Sep 112015
 

Here are three different versions of M16, The Eagle Nebula in the constellation of Serpens Cauda. Interestingly, the constellation of Serpens is unique in that it is the only one that is split into two distinct pieces, namely Serpens Caput (the head) and Serpens Cauda (the tail). All of these images have been recently taken using the amazing telescope that I co-share with Australian amateur Jason Jennings. This scope is hosted in the iTelescope.net ‘barn’ at the Siding Spring Observatory, Coonabarabran, NSW, Australia. I’ll write another post about the scope soon, but it is an amazing 16″ f/3.5 astrograph.

This first version is a ‘traditional’ LRGB image, meaning it has been made by taking separate images using Clear (Luminance), Red, Green and Blue filters and then combining those to make a final colour image. This should be close to how the eye would perceive the colour because the R,G and B filters pass frequencies of light similar to the sensors in our tri-colour vision system. The clear filter is used as a luminance channel and is where most of the sharpened detail resides.

As with all the images, please click on them to see a full-sized version.

M16 LRGB Version

This next version is taken using three narrowband filters. These are H-Alpha (Ha), OIII and SII. The wavelength of these filters are commonly used by astronomers because there are a lot of emission nebulae that have excited atoms in them that emit light in these wavelengths (especially Ha which is nearly always the strongest). So, to produce an ‘RGB’ image from them requires that they are mapped to the Red, Green and Blue channels of the image. I have chosen to use the ‘Hubble Palette’ which maps the SII to Red, Ha to Green and OIII to Blue. Here is the result:

M16 Narrowband Version

You will notice that the star colours are not good in the narrowband version and this is a consequence of the filter mapping and also because of the relative strengths of the three channels. So, in the third image below, I have combined the stars from the RGB image with the nebulosity from the narrowband image. Here it is:

M16 – NB with RGB stars

I’m not sure which version I prefer!

Finally, a 4th image (I lied!) taken last year with a longer focal length instrument (12″ f/9 RCOS) which shows the ‘Pillars of Creation’ in more resolution. This was also taken using the Hubble Palette which is appropriate because the iconic pillars were made famous by those fabulous images from the Hubble telescope.

The heart of M16

 Posted by at 2:13 pm

Nova Delphini 2013 – It’s official!

 General Astronomy  Comments Off on Nova Delphini 2013 – It’s official!
Aug 162013
 

The possible nova with the catchy designated name of PNVJ20233073+2046041 has now officially been named as Nova Delphini 2013.

It was clear here last night for an hour or so just as the sky was dark enough for me to make out the stars in Delphinus and Sagitta, so I took this shot of the new star with a 50mm lens on a Canon 60D. I’ve annotated the image so that you can where to find the Nova.

 Posted by at 7:59 am

A New Star in Delphinus

 General Astronomy  Comments Off on A New Star in Delphinus
Aug 152013
 

A bright Nova has appeared in the little constellation of Delphinus (The Dolphin). It is on the limit of naked-eye visibility, at roughly magnitude 6.3,  but binoculars will show it well. Here is an image I took of it this morning from a telescope in Australia, but it is well placed now for Northern hemisphere observers, and I hope it might be clear enough tonight to photograph it from here in the South of England.

 

Below is a map showing the constellation of Delphinus relative to Altair in Aquila and Albireo the head star of Cygnus the Swan. The position of the Nova is marked by the red circles. Click on the map to see a full size version.

 

This Nova, discovered by Japanese amateur Koichi Itagaki, is caused in a double-star system when material from one of the Stars builds up, or accretes on to its companion star (normally a white dwarf) until it undergoes a thermonuclear explosion and brightens very dramatically.

For those interested in finding the exact position, the co-ordinates are RA 20h 23m 30.7s, Dec +20° 46′ 03″

 

 Posted by at 3:59 pm

Zooming in on The Ring Nebula

 Deep Sky, General Astronomy, Zoom in on ... series  Comments Off on Zooming in on The Ring Nebula
Aug 092013
 

What was it about The Ring Nebula (M57) that inspired me to put together this little blog article? I guess it must be that it was the first telescopic ‘deep-sky object’ that I ever learned how to find and observe . (I didn’t call them deep-sky objects back then and the brighter wonders such as the Andromeda Galaxy and the Orion Nebula which are visible to the naked eye don’t count! ) I remember using my 60mm Tasco refractor back in 1971, as an 11 year old to look at this lovely object, and was amazed by it. Within a few months I would see it in Patrick Moore’s 12″ Newtonian Reflector – well what can one say – incredible!

It was always likely to be M57 (out of many other objects) because it is really easy to find, located as it is between two stars in the ‘parallelogram’ of Lyra the lyre. Also, Lyra itself is easy to find because of its brightest star Vega, and the fact that Lyra is a compact constellation right next to it.

