Venus not Jupiter

Posted by XTSee on 2nd January , 2009

Tonight on my evening walk with the dog, I took out a small pair of binos I recently bought from our local Aldi store in their basement bargains section for just 6 pounds! Not that I expected much from these 12×32 binoculars. They look ok, but are pretty basic and a bit tinny to feel, and the rubber eyecups have bent whilst in the box and won’t go back to their proper shape. Never mind, they are light and easy to use on a casual walk, and this is the first time I have seen any stars for about 3 weeks now, due to constant cloud cover here in Lincolnshire. I had hoped that over the Christmas break I might have been able to do some viewing :( .

So this evening the clouds parted for about 2 hours, but since we were going out with friends for a meal, there wasn’t enough time to get the XT10 out, so instead I setup my 20×80’s when I returned from my walk. Primarily this was because Jupiter seemed exceptionally bright, and a short distance from a quarter Moon, and I wondered what I might be able to make out of the planet.

Well, I wonder how many other folk make this mistake? A quick check on Stellarium showed it to be Venus, not Jupiter, and I also noticed that both Uranus and Neptune should be visible in the same region of sky. I made some comparisons with the Stellarium display, and was pleased to confirm that I was able to see not only Venus, but also quite clearly Uranus, and although considerably dimmer Neptune could just be seen.

My Adler Optik Jupiter 20×80 Giant Observation Binoculars really do provide excellent viewing.

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Star Testing the Orion Skyquest XT10i

Posted by XTSee on 12th December , 2008

Tonight I had a go at star testing my XT10i telescope to check the collimation and optics.

There was a full moon tonight, transparency was not particularly good and only the brighter stars were properly visible, so there wasn’t much point in trying to see much else, and instead I figured better use of my time would be familiarising myself with how to do a star test and see what it looks like. I have tried in the past but think I just didn’t understand what I was supposed to be looking for. This was prompted by an article in November issue of Sky at Night, which included some good photos of what to expect.

I also wanted to see if I could get it captured on webcam to show on my website some footage of what is seen while focusing inside and outside of focus. Unfortunately the view was not bright enough to show clearly what I was seeing, so I gave up on that.

The S@N article suggests that the eyepiece should give a magnification of 1.6x the aperture of your telescope. For my XT10i this is 254mm (10 inches) x 1.6 = 406x. So divide the focal length of my XT10i which is 1200mm by 406 = 2.95mm eyepiece. I don’t have an eyepiece this small, so I needed to use my 2xBarlow lens to help double the magnification of my Hyperion eyepiece. This Hyperion EP has fine tuning rings which increase the mag, and with both added they increase the 13mm to be 8.1mm, then with the Barlow it effectively becomes 4.05mm (296x), which is the closest I can get to 2.95mm.

With a dobsonian mount, and no motorised tracking, you must select a star which won’t move much, and the obvious choice is Polaris in Canis Minor. However, I found that with this much magnification the pole star, which was already quite faint tonight, was made even dimmer, and it helps to have a fairly bright star when star testing. Also the high magnification made lining up on the star a bit troublesome.

After a while, as an experiment, I replaced the Hyperion with my 10mm Plossl + the Barlow and found that this gave a perfectly adequate view of the star when defocused. It was a bit brighter, and easier to centre in the view too.

Tube air currents were a right pain in the ass, making the unfocused star image shift constantly, and so at first making it very difficult to see the star test properly. So I got a desktop fan and set that up at the base of the telescope tube blowing the cold night air into the bottom of the tube in an effort to cool the tube better (although I do have a small computer fan mounted to the underside of the primary mirror cell, this cools the mirror, but doesn’t move air in the tube very well). The faster air current helped break up and move the slowly shifting thermal distortions, and also cooled the primary mirror much faster.

After a while the tube currents were broken up sufficiently, and the mirror must have cooled a good deal more, because I started to identify the concentric rings that are the key indicator used in a star test for the state of the optics.

After comparing the concentric rings both inside and outside focus, I was pleased to discover the collimation of my scope was pretty well spot on. I found the trick to being able to see the concentric rings was not to defocus too far, and to try to ignore and “see through” any thermal distortions which cause “bleeding”, a kind of flickering flame effect that spreads out from the central part of the defocused star image. I found that the rings were quite hard to see at first, but I think this may have been due to Polaris being so dim tonight.

