Thursday, 14 December 2017

New dobbie mount for an existing telescope.

Hi all,

With the horrid run of astro weather we have had here in Sydney, I've had to keep myself busy with other astro projects to keep my hands occupied.  So, it became the perfect opportunity to revamp a flawed little scope, and transform it into a brilliant performer!

I’ve had this 130mm Celestron Astromaster scope for a little while.  The single biggest problem with it is the poor equatorial mount it comes with.  The mount is too wobbly, and really more of a pain in the neck than what it offers.  And for beginners, this mount is the single biggest frustration that leads to this and similar scopes being put away and never used again.

The finder bracket on this scope had also broken off.  I am not too sorry about this as the original finder it came with was rubbish too.  Too close set to the tube made using it difficult, and its design is not easy to use.

So, the solution to this scope to give it a new lease on life is to ditch the eq mount and make a new table top dobbie mount for it, and install a better red dot finder to it.

I went to town on this little scope!  I had some fine materials left over from some other DIY projects, so I was able to use the following stuffs:

·      *   15mm marine grade plywood
·      *  Ebony Star laminate
·      *   Teflon bearing pads
·      *   Marine grade varnish
·      *   Stainless steel azimuth pivot bolt and washers
·      *   And a brand new 20mm red dot finder on a dovetail block.

Many dobbie mounts, including table top designs, do not have a balanced Optical Tube Assembly (OTA).  This means that if you switch between a wee little eyepiece to a very heavy eyepiece, the tube become top heavy or tail heavy when you switch back.  So these mount have a friction mechanism by which the altitude bearing is tightened, and there by making action of the altitude bearing stiffer so the tube does not drop under a heavy load.  Biggest problem with this being the quality of the action of raising and dropping the scope not only becomes harder/stiffer, but it makes tracking a target at high magnification as the action becomes jerky and very difficult to control.

Not with this little scope!

I designed the mount without any friction mechanism, but the OTA is perfectly balanced and the mount allows for the OTA to be loaded with any size of eyepiece, and the scope does not drop or rise – it stays put and the quality of the action not only remains exactly the same all the time, but it is silky smooth ALL the time!

This little scope now is a red hot, stable and very user friendly instrument.  I can swap eyepieces and the tube does not shift, even with no eyepiece in the focuser.  I can more easily locate targets because of the higher set red dot finder, and I can easily keep track of targets no matter the magnification I am using!


Wednesday, 13 December 2017

Links to fellow Astro-Sketcher sites and blogs, and other astro-sketching resources

Hello all,

I've added a new links gadget to my site in the right hand side margin - Sites and Blogs of fellow astr-sketchers and other astro-sketching resources.  It is dedicated to the websites and blogs of fellow astro-sketchers and other astro-sketching resources.

I've started on a journey to find as many fellow astro-sketchers, and add their sites to the listing.  Different artists use different media, some pencil and paper, others soft pastels and black paper like myself, others work with digital processes, and many other different materials and media.  Astro-sketching though a very small niche, there is a wide variety of media, materials and techniques being used.  By adding the sites of as many astro-sketchers as I can, I aim to give exposure to all the different ways people illustrate and fulfill their passion for astronomy and sketching in its many forms.

There are a few people who cannot view into their telescopes due to physical limitations, so they use electronically assisted methods, such as video astronomy, to produce an image on a monitor, and they then make a sketch of what they see on the monitor.  Technology now provides a means of allowing a wider audience to participate in astronomy, and gives them tools by which to facilitate their own passions within astronomy and art that prior to this technology being available these people had no way of doing so.  Marvelous stuff!

If you know of a site that I have not listed, PLEASE let me know of it!

Please explore the work of these fellow astro-sketchers.  They all offer a different take on their art, different experiences and different approaches.


Wednesday, 22 November 2017

Mad rush with a 4 day old Moon!

Hi all,

This really has been a miserable astro year for me and all of Sydney for that matter.  We may have sunny days, but the evenings are cloudy or windy or seeing is just the pits.  Yet we amateur astronomers are an optimistic bunch, and opportunistic if need be.

Yesterday was another one of those sunny teasers.  Few clouds all day long, and sunset saw the clouds disappear!  But this was just a tease.  On the horizon there was an ambush of rainclouds waiting for the final rays of the sun to disappear to mark their charge upon the Sydney sky.

