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Showing content with the highest reputation since 21/07/18 in Blog Entries

  1. 8 points
    Hi all Been a while since my last entry, so thought it about time to log another! Things are getting a lot busier at work. My area has changed, and I have now taken on Norfolk, along with Bristol and South Wales. I am a Regional Systems Manager for Greene King Pub Co. and look after all the sites IT and till equipment. So, more sites means more meetings and more miles, but I love it - getting out and about, and seeing areas of the country I haven't been too before. The other day I had to drive from Shrewsbury to Sheffield, and the SatNav took me over the Moors near Manchester, and the High Peaks near Buxton. It was a lovely drive!! As a result of the above, my leisure time has taken a bit of a hit, but I have still managed to get out with my Telescope on quite a few occasions, albeit from the back garden. When the weather has cooperated anyway! I will do a more detailed write up later, but I have made good in roads on my Lunar 100 challenge, and also made good progress in re-learning the sky. All being well, I will be heading up to the area around Ashbourne / Ilam in a few weeks. I have a friend living out in the sticks, and he has graciously let me use his back garden. Its proper dark there - compare to my garden anyway, so that’s something to look forward too. I have also taken my first, probably ill-advised step, into AP!!!!! I went out last night and took some pics of the full moon. I used my 25mm eyepiece, and hand held my iPhone up to it. I wasn't expecting anything amazing, but was fairly pleased with the results: Not completely in focus, but as I said, it was all hand held! Makes me think if I can mount the phone in some way, I could get some sharper shots. I have also found an old webcam - I have butchered it, and made some adaptions to allow it to attach to the focuser. I gave downloaded various software to hopefully allow me to get some video of the moon for stacking purposes. Not tried it yet, as I need to get a longer extension lead for the laptop. But I think it should work ok. I will do a full post on it once it has been for its first test drive!! Clear Skies!! Nige
  2. 6 points
    It finally happened – after waiting two weeks and a day, the clouds parted, and I was greeted with a clear, still and cloudless sky!! Whoop Whoop!! 15 days is a long time to wait! The scope (SW Explorer 150-PL) had been sitting in my dining room since Christmas, and despite a very short outing last week, that lasted about 10 minutes, last night was the first time I used her properly. I popped the tube outside a good hour before I intended to go out to observe, giving it plenty of time to cool down. I then put the mount together – I did this inside, so I could see what I was doing! Once it was all secure and bolted together, I set the declination (?) to 53 degrees and took the whole thing outside through my patio doors. Before I popped the scope on the mount, I did a basic polar alignment. I was chuffed – I had the declination spot on, and just need a tweek to the left and it was there – not perfect, but enough for my first observing session. I then put the OTA onto the mount and secured it. I had been playing around with it in the house the previous week, and had found the balance point, and marked the dovetail bar, clever eh?! I then moved the counter weights about to get that balanced as well – it all worked out fine, and the lightest touch when the clutches were off was enough to move the scope about. I fitted the finder scope and got it aligned with tube – I did find this a bit tricky to start with, and a couple of times during the evening I managed to knock it out of true with my arm / head / face!! And I was now ready to go! My observing location is pretty limited at home – the front / side of the house is now flooded with light from an LED street lamp – the red circles show the street lamps, and the red cross is where I set up the scope. I had good views to the North and to the West though: I'm not shy to say that my knowledge of where things are in the night sky is limited!! This will change as the year progresses, so i content myself to first locate M31. I found this quite tricky - the finder scope is a straight through job, and the angles can sometimes make looking through it a challenge. So I bought out the 20 x 80's and quickly found it. I then pointed the scope in the same direction, and a few twists of the slo-mo controls and there it was. I had the 25mm eyepiece in and I realise that the target was waaaay bigger than the view through the eyepiece!! However, the core was revealed. I looked for quite some time, and small details began to come out and I'm sure I saw the darker dust lanes. I then took a look for