Maybe better results next time, but at least I know now what constitutes a star test. Anyway I finished off by spending some time viewing the Moon.

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M42 Orion Nebula with XT10i Dobsonian

Posted by XTSee on 4th December , 2008

Hey hey! I’m pleased as punch. I’ve taken a picture of M42 The Great Orion Nebula showing the Trapezium stars using my Orion Skyquest XT10i telescope.

“Yeah, so what, loads of people take photos of the Orion Nebula with their scopes”, you say.

Aha, but how many people attempt it with a Dobsonian mounted scope WITHOUT motorised tracking?

Yep - No EQ tracking.

Just aligned by hand, and photographed using a humble webcam.

Well here it is, and you can read how I did it on my website page:-

M42 Orion Nebula and Trapezium taken with Orion XT10i dobsonian mounted telescope

M42 Great Orion Nebula taken with XT10i

M42 Great Orion Nebula taken with XT10i

There are more pics on the article page, and details of how I used K3CCDTools and Photoshop to enhance the basic movie footage I took of the nebula. There’s plenty of room for improvement, but I reckon its a pretty good first attempt.

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Review of Orion Dual-Speed Low-Profile Crayford Focuser + AccuFocus

Posted by XTSee on 16th November , 2008

I have now finished my latest review article about the Orion Dual-Speed Low-Profile Crayford Focuser that I got for my XT10i telescope recently. At the same time I also got the Orion AccuFocus Motorised Focuser to provide vibration-free fine focusing of my telescope. Both these are detailed in the XT10 Telescope Modifications section of my web site.

Orion Dual-Speed Low-Profile Crayford Focuser plus AccuFocus Motorised Focuser

Orion Dual-Speed Low-Profile Crayford Focuser plus AccuFocus Motorised Focuser

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Primary Mirror Collimation / Barlowed Laser Method

Posted by XTSee on 9th November , 2008

I’ve just finished a new article on the main web site in the Collimation section describing How to collimate the Primary Mirror using the Barlowed Laser Technique. Of course this requires a Barlow Lens and a Laser Collimator for this method to be used, but the page also provides links to some excellent resources detailing collimation methods.

Barlowed Laser method of collimation

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Crazy Binocular Viewing Chairs

Posted by XTSee on 29th October , 2008

You may have read one of my recent posts reviewing the Adler Optik Jupiter 20×80 Giant Observation Binoculars.

With binoculars of this size, they are quite heavy and suitable methods of supporting them is a must. Not only will your arms buckle under the weight after a while, but they just cannot hold the binos steady enough, and stars will just be a constant blurry motion.

While a good sturdy Tripod is the simplest method, why not consider one of the following alternatives, from the sublime to the ridiculous!

All of these are homemade chairs, and a couple of these sites will supply the chairs as kits for purchase.

Thanks goes to Walt Reil at Central Coast Astronomical Society for the above fascinating links. You can see more pictures of Tom Frey’s EZ Gazer Astro Lounger Chair in use at this CCAS Star Parties page.

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California Nebula and the return of Orion

Posted by XTSee on 25th October , 2008

With clear skies gradually returning now that the colder evenings of autumn are upon us I have been enjoying the views of the heavens while walking my trusty dog Ben on the public footpath in fields at the back of our house. For stargazing I suppose I’m lucky that I can be out in the complete darkness of the fields in just 2 minutes. While he chases out rabbits I crane my neck upwards to look at the Milky Way, and Ben wonders why I’m walking so slowly, then impatiently stops and runs back as if to say “What have you found?“.

It is now nearly a full year since I first got my Orion Skyquest XT10i newtonian reflector and I have learnt a good deal about astronomy, and come to appreciate the splendour of the universe even more. A year ago I had not really “seen” the Milky Way properly. Of course I knew it was there, but I suppose I never really understood which constellations it passes through, and generally mistook what I was seeing for very light haze or cloud. Now when the sky is clear and bright enough I can easily make out its shape as it passes overhead through Cygnus and Cassiopeia. I think its fascinating that we are inside this galaxy looking outwards through its spiralling arms into deep space, and that there are so many millions of stars in our own galaxy, that they just look like a misty haze!

