution, compounded by cloud during the evening, thus prohibiting any imaging.

The incomparable Grand Canyon by day. Whilst we stayed around for sunset, unfortunately light pollution and cloud later prevented further nightscape imaging.

As a more remote location I had always envisaged that next stop at Monument Valley would be my first real opportunity to undertake some night imaging, for which purpose I had taken along the Vixen Polarie and a tripod. In preparation I had previously studied the sky in this part of the world using Cartes du Ciel, which indicated that the Milky Way would be well positioned during my visit; being 35^o latitude and 5,000 miles west of Fairvale Observatory meant that the sky was similar to that viewed in the UK three months ago and therefore included my favourite constellation Orion. Unfortunately I had overlooked one problem and my long-time nemesis, the moon.

The night sky from Lowell Observatory on 30th March 2016 – no Moon.

10-days later: night sky from Lowell Observatory on 10th April 2016, now with the Moon!

I was in the USA from 5^th to 17^th April but for some reason had modelled the sky in Flagstaff on 30^th March. It turned out that between then and 10^th April, when I was in Monument Valley, the by now half-moon had moved into the night sky and ruled out any chance of seeing or imaging the Milky Way. Of course, even if I had correctly identified the problem beforehand there was nothing I could do about it but it was still frustrating. Notwithstanding, it was a clear sky and not to be defeated turned to Plan-B, which instead took advantage of the moon’s position and in my opinion turned out quite well.

Monument Valley by Day: left to right – West Mitten, East Mitten & Merrick Buttes

Despite the remote location at Monument Valley there was noticeable light pollution from the hotel and ancillary facilities. However, being on the ground floor it was possible to set-up adjacent to the room’s balcony looking east, which was fortunately in the building’s own shadow, thus enabling a sequence of images to be taken of the night sky set against the buttes that typify this region. UnfortunateIy I overlooked setting the Vixen Polarie to half-sidereal tracking speed, which subsequently resulted in a blurred landscape when stacked but the original subs capture the buttes in some detail, themselves illuminated by the moon’s light = result!

Monument Valley by Night; order of buttes same as above. Canon 700D + Sigma 10mm wide-angle lens | 15secs @ ISO 6,400 | 10th April 2016

Monument Valley at Night – mulitple stacked shots: Sidereal tracking results in better sky but blurred landscape. Canon 700D & 10mm Sigma wide-angle lens | 20 x 15 secs @ ISO 6,400

Three days later I was in Bryce Canyon, the location of extraordinary geological features called hoodoos, which are the result of unusual and extreme weathering of the limestone cliffs found there. The land forms consist of thousands of various sized pillars of white and red limestone, seemingly lined up like soldiers along miles of the east facing limestone cliff face. Once again I used the moon to illuminate and capture the scene, this time using half-sidereal tracking. The result is somewhat haunting in nature but shows almost as much detail into the far distance as during daytime; I still find it incredible how sensitive the camera’s sensor is in gathering available light at night when extending exposure times and / or turning up the ISO setting.

Bryce Canyon at Sunset Point by Day

Bryce Canyon at Sunset Point by Night: Canon 700D + Sigma 10mm Wide-angle lens | 15 secs @ ISO 3,200 | 13th April 2016

It is clear I have much to learn about the deceptively simple nightscape photography using the Vixen Polarie but it is equally clear that the equipment provides significant potential and I look forwards to catching the Milky Way one day when the sky is clear and the moon absent. Notwithstanding the disappointment of missing out on the Milky Way this time, in the spectacular big country of Southwestern USA the sky’s the limit and I hope to go back again one day.

Too much light pollution perhaps? Even in the Big Country of the Southwestern USA getting the right conditions for astrophotography remains a gamble!

Fairvale Observatory Part-3, Progress: modded DSLR, computer control, autoguiding etc.

April 4, 2016 by grahamrob in Autoguiding, Equipment, General Astronomy, Imaging, Software and tagged DSO Imaging, Photography | 4 Comments

It’s been a while since I last took a look at developments here at Fairvale Observatory (Part-1 & Part-2) and looking back it’s pleasing to see that progress has continued with positive results. After acquiring the William Optics GT81 refractor and AZ-EQ6 mount in 2014 I have been experimenting and enjoying the equipment’s significant abilities until recently but have now embarked on some new, potentially important improvements that hopefully will result in significant breakthroughs.

At the start perhaps the biggest problem for imaging was polar alignment, made very difficult here as my house almost completely obscures Polaris. It took some time but I’ve now overcome this by using the Synscan handset polar alignment technique, which now enables me to achieve an accuracy of just a few arc-seconds and has led to a significant increase in imaging times of at least 180 seconds.

