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.

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.

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

Christmas Comet

December 27, 2014 by grahamrob in General Astronomy, Other, Solar system and tagged Comet | 1 Comment

C/2014 Q2 Comet Lovejoy is a long-period comet, only recently discovered by Terry Lovejoy in August; it is the fifth comet discovered by Terry. By December 2014 the comet had brightened to a magnitude of +7.4 and by mid-December had become visible to the naked eye with dark skies. This weekend on 28th and 29th December, the comet will pass 1/3° from the globular cluster M79, subsequently brightening in January to a magnitude of +4.0 to +5.0, as it moves west of Orion and onwards towards Aries and Triangulum, thereby becoming one of the brightest comets for years. On 7th January 2015 the comet will be at its closest to Earth at a distance of 43,600,000 miles.

C/2014 Q2 Comet Lovejoy Projected Track

Before entering the planetary region in the 1950s epoch, C/2014 Q2 had an orbital period of 11,500 years, after leaving the planetary region in the 2050 epoch it will have an orbital period of about 8,000 years. Thus, unbeknownst to me, it has been with me since I was born and will remain with me for the rest of my life!

I have not seen the comet yet but have just been sent an excellent picture just taken from Joan’s Tacande Observatory in La Palma , which I visited earlier this year. Of course, I’ll be looking out for C/2014 Q2 at the weekend and hope to follow its journey during the next few weeks and beyond. Well done Terry and thanks again Joan.

C/2014 Q2 Comet Lovejoy R120 Canon 350D | 180 secs @ ISO 400 | taken by Joan Genebriera at Tacande Observatory, La Palma, 23rd December 2014

C/2014 Q2 Comet Lovejoy
R120 + Canon 350D | 180 secs @ ISO 400 | Taken by Joan Genebriera at Tacande Observatory in La Palma, 23rd December 2014

The absence of light

November 10, 2014 by grahamrob in General Astronomy, Imaging, Viewing, Widefield Imaging | Leave a comment

“Light thinks it travels faster than anything but it is wrong. No matter how fast it travels, it finds that darkness has got there first, and is waiting for it.” Terry Pratchet, Reaper Man.

It may seem something of a contradiction that as astronomers we seek very dark places and skies in order to see light, light that may have travelled millions of light years to get here – light travels 6 trillion miles in one year. For human beings the perception of darkness differs with the mere absence of light, due to the effect of afterimages that are produced by the unstimulated (by light) part of the eye. Typically our eyes will take between 20 and 30 minutes to fully adjust to darkness, at which time the eye becomes between ten thousand and a million times more sensitive than in daylight.

Objectively the Bortle Dark-Sky Scale describes nine levels of darkness and thereby quantifies the astronomical observability of celestial objects and impact of light pollution http://en.wikipedia.org/wiki/Bortle . With digital photography the colour of a point is described on the camera’s sensor by three RGB (red, green, blue) values, each ranging from 0 to 255. Thus when each pixel is fully illuminated each colour component measures 255 or for an RGB image 255,255,255. Conversely when all values are zero or 00,00,00, it appears black. However, the night sky is not black but measures somewhere between 10 and 30 when imaged.

Night sky image (Eastern Veil) with dark point set at 0,0,0

Dark sky image (Eastern Veil) with dark point set at 20,20,20. This approximates best to the natural darkness of the night sky.

There are even four subdivisions to describe approaching darkness at night:

Civil Twilight: begins at sunset and ends when the sun is 6^obelow the horizon or more practically, it can be described as the period after sunset during which terrestrial objects can still be clearly distinguished. Normally the end of civil twilight is usually 20 to 30 minutes after actual sunset.

Nautical Twilight: describes the period when the sun is between 6^o and 12^o below the horizon, during this time it is now possible to take reliable star sightings at sea. It may more commonly be described as nightfall but it is still not strictly dark yet.

Astronomical Twilight: defined as the period when the sun is now between 12^o and 18^obelow the horizon. To the casual observer this may be considered dark but it’s not, only when Deep Sky Objects such as nebulae and galaxies can be viewed is it fully dark.