Last night while looking through the telescope my wife came out to me and for just the second time since getting my scope she looked through it and was amazed at the beauty of the Pleiades and then the double-cluster between Perseus and Cassiopeia, saying “My god, there’s thousands of stars!“, two sights I knew would be dead quick to locate and show her before she got too cold or bored. She seemed truly astounded.

My mission last night was to try and see the California Nebula, recommended in the October edition of Sky at Night magazine. Big, red and shaped like a foot, NGC1499 next to Xi Persei and 12 degrees north of the Pleiades is named after the USA state it is supposed to look like. Apparently from a dark site it is possible to see this quite large nebula (think 3 Moons long) as a misty patch with your eyes, and with binoculars, or with a low-power eyepiece in the telescope (use low-power otherwise you’ll be looking straight through it, rather than at it). Well try as I might I just could not see it. My eyes were quite well dark adapted, and I tried to see California with my 20×80 binos and with my 38mm SWA eyepiece, and even using my recently purchased Baader UHC-S Filter with my Hyperion 13mm and 25mm Plossl. I tried for a good half-hour to make out what I thought should be a fairly obvious night-time feature, but to no avail. In comparison I was pleased to be able to make out M37 tonight, the dimmest of the clusters in Auriga, and one I was unable to see on a previous occasion when there was a full Moon. Oh well, you win some, you lose some! I suppose my backyard is simply not dark enough?

Have you been able to see the California Nebula? - Did you find it difficult?

To make up for the disappointment of not seeing NGC1499, I focused on the Andromeda galaxy, and took in its huge size, and pondered on the possibility of a little planet somewhere in the Andromeda galaxy with some guy looking up and out towards their nearest neighbour called The Milky Way. A theoretical “dopple-ganger”!

At about 1.00am I noticed that Orion was rising above the house behind ours, and I watched patiently for my first chance this autumn to view the great Orion Nebula. As it came into view and I focused carefully to get the best image I was transported back in time a year to the very first night, my “first light” when after I had finished building my scope I eagerly took it outside and lined it up on Orion.

Welcome back Orion.

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How to flock a Newtonian reflector telescope

Posted by XTSee on 20th October , 2008

Darkness is what matters in Astronomy. Stars shining brightly, painted on the black canvas of space.

And there’s nothing spoils the view more than having a grey or washed out view through your telescope.

One form of light pollution is of course the overhead washing out of the sky due to street lights en-masse shining up into the atmosphere, which is then reflected back down to earth by water-vapour in the air. Filters are used to help astronomers with this kind of light pollution, and when it is impractical to visit a location that is away from the source of the lights. When the full Moon shines high in the sky, you instead choose brighter objects to observe, such as the planets and more dominant stars and constellations. Of course you can take time instead to appreciate the beauty of the Moon herself.

The other form of light pollution that causes bad contrast in telescopes which we do have a little more control over, is stray, unwanted light coming into the end of the telescope at an angle from nearby domestic lighting; be that from streetlights, decorative garden or patio lighting, house lights, the next door neighbours pesky football pitch floodlight, or the gentler but still invasive light from the Moon.

Well at least the Moon has every right to be there.

You can close curtains or turn off un-necessary house lights, garden lights, and have a friendly word with the neighbour. You can even write to the local council to see if they will do something about the nearest streetlamps. Or you can purchase a “dark-cap” or “dew-cap” to wrap around the end of the telescope to help prevent strong side-lighting. I often use a large patio-table umbrella opened up and laid on its side to shield me from a particularly annoying streetlight.

The main issue here is that the interior surface of the telescope tube, even when painted matt black by the manufacturer, still has a degree of reflectivity that causes the light to scatter and bounce its way down the tube, and into the eyepiece, where it adds a subtle lightening of the background, and this reduces the resolution and contrast, and therefore the enjoyment of observing stars, and can make viewing deep-sky objects far more difficult.

A very effective and permanent solution to employ with open tube telescopes such as Newtonians, is the addition of materials with low light reflectivity to the inside surface of the telescope tube, and this procedure is known as “flocking”.

Read my latest article on How to flock the interior of the Orion Skyquest XT10 newtonian reflector OTA tube.

In this article I describe how to add black flocking material (ProtoStar Hi-Tack Flocking Sheets) to the interior of my Orion XT10 newtonian reflector telescope tube to increase the contrast when observing the night sky.

