Moon

Moon

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.


Alex.

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.

Alex.

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.


Alex.

Monday, 10 April 2017

Tricking up rigidity on a DIY wedge

A few years ago I salvaged an old set of SCT forks that was about to be trashed.  The RA motor still worked, and its handset still controlled the RA rate.  I realised that this old fork mount would be perfect as a video astronomy rig.  So I turned my DIY hand to making a wedge to suit.






For my purposes, my immediate design appeared to be fine.  With sketching being my primary niche in astro, and at the time using another SCT, I never really paid much attention to the consistent error in alignment that the mount had.  No matter how accurately I set the wedge to my latitude, and no matter how much care I took with my rustic alignment, there was a persistent misalignment that saw the object drift out from the FOV.

I recently bought a brand new SCT OTA that I coupled to these old forks.  When I coupled the scope to the wedge, I noticed something shocking!  Something that I should have been aware of and stopped from occurring when I built the wedge – FLEX!!!




Despite the 30mm thickness of the platform that the mount sits on, long and unsupported cantilevered plywood platform yields to the large mass of the likewise cantilevered mount!  A doubly cantilevered system.  And now add the heavy mass of the new OTA, and the amount of flex in the platform increased.

This explained the consistent misalignment of the video rig!

But how to fix this?

Simple!

A pair of aluminium angle brackets placed along the length of the mounting platform.

The mechanical properties offered by the brackets acts much like an RSJ bar (I bar).  And with using just four screws to fix the brackets, the bracket/platform arrangement acts just like a laminated system, increasing the rigidity of the system.






Over the weekend I tested the pimped wedge.  When I coupled the mount to the wedge I cannot say I noticed any flex in the platform.  With the magnification on the scope at 250X, there was only the most minor misalignment noticeable that despite my rough and ready alignment of the wedge kept Jupiter in the FOV for a couple of hours. 

Flex problem 95% solved!  Any further improvement to the remaining flex will mean rebuilding the whole wedge - something I have not totally discounted as this pine plywood can be improved upon that will further improve rigidity, the new design would reduce the length of the unsupported mounting platform, and the wedge bracing would also be more centred over the tripod.  All of these are weak points in the current wedge.

Now for some clear skies for a sketch or two!


Alex.

Thursday, 6 April 2017

My $1 scope case (well, sort of $1...)

Hi all,

With the sky continuing to be terrible for sketching, it has afforded me time to consider other projects I’ve had in mind for some time.

Well, I have my Frankenstein SCT, but I don’t have anything to store it in out of harm’s way other than a plastic bag – and that just won’t do.  My old orange tube C8 came in a trunk, and something that size would be perfect for this “new” instrument.

Purchasing something ready-made though was not ideal as really for a few reasons:  either be too large or too small, not support the scope as needed to minimise undue stains on clutches and the OTA, and adapting a ready-made case may be either difficult or implausible due to the materials it is made from.

So the only option is DIY.

The other day I went to my local hardware store to look for some plywood for this project when I noticed a few long sheets of MDF that were being collected for disposal.  Their apparent size quickly drew my attention, and with a tape measure I realised that just one of these sheets would be perfect for my project!  So, $1 later, I carted off a brilliant find for me.

Ok, the $1 cost of the case is just of the MDF.  But this was the only additional expense I had in making the case as every other component I already had at home.  The true cost of the case with the other components considered was closer to $60.  Other than the MDF, all the other timber elements were scavenged off-cuts from home, and the foam rubber was also off-cuts.

Knocking up the box was easy.  What concerned me was making it too easy for little creepy-crawlies to sneak in through the gap between the lid and base, so from a plywood off-cut I fashioned a lip that the lid sits around, and provides a better seal.




Ok, now I have a very drab case made out of MDF large enough to hold the scope.  So it won’t be enough just to make a scope case, but the MDF needs to be pimped too.






The real work now commences to fabricate the necessary supporting elements.  That was the one problem with the case of my old C8 – the case was just that, an empty box, and the fork and OTA were pretty much left on their own inside the foam filled case.

First thing though was to varnish the entire case inside and out to protect it from shedding its uncoated fibres.  The varnishing is also the first part in the pimping process to seal the surface.  This allows for the decorative processes to happen.

The OTA is supported as is the fork mount, to minimise undue stain on the clamps and mounting brackets, and to allow for the OTA and fork mount to be supported should the clamps come loose.  The distribution of the supports and the OTA also allows for plenty of storage space for bits and pieces.  Down the track I can install compartments to hold accessories.






The decoration of the external MDF surface was done taking inspiration from some how-to videos on Youtube on how to achieve a faux-timber appearance on MDF.  The decorating was done before the aluminium trim was fitted.

The screws used to fix the trim were selected according to the faces that the case is to sit on, namely the bottom face, and the back face with the hinge (the case is stored standing on this hinge face).  Those faces not taking the weight of the case have pan-head screws that sit proud above the trim.  Those two faces which are used to sit the case on, the screws are countersunk below the trim.

Even the handles have special consideration.  As MDF is not the hardest material, special measures need be taken to reinforce the areas around the fixing screws.  The top pair of screws bite into the hardwood plywood lip.  The bottom pair of screws are machine screws that back onto a pair of massive washers to distribute the load of the case over a very large area, and thereby avoid the risk of screws pulling out.

I am very happy with the way this case has turned out.  A couple of friends have commented that they couldn’t believe that this was MDF!  There are plenty of hollows which can be used to store accessories, such as a diagonal and finder.  I can add compartments to the case as my experience with the case grows.  Velcro straps could also be used to hold some of the accessories.









If you’ve been considering scope case options, I hope this project of mine has given you some ideas on what can be done.  My project is certainly not the be all and end all with scope cases.  It is just my take with the materials I had at hand, the ideas of what I wanted, and the inspiration that came to me.


Alex.

Saturday, 11 March 2017

Bugger it! Sometimes you just need to take a hammer to it...

I recently purchased a new SCT optical tube assembly to replace my lovely orange tube C8 that I retired from action.  I’m pleased to say that the Old Girl has found a new home with a collector who will look after her.

So, this new SCT needs a mount.

I purchased this scope knowing that I have a German Equatorial Mount (GEM) that can take it.  However, GEM mounts do not place the eyepiece at the most convenient location.  There is also the meridian swap in order to keep the motor drive loaded appropriately without undue stain.  Yet a fork mount has a much more limited range of eyepiece placement, and is not affected by the strain of meridian shift.

So, I’ve got a new OTA, but which set of forks?

One reason that I bought this particular OTA is that it has screws on it that would seem to correspond with the coupling holes on the fork mounting plates.  I have an old set of forks from the same brand as the OTA, so why not look at seeing if I could couple this OTA with these old forks?  I’ve been using these old forks as my video astronomy rig, having made a platform that spanned the forks.





Alas at first glance not.  The OTA appeared to be wider in diameter than the span of the forks and the coupling holes did not match.  The latter was by just 1mm, but enough for the screws not the fit.

So begins the search for a set of forks to match, and an interesting saga of near misses, useless sources of information, wonderful people willing to help, and pigheaded, devil may care, try it and see try to fix it attempt.

So, after the question asking, frustrations, and fruitless searching, the promise of finally a clear sky and the chance of finally doing a sketch of the Moon, I decided to have another go at fitting the OTA to the old forks.  I mean, how hard could it be, right?  So after dinner, I disappeared into my workroom and let the Devil take over!

I decided to take the arms off the mount, modify the holes to allow the screws to fit the OTA.  This was very quick and easy to do as it was just a minimal amount of material that I had to adjust.  To my joy, the third hole in the coupling plate was a perfect match to the corresponding hole on the OTA.  Bonus!  This allowed me to first couple the tynes to the OTA with this third, leaving the two other holes easier to deal with.