Expecting this, I had a quick look towards the west as a very thin waxing lunar crescent was low in the sky and close to Saturn.  The Moon just proved irresistible, and a huge urge to sketch the gorgeous scene had me thinking – “Do I have enough time?  Can I get the gear together fast enough and smash out a sketch before the Moon dips too low and beat the impending rush of cloud cover?  Shall I chance it? YES!”

In two minutes I set up my ED80 refractor, and four minutes later again I had my pencils sharpened and sketch pad in hand.  A quick compass scrawl of an incomplete circle for the outline of the Moon, off-set for composition value, and then started the mad rush to get as much detail down as possible.  The Moon was no more than 30° above the western horizon and dropping fast.  In my favour was surprisingly stable seeing over what normally is a very warm and shimmer laden western sky.  And as always, the more I look the more detail I see.  But there’s no time!  The leading charge of clouds started moving in, taunting me as the Moon was briefly obscured.  No time to pause.  What can I see through the haze that I can lay down in the sketch?  MOVE IT! Alex!  Keep it neat!  Don’t dawdle.  MOVE!

And in half an hour it was done, and the Moon disappeared behind clouds right on que!

What a rush!

With the crescent done, I just filled in the Earthshine with a paint brush using soft pastel dust and tidied up any loose markings along the limb.  Finished.

I am really happy with this piece.  The composition works really well being off-set, and that some of the Earthshine part is cut off works too as goes to make the crescent the focus of attention.  It has a certain 3D feel to it, like you are passing by the Moon on your way to another destination.  I hope you enjoy this piece too.


Object:  4 day old Moon
Scope:  ED80 refractor
Gear:  9mm TMB Planetary Type II, 72X
Date:  21st November, 2017
Location:  Sydney, Australia

Media:  White soft pastel and charcoal on A4 black paper

Monday, 11 September 2017

Busy Sun - Coronal Loops and Prominences Galore

Hi all,

There’s one variety of solar prominence that I’ve been wanting to see for a long time.  Even from before acquiring my first Hydrogen Alpha telescope.  Coronal Loops.

I’ve been starved of any form of solar observing for a long time thanks to the terrible run of poor seeing conditions that have persisted over Sydney for several months.  Even just at 50X magnification, the image of both the Sun and the Moon are unbearably shimmering.  Yesterday I took a chance on a break in conditions, and boy, I was richly rewarded!

My first peak through the eyepiece saw my jaw hit the ground, and I started “Yahooing”!  Coronal Loops!  A big cluster of them too!

This is where another part of my fascination with astro kicks in.  I did not know the name of this type of prominence, so if you don’t know something, you ask.  I sent a text message to a fellow solar buddy of mine, Ivan, about the fabulous apparition.  He was also kind enough to enlighten me on the association that these proms come from.

These are a rare prominence type, associated with highly volatile Active Regions on the Sun’s surface.  Here, very high temperature plasma (atoms that are so hot they have been stripped of their electrons), is electrified and is racing along magnetic fields.  These magnetic fields are also connected to areas containing Sunspots.  Sunspots are a common feature on the Sun’s surface.  However, Coronal Loops are not always present.  They are only seen during periods of high activity, particularly during the Solar Maximum.

The Sun has been very subdued for a time, with very little prominence activity.  These last few days has seen things take a major turn with not only several prominences appearing, but the Coronal Loops indicate a burst in activity.

This first sketch shows a complex set of Coronal Loops, erupting from several points.

Today, Ivan sent me a message to bust out the solar scope again.  I couldn’t resist the suggestion.  The Coronal Loops cluster had changed in appearance, and I just had to sketch this new apparition.  There’s also two sets of sun spots that can be seen towards the bottom of these first two sketches.  It can be seen the difference in the position of these two sets from one day to the next, indicating the rotation of the Sun during the 24 hour period.

The circumference of the sun was riddled with hedgerow proms, pillars, detached proms, pyramid proms, spicules, inclined proms, and one massive eruption.  Along with the extraordinary Coronal Loops, the entire scene just demanded a sketch of the full disk – something I had not done before.

For my prominence sketches, I use a Quark Prominence filter on an ED80 refractor.  While this filter is exquisite for prominences, details on the chromosphere are not particularly evident.  These details are still there, but they take some doing to tease out.  To help me tease out these details more easily, I use a little PST.  This little scope allows me to quickly identify where significant chromosphere and then I use the Quark to pull out more detail from these specific areas.  This way I was able to more easily identify where several filaments were, and another Active Region around a small group of sunspots.