With the short focal length of the fast William Optics this level of alignment error works well and I’ve been pleased to obtain decent images of larger DSO features such as the Great Orion, Rosette and Veil nebulae i.e. near / middle distance objects, ideally at least 1^o in size with an apparent magnitude of +7 or better. Once I’ve exhausted all these targets, and I have fortunately been discovering more and more, it’ll be time for another telescope!

The small things matter too and in this regard I’ve added a number of useful items:

Made a solar filter and finder tube for the WO GT81;
At last, I recently collected the cables together into two looms;
Purchased a 12mm reticle to aid alignment;
Astronomik CLS light pollution clip filter;
Photoshop – an old version but I’ve been successfully using it for processing.

The set-up has become a lot tidier and logistics made easier by collecting the power and camera cables into two separate looms (camera loom not shown) and permanently attaching the HiTec Astro control cable to the mount – why didn’t I do this before?

More significant additions that I’ve already reviewed include a modded Canon 550D DSLR, which together with improved tracking has revolutionised imaging and a recently a Vixen Polarie, that has transformed widefield photography and added a new dimension – transportability. It’s early days and I have not really got to grips with the Vixen Polarie yet but initial use suggests it’s going to be a very useful addition and potential game changer.

At the end of last year in Reflections I outlined my goals for 2016 and I am pleased to say that I have at last just started to establish the equipment and software to start autoguiding, the holy grail of astroimaging that when fully working should enable me to achieve exposure times significantly greater than present – which is likely to be at least another couple of months. For a while I have been successfully using EQMOD /ASCOM combined with Cartes du Ciel for tracking. There were some initial connection problems but now using a HiTec Astro EQDIR adapter and a better quality USB cable seems to have improved this matter; I’ve also recently secured it to the tripod making the set-up more stable and aiding logistics. I still polar align with Synscan before switching to EQMOD-Cartes du Ciel for additional star alignment, slewing and tracking.

Using EQMOD-Cartes du Ciel makes slewing to any chosen object much easier than Synscan but its use has introduced another operating problem. After slewing to a chosen object or star it is never exactly centred and some manual fine alignment is almost always necessary at this point. The problem is that this requires being at the eyepiece, which of course is not located by the computer, which means frequent toing and froing between the two locations and a lot of guesswork when adjusting the mount from the computer. In reality this is not very practical and I have therefore just purchased a gamepad that links wirelessly to the computer and allows mount adjustments to be made when at the eyepiece. It’s not quite set up yet but nearly and I’m impressed; ASCOM even allows you to add WAV files that speak to you when making changes – sounds like a gimmick but when in the dark with lots of items to attend to it is actually very useful and will hopefully reduce the possibility of making mistakes.

Wireless gamepad provides extensive control of critical alignment functions without being at the computer: front x4 buttons are assinged to set various slew rates, the mount-telescope can be directed either via the rear (shown right) joystick or POV buttons on the right, button-1 parks and button-2 syncs. Other buttons have yet to be allocated.

It had been my intention to use the ZWO ASI 120MC webcam for guiding, in fact I upgraded to this at the time of purchasing in 2014 for this very purpose as it has a specific port for ST4 autoguiding directly with the mount. However, very recently a Starlight Express Lodestar X2 guide camera came up second-hand and being widely acknowledged as one of the best guider cameras available I couldn’t resist! Of course, despite its pedigree like most things with astroimaging it has not been that simple to get working.

Starlight Express Lodestar x2 Guide Camera can be used either via the mount’s ST4 port or via ASCOM and the computer for pulse guiding – I’m doing the latter.

Despite being a dedicated guide camera with high operating specifications, at first I could not obtain any sort of image to prove it was even working but by transferring the lens from the ZWO camera and fiddling with the software I eventually got an image, phew! It’s important to say here that for guiding it is also necessary to use suitable guiding software and I‘m inevitably using PHD2, which itself is full of wonderful features and mischief that I am at the early stage of learning and trying out with the camera.

William Optics 50mm x 200mm with focus tube and Lodestar guide camera – after lengthy experimentation, insertion of a x2 Barlow barrel eventually achieved focus.

At this early stage the other inevitable obstacle has been achieving focus. The William Optics GT81 telescope conveniently comes with its own guidescope rings that elegantly form an integral part of the OTA shoe attachment. With guiding as a long term goal, I therefore obtained the matching 50mm William Optics guidescope at the time of purchasing the main telescope, which until now has been sitting in its box as I built up the courage to put it all together and attempt guiding.

