Er, did I mention I'm doing my dissertation??
I worked 14 hours straight on it today. Ok, to be honest it was 1 hour's work (4.00am to 5.00am) - Breakfast - 6 hours work - wine with lunch - sleep - 7 hours work. I'm trying to do another hour or two before bed but things are getting blurry.
I was looking for an argument against dualism and stumbled across this great philosophy blog:
His final post made me smile:
I “withdrew” from this university semester, and don’t plan on going back. Although it is unfortunate to quit before I can figure out whether (the vast majority of) philosophers are actually as staggeringly incompetent as they appear to be, or are simply playing an elaborate practical joke, I simply couldn’t stand it either way.
It’s technically possible that I’ll post more to here, but it’s unlikely. In any case, thanks to everyone who was supportive. No thanks to this discipline for turning what should be a worthwhile pursuit into a massive waste of time.
It's all about the dissertation now. I'm doing nothing else, apart from showing up at work, which is, frankly, a real inconvenience.
It's a tough time, broken by only brief moments of excitement, eg when I spotted this mistake in tonight's dinner.
It's a little thing I know, but they must pay people to produce this, then they must pay other people to check what's been produced, so how does it get through??
"Oh God, please don't show me any more of your faint fuzzies!" I hear 4AoSers cry. This is one of the captures from the other night. Deep sky observing is over for the next 10 days as the moon is up, and I'm into the final stages of the dissertation. Actually this astro image manages to be one of the most boring and one of the most exciting. The reason is that the galaxy is 90 million light years away; the most distant object I've ever seen. The light that hit my retina set out when dinosaurs ruled. 286,000 miles a second for 90 million years; that's a bit overwhelming isn't it?
Just a few more days before the final deadline for the MA dissertation. I've been sneaking out late at night for an hour or so with the galaxies, but I shouldn't really, as it leaves me tired the next day. I really really try not to do it but when the faint fuzzy monkey is on your back it's almost impossible to resist.
Luckily, the moon is up now and there's won't be any proper dark skies for 2 weeks so I can concentrate without distractions. Perfect timing!
One of the last, then. I'm really pleased to have captured this one. It's one of the faint dwarf companion galaxies to the famous Andromeda galaxy.
Here the image I took nearly 4 years ago, showing Andromeda and the 2 satellite galaxies:
And here's the sketch of the dwarf companion
What's the point in spending ages tracking down an almost imperceptible smear of light in the night sky? I've asked myself this on many an occasion over the years, normally at about 2 in the morning after my telescope has misted up and I've lost the feeling in my fingers.
Here are 2 recent "conquests."
There's the excitement of the chase of course, then there's the pleasure of actually finding the target and seeing the faint fuzzy appear in the eyepiece. But most of the excitement comes from knowing what it is that you are looking at.
The one on the left is NGC 6905, another for my Herschel 400 collection.
Is it my imagination or are my digital-astro-sketches getting better??
It's the remnants of an exploded star, some 3000 light years away:
And the other is NGC 7006. This is as close as I can get to showing you exactly the view though the eyepiece. This faint blob is actually hundreds of thousands of stars at a distance of 127,000 light years. That's well outside the milky way:
Dad has kindly lent me his Nikon D3100 DSLR camera. I opened up the aperture, put ISO to 3200, put it on the ground (on a piece of card...) and took a 30 second exposure. Here's the result (after enhancing in Photoshop)
The milky way around the constellation Cygnus is clearly visible, and I'm pretty sure this is NGC 7000, The North America Nebula, so called because of its shape:
2 Herschels bagged the night before last. At the top is the open star cluster NGC 6939, and lower right is the faint galaxy NGC 6946. It took about 40 minutes to track down the cluster and to sketch it, and another 20 minutes to find and record the galaxy. It may not look like much but I'm really pleased with it because the postion of the stars is pretty accurate when comparing it afterwards to images online, including the 'strings' of brighter stars at the bottom of the cluster:
There are 231 galaxies in the Herschel 400 (previous post) and I'm going to bag every one of them. I searched long and hard for these 2 in the constellation of Draco (just above the Plough) the other night but couldn't see them. Eventually I realised the front lens on the telescope had misted over. Deep Sky Astronomy is a cruel mistress.
NGC 5907 is an edge on spiral galaxy. This is what our galaxy looks like from a distance of 50 million light years
I'm now in serious dissertation writing mode, but still allow myself a little fun at night with the telescope.
Here's my digital-astro-sketch of M13, the biggest and best globular cluster visible from northern skies:
Not impressed with the glob? That's ok, because my real target lay above it (I'll come back to M13 another time).
It took me 3 nights to track down one of the faint galaxies discovered by Herschel: NGC 6207. It turns out I was looking in the right place but the slightest interference from light - in this case the Moon - destroys any chance of seeing it. It's very faint, at a magnitude of 12. It may well be the faintest object I've recorded so far.It would have to be 70X brighter, and all its light focused into a star-like point, for it to have any chance of being seen by the naked eye, even from a very dark sky.
It's 30 million light years away, that's 1200 times further away than M13. Its apparent size is 1.7 x 3.3 arc minutes.
Oh, and here are the original sketches:
I don't like maths but it's time to get serious with my observing. Tracking down faint fuzzies (galaxies, nebulae, etc) is tricky at the best of times, but even more so when you are hunting for the Herschel objects, most of which are very faint. The tried and tested way is to star hop, ie, start from a star you know and work your way across to progressively fainter stars till you find the target, or more likely don't find the target.