It has been quite a wonderful return to solar sketching these last couple of days.  From nothing for several months to three pieces that filled me with excitement.  From very little solar activity, to a spectacular set of Coronal Loops and a massive eruption and an amazing collection of different prom types.

I hope you enjoy these three pieces too.


Thursday, 11 May 2017

Drygalski and Full Moon Mountains, & Getting Back in the saddle

Hi all,

It has not only been a long time since my last DSO sketch, it’s also been a long time between lunar sketches too.

One thing that’s kept me in touch with my scopes has been making bits and pieces for them.  One has been the new case for my SCT that I posted a few weeks ago.  I’ve also changed the secondary holder and spider of my 17.5”.  I’ve now also modified the large fine focus knob I made for my SCT.

I made a large dial knob for both my old orange tube SCT and one for my new instrument.  However, just making the same thing all over again left me feeling a bit ho-hum about it.  It lacked a little bling.  So, after a friend asked me to make a new pimped up dial for a controller of a scope of theirs, I went to town on mine!  It looks like a 19th century time machine exploded all over it!  As some of the gears have a lot of height to them, I first had to make sure that the position I put them in did not interfere with the operation of the scope nor with stowing it.  This Steampunk treatment complements the timber of the knob, and has given me ideas on how to possibly give the Steampunk treatment to the new case for this scope.  I also have a few old glass electronic valves that I can use for this exercise.

This week also saw the lunar drought break for me with two sketches!  Hooray!

Sunday night proved to be the break of the drought with a gorgeous clear night.  My initial examination of the Moon threw up two great sketch candidates.  One was around the elongated crater Schiller that I’ve been wanting to pen for some time.  This area is very busy.  The other area was around Aristarchus, with the sun just illuminating its rim edge, and a more gentle area of smoother Maria.  Not having sketched the Moon for so long, I felt very rusty and in need of getting my eye in again before tackling something like Schiller.  Also, with seeing not being too flash, I felt that I would struggle more with a more detailed crater ridden area compared with a more smooth plain area.

Dawn Rising Over Aristarchus proved to be a most enchanting piece.  The flat maria lunar surface is rolling back around the Terminator, giving a lovely 3D effect, and the shadows cast by the nearly totally flooded crater Prinz and a series of lone mountains next to Prinz, made for a wonderful juxtaposition between light and shade, giving a lot of drama and precious detail to the piece.

Object:  Dawn over Aristarchus and Oceanus Procellarum
Scope:  8” SCT
Gear: 9mm TMB Type II, 223X
Date:  7th May, 2017
Location:  Sydney, Australia
Media:  Soft pastels, white ink and charcoal on A5 size black paper

Drygalski and Mountains During Full Moon was done a couple of nights later on the Wednesday that followed.  Smack bang in the middle of the Full Moon phase!

I LOVE the full Moon!  LOVE it!

Most astronomers wouldn’t even think about hauling out a scope during the full Moon.  Me, I see it as the perfect time to spot one of the most striking features on the Moon itself,  its mountains and lunar scape seen from profile, instead of just from above!

Most people think that there are no shadows to be seen during the full Moon.  Not so!  The only time that there would be no shadows visible is during a lunar eclipse, which is the only time that the sun’s rays fall perfectly perpendicular on the Moon to us.  But as the Moon most often orbits the Earth above and below the Earth’s orbital plane, some degree of shadows been cast will always be seen.  And the full Moon phase allows for a most extraordinary display of shadows cast over hills, rolling plains and behind mountains.  A most extraordinary sight.

I have sketched Drygalski before.  However, libration of the Moon had it in a much more favourable position that first time, with the crater floor visible then, but totally black filled this time.  It and every other crater is VERY squashed and elongated due to foreshortening.  And as the scene is such a wonderful field, I had to sketch this spot to a much wider size.

Object:  Crater Drygalski and Mountians during the Full Moon phase
Scope:  8” SCT
Gear:  9mm TMB Type II, 223X
Date:  10th May, 2017
Location:  Sydney Australia
Media:  Soft pastels, white ink and charcoal on A5 size black paper.

Two widely different scenes, one Moon.


Sunday, 7 May 2017

A galactic neighbour - NGC 4945, sketch

Hi folks,

It has been a miserable run of poor weather each and every new Moon weekend for so many months.  Finally the streak has broken, and I was able to achieve my first DSO sketch in as many months.