Therefore, only after this sequence is completed, which takes almost two hours after sunset here at Fairvale Observatory at this time of the year, does true astronomical night or darkness occur. The excellent FLO Clear Outside weather forecast website, which is linked on the front page of this website, shows the current timings for each of these periods every day along the top horizontal bar, just below the hourly sub-division headings.

Obviously this has a major bearing for astronomers and perhaps more so for astrophotography. So sensitive is the camera’s sensor that when using long exposures the cumulative light recorded, even in a dark-sky environment, may result in a bright image that will need to be corrected during processing. Notwithstanding, the holy grail for astronomers is a dark, clear sky and the biggest enemy (other than bad weather and cloudy skies) is light pollution, which is spreading inexorably across the globe.

At the beginning of this post is a NASA picture of the Earth at night, produced as a composite of image data from the Suomi National Polar-orbiting Partnership (NPP) satellite, taken in April and October 2012 over a period of 312 orbits. NPP passes over any given point on Earth’s surface twice every day, flying 824 kilometres (512 miles) above the surface in a polar orbit, circling the planet about 14 times a day http://earthobservatory.nasa.gov/Features/IntotheBlack/ . Away from the cities much of the other light from wildfires, fishing boats, gas flares or mining operation is also visible. Whilst undeniably a beautiful picture, for astronomers it highlights one of the major obstacles we are up against, light, or more accurately light present here on Earth. The night sky before the invention of the commercial light bulb by Tomas Edison in 1878 must have been a wonderful sight; I doubt that Messier (1730-1817) would have successfully catalogued all his 110 objects as easily with today’s skies.

The dark side of the world: city lights of Europe, Africa, Middle East & Central Asia

The dark side of the world, with light just over the western horizon.

Rendezvous

November 3, 2014 by grahamrob in General Astronomy, Other and tagged Solar system | 2 Comments

At first this picture looks like something taken whilst walking in the Alps but, look again. It is a composite photograph taken on 28^th October by the Rosetta space probe, currently orbiting the 67P/Churyumov-Gerasimenko comet, approximately 7.7 km from the surface. I must admit I had been somewhat doubtful about the nature and chance of success of this mission but there’s no denying the science and technology is amazing, almost, but not quite, as exciting as the first Moon landing on 29^th July 1969.

The Rosetta probe was launched on 2^nd March 2004 and has since taken a circuitous route through deep space to eventually rendezvous with the comet in August this year. Initially approaching the comet at a maximum relative speed of 19,000 mph, the probe was put into orbit around the comet on 10th September, since when it has been mapping the comet’s surface and sending back some truly amazing photographs. This link provides real time tracking data from the probe, which locked together with the comet is currently travelling at 40,000 mph relative to the Sun. http://www.livecometdata.com/comets/67p-churyumov-gerasimenko/

Even now it sounds like science fiction and the best is yet to come. In nine days, on 12^th November, Rosetta is scheduled to send a lander to the comet’s surface. After attaching itself to the comet, a scientific mission will be undertaken by the lander in order to study its nature, origin and possible implications for life on Earth itself. Wow, can’t wait!!!

http://www.esa.int/Our_Activities/Space_Science/Rosetta/Europe_s_comet_chaser

Taken on 7th October, Rosetta takes a 'selfie' whist imaging the comet 16 km away.

7th October: Rosetta takes a ‘selfie’ whilst imaging the comet 16 km away.

It’s all about the wavelength

October 20, 2014 by grahamrob in General Astronomy, Imaging | 1 Comment

For the moment, putting aside the duality of light as a wave-particle (quantum) form, the behaviour of light in the visible spectrum can be both fascinating and a problem for the astronomer. As my tracking has improved (and hopefully will get even better) it has been possible to increase exposure times from a maximum of 40 seconds (and that was pushing it), to comfortably 90 seconds and sometimes more. The impact is that more light is gathered by the camera’s sensor and the outcome is greater detail and more colours – this all helps, a lot, when the light may travel for thousands or even millions of light years before hitting the sensor.

