I have gone for one of my “single bright star” images for this Month’s “Image of the Month”.  This Month’s object is the star Procyon or 10-Alpha Canis Minoris in the constellation Canis Minor.  Procyon shines brightly in this region of sky at magnitude 0.40 and part of the reason it is so bright is that it is very close to us at just 11.41 light years.  With an F5IV-V spectrum, Procyon appears bright white in the sky, and also in this image.  You don’t need very long subs when imaging bright stars, but if you want to capture a decent number of background stars you need to use subs from 3-5 minutes long.  In order to reduce the noise it is a good idea to get at least a couple of hours of total exposure time, though if conditions are favourable you will get a good result with just an hour or so.  As this image was taken with the Sky 90 refractor it is clear that the spikes are “software spikes”.  When a single star is the subject of the image I prefer to see some spikes rather than a bright ball of light with an extended fuzzy outline – but that is just personal preference.  There are some cases (M44 immediately comes to mind) when I prefer no spikes at all, it depends a great deal on the subject and its setting.

There isn’t much apart from Procyon in this region so this one is a case of all or nothing, only really worth taking if you are building up a portfolio of  the brightest stars in the sky.

Until next month – good imaging

First off, a very Happy New Year to you all.  Well – 2011 can’t be said to have been the best imaging year on record, in fact I think it is fair to say that it is the worst imaging year overall I have recorded in my log book – and that goes back to September 2004.  Let us at least hope for a better year, weather-wise, this year.

So what is this month’s Imaging Object of the Month?  I have decided again to steer clear of the Orion goodies and move to nearby Auriga.  Now Auriga usually means IC410/IC405 the Flaming Star nebula – but lying very close by there are a bunch of very nice open clusters and some smaller regions of emission nebulosity.  So my Imaging Object for this month is the M38 open cluster region in the constellation Auriga.  M38 (NGC1912) is quite a sizeable open cluster at 15 minutes in diameter and pretty bright at magnitude 6.4.  Lying just underneath M38 you can see another little open cluster – NGC1907 – which very nicely offsets the subject of the image, M38.  I have both clusters offset from the centre of the image as this is part of a much larger mosaic which will eventually include M36, IC417, IC410 and IC405.

As per usual with any open cluster you don’t need to use particularly long subs but as I wanted to catch the outer fringes of all the emission nebulosity surrounding IC410 and IC405 (which you can see towards the top right of the image) I used 5-minute subs with the fast f#2 Hyperstar III system – so this image goes pretty deep.  As usual, you need at least 4 hours worth of data to start getting on top of the noise in the faint regions.  Plenty of stars, plenty of faint nebulosity, the M38 region is certainly worthy of your valuable imaging time.

Until next month – clear skies

I thought I’d take a break from the usual Orion object this month and instead present just a single star image.  This month’s object is the star Aldebaran, the eye of the Bull in Taurus.  If you had a much bigger field of view you could capture Aldebaran and the whole of the Hyades star cluster as well – there aren’t too many good images of that lot about.  However, returning to Aldebaran, what makes it nice and interesting of course is that there is some colour associated with this star.  Aldebaran is a red giant lying just 68 light years away.  Aldebaran has a diameter 38 x that of our Sun and it shines with 150 x the Sun’s luminosity.  Being so bright means there is very little effort involved in imaging this one, and it’s more a matter of how your optics reproduce a bright point source.  This image was taken with the (highly) modified original Hyperstar and the little H9C one-shot colour camera.  The four cables coming out the back of the H9C lead to the diffraction spikes from the star (the splitting of the spikes is due to the cables not coming out at precisely 90 degrees to one another) – there has been no addition of software spikes to tidy this image up.  In addition there is an array of fine spikes close in to the star as well as an outer halo probably caused by the outer round aperture I used to use with this kit.  I made up an aperture to go around the edge of the C11 taking the aperture down from 11″ to 10.5″ (with the speed of the Hyperstar this loss of aperture made no real difference to my imaging times) – but what it did do was to considerably sharpen up the stars – I guess there might have been a little bit of “rounding” of the mirror edge?  The edges of the lenses of the Hyperstar were blackened with matt black paint – otherwise there would have been a terrible lens flare to deal with from such a bright source.