Working in the dark is the first difficulty. You can use a faint red light to read star charts and descriptions, but it's amazing how unhelpful they often seem to be when you are in the field. Also, the charts show the stars in the position they actually are in the sky but the finderscope (the little telescope on top of the big telescope) inverts the image left to right and top to bottom. You use the finderscope in conjunction with binoculars, which don't invert in any direction, but then the telescope view is inverted left to right but not top to bottom.
Binoculars = N up, S down, E left , W right,
Finderscope = N down, S up, E right, W left,
telescope = N up, S down, E right, W left.
Since all stars look pretty much the same, it doesn't take long before you are driven mad by this.
There's also a description you can follow to star hop to the target. Remember this little globular cluster the other day, NGC 6229?
Here's the instructions I followed to find it: (O'Meara's Guide to the Herschel 400)
"Find star 52 Herculis, which is 7 degrees north of 3.5 magnitude star Eta Heculis. It forms the north eastern apex of a near equilateral triangle with the 4th magnitude stars Sigma and tau Herculis. Move 40' north-north east to 7th mag star alpha. Now make a slow sweep 1 degree north west to a pair of 8th mag stars oriented north northwest to south-southeast and separated by 5". NGC 6229 is only 5' east-northeast of the pair."
You can easily lose an hour this way.
What helps a bit is knowing what a degree, a minute (1/60th of a degree) and a second (1/60th of a minute) looks like through the binoculars and scope - in other words what the field of view (FOV) is - but each time you change the lens, the FOV changes too. I've finally worked it all out properly, rather than just guessing all the time. Here goes:
15X70 relelation binoculars: FOV 4.4 degrees. The moon is half a degree, so you could fit 8 moons side by side.
My telescope has a 10" (254mm) diameter mirror, and its focal length is 2500mm. That means light from astronomical objects are brought to a focal point 2.5 m from the lens.
But, you say, the scope isn't 2.5m long.
(Previous post 4 years ago)True, but it's a Cassegrain Schmidt scope, which uses a convex secondary mirror and a corrector plate, which, simply put, "trick" the main mirror into behaving like one of a much shorter focal length. Or as I said on the previous post, even more simply put, the scope's wearing glasses.
Without the glasses the tube would need to be this long!
Magnification is a product of the focal length of the main mirror and the lens used.
Here's my main deep sky lens. It's a super quality lens, the 40mm TeleVue Plossl. (review of all the lenses here). Cost: £110, now, though can't remember what I paid 23 years ago for it.
(modelled, as always, by the ever-helpful UniM)
Its focal length is 40mm. 2500mm divided by 40mm = a magnification of 62.5X
The apparent view of view of this lens - ie how big the circle of light is when you look through it with the naked eye, is 43 degrees. The actual FOV (AFOV) is the FOV divided by the magnification, because obviously, if you magnify something eg 10 times you zoom in 10 times and can only see a tenth of what you could previously.
So, 43 degrees divided by 62.5 magnification gives a field of view of ... 0.688 degrees. The moon is half a degree, so through the scope using the Plossl, the full moon will almost 3/4 fill the field of view.
You can see the value of knowing this for faint fuzzy hunting. When the instructions say "make a slow sweep 1 degree north west from star Y, you know how far to go. To move the star from the centre to the edge of the FOV = 0.35 degrees (half of 0.688) and then you need to move the same distance again twice, ie a total move of 0.35 x 3 = 1 degree. Sorted!
This is my mid-power lens. The Meade MA 25mm, 40 degree FOV. It's not a particularly good lens apparently (£33 new: a lens for the "price-conscious amateur." That's me) but it's a proper workhorse, and has served me well for 23 years. Leaving it in a wet garage for 3 years hasn't made it prettier but also, luckily, hasn't affected its performance.
I'm sure you can work out the magnification now:
2500mm / 25mm = 100X.
And the FOV is 40 degrees so AFOV is 40 / 100 = 0.4 degrees. The moon, then would completely fill the view through the scope
This is my top lens: the Meade Series 5000 UWA (Ultra Wide Angle) 6.7mm lens, costing £170. 275g of quality glass.
Magnification: 2500/6.7 = 373X!
FOV = 82 degrees, so apparent view is 82/373 = 0.22 degrees. Notice that it gives almost 4X the maginification of the MA lens but still gives over half the field of view of the MA.
Summary (for me,as much as for anyone else)
How marvellous! While writing this post I stumbled across this eyepiece, which I'd never used before.
It turns out to be a really super one for deep sky work. It's 125 magnification but is wide angle and gives an AFOV of over half a degree, significantly more than my 'workhorse' 100 mag. lens
Ah, I do love a planetary nebula. It's "a kind of emission nebula consisting of an expanding glowing shell of ionized gas ejected from old red giant stars late in their lives. The word 'nebula' is Latin for mist or cloud and the term 'planetary nebula' is a misnomer that originated in the 1780s with astronomer William Herschel because when viewed through his telescope, these objects appeared to him to resemble the rounded shapes of planets. Herschel's name for these objects was popularly adopted and has not been changed. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years."
Last night the skies were clear and dark, and I managed to bag these two beauties. My astro-sketching is definitely improving; this is a good approximation of what I actually saw last night.
And the Blinking Nebula is so called because when you stare at the central star the nebula seems to disappear, but reappears when you use peripheral vision.
Agian, this is a pretty good impression of what I saw: