Cheap Astronomy – Things That Are Free: Meteoblue's "Astronomical Seeing" Prediction

When I prepared myself for the Triple Conjuction, I had to drive to another site – so I wanted to know beforehand how the weather would be, and especially if there were clouds or not.

One thing I found mildly helpful was looking into nearby airports. I have two small airstrips near by, and both have some interesting weather information. One is military and has some cloud predictions, the other is a small private one with temperature and dew point record for the last 24h, plus current webcam images

Since then I tried to find a website which is more dedicated to weather in the context of astronomical seeing. Of course one immediately finds the "Clear Sky Chart" website and Weather Underground's Astronomy service – but unfortunately they cater mainly to the continental US and Canada.

I then searched some more and found the "Astronomical Seeing" service by Meteoblue. Until now I have mainly used their cloud prediction and found it to be quite reliable.They have many more features (like "seeing"), and I hope to utilize them in the future – but I am neither proficient enough nor have I used it other informtion to comment on the quality of their "seeing" information.

Sow what else do they offer? They offer quite some information, with hourly resolution for three days. Most of it presented in color, so one can immediately grasp what one has to expect for the next days.

The Meteoblue information for the current day for a semi-randomly selected city in Russia – things like daytime/nighttime and cloudcover are immediately obvious. Notice the "mouse-over" with planet information in the lower right corner.

The information about astronomical weather they display is:

• Cloudcover (low, mid and high)
• Different seeing indices (different calculation methods)
• Jet stream and "bad" layers
• Temperature and humidity

Furthermore they show some information about our Solar System:

• Daily Sun rise and Sun set
• Daily Moon rise, Moon set and Moon phase (both as number and as text)
• Hourly information for visible planets* (with coordinates via "mouse over")

It is all presented very nicely and I usually look once a day to know if I should prepare for an astronomical session (or not).

*All eight planets except the Earth – duh – plus the dwarf planet Pluto.

Cheap Astronomy – Put Some Flock On Your Barlows!

I would have wanted to look at the Moon tonight, but the clouds are prohibitive today. So I played a bit around with an artificial target I have and to my horror found out that my Barlows were not useful for looking at bright targets. By now I have six Barlows and – with the sole exception of the "KSON 3x achromatic" – each and everyone had problems with internal reflections. Thankfully in each case the usefulness of the Barlow was hugely improved by putting flocking material on the cause of the internal reflection.

These are the Barlows I have now:

• 3x "long barrel" cheap plastic Barlow (0.965 inch)
• 2x all metal "Japan" Barlow (0.965 inch)
• 2x "shorty" cheap plastic Barlow with singlet glass lens (1.25 inch)
• 2x Knight-Owl Barlow (1.25 inch)
• 3x Knight-Owl Barlow (1.25 inch)
• 3x KSON achromatic Barlow (1.25 inch)

And as I said the KSON was the only one that did not need any modification. All the others had internal reflections that degraded contrast and made the image blurred. This was especially annoying when looking at the Moon, as the image became so "washed out" that the Barlows were useless – a child's marble would produce a better image.

What to do?

To check a Barlow, put the Barlow in the focuser (best to test in the fastest scope you have and do not put a eyepiece in), and then shine a flash-light in the scope: When looking into the Barlow, do you see any reflections? Flock 'em! Smoke 'em out! Only a flat black surface is a good surface.

Similarly you can go and remove the Barlow, shine a flash-light into the scope's front end and then look into the focuser: Do you see any reflections were they shouldn't be? Flock 'em!

And for ultimate satisfaction, put eyepiece(s) in the focuser, shine the flash-light from the front and then look from the front: Do you see any reflections? Remove 'em! All my eyepieces (and all my star diagonals) had chrome barrels were the front edge and the inside of the barrel reflected light like crazy. And even if the inside of the barrel was painted in flat black, it was not nearly enough. Especially in the case of the 2" star diagonal I had a huge improvement by flocking the barrel.

So, if it shines in the flashlight, it is bad for contrast. It is most obvious on objects like the Moon or the planets. In other cases (e.g. when there are bright stars a little bit out of the FOV for a dark nebula) the result may be a little less obvious (though probably worth a try as well). As one of the next objects I want to see is Jupiter, I will be needing my Barlows, and I will want every bit of contrast I can squeeze out of my scopes. So the cloudy skies tonight were a blessing.

And one last thing I found: My SR6mm eyepiece has a lot of shiny black plastic surfaces at an right angle to the optical axis – putting some flocking material on it improved contrast especial in when used in combination with a Barlow.

BTW: In many cases I do not stick the flocking material on. I simply leave the protective foil on, roll up the flocking material and put it on the inside of e.g. a barrel. One just needs to cut it to the exact inner diameter of the tube (first make it a bit to long, then cut off small slices until it is "just right"), then one can lay it there "flush" and it will have a little bit of tension that holds the material there.

On other surfaces I try to put it in there so the flocking material holds there "mechanically".

Only in stuborn cases (were the material will not hold "by itself") do I need to remove the protective foil and stick it on the surface (point in case: the inside of the plastic retaining ring).

The Effective Spy?

Adam Curtin: BUGGER

… The spy world became a fascinating other universe that was full of layer upon layer of deception, where the men who inhabited it spent their time trying to penetrate through the circles of falsehood to the inner sanctum of truth.

It was an image that was powerfully helped by John Le Carre's novels - and his anti-hero George Smiley. Le Carre's novels were a clever piece of PR - because they appeared to be more gritty and realistic than the glamourised James Bond image.

But it was just another layer of deception - because Smiley and his search for a hidden mole expressed powerfully the paranoid and unfounded fantasies of the dissident MI5 agents.

But it was a world that was all made-up. Le Carre - who had himself been a spy - admitted this, and described what the true reality of the spy world was:

For a while you wondered whether the fools were pretending to be fools as some kind of deception, or whether there was a real efficient service somewhere else.

Later in my fiction, I invented one.

But alas the reality was the mediocrity. Ex-colonial policemen mingling with failed academics, failed lawyers, failed missionaries and failed debutantes gave our canteen the amorphous quality of an Old School outing on the Orient express. Everyone seemed to smell of failure.

Cheap Astronomy – Blast From The Eighties: 60 / 900 Refractor With EQ-2 Mount

I could not resist it, I had to buy another cheap scope… :-) The scope was incomplete, and I bought it mainly for the EQ-2 mount – but it might turn out to be a nice entry level scope.

Some data:

• Bresser Art. Nr. 45-1200 
• Labelled "Circle T" (which means it came from the Japanese Towa company)
• No indication in which country it was actually manufactured (Japan? Taiwan? China?)
• Achromatic doublet refractor (commonly referred to as "Fraunhofer-type")
• The nominal aperture is 60mm
• The nominal focal length is 900mm
• This comes out to a long focal ratio of f/15
• Silver OTA
• The eyepiece size is 0.965 inch
• Came with an EQ-2 mount
• 6x30 finderscope with cross-hairs
• Focuser has "dual action": Rack-and-pinion and "pirate scope" sliding drawtube
• Almost everything is made from metal

The scope seems to be very similar to what has been (during the same time) sold under the Tasco Meade brandname in the USA. As far as I can see it is very similar to the Meade model 291 refractor. As far as I can see the 291 were made by Towa as well, though I could be mistaken. The silver series was supposedly the "slightly better" one from Bresser back then.

The scope came with the OTA, an EQ-2 mount without tripod legs, one prism diagonal, one "Porro" erecting prism for terrestrial use, a 6x30 finderscope with bracket and all of the little screws and most of the caps (plus the packaging from a similar "Apollo" telescope). What was not included were eyepieces, nor were there any tripod-legs, the eyepiece tray or light for the tray (but the tripod legs from my EQ-1 fitted somewhat, so I borrowed them). Missing as well was the counterweight-rod and control cables for the EQ-2 mount (again, borrowed from my EQ-1), as well as one nut for closing the OTA-bracket.

Both the scope and the mount seemed like they have been seldom (if ever) used, though there was some wear on the finderscope and the prism diagonal. There is even still the protective foil on a scale of the mount and on the knobs of the focuser!

Granted, the aperture is small, but the focal length is long, so I should be able to try higher magnifications for planetary viewing on Saturn or Jupiter with my still limited selection of eyepieces.

And of course, when one buys a scope, the weather turns bad. So I made only some preliminary tests. The chromatic aberration seems very small, as should be expected from a f/15 focal ratio. During the daytime I could increase the magnification so far (with my cheap 3x Barlow) that I started to see dust on my Ortho10mm, and started to see some floaters and other crud in my eyes with my H6mm.

Some of the things I noticed:

• OTA outer diameter is 63mm
• The counterweight-rod for EQ-2 mount has probably an UNC 1/2"-13 thread, (unlike the M12 thread on my EQ-1)
• The counterweight-bar of the EQ-2 rotates with the scope (unlike the EQ-1)
• The tension of the "pirate scope" focuser is maintained by cardboard – obviously this cardboard has deteriorated over the years, and the focuser has lost tension. So I needed to take the focuser apart, put one carefully placed piece of electrical tape on the cardboard (not on the circumflex, but along the length of the cardboard) and reassemble it all. Now it is a bit too firm, but that is OK.
  [Update] I had to completely remove the cardboard from the drawtube, it was getting loose again and adding tape made it worse. I put three strips of "textile" tape in there, padded it with several layers of electric tape and topped it of with thin "aluminium tape" – now it seems good. And what's more, it is easy to add tension by adding layers of aluminium tape. [/Update]
• Little pieces of the cardboard (from inside the focuser) had found its way on the rear surface of the lens. And there were some defects in coating of the rear surface, probably caused by the rotting cardboard pieces. But after removing the dirt, the damage seems benign.    
• The finderscope seems OK.
• The finderscope's bracket is of "single ring" type, with three set-screws – and adjusting it is impossible without modification, as the end (opposite of the set-screws) is too wide for the finderscope. After I put a layer of electrical tape around the finderscope (opposite the set-screws) I could adjust the finderscope reasonably well (and when tightened down all screws a bit, the finderscope seems to stay in alignment – everything is metal, after all).
• The 60/900 is much lighter than my 76/700 Newton – the one counterweight I have (which is just about enough for the Newton) is too much for the 60/900!
• The OTA and focuser seem to be properly baffled. The baffles inside the focuser's drawtube are small, however both a rough estimate and a visual inspection confirm that the baffles are very well placed. (Only minor point is that both baffles inside the drawtube are not painted black, but instead have their "natural" metal brass?/galvanized? finish)
• [Update] The focuser had some shifting, and I when I dismantled it to remove the cardboard, I removed the single piece of textile tape that was put there in the focuser – focuser shifting is awful at an telescope and most of the time it would be completely avoidable during production with some simple measures. But one can make a simple DIY solution: Instead of the single piece of tape, I put two "rails" from flocking material in the focuser (as I did in the 70/300). That greatly reduced focuser shifting, but there is still some. I will have to improve the "rails" at least once more, but I'm confident that I can remove the shifting almost completed within two iterations. [/Update]

I'm going to play around with a bit, and ask a friend to make me make myself some simple wooden tripod-legs for it. And then I need to get another counterweight rod and something as counterweight.

It seems like a nice scope.

[Update 2013-08-14]
Today I tried solar projection using an Carl Zeiss Jena microscope-eyepiece (Huygens 35.7mm) and I must say this scope (with its small aperture, long focal ratio and metal baffles) is well suited for observation of sunspots. As long as we still have observable sunspots, that is.

An image made today (14th August 2013) by the SDO solar space observatory captured in the 4500Å continuum. The image shows the two medium sized sunspot groups (or rather several groups), which I could spot as well with my 60mm/900mm refractor by using eyepiece projection.

Cheap Astronomy – A Quick Look At The Bresser 76 / 350 Table-Top Dobson

A supermarket chain here has been selling off the "Bresser 76 mm (3 inch) f=350mm table-top Dobson telescope" at a very very low price. So naturally some of those sold wound up at eBay, with an surcharge (naturally), and naturally I had to buy one. (Had I known of this offer by the supermarket chain in the first place, I would have obviously bought directly there, saving myself a bit of money – but I digress, back to Cheap Astronomy).