the Double Cluster, and wow!!! What seemed to be hundreds of stars, packed into the view! I was getting happier by the minute! I content myself to just scan the star fields in that area for a while, and then swung around to try and and find M51. Using the 20x80 technique I found it, and turned the scope to it. It was a faint fuzzy at 48x, so I upped the mag to 120x with the 10mm eyepiece - it became a larger fuzzy object, and I couldn't really see any structure, but knowing the light coming into my eye had covered 20 million light years was awesome! It was getting late, so I took off the tube and carried it round to the garden with the street light over it - I wanted to look at M42 before I packed up. However, the glare from the street light overpowered the finder and I couldn't see anything. Tried to shield it with my hand, and although it stopped the glare, it was all a bit washed out. Shame - perhaps an air rifle would be a good investment . . . . . !! So, overall I thoroughly enjoyed my first night out with the 150PL. A few early observations on the scope and mount (this blog will be like a long term review for the scope): The OTA with tube rings and dovetail bar weighs in at 6.4kg / 14lb, according to my scales. This is right at the limit for the NEQ3-2 mount. Added to the weight, the tube is long at and although I got the balance spot on, it took several seconds for the vibrations to die down following focusing. However, using the slo-mo controls didn't induce any noticeable shaking when tracking objects, so thats a bonus! I think a heavier mount will be needed at some point. I hope to try and save for the HEQ5, but with daughter going off to uni in September that may be a while down the road!! The eyepieces and barlow that came with the scope appear to be fairly solid - I only really used the 25mm, and I have nothing to compare them too, but the view seemed bright and sharpe. The finder scope is a generic 6 x 30mm. While the view is crisp, trying to look through it gave me a cricked neck after a while!! A 90 degree finder will defo be required The dovetail bar is a lovely green colour, but does appear to be quite soft - just mounting the scope the few times I have used it as already left some marks and dints in it. The focuser is fine for my use - not stiff at all, and with enough friction to make small adjustments easy. I see no need to upgrade this yet. So - lets hope the weather stays clear, as I am keen to turn the scope on to the Moon!! Thanks for reading, and a Happy New Year to all!! Cheers Nige in Derby
  3. 4 points
    Perhaps the open outlook to the east Ensures the leaded panes catch every ray And part explains why on the dullest day My eye is drawn up to the colour feast, After a rubbish couple of months, finally a holiday........a week in the Yorkshire Dales, only a 7.5 hour drive from Kernow but worth it! A little cottage east of Hawes, nothing but sheep and pheasants and yes dark skies. Great food in small pubs with the friendly locals, Abbey ruins visited and gloriously recommended to sooth the soul and switch off the rat race (Easby Abbey nr. Richmond, Jarvaulx Abbey nr. Ripon), honestly THE best chips from The Chippie in Hawes and of course beautiful scenery! With not much room in the car (have to take the family not just the scopes?) I only packed the Heritage 100P and my BST eyepieces, opposite to my home viewing where I can only see the southern sky, here it was the West and North, typically for me the cottage had the only street light for at least 100 miles to the south.....still new things to spend time on........ So two clear nights.....once I got over the nervousness of total dark away from civilisation and wild animal noises I've never heard before....out with the little dob Auriga....the 3 open clusters, M36/37/38, even with a waxing moon, still was able to pull these out, have to say that the 12mm BST is turning out to be a particular favourite, reckon I could make out about a dozen of the brightest stars in the pinwheel cluster. Stars Capella and El Nath (start the Taurus debate here...) a lovely distraction....now if I hadn't taken the wife and son would I have seen the famous nebulae with my 8" Dob? On to Cassiopeia....and after the owl cluster.....and what a revelation. The first time viewing and frankly spent far too long staring at this beauty....actually think I could see it in my sleep that night! The whole constellation was a wonder confirming I need to be less lazy and get my scopes to local dark skies more often......just don't let work life get in the way Spent a fair bit of time viewing the moon, decent views with 5mm BST, and just staring up with my eyes at a dazzling dark sky full with stars. All in all a wonderful week, great days out, dark and clear skies at night, great food (and drink), if you get the chance, pack away some clean undies and a scope and head to the Yorkshire Dales (If you're interested...opening lines are from a poem called east window by Alan Hartley relating to a stained glass window in Leyburn)