My observing buddies and I have also been looking for a new observation site ever since the passing of my good friend Rod Hay meant we lost access to Katoomba Airfield.  One location we found we lost due to regeneration works by National Parks.  I visited other potential sites, and for various reasons I had to discount them – difficult access, restricted horizon due to trees, location being contaminated by dumped rubbish, and at one fabulous location, feral dogs being a very dangerous problem!

During all this time, I’ve also been busy asking as many people as I could about either using their big fields by our little band of astronomers, or if they knew of someone who may be able to help.  The greatest difficulty has been finding a location that provided as many of the conditions that are best suited to astronomy.  After many months, a knight in shining armour has finally appeared.  We have been granted access to a fabulously big field out on the Shipley Plateau in Blackheath (in the Blue Mountains).  This new site is only a little further out from the Airfield, and is 100m higher in elevation.  The horizon is astonishingly good, with the tree line at least 100m in all directions from where we set up our gear.

As an added bonus, as the sun begins to set, the local kangaroos emerge from the surrounding bush to graze on the turf on the lush field.  As I entered the site, I was greeted by some 50 roos grazing and enjoying the last rays of the afternoon sun.

The roos remained on the field all night, keeping us company, though they kept their distance.

I had changed the entire secondary mirror holder and spider of my 17.5” dob.  I was never very happy with the spider and holder that I repurposed from the Odyssey 2, a Novak spider.  The vanes were too soft, yielding too easily , and the collimation screws were too difficult to access and adjust, requiring a screwdriver to do so!  As I also build telescopes, I had enough of the troublesome old Novak secondary arrangement and made my own.  What a brilliant improvement!  I installed my own dew heater to the secondary mirror along with an integrated wiring arrangement that connects to a 12V battery that’s fixed to the mirror box, which provides additional ballast for the heavier eyepieces I tend to use now.  First light with this new arrangement took a little bit of tinkering to get going, and once it was up and running, my planning proved to be the improvement that it needed!

I have wanted to sketch the lovely galaxy NGC 4945 for some time.  I still recall my first view of 4945, and I was staggered to see how detailed it has.   What makes 4945 special is not just the galaxy itself, but the theatre that the surroundings give to the view.

For being an edge-on spiral galaxy, 4945 is far from displaying an orthodox edge-on appearance.  The southwestern edge of 4945 (top left edge in the sketch) shows as a glowing leading edge.  While the glow is an artefact of the galaxy itself, the glow here seems to come as a reflection from a bright star immediately to the south.  The effect is quite striking.

Dark nebulosity from within 4945 carves a streak across the southeast edge, which curls in onto the middle, resembling the ball head of a femur bone.  The rest of the galaxy has a mottled appearance, and the overall effect really is of an elongated jumbled glowing mess.  Far from the more typical single dusty line that cuts across the middle of other edge-on spirals.

The odd appearance of 4945 is further heightened by being located behind one of the arms of the Milky Way.  If 4945 was located in an area of less dense stellar concentration, the background would be significantly darker.  But that 4945 sits behind a curtain of stars, the background is ablaze itself.  Yes, there are many stars that can be individually made out, there are so, so many unseen stars that as a whole lend their shine to the overall glow of the background.  The amount of dust and molecular gas that lies in front of 4945 dampens its glow by at least one whole magnitude.

This last aspect, the background glow, made for a real challenge on how to depict it.  I laid down as many of the individual stars as practical, but the background really needed some sort of treatment.   A dusting of soft pastel with a big soft brush I felt was not the right technique here.  The tool that I resorted to was to “machine gun” the entire field, just as I would when finishing off a globular cluster.  What this does is allows for some of that “undefined directly, but define by averted vision” effect, and structure to a mottled effect can also be achieved, and adds a little more solid brilliance to the background glow as can be seen through the eyepiece.

The above close up section was adjusted to accentuate those many hundreds (if not thousands) of tiny and oh-so-soft pinpoints I machine-gunned, and the stark difference between the glowing background and what would be a starless background.

If you would like to see what I mean by "machine gunning" with a soft pastel, have a look through my tutorial video on the Mellish Technique I use:

video link:  Astronomical Sketching using The Mellish Technique

An added bonus to the scene is an additional galaxy, NGC 4976.  It is seen here just above 4945 to the top right.