The scope has arrived this morning, so I hadn't had a chance to test it on the night sky. I however played around a bit with it, and I thought I write down what I learned so far (and as I doubt I have the energy at the moment to do a proper review of it anyway). [Update] And of course the weather turned bad the afternoon… [/Update]

What's in the box:

• The table-top Dobsonian telescope (Art. No. 88-43201)
• Nominal aperture is 76 mm (3 inch)
• Nominal focal length is 350 mm (13.8 inch)
• The nominal focal ratio is f/4.6
• An H20mm Huygens(?) eyepiece (1.25 inch), giving a nominal 17.5x magnification
• An SR6mm Ramsden eyepiece (1.25 inch), giving 58x magnification
• An 2x "shorty" Barlow (1.25 inch), increasing the nominal magnification to 35x and 117x respectively
• And blue "Moon filter"
• Caps for focuser and Barlow, canisters for the eyepieces
• An planisphere
• An CD with the Stellarium software
• Some documentation
• A finderscope is not included

The telescope (and mount) features:

• An 1.25 inch focuser 
• A single-arm secondary mirror support
• The OTA has an outer diameter of about 95mm (the end caps are about 1mm larger in diameter)
• Two setting circles, one for azimuth and one for altitude
• The tension of the altitude axis can be adjusted with a large knob
• An wobbly compass in the base

A quick estimate regarding the secondary and effective aperture:
The secondary mirror has about 19mm diameter (small axis, +/- 1mm) and is about 235 mm (+/- 10mm) away from the main mirror.

If I did not make an mistake:
To illuminate an 20mm diameter field at the eyepiece, the secondary diameter would have to be about 40mm – for 5mm this comes out to about 29mm diameter. With an 19mm secondary, the on-axis aperture becomes around 60mm.

Taking into account the (arguably small) obstruction of the secondary with sqrt(60*60 - 19*19) sqrt(30*30-14.5*14.5)*2, we end up with about 57mm (2.25 inch) effective aperture. (For comparison a 29mm secondary would yield an effective aperture of about 70mm)

Blunders, big and small:

• The main mirror is probably spherical (will see how the stars look)
• The main mirror is not adjustable (adjustment on mine seems fine though)
• The secondary is (probably) too small
• [Update] After a short visual inspection I can confirm that the secondary is definitely too small.
• [Update] Furthermore the position of the secondary is not centred when viewed from the focuser (the secondary is moved too much towards the front). The collimation screws of the secondary are too short and make achieving a proper collimate impossible! One has to replace the screws with longer versions!
• [Update 2013-10-06] I replaced the secondary's screws with a bit longer versions – now I could put the secondary were it belongs. (And I need to buy some long M3 screws.) I collimated the secondary (no Cheshire, no laser) and I hope it should now be better – a daytime test was promising. Before collimation the image from the Pleiades was a bit disappointing compared with my 70/300 refractor – let's see what it does the next time at the nightsky after collimation.
• [Update 2013-10-07] With longer screws and after collimation the scope is much improved. Looking at the Pleiades the view is almost like that from my 70/300 refractor – the Pleiades were not a pretty sight before collimation in the little Dobson. Maybe with proper collimation tools (Cheshire and Laser) I could improve it a bit more beyond that – but this has to do.
• The focuser shifts quite a bit. 
• The eyepieces are not parfocal (which is aggravated by the focuser shifting)
• Using the eyepieces with/without the Barlow is not parfocal (again bad due to focuser shifting)
• The altitude setting circle has some +/- 5 degrees play with respect to the telescopes altitude (with 0 degree deviation from true altitude being on the end of the play!)
• The altitude setting circle furthermore is black on silver
• The altitude tension is very difficult to adjust
• The azimuth tension seems a bit to light (and is not easily adjustable)
• Already during the daytime the planisphere is impossible to read!!! Seriously, WTF???
• The mate black paint in the OTA is not fully dark. It seems however to be somewhat OK (and I refuse to flock anyway).
• There are no provisions to add an finder 

Other

• The H20mm eyepiece has its field stop before the field lens – this indicates that it is in fact not a Huygens type eyepiece. (The optics looks the same as those from the H20mm eyepiece supplied with my 70/300). Whether this eyepiece is a Ramsden or a Kellner eyepiece, I don't know.

What's nice:

• The focuser has enough travel (especially compared to my 76/700 Newton)
• The focuser position is located at an angle (some people like that, some people hate that…)
  
• The focuser retention ring can be (with some fiddling) exchanged with my 70/300 refractor, making it possible for me to use both 0.965" and 1.25" eyepieces – though this fiddling will be a bit hard under night-time observation conditions…
• The telescope vibrates when touched, but being so lightweight the vibrations die down completely within an second (give or take).
• The setting circles, are both quite large – during the daytime they helped me measuring out the local horizon at one observation site. Whether they are helpful during the night is doubtful though.
• The azimuth setting circle is printed white on black, which is good (though the font and scale used is a bit "thin", which is bad).
• The compass looks like a toy (and behaves like a toy compass), but it is a nice touch.