  4. 2 points
    Measurement of Doubles and a Jovian Moon - Baader Micro Guide Introduction The reason for this rather long blog entry is to highlight what has been possible using simple and relatively inexpensive gear to measure the separation and position angle of a number of double stars and the sizes and distances of various objects within the Solar System. The preliminary goal was fivefold: to further skills in star-hopping and to gain a deeper understanding and appreciation of star magnitude. to garner some experience in measuring double stars as accurately as possible. to work out the sizes and distances of a number of night sky objects. to evaluate the capabilities of the 4” refractor. to pass on information that may be of interest or use to others. The Gear Mounted on an equatorial CG-5, I used a four-inch Tal 100rs f/10, a Celestron x2 Barlow and a Baader Micro Guide. This particular eyepiece is an Orthoscopic Abbe with a focal length of 12.5mm and equipped with a laser-etched reticle and screw on red-light variable illumination system. The multi-function astro-metric eyepiece provides sharp images across the field of view and has a twist up and down focuser which is not for eye-relief but to sharpen the finely etched designs for the observer. When focused at the centre, the edges of the scale do not blur and are crisp throughout but might be difficult to read on occasions due to the illumination system sometimes being uneven. There is no glare, stray light or internal reflection from the illuminator but on tighter doubles with a dimmer secondary component or on faint DSOs, for example, one finds they fade between subtle differences in reticle brightness. Lessening this brightness to capture the dimmer object sometimes makes it complicated to read the 360º protractor scale and I have found that the best remedy on such occasions is to dim in and out and use the eye’s memory to capture the reading. The sharply etched reticle scales include a 360° protractor at the edge of the field of view (4), a number of concentric guiding circles (3), a semicircle (2) and a linear scale across the centre (1). For general beginner’s use, the Micro Guide will be very useful to those who wish to work out seperations and angular distances of binary stars and sizes and distences of Solar phenomena, Lunar features, and other objects found within the Solar System and beyond. Focal Length In measuring a binary star’s separation in something as small as arcseconds, it is important to maximise that separation by using as much of the linear scale as possible. By using a barlow, one effectively increases the telescope’s focal length which in turn ensures not only a greater magnification but also a more accurate measurement along the 60 divisions etched onto the Micro Guide’s 6mm linear scale. This means that if separations or sizes are to be measured evermore accurately with only this eyepiece, different and greater focal lengths will eventually be required. Calibration Before being able to use the Micro Guide it is necessary to calibrate its linear scale, that is, to estimate the number of arcseconds in each division in accordance with the given telescope and if used, the given barlow. If ever the barlow or telescope is changed for another or not used, one must repeat calibration with the new set up. There are a number of ways of going about this and I include two methods, ignoring those given by the instruction manuel. The Split Method Find a known double star and note the number of divisions on the linear scale separating the primary from the secondary. If, for example, Albireo has a separation of 34.7” arcseconds and I see that this separation spans 4.6 divisions on the reticle’s scale, then I conclude that each division is 7.54” arcseconds in length. It is a good idea to measure the chosen double star 30º above the horizon to avoid overt atmospheric disturbance or refraction and to take a good number of measurements of that given star to find the mean average. For this method I chose similar partners in beauty but of various separations none of which were so tight that measurements would be rendered near guesses. StarRho ( ρ)Counted DivisionsScale ConstantAlbireo34.7"4.87.23"Almach9.7"1.37.46"η Cas12"1.77.06"ζ Lyrae43.7"5.97.8"Summing and finding the average I now had a workable scale constant of 7.38" which would remain valid so long as I used the same gear. The Drift Method Again, the drift method is to determine the scale constant – the number of arcseconds per division - but I feel gives a more detailed approach and one less reliant of guessing. However, with that