NGC 4945 is one of the closest big galaxies to our own.  A seyfert galaxy (very active core), and one of the twelve “Council of Giants”.  This groovy title comes from a group of giant galaxies that surrounds the Local Group.  Other members of this Council include the Sculptor galaxy (NGC 253), Centaurus A and M81 and M83.  4945 is also called the cousin of the Milky Way as its size and mass is very similar to that of the Milky Way.  The main differences between the two is the larger amount of stellar creation in 4945 and its very active core.

This was a most satisfying piece, with lovely optical illusions, gorgeous details, and an electric background that challenged my thinking on how to depict it.


Object:  Galaxy NGC 4945
Scope:  17.5” Karee push-pull dob
Gear:  24mm 82° eyepiece, 83X
Date:  29th April, 2017
Location:  Blackheath, Australia
Media:  Soft pastel, white ink and charcoal on A4 size black paper

Tuesday, 2 May 2017

Large Scale LMC sketch, pt 3

Hello folks,

Back in November I made a post regarding working on very large scale pieces.  The post was concerned with preparations being made for a commission sketch of the Large Magellanic Cloud (LMC).

One thing that was very much apparent to me about this sketch is it wasn’t going to be a piece that would be completed in just one session.  Having just been able to make a start on the actual piece, the way this start experience panned out, that this piece would be a multiple night work became very much evident.

With this being the case, I thought that I could make a journal of the development of this commission piece, beginning with my post from back in November last year, which I have now re-titled as LMC, sketch (pt1) and the follow up post as LMC sketch, pt 2.

From where I finished off part 2, I had made preparations for a practice sketch of the LMC using a found image from the internet.  As the view through the telescope would be of a narrower field of view than what the found image was of the LMC, I made a mask from dark cardboard that approximated the field of view provided by the telescope/eyepiece combination that also approximated the scale of the image on the screen.  This was an attempt to familiarise myself with the sort of technical complications I would encounter out in the field sketching such a massive object.

Below is a picture of that experimental sketch.  It is immediately obvious that the scale of the sketch is too small for the size of paper I am using.  At first I was annoyed by this, but it then became apparent that it was actually a blessing in disguise!  Now having some experience with trying to depict the sheer size of the LMC, I saw not only the restriction that this masked image presented to my eye in terms of the depiction on the paper, but that I needed to make a conscious decision from where I would start the actual piece, and the liberty/freedom of movement to give myself at the page – it is such a large sheet that I do not need to be so precious with the depiction.

A few weeks ago I was able to make a start on the actual piece.  As mentioned in pt 1, I am using a 100mm f/5 achromatic refractor with a 30mm 82° eyepiece.  The transparency of the night was fabulous, with the Tarantula Nebula in the LMC being not only very easy to see, but I could also make out some detail.  But I also knew I had limited time to work as cloud cover was expected to roll in late in the evening.

I decided to use the spur where the Tarantula Nebula is as my starting point.  What the test sketch showed me was the massive extensions of this dwarf barred spiral galaxy has.  So starting at one end of the dominant Bar, laying down its position and size, I then had the skeleton of the LMC to not only develop the rest of the structure, but when I was able to continue with the sketch out in the field, I had the necessary scale, structures and luminosity to continue.

With the sketch, I followed the normal way I start all my pieces while using the Mellish Technique.  I started with a soft spot of the Tarantula and then continued with a soft depiction of the bar.  Then I continued by giving the Tarantula some depth and detail and also the Bar.  Once I had the nebulosity of the Tarantula and the Bar, I continued with the soft extensions of the disk.  Above you can see the result of the first two hours of work.  It might not seem like much, but the scale of the piece fits really nicely with the size of the page.  The nebulous extensions are actually quite detailed even without the stars being noted.  And so much of the structure of the LMC can be traced out when compared to photographs of it.

Those two hours also showed me that much of the brilliance comes from the multitude of individual star clusters.  It is these clusters that give the LMC its telescopic brilliance.  There are literally thousands of individual deep sky objects within the LMC:  open and globular clusters, supernova remnants, planetary nebulae, emission nebula, dark nebulae, all pushing their own stories.

Incidentally, both of the above photos were taken at the same scale.  The sketches were mounted on the sketch platform that I made which explains the shadows on the top part of the photos.

I am hoping to have an opportunity to sketch some more of the LMC in late May.  Otherwise the window of opportunity will be closed until later in the year when it once again comes into more favourable timing at night.