tl;dr

• Focuser shifting is awful. Fixing the shifting is difficult, as the space between drawtube and focuser is small – the "two rail" solution I employed at my 70/300 refractor is not easily possible here…
• The secondary mirror is too small (which is probably for the better, considering the probably spherical main mirror): The effective aperture is probably about 57mm (2.25 inch) according to my calculation (which might be wrong)
• The actual focal ratio therefore is probably closer to f/6.1
• But other than focuser shifting, the telescope seems usable to play around – though I have not tested it properly yet.

[Update 2013-08-17]
I shortly tested it on the Moon tonight. The phase was 45° (waxing gibbous) and the Moon was already very bright. I forgot to bring the "Moon filter" with me (nor any of the other filters I have) which was a big oversight – after the session my observation eye was in photopic vision. o.O

Both the H20mm (which is really a Ramsden or Kellner) and the SR6mm performed admirably when observing the Moon in this table-top Dobson. I brought my other 1.25" eyepieces with me (an PL10mm, an SPL12.5mm and an SPL25mm among others) and they too provided very nice views of the Moon.

I then tried the supplied 2x Barlow and the result was quite a bit visible "false color", blue and orange/purple fringes – regardless of which eyepiece. Furthermore the field seemed a bit tilted, which made focusing the entire field not really possible, plus the color seemed not the same on all edges. Possibly the Barlow's lens is tilted. So at least in this fast scope such an cheap supplied Barlow is not a good choice. However with an good Barlow on the Moon this scope should be able to provide more than 120x, or so I would guess. I have ordered (hopefully better) Barlows and I will see how they do in this scope.

This observation of the Moon was followed by a serendipitous naked eye observation of an ISS pass (As Tony Darnell says: "Keep looking up!"). It was quite a sight! But the ISS's magnitude of -3.2 was, with an waxing Moon, "only" comparable to one magnitude less without the Moon in the sky… Still, it was very nice.
[/Update 2013-08-17]

[Update 2013-08-20]
I took a good look at the Barlow and found that the retaining ring (coarse plastic thread) was threaded in tilted. I removed the retaining ring, removed the white goo from the lens (what seems to be a singlet(!) lens, but at least a glass lens), blackened the edge of the lens and put it all carefully together again. Then I made another threaded hole for the retaining screw, as the original was slightly angled in such a way that it pushed out an eyepiece if you tightened it down.

Then tonight I made a short test at the Moon. This time I had my filters with me. I tried them all. The supplied blue "Moon Filter" has a nice color, but is not nearly dark enough. Of all my other filters only the "B+W #103 8x" (optical density 0.9, adds 3 stops) brought down the light level enough, and just barely at that. A combination of filters would have been interesting, but the reflections on two adjacent filters meant a stark degradation of the image – so only the ND filter.

First of all: the "strange color" which I saw is only visible in the supplied H20mm – whatever it is, it seems to be a problem of the eyepiece design. Otherwise the H20mm eyepiece seems sharp. Will see how it does with longer a focal length telescope.

I again tried the Barlow with my H20mm, PL10mm and SR6mm eyepieces (as the other eyepieces have no threads for filters). It was not possible to focus the combination of SR6mm and 2x Barlow – there were always weird halos and everything was washy. Both the PL10mm and the H20mm gave an somewhat sharp image, but it was discernibly worse than without Barlow – not but a large margin, but noticeably.

So as expected the Barlow is not something one should pay money for.

And while the focuser shifting is somewhat reduced with the "two rail" measure I took, it is still awful.
[/Update 2013-08-20]

[Update 2013-08-24]
After fixing one last problem, I can say that the Barlow is not so bad after all!

I found one more spot in the Barlow were there was a black shiny plastic surface causing an internal reflection: The inside of the lens' retaining ring! Small, but vicious. After I put a little strip of black flocking material on the inside of the retain ring I was rewarded with an hugely improved contrast! All my eyepieces now produce a (almost) sharp image. It is not "tack sharp", but it is not so bad compared with my other (more expensive, and better) Barlows.

It is of critical importance to track down and remove all sources of internal reflections! This is especially important in fast scopes, as their divergent light path is much more susceptible to cause internal reflections.
[/Update 2013-08-24]