The black art of autoguiding and infamous PHD2 screen; I have just for the first time got the camera and PHD2 working together: focussed, calibrated and guiding. The nature of the blue (RA) and red (DEC) traces indicates there’s still much to learn but at least it’s working and holds much promise for future imaging!

As a matching guidescope and a dedicated top-of-the-range guide camera I assumed it would all fit together and with a little adjustment focus could be obtained, right? Wrong. I played with the camera’s position but failed to get any idea where the point of focus was. Next time I initially had the same result but by now knew that the camera was working so persevered and by using the barrel from a x2 Barlow with the lens removed eventually found focus, about 2cm back from the maximum position achieved using just the guidescope + focus tube and camera. I know that there are many makes of equipment and permutations but surely a matched guidescope and standard, best-in-class guide camera should be designed to work together from the outset?

So what’s next? I am hoping that after a few more sessions with the guide scope and PHD2 I will able to start autoguiding properly. However, two years of astronomy and an early look at PHD2 tells me it probably won’t be that easy. Notwithstanding, two years of astronomy also tells me that perseverance is essential and usually pays off. Watch this space!

Nocturnal Safari

March 16, 2016 by grahamrob in Deep Sky Objects, General Astronomy and tagged Canis Major, Constellations, DSO Imaging, Monoceros, Nebulae, Orion | 3 Comments

night eyes

Asterisms of the night sky have long been the basis for astronomy, navigation, astrology, myths, general stories and even religion. Whilst over millennia their shapes inevitably change, on the scale of human life there is an element of permanence and certainty. With so many stars it is not difficult to ‘join-the-dots’ in order to arrive at a recognisable shape, thereby making identification easier. Simplest amongst these are the seasonal often geometric asterisms such as the Summer Triangle, Winter Hexagon and The Plough or Big Dipper. However, it is the 88 constellations that dominate our definition and description of the night sky.

Computer based planetarium usually trace the relevant shapes and often the underlying historical figures from which they were originally derived – though frankly in some cases these can be quite spurious and even misleading. Of the total constellations: 17 depict humans or mythological figures, 29 inanimate objects and a whopping 42 animals – the night sky might literally be described as something of a zoo!

Despite my cynicism the patterns can be very helpful when initially learning the night sky, as well as for navigating and descriptive purposes. When starting out in astronomy I deliberately did not purchase a GoTo mount in order to first better master the geography of the night’s celestial sphere. For this purpose I purchased a planisphere and to a degree (no pun intended) it did initially help but with so many stars, light pollution and the odd cloud it wasn’t always easy when it came to essential star identification and alignment. I am sure I will forever benefit from the effort but this is 2016 and inevitably I have succumbed to using Google Sky on my smartphone to identify or at least confirm a star’s identity. Equally inevitable, I now use an AZ-EQ6 GoTo mount, which when linked to the Cartes du Ciel planetarium software is a quick and powerful combination for locating and tracking objects.

As previously discussed, this winter has been unusually cloudy but I recently managed a rare though decent imaging session in which I was able to capture night animals of a different sort. Probably like most astronomers I find the mid-winter night sky to be the highlight of the year, making the aforementioned seeing problems all the more frustrating. I have already imaged various parts of everyone’s favourite, the Orion constellation and so this time was looking for alternative objects in a similar region that would be suitable for the William Optics GT81. Whilst I find many if not most of the star asterisms unconvincing, there’s no denying that some of the DSO shapes really do look like animals and this time I found two.

animal2

NGC 2174 or the Monkey Head Nebula is located within the Milky Way, between Orion’s club and Castor’s left foot. An HII emission nebula, with an apparent magnitude of +6.8 and 40’ apparent dimension, it was a good target and a very convincing monkey’s head. Closer inspection of the image shows another smaller HII nebula north above NGC 2174 called Sh2-247, that is not only connected to the monkey but they are both part of the even larger GEM OB-1 molecular cloud complex which covers a massive region of 570 x 770 light-years!

NGC 2174 & Sh2-247 nebula above. WO GT81 & modded Canon 550D + FF | 20 x 180 sec @ ISO 1,600 | 10th February 2016

NGC 2174 The Monkey Head Nebula, cropped & inverted

In addition, situated between the constellations of Canis Major and Monoceros is IC 2177 the Seagull Nebula, which is also within the Milky Way but ‘flying’ lower than the Monkey Head Nebula to the left (south-east) of the Orion. More than 2.5^o from wing to wing, a number of bright star clusters are associated with this emission nebula, notable of which is the ‘bird’s head’ designated NGC 2327; IC 2177 is also known as the Parrot’s Head Nebula, which given the form of NGC 2327 I’m inclined to prefer.