Before we go zooming in on M57, what exactly is it? It is a planetary nebula, so called because, at first glance,  it presents a planet-like disk to an observer through the telescope. However, instead of being at Solar System distances, it is roughly 2,500 light-years away and was formed when a dying red-giant star blew out its outer layers before becoming a white dwarf. Such a fate will probably befall our own Sun in about 5 billion years! Now, we see the remaining shell of ionised gas as it expands into the interstellar medium.

So, the idea behind this blog is to locate M57, and zoom into it using images that go from wide-angle camera shots to high resolution images from large telescopes. First, I’ll transport you back to my world of the early 1970’s by showing this scan from the wonderful star maps at the back of the classic Norton’s Star Atlas. I still reach for this book when I need to remind myself of various bits of the night sky! Here is the scan, I added the insert showing Lyra at a larger scale, but the map itself in very evocative to me, covered with the rubbed-out tracks of pencil-drawn trails from long-gone Perseid or April Lyrid meteors. You will see M57 indicated between the stars β (Beta) and γ (Gamma) Lyrae at the bottom of the parallelogram shape (which I have outlined).

 

Now, on to the first image. I took this back in early June this year using a Canon DSLR camera and an 18mm lens, giving a nice wide field view. (as with all these images – click on them to see them at full size, then click again to return). I have indicated a large green triangle which is known as The Summer Triangle consisting of the 3 bright stars Vega, Deneb and Altair. I have also annotated the cross shape of the constellation of Cygnus the Swan which is getting rather swamped by the Milky Way in this picture. You can see Lyra near the top.

 

The next image is only a bit more of a close up Lyra, taken with a 28mm lens this time. I have added the names of the two stars that straddle either side of the ring nebula. As you can see Beta Lyrae has the proper name of Sheliak, and Gamma is called Sulafat. Also annotated are a few of the other brighter stars in this field – Albireo is the head (or beak) star in the cross of the Swan. Many of the proper names of stars in use today come from an Arabic origin and Sulafat comes from the Arabic for ‘turtle’ or ‘tortoise’ as it seems that most fine harps (or lyres) were decorated in tortoiseshell.

 

So, let’s zoom in a bit further. Next I changed to a 50mm lens and have also added an insert to this image. The insert is at the full resolution of the image whereas the rest of the picture has been much reduced in size to get it on this page. Now we can actually see the Ring Nebula! It’s pretty small as you can see, in fact it is approximately 3.5′ (arc-minutes) across which is, roughly speaking, only one tenth the apparent diameter of the Moon. Note the use of the word ‘apparent’ there; The true size of M57 is some 3 light-years across!

 

Now the last camera shot, before moving to a ‘proper’ telescope (telephoto lenses are telescopes really, but you get the idea). This time, I used a 200mm lens and I have cropped out the Sheliak/Sulafet region. Now we can see the ring and can understand why this is known as a planetary nebula.  It certainly confused its discoverer. French astronomer Antoine Darquier de Pellepoix in January 1779, reported that it was “…as large as Jupiter and resembles a planet which is fading.”  This is a good description as Jupiter is typically about 45′ across, but much brighter of course! Another Frenchman, Charles Messier, independently found the same nebula later on in the same month while searching for comets. He entered into his famous catalogue as the 57th object (Note that the main reason for Messier’s famous list was so that he would remember these ‘fuzzy’ objects and not confuse them with Comets which were his main interest).

 

The following image was taken with my Celestron C11 telescope and an ATIK 383L cooled CCD camera. I used a filter called an H-Alpha filter which passes light in a very narrowband of frequencies. I was after the outer shell of M57 – something I had never really seen in older photographs, but nowadays it is commonly captured by amateur astronomers using sensitive CCDs. It does require long exposures to bring the faint outer shell out, and I stacked together several 20 minute exposures to reveal it here.

 

 

The previous, rather noisy, image is certainly not my finest moment! I really don’t have a good telescopic image of M57. So to finish this article with a splendid image, I asked Robert Gendler if I might use one of his (for those of you who don’t know, Robert is one of, if not the best deep-sky imagers and image processors in the world) . He kindly suggested that I use this incredible image of M57. For more information about this particular image, and about M57 in general see Robert’s page here:

http://www.robgendlerastropics.com/M57-HST-Subaru.html

 

That’s it for my take on M57. Maybe I’ll make the Zoom into theme a regular feature here, so watch this space!

 

 Posted by at 4:23 pm

Meet The Spodies!