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Webcam imaging: Jupiter/Moon and exploring Auriga

Posted by XTSee on 12th October , 2008

Tonights viewing was an attempt to obtain some better webcam footage of Jupiter. As usual though, it was very low in the sky, and I have only a short timeslot due to gaps between buildings. In fact I stood the XT10 on top of my patio dining table to give it sufficient height to see over the garage rooftop. Aligning the scope when standing precariously balanced on the chairs and/or table is not very good, and it took ages to get everything set up well enough to start capturing Jupiter.

Managed to get some short captures using K3CCDTools at prime focus, and reasonably sharp focus thanks to the new dual-speed crayford, but when attempting to get Barlowed capture it was incredibly blurry from bad seeing, and with probably only 15 minutes til Jupiter set below the rooftops. I will see whether K3CCD or Registax can pull anything better from these captures.

Next took some new Webcam footage of the Moon, something I have not done for quite a while. Moon is 1 day from full, and very bright tonight in an almost cloudless sky. Seeing is giving the classic underwater effect on the Moon’s surface. This time I have not used the moon filter, but instead adjusted the gain right down, and FPS up, so as to give a nicely dim image, with plenty of detail, and as well-focused as I could. Again the dual-speed Crayford is doing a fantastic job of focusing very finely. Got several passes captured to video which can be worked in Registax later on.

Did some extensive experimentation of video capture settings with the webcam to see what magnitude of stars the webcam could pull out. Some of the primary stars in Cassiopeia and Auriga were nice and bright with diffraction spikes clearly visible on the bright stars, and still picking up fainter stars probably down to approx 8th or 9th Mag. For the faintest 5fps was required with absolutely minimum (slowest) shutter speed, and almost max gain, max contrast, and centre brightness. Monochrome image, and picture enhancement off. The Pleiades was also a good test, clearly able to capture the brighter stars, although I’m beginning to realise that the field of view of the webcam is rather restricted, and capturing the whole of the Pleiades is impossible, it only manages to get 2 or 3 of the seven sisters at once. So while this might be hopeful for getting images of bright starfields, it seems like I now need a new lens for the webcam to give a wider field of view.

Finished experimenting with the webcam and decided to just do some normal observing. Tonight the sky is very washed out by the almost full Moon, so it was interesting to see how deeply I would be able to see using the SWA 38mm, and Hyperion 13mm EP’s, in Perseus, around Mirphak. Comparing against Stellarium I could make out down to about 11th mag, which I thought was quite good, and once again proves not only how good the XT10 is at bagging as much light as possible, but also that first impressions of a poor night sky are usually proved wrong, and that it is worthwhile getting the scope out. In Auriga I hunted out M36 and M38 successfully, but was unable to view M37, which the Moon was overpowering, and my star-hoppping was unable to locate.

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Mod: Counter-balance weights / Dual-speed Crayford Focuser

Posted by XTSee on 6th October , 2008

Two things of note in this post, both of which are related to Skyquest XT modifications - well one is specifically for Orion Skyquest XT scopes, while the other could be of use for most solid tube-type dobsonian mounted telescopes.

  1. I’ve added a new page to the mods section detailing the creation of cheap, simple, easy-to-make weights that can be used to counter-balance the telescope altitude adjustment. In fact I made these counter-balance weights quite a long time ago, but didn’t really consider them particularly exciting! However I read a forum post the other day where folk were asking how other people achieved balance for their Dobsonian mounted tube telescopes. The page is: How to make counter-balance weights for a dobsonian telescope.
  2. Just last week I received my latest purchase; a Low-Profile Dual-Speed Crayford Focuser from Orion USA, (see here) complete with an AccuFocus Electronic Focuser also from Orion. These are very nice well-engineered pieces of kit, which I have just finished installing to my Orion XT10i. I’ve taken tons of pics of these two items, and very soon I will create another page for my Mods section reviewing them, comparing the old and new Crayfords and showing the installation of a) the new Crayford focuser, and b) the AccuFocus electronic motorised focuser onto i) the old single-speed crayford focuser, and of course, ii) the new dual-speed crayford. In fact the AccuFocus can also be installed on older rack-and-pinion style focusers.

A quick try-out last night with the XT10i and everything installed, provided excellent pin-point fine-adjustment of focus, without any jarring/vibrating of the scope as is usually the case when focusing by hand.

So keep an eye out for this if you’re interesting. I’ll announce it here in my blog.

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