Once both tynes were fitted, I lowered the OTA onto the mount.  I expected there to be a gap between the mount and the tyne attachment points, and had thought of a way to deal with it.  But to my surprise, there was no gap!  It was a perfect match!  Perfect!





Finally I have a brand new SCT OTA with the convenience of the fork mount that I preferred.  I am overjoyed that I have been able to once again re-purpose the old forks.  The wedge I made some time ago and my kids decorated it, and the tripod is a surveyors’ tripod.  So my “new” scope is a real Frankenstein, made up of old and new, DIY and re-purposed.  And it all works brilliantly 😎




Now, to get scope time once again. I’m hoping that the sky finally clears this weekend.  The forecast is promising.  I’m now all dressed up, and nowhere to go until the clouds clear.  Oh, well, that’s how things go with astro…


Alex.

Sunday, 22 January 2017

A Low Contrast Moon

Hooray!  Scope time!!!

Of late, I’ve whinged many times about the lousy weather we’ve had over the last few months.  This latest stretch really has been just terrible.  If not overcast, then too hot, or seeing has been miserable.

Earlier this week I did manage some time with a scope with a mate who came by with a couple of new scopes (a couple of lovely refractors) and some eyepieces.  We had a great time putting his scopes and eyepieces through their paces, and using his eyepieces in a Newtonian of mine for comparison.  Seeing was not great, but we managed some good testing of his gear with our combined experience.  No sooner did we call it quits, clouds rolled in, spelling the end of a potential Moon sketch for that evening… <sigh>

This Sunday morning was surprisingly clear, and the Moon was pretty much at zenith (straight overhead).  At 9:30 in the morning, the Sun is well up, and the sky a brilliant bright blue.  While the Moon looks lovely and bright up in this bright blue sky to the naked eye, through a telescope, the Moon is a very low contrast object, and only a low power proposition.  Yet, the blue and white composition really appealed to me!  Knowing that I had sky blue paper, I decided that the Moon was fair game today, and the low contrast challenge made it all the more appealing to me as I haven’t undertaken such a sketch before – yep, I’m a weirdo… LOL!  So, I set up my ED80

First thing to decide on was the optimal magnification.  Very low, the contrast is improved, but the details are too fine.  High magnification, the contrast is too low to make out any details.  So for the first time I used my Baader zoom eyepiece.  The zoom feature makes it much easier to figure out the best magnification to use.  So, today, 20mm was just right.

Not have experienced such a low contrast situation before, I was on new ground to work out how to go about this.  Colour selection of the soft pastels was the first.  Black was out straight away as it is just too strong and not actually what’s seen through the eyepiece.  I have a blue soft pastel, but it was too intense and not the right hue.  So, from what I had at hand, I decided to use white and the grey soft pastels.  The grey, while also too dark neat, it would be easier to tone down by going over it with the white.  And a little experimentation as I go along is also in the mix.

The image through the eyepiece was beautiful.  The leading edge being so bright and sharp.  The terminator faded into the blue of the sky gradually.  The maria, mountain ranges and craters varied so softly in shades of pale blue that it made keeping track of the feature I was laying down difficult.

This was not a sketch with which to lay down the most intricate of details.  I became aware that the piece would best resemble an Impressionist work, with only the gross details identifiable, and finer details hinted at with the texture of the paper and the way the soft pastel is handled.

After an hour I was done.  It became too difficult to pull out and follow the fine details as the low contrast was becoming too difficult to negotiate.  Only then did I examine the overall piece – and I surprised myself!  Soft pastel being what it is, depending on the angle that the piece is examined the brilliance of the paper is toned down, and the soft pastel begins to glow.


I hope you enjoy this piece as much as I do myself.

Alex.

Object:  “Low contrast Moon”
Scope:  ED80 f/7.5
Gear:  Baader zoom @ 20mm, 33X
Date: 22nd January, 2017

Location:  Sydney, Australia