Unfortunately Fairvale Observatory is located on the southern edge of London and about 8 miles north of Gatwick airport, the result is that all that lovely light that has travelled from distant objects in the Universe has to compete with man-made light pollution. Last week I therefore invested in an Astronomik CLS filter http://www.astronomik.com/en/, which clips inside the camera, just behind the lens, and blocks the spectral lines of mercury and sodium-vapour lamps, letting the remaining part of the visible spectrum and H-alpha through.

The horizontal axisis the Wavelength in Nanometers (nm). 400nm is deep blue, at 520nm the human eye senses green and at 600nm red. At 656nm is the famous “H-Alpha” emission line of hydrogen.
The transmission in %is plotted on the vertical axis.
The redline shows the transmission of the filter.
Visual filters: The greyline in the background shows the relative sensitivity of the human eye at night. The maximum is at ~510nm and drops to longer and shorter wavelengths. You can easily see, that you can´t see anything of the H-alpha line at night (even if you can during daylight!) The sensitivity at 656nm is 0% at night!
Photographic filters: The grey line in the background shows the sensitivity of a typical CCD sensor.
The most important artificial emissionlines are shown in orange. The artificial light pollution is dominated by see mercury (Hg) and sodium (Na), which are used in nearly all streetlights.
The most important emission lines from nebulasare shown in green. The most important lines are from ionized Hydrogen (H-alpha and H-beta) and double ionized oxygen (OIII).

The major emission lines of nebulas:
H-β 486,1nm | OIII 495,9nm | OIII 500,7nm | H-α 656,3nm

Since my recent success imaging the Orion Nebula I’ve been frustrated by bad weather, cloudy skies and a full Moon. With a brief gap in the clouds last night I therefore couldn’t resist the opportunity to try out the new filter with the camera but without using the telescope. Shooting two sets of pictures, with and without the filter, and using a telephoto and 50 mm standard lens, the results were both successful and perplexing.

As expected it darkens the sky, a lot, but also skews the resulting image towards blue which subsequently has to be adjusted during processing, complicating the question of what is the right colour even more. It is a known fact that despite the obviously very large distances of astrophotography subjects, some camera lenses need to be focussed just short of the lens‘s infinity position. However, with the standard lens the focus point was very different when using the filter, noticeably less than without the filter. This seems quite strange and I have not quite worked out why this should be so, except the loss of and therefore change in wavelength of the light?

It will be interesting to see how the filter works when imaging deep sky objects using the telescope once the weather clears but the preliminary tests are promising. Certainly the ‘loss’ of light incurred will require longer exposures so I had better sort out autoguiding soon, my next challenge.

Without CLS filter, 8 secs @ ISO 800

With CLS filter, 8 secs @ ISO 800

Milky Way - in the Tarazed region - 60 seconds (only!) @ ISO 800

Milky Way (Tarazed region) without CLS filter 60 seconds (only!) @ ISO 800

Veil Nebula, with CLS filter, 90 secs @ ISO 800 (+ plane trace!) - unprocessed

Veil Nebula (and aircraft trace!) with CLS filter 90 secs @ ISO 800 – unprocessed

Veil Nebula Canon 700D + 50mm lens, with tracking, unguided & processed 15 x 90 secs @ ISO 800

Veil Nebula
Canon 700D + 50mm lens with CLS filter, tracking, unguided & processed 15 x 90 secs @ ISO 800

The centre of the world

October 16, 2014 by grahamrob in General Astronomy | 1 Comment

As a geologist the centre of the world is very clear to me. Depending on where you are, on top of Everest, in the Mariana Trench but more relevant here at Fairvale Observatory in Redhill, the centre is approximately 7,900 miles beneath my feet. Less geologically minded will argue this is the centre of the Earth and might instead therefore like to adopt Mr Wikipedia’s definition of the geometric centre of all land surfaces, which is 40°52′N 34°34′E (180 km northeast of Ankara, Turkey). However, for an astronomer and mankind in general wanting to navigate either the sky or the world it is the Prime Meridian, which passes just over 5 miles east of here at Fairvale Observatory – I often cycle across it, though you wouldn’t know it!