IC 2177 The Seagull Nebula. WO GT81 & modded Canon 550D + FF | 20 x 180 sec @ ISO 1,600 | 10th February 2016

I’ve previously imaged a number of other animal-like DSO objects: Jellyfish Nebula, Crab Nebula, Pelican Nebula and the famous Horsehead Nebula. Unlike the constellations they generally but not always, really do resemble the form their names imply. Now adding to this list the Monkey Head and Seagull (Parrot) Nebulae it sometimes seems like a safari rather than astronomy!

Sky Animalscrop

It’s all in the stars

February 24, 2016 by grahamrob in Deep Sky Objects, General Astronomy, Imaging, Universe and tagged Auriga, DSO Imaging, Hitchhiker's Guide to the Galaxy, Milky Way, Nebulae, Star Clusters | 2 Comments

After 24-weeks I have just completed Imagining Other Earths, a Coursera MOOC presented by David Spergel, Charles A. Young Professor of Astronomy at Princeton University – soon to become Director of the new Computational Centre of Astrophysics, NY – and cannot speak too highly of the course. In my quest to better understand what I am seeing and imaging, I have participated in five astronomy courses and this is by a country mile the best; how many country miles in a parsec I wonder? There was very little not covered about astronomy in the course, including related geology and life itself but it was outstanding for three reasons:

Frequent use of easy-to-understand equations to explain and link various processes responsible for the Universe and everything in it;
It is very comprehensive, thorough and well produced, and…
David’s lecturing is just very good – easy to understand and well delivered.

For some while now the trend in my astrophotography has been increasingly directed towards seeing the big picture and by coincidence the course followed a similar scientific theme in order to Imagine Other Earths throughout the Universe; a metaphor for life itself and possibilities across the Universe.

The ultimate question starts at the beginning – where do we come from? Moby and astrophysicists seem to have the answer: we are all made of stars. How we get from that to here may be an even bigger question and like the philosophers in The Hitchhikers Guide to the Galaxy looking for the meaning of life (answer = 42!), should keep many astrophysicists gainfully employed for aeons.

In the meantime there is strong evidence that we do indeed come from stars and their evolution through the process of nucleosynthesis, which is responsible for all but a few man-made elements that we find on Earth. Through the action of nuclear fusion a star burns its way through the periodic table, first from hydrogen to helium then carbon-oxygen-magnesium-silicon and eventually iron. Thereafter the other, heavier elements require even more extreme conditions – heat & pressure – that can only be found in the late or final stage of a star’s life such as a Super Nova.

When the Periodic Table was initially formulated in 1863 by Dimitri Mendeleev there were 53 elements, which through subsequent discovery have now grown to 118. I find it wonderful and exciting that almost all of these can be attributed to stellar evolution, which can be viewed and imaged in the night sky.

At this time of the year the Milky Way is a dominant feature passing across the winter night sky which provides numerous, sometimes spectacular objects that are favourable for imaging. Located close to the western edge of the Milky Way in the constellation of Auriga about 1,500 light-years from Earth, is IC 405 or Flaming Star Nebula and nearby (visually) IC 410 or Tadpole Nebula, itself at 12,000 light-years distance. Located across the central area between these objects is a star field, notable of which and actually within the IC 405 is the O-type blue variable star of AE Aurigae, that is responsible for illuminating the nebulae.

IC 405 is formed of two sections, consisting of an emission and reflection nebula. Radiation from the variable star AE Aurigea, that is located in the lower part of upper-east (left) lobe, excites the hydrogen gas of the nebula which then glows red, while carbon-rich dust also creates a blue reflection from the same star.

IC 405 (right)-The Flaming Star Nebula inc AE Aurigae varibale star & IC 405-The Tadpole Nebula: WO GT81 & modded Canon 550D + FF | 15 x 180 sec @ ISO 1,600 & full calibration | 8th December 2015

Located within the nebula IC 410 and partly responsible for its illumination is an open cluster of massive young stars, NGC 1893. Being just 4-million years old these bright star clusters are the site of new star formation and therefore are just starting their creation of new elements. The so named ‘tadpoles’ are filaments of cool gas and dust about 10 light-years long.

IC 410-The Tadpole Nebula: Illuminated from within by the NGC 1839 star cluster. Image cropped and forced to highlight the two ‘tadpoles’, which can just be seen indicated in the green ellipses (‘tails’ upwards)

Each nebula is large, respectively 30’ x 20’ and 40’ x 30’, with an apparent magnitude of +6.0, which combined with the star AE Aurigae makes an excellent target for the William Optics GT81. I find it thrilling to consider the processes taking place in these objects that I have captured in the photograph, which surely represents the ultimate Big Picture?