said the final scale constant was very similar to the Split method. Turn off any mount drives and time the passage a given star makes along the length of the linear scale from zero to sixty. The star doesn not have to be a double but will need a stopwatch counting to the 100th of a second. It's a good idea to find a star above 30º declination and not too near the Cestial Pole. You turn the eyepiece until the star drifts exactly along or parallel to the linear scale and as it crosses the zero line start timing until it crosses the sixtieth division. You repeat this process about 20 to 30 times in total over a number of days. To ensure as much accuracy as possible try to measure three different stars over a week and with the various timings for each star, calculate their mean average. The Drift’s Scale Constant You’ll then need to convert these particular results into arcseconds with the following formula: S.C. = 15.0411 (T.avg) cos (dec) / D S.C. – Scale Constant. 15.0411 – Earth’s rotation rate per hour in degrees. T.avg – The given star’s mean average drift time. Cos (dec) – The cosine of the star’s declination / - Divided by D – The number of division on the linear scale And that’s it. The resulting figure will be your scale constant and will remain valid so long as the optical gear you use remains the same. In my own case, I found that the average scale constant was again around 7.5” arcseconds per division. Putting Numbers into Practice Over the following days, I tried to measure a number of double stars in the constellation of Perseus. In particular, doubles that I had never worked with. I chose Eta Persei, Struve 331 and Epsilon Persei as guinea pigs for the experiment. I took a number of measurements for each star and again estimated their average separation. The following highlights the concluding results where Est Rho is my estimation and Rho is the official separation. StarEst Rho ( ρ)Rho ( ρ)Errorη Per28.5"28.3"0.7%Σ 33112.9"12.3"4.8%ε Per8.1"8.7"7.4%As can be seen the margin of percentage error is significant and there is room for improvement. Nevertheless, the results were all within 1” arcsecond of error which accords with the kind of results expected from the Micro Guide. Baader informs the reader that “...such measurements can be estimated to an accuracy of about...2” for a focal length of 2000mm.” Working Out Position Angle I found that working out how to take a binary’s position angle quite complicated but eventually the following procedure was taken. The binary is centred in the eyepiece and aligned in such a manner that both components drift through the bisected middle linear division marked 30 on the Micro Guide. The two stars are allowed to drift toward the etched 180º semi-circle and as the primary crosses the inner 360º protractor scale one reads the given angle. It’s a good idea to take a number of measurements, but better still, place those stars dead centre for a general reading error of about 1º to 2º degrees. Measuring Sizes and Distances To measure size (S), count the number of divisions the given object takes up on the linear scale (sc). Divide this number by your set up’s focal length (fl) which will give you a general image-size (i). Multiply this with the known distance to that object (d). S = d (sc / fl) For example, to work out an estimate of the size of Ganymede, I found that it measured no more than about 0.01mm or 0.02mm on the linear scale: a mere dot on the etched reticle. The mean average of this number was divided by my set up’s focal length, giving me the estimated image-size. Noting that Jupiter was about 4.8 AU from Earth (718,069,776km) and that Ganymede has a average distance of about 1,605,000km from Jupiter, I calculated that Ganymede was around 716,464,776km from Earth. This number was multiplied by the image-size giving me a rough size of Ganymede at around 5,373km in diameter. An error of about 2% or around a 100km out. To calculate distance (d), you divide your focal length (fl) by the image-size (i) and multiply this by the known size (s) of the object. d = s (fl / i) Ganymede’s distance from Earth, I knew its size was about 5,373km (really its 5,268km) and was measured on the scale at about 0.015mm. You then divide the focal length by that image-size and multiply by the size of the object. In my case, I found Ganymede’s distance from Earth was about 716,400,000km. Again, an error margin of around 2%. Conclusion The Baader Micro Guide does not come cheap. In Europe it sells for around €165. In the boxed package you receive instructions (often vague), a decent 12.5mm Abbe Orthoscopic eyepiece with the built in finely etched reticle and a battery operated screw-on illuminator. Most will probably think that such an item is an unnecessary expense to include in their eyepiece collection but to counter this argument