We are now well into the winter objects and we have the long dark evenings – even if very few of them are clear and Moonless   But we carry on regardless as it’s what we love to do.  So until the New Year of 2012 is upon us I just wish you a Merry Christmas and hopefully some clear dark skies as a bonus pressie

This month’s composition is a little different from the form I normally follow.  I wanted to get a nice bright single star image, but I also wanted something else of interest in the field of view apart from other stars.  So I took a good look at the star map to see if there was a main star with something nice and interesting lying close by.  I came up with Phecda in Ursa Major for the bright star, and lying close by are the spiral galaxies M109, NGC3953, and a bunch of other galaxies too.  This image was taken with the Sky 90/M25C combo piggy-backed on the C11 in the south dome.  For this image I used 10-minute subs as I wanted a decent exposure for the little galaxy (and to stand a chance of seeing all the other faint fuzzies in the region).  My notes tell me that I managed to get 27 sub-exposures in all and managed to use the lot giving me a 4 and a half hour total exposure time.  It came out well enough, but of course it would have benefitted from even more time – I usually try for 8 hours if possible using the Sky 90/M25C and 10-minute subs meaning somewhere around 50 subs in total.  This is pretty much the “sweet-spot” for imaging from my moderately light-polluted location with the Sky 90/M25C.  More subs will give a smoother image but beyond 50 and you are definitely entering the realm of diminishing returns where it takes a LOT more extra subs to make any noticeable difference.

The clocks have gone back, and if only the Gods would give us some clear decent skies we could be out imaging by 6:00 p.m.  Weather hasn’t been kind to us for a couple of weeks and as we are now getting into winter constellation time I am wishing for a change for the better in our weather.  The mini-WASP is built and ready to go so it isn’t as if I’ve just bought a load of new kit for the weather to mis-behave in this way.  Here’s hoping we have some improvement during this November so that I have something interesting to report next month.

So until December – clear dark skies, and start grabbing those winter gems

We’re now well into some decent long dark evenings

This month’s object is rarely imaged it seems – I am going to look at the open cluster Stock 2 in Perseus this month.

This is a beautiful, colourful open star cluster lying just to the north west of the Perseus Double Cluster – and THAT’S the reason that Stock 2 rarely gets any air-time – it has a far more glamorous imaging neighbour just down the road!  But to not have a go at imaging Stock 2 is to miss a wonderful imaging opportunity, an opportunity of putting together a mosaic that includes both the Stock 2 AND the Double Cluster!  I have all the frames for this one taken and I am waiting for Noel Carboni to put the whole thing together for me – I think it will make a wonderful image.

Still – back to Stock 2 – this is quite a large open cluster and for once the large field of view of the Sky 90/M25C is needed – that it 3.33 x 2.22 degrees covers the region nicely.  As this is an open cluster it’s the usual 3-5 minute subs and 80 – 100 of them for a low noise final image.

If you can pull yourself away from the Double Cluster – Stock 2 is certainly worth a look, and it provides much more interesting colour than the Double Cluster as well!

Until November – clear, dark skies to you all

Hooray – September – and some decent long evenings after what has been a very long wait.

So what can we spend our time on this month to make all the effort of maintaining an interest in this hobby worthwhile?

Well, I particularly like imaging in the north, mainly because this isn’t done too much.  And what about going for the most northerly Caldwell object?  Caldwell 1, otherwise known as NGC188 – a nice large open cluster in Cepheus.

NGC188 lies around 4,800 light years away and shines at a magnitude of 7.1 (O’Meara) with an apparent diameter of 15 arc minutes – so fairly large.  There isn’t much up this high in the northern wastes so NGC188 is a bit of a gem out there all on its own.  It does quite well even in the large field of view of the Sky 90, and the large FOV does accentuate the barren surroundings of Caldwell 1 – something that once again gives the image a little bit of impact.

As with clusters in general, I recommend 3-5 minute sub-exposures and as close to 100 as you can get for a nice low-noise image.

NGC188 is one of my favourite open clusters, and as it doesn’t seem to get much imaging time, why not give it a try this year?

Until October – clear, dark skies to you all

We are just about to enter the longer evenings where we can once again return to getting some decent quality deep-sky images.  To be frank, it never really gets dark enough to do good work for all of June, and most of July.

So this month, as we are still effectively in summer, with the summer triangle overhead, our object is (as usual for August) something in Cygnus.  That something is the bright star Sadr, the central star in the constellation – and as you can see from the accompanying image – it is completely surrounded by emission nebulosity – so this is a nebula image for a change.

Again – considering the deep-sky image as a whole – just a mass of red (emission nebulosity) can look very boring.  It is much better if you can break up the monotonous red region with something interesting – like a reflection nebula [NGC6914] which lies a little north of the current region.  In the present case I have broken up the red monotony by placing the bright star Sadr in the centre of the frame.  This must have also impressed the APOD guys as this image made APOD for January 4th 2007.

Sadr is the supergiant star Gamma Cygni and the two “winged” regions to the left of Sadr form the Butterfly Nebula IC1318.  Above and left of Gamma Cygni are the stars forming the group NGC6910.

Gamma Cygni lies at a distance of only 750 light years, while estimates for IC1318 and NGC6910 vary from 2,000 to 5,000 light years.

So there’s plenty more than just a uniform region of red in this image

We’re coming up to my favourite imaging month now -for the first time since May we get decent dark skies that will yield us the best quality images.

So until September – clear, dark skies

This month’s deep sky object is a Globular Cluster, this time M56 in Lyra.  Why?  Because I really like Globular Clusters with a Milky Way background – and this is what the M56 region offers us

M56 lies at a distance of 31,000 light years and shines at magnitude 8.4.  It is pretty small at a mere 7 arc minutes in diameter, so it would benefit from focal lengths in excess of 1,000mm – but having the Milky Way background makes this a good region for wide field imaging as well.

As usual with star clusters, we don’t need very long subs, anything from 3-5 minutes will be fine.  And if you want to get a nice glassy-smooth noise-free image at the end you will want to aim for around 80 – 100 subs in total.

As with all deep-sky portraits – the framing is all important, what other objects lie in the same frame to give the image that WOW factor?  In the case of M56 it is the Milky Way background that does this.  So a reasonable sub exposure length together with a nice large number of subs should yield a very impressive star image.

Fortunately, the evenings are once again starting to get slightly longer.  It’s still far from ideal for deep-sky imaging, but we have to feed the withdrawal symptoms somehow, and things start to improve by leaps and bounds once we get through next month.

So until August – clear skies to you all!!

As per usual, the skies simply don’t get dark enough this time of year for me to bother imaging deep-sky objects.  I will probably try to get some ultra-wide-field Milky Way shots using the AstroTrac and the DSLR this year – but the deep-sky kit will be mothballed for the month.

So it’s the usual, clean out the observatory, if you have a fibreglass dome wash off the last year’s worth of algae slowly turning the surface green.  Regrease your mount and check all the fastenings are tight.  Maybe give the optical train a good blow if you’ve got any dust bunnies, and check the collimation.  Not a bad time to get the polar alignment really tuned in well, you can spend several nights on this if necessary, you’re not losing good imaging time.

This year I will use this month to really push ahead with the mini-WASP array construction.  I am aiming to have the basic setup installed in a new dome by the end of this month – we’ll see!!

Until July – clear skies, even if they’re not particularly dark ones

The imaging object of the month for May 2011 is a Messier object, Spiral Galaxy M106 in Canes Venatici.  I particularly like this galaxy and have imaged it several times – it looks to me like a piece of celestial “Mother-of-Pearl” – quite beautiful colouring if you manage to get deep images of this one on a clear (good seeing) night.  M106 is about 22 million light years away and shines at magnitude 8.3 with dimensions 18.6 x 7.2 minutes of arc – so reasonably large.  Even so – this one is better imaged with much longer focal lengths than my 405mm using the Sky 90 with reducer-corrector.  I would recommend focal lengths in excess of 1000mm and sub-exposure times of around 10-minutes with the usual minimum of around 50-60 subs.

The evenings are now getting shorter and this is the last month of imaging (for me at least) for a few weeks now.  Make the most of any clear Moonless nights we get this month – we’ve got a while before we can grab some deep-sky photons again.

Until June – clear skies!!