The notion of longitude was developed by the Greek Eratosthenes (c 276 – 195 BC) and Hipparchus (c 64BC – 24BC) but it was Ptolemy (c AD90 – 168AD) who first used a consistent meridian for his map in Geographia. Subsequently various other ‘meridians’ were adopted over the following centuries by various cultures and map makers, located according to local, scientific and often political interests.

In the early eighteenth century the quest had become urgent to improve the determination of longitude at sea, leading initially to the development of the chronometer by John Harrison. But it was the development of accurate star charts, mainly by the first British Astronomer Royal , John Flamsteed, between 1680 and 1719 and continued by his successor, Edmund Halley, that enabled navigators to use astronomical methods of determining longitude more accurately. Following the success of Neville Maskelyne’s Nautical Almanac between 1765 and 1811, today’s Prime Meridian was finally established by Astronomer Royal, Sir George Airy in 1851 at the Royal Observatory, Greenwich in London and has since formed the principal basis of all earthly (longitude) and celestial (right ascension or RA) navigation; these two are not the same but are both derived from the prime meridian as a starting point. The Prime Meridian established in 1851 passes through the Airy transit circle at 51° 28′ 40.1247″ North 0° 0′ 5.3101″ West at the Greenwich Observatory.

The Greenwich Meridian (marked by a stainless steel line and globe) viewed from behind Airy's transit telescope. School children line up along the line, which separates the west of the world on the left of the picture from the east of the world, on the right.

The Greenwich Meridian (marked by a stainless steel line and globe) viewed from just behind Airy’s transit telescope. On a wet day school children line up along the meridian line, which separates the western hemisphere of the world on the left of the picture from the eastern hemisphere on the right.

I am currently a member of the Flamsteed Society, an amateur astronomy group based at the Royal Observatory and National Maritime Museum in Greenwich and earlier this week spent the day there to attend some astronomy shows and lectures, whilst also viewing exhibits, some of which I first saw as a teenager in the 1960’s. Professional British astronomy has long since ceased at the Observatory due to London’s light pollution; at first moving on to Herstmonceaux in East Sussex, then La Palma and now (I believe) Chile? However, the site remains steeped with an unparalleled history of time, navigation and astronomy, which are fascinating and marvellous to behold – a must-see for any astronomer.

Flamsteed House designed by Sir Christopher Wren. First used in 1833, each day at exactly 12.55pm the red ball (Time Ball) on the roof rises half way up the mast and at 12.58 continues to the top, when at exactly 13.00 it drops.

Flamsteed House designed by Sir Christopher Wren in 1675 – today the building houses various permanent and occasional exhibits related to time and astronomy. First used in 1833, each day at exactly 12.55 the red ball (the Time Ball) on the roof rises half way up the mast and at 12.58 continues to the top, when at exactly 13.00 it drops so those around can tell the time accurately once a day.

A telescope that is worn (note straps behind) and has a candle to assist with seeing where you are moving!

A telescope that is worn on the head (note straps) and has a candle to assist with seeing where you are!

Edmund Halley’s Quadrant, used to measure and record the transit of his eponymous comet.

I am proud of my nation’s achievements in the establishing The Prime Meridian and it is strangely of comfort that the Meridian passes close to my front door. However, as a result of modern satellite navigation and a more accurate understanding of the Earth’s shape and gravitational effects, today’s Prime Meridian 0^o 00’ 0.00” – or International Reference Meridian as it is now officially known – has shifted 5.3 arc seconds to the east of Airy’s original line (I make this a whopping 102.96 metres). Furthermore, and pleasingly British in nature, the meridian used by the Ordnance Survey for its mapping is about six metres west of Airy’s meridian, known commonly as the Greenwich Meridian; having been previously established in 1801 by the third Astronomer Royal, James Bradley in a room adjacent to and therefore six metres away from the location of Airy’s transit instrument used to establish the Greenwich Meridian – the OS have simply continued to use Bradley’s Meridian to this day!

Airy’s transit telescope, used to establish the Greenwich Meridian in 1851 – viewed from behind looking south i.e. east is left and west is right.