 General Astronomy  Comments Off on Meet The Spodies!
Jun 072013
 

Astronomers like to blame ‘Spode’ when skies are cloudy, or when things go wrong. I’d like to introduce characters called ‘The Spodies’ who are the brainchild of Roger Prout. Roger was one of the founding members of the South Down Astronomical Society (SDAS), based in the Chichester area of West Sussex. (The South of England).

Many years ago, as a teenager in the 1970’s I was assistant editor to John Mason, producing a magazine called ‘Supernova’. This was the magazine of the SDAS, and it was widely regarded as the best astro society magazine in the UK at that time (well we certainly thought so). Here’s what a typical cover of Supernova looked like (we even had photos on later editions which was very rare at the time!)

 

Here’s one of the cartoons. This one showing the Spodies craftily directing clouds. This shows the Selsey peninsula and the telescope in question will certainly have been one belonging to Patrick Moore! (Patrick being a good friend of the SDAS).

 

Two more are shown below (click on them to see full-size). One refers to the state of British astronomy and the discovery of  a nova in Cygnus by Japanese observer Minoru Honda (V1500 Cyg – Nova Cygni 1975). The other was topical at the time when Jupiter’s Great Red Spot all but disappeared.

 

Finally, meet the lovely Andromeda. Another of Roger’s creations, she graced the pages of Supernova from time to time. I always remember this particular cartoon, and I still chortle when I see it.

 Posted by at 12:07 pm

Jupiter Near Opposition

 General Astronomy, Jupiter, Planets  Comments Off on Jupiter Near Opposition
Dec 052012
 

Jupiter reached Opposition at about 1am UT on the morning of 3rd December 2012. Here are two images of different aspects of the planet. The one with the GRS was taken on the night of the 3rd and the second image taken on the 4th, with slightly better seeing conditions.

Opposition means that the Sun, the Earth and Jupiter are in a line. The Sun is therefore shining directly on to the face of Jupiter as we look at it. It also means it is closest to us and hence the disc is the largest it gets in this apparition.

 

 Posted by at 1:00 pm

BBC Sky at Night 55 year party

 General Astronomy  Comments Off on BBC Sky at Night 55 year party
Apr 172012
 

What a great event! I was very honoured to be invited to the party at the BBC Broadcasting House to celebrate 55 years of the Sky at Night. The remarkable Sir Patrick Moore has been presenting this excellent programme since it first aired on 24th April 1957 – an achievement unparalleled in broadcasting history, and the longest running TV programme ever.

Patrick is the greatest communicator of astronomy in history – fact! Forget the web, twitter, facebook and the rest, (says he on his blog!), this man has inspired more people to become astronomers, or to simply love the subject more than any other influence.

The party itself was brilliant. It was great chatting to the likes of Sir Tim Rice, Brian May, Jon Culshaw, Sir Terry Pratchett along with plenty of dedicated astronomers, both professional and amateur. I have shamelesly included some celeb pictures below! Thanks also to Pete Lawrence, Damian Peach and Ninian Boyle for your excellent company and banter during the trip up from Selsey.

 Posted by at 8:58 am
Apr 052012
 

A glorious sight in my 75mm APO refractor telescope last night. The night of April 3rd was cloudy when Venus was nicely in the main cluster, but I was still able to get both Venus and the Pleiades in the same field of view last night.

Venus is massively over-exposed here, but I like the effect of the burn-out and spikes it causes. You can just see the faint nebulosity around the main stars in the Pleiades. This image is the result of stacking 20 exposures each of 20 seconds using my ATIK 383L CCD camera and a white luminance filter – through the Pentax 75 APO.

 Posted by at 7:18 am

Bathing in Solar Radiation and Smugness!

 General Astronomy  Comments Off on Bathing in Solar Radiation and Smugness!
Mar 302012
 

This is vaguely astronomical I suppose, but I’m feeling pretty smug because today we commisioned our new Solar water heating system. We had Solar PV installed back in October and last week we went over the 1 MWh barrier and that’s during the Winter months! That means we could have powered an old-fashioned 1kW bar fire for 1000 hours, or lit a 15W energy-efficient light bulb for over 7.6 years. In any language, we could  have powered the average American family for about 100 days!

So, today, the Solar water system went live. It’s already heated a full tank of hot water to 50 degrees C in just the afternoon so we won’t need to turn on the gas-fired boiler at all tonight.

Last week we had the loft re-insulated to over a foot thick, and the pipes re-lagged for free! (Thanks Tesco). Last year the 20+ year-old windows were replaced with very efficient new UPVC double-glazed units, and the walls are cavity insulated. We work mainly from home, so the cars remains on the drive for much of the time. Two Labradors and Chickens eat nearly all our food waste, and what they don’t eat gets composted.

Yep – feeling pretty smug right now! Pictures below.

 Posted by at 5:05 pm