Suits you sir

October 14, 2014 by grahamrob in General Astronomy | Leave a comment

This year’s Indian summer is now just a memory; the weather is cold and wet and the skies overcast – no astrophotography then at the moment! Notwithstanding, it’s time to think about the forthcoming winter skies, imaging possibilities, plans and what to wear? Winter is generally recognised as a better time for astronomy (when it is dry and clear) – darker skies, exciting objects to view and image – but it does get cold. Normally this would require more and thicker clothes but after a visit to the Longitude Punk’d exhibition at The Royal Observatory yesterday, I realise I need to raise my game.

Two fetching astronomer’s outfits show that astronomy can be about style as well as substance. A natty red observing suit particularly caught my eye or a less flamboyant but nicely eccentric blue silk jacket and brass work tray with accompanying gadgets (hand lens, mirror, sextant, candle and pipe) for recording observations etc. Time to speak to my tailor!

Smoke and mirrors

September 23, 2014 by grahamrob in Comments, Deep Sky Objects, Equipment, General Astronomy, Imaging | 1 Comment

My brain hurts! The Talking Point section of the recent October edition of the Astronomy Now magazine really poses a serious problem for astronomers, if not the Universe itself; matters don’t get much bigger. The matter being, Is the Universe a Hologram? It transpires that one of the theoretical consequences of quantum physics and, in particular, very small matter, is that at the smallest scale the Universe may be two dimensional. The third dimension, emerging in the same sense that an impressionist painting is the macroscopic effect of thousands of spots of coloured paint that, when viewed close up, gives no clue to the overall scene. I am not making this up. So serious is this question that Fermi National Laboratory Accelerator Laboratory (Fermilab) in the USA is currently undertaking an experiment to assess the answer; what happens if it is a hologram, do we disappear? As a result of this devastating possibility, I have read around but frankly am battling to fully understand the concept and its consequences. http://www.smithsonianmag.com/science/what-universe-real-physics-has-some-mind-bending-answers-180952699/?no-ist

In the event that the answer is in the affirmative, then what have I been photographing out there?

Astrophotography seems to consist of many black arts, not the least of which, in my case, is Polar Alignment. Since getting into this astronomy malarkey I have, wherever possible, taken the easy route – unfortunately this is no longer compatible with my ambitions and I must deal with my astronomy fears: polar alignment, computer control and using a guide scope. All are essential if I am to improve my pictures and bag some of the more elusive DSOs as well as more mundane objects. Initial use of the AZ-EQ6 GT mount has already been rewarding through the use of star alignment but without good polar alignment too, a critical piece of information for finding and tracking objects is missing. In order to track objects across the celestial sphere using an equatorial mount, it is essential to line up the axis of the mount with the Polaris star, which marks the central point around which the celestial sphere effectively rotates.

The AZ-EQ6 GT mount does have a polar scope through which to look directly at the Polaris star and line up the mount. Alas I cannot use it as my house is directly in the way of Polaris and I don’t really feel like knocking it down, though you never know. However, there are cunning ways to overcome this problem (i) using another sequence programmed into the mount’s SynScan control handset to achieve polar alignment without a polar scope (see manual #11.3) or (ii) drift alignment, a technique of iterative realignment of the altitude and azimuth by linking the telescope to specific computer software (I believe it can also be undertaken by just using a star trace obtained by a DSLR or CCD camera).

For the moment I am having great difficulty attempting to use the SynScan routine. Having spent much of Sunday studying the technique, subsequent hours of practice at night brought little success; despite my best attempts, the SynScan handset routine does not seem to be the same as that outlined in the Manual – not a good start. Sometimes the operation of this complex equipment seems elusively to be driven by smoke and mirrors, let’s hope the Universe fairs better at Fermilab.

M2 Star Cluster; after hours of preparation and attempts to apply the Synscan polar alignment routine, with the P{olar Scope, success proved elusive and tracking poor. Canon 700D | 15x30 sec @ ISO 400

M2 Star Cluster; after hours of preparation and attempts to apply the SynScan polar alignment routine, without the Polar Scope, success proved elusive and tracking was poor.
Canon 700D | 15×30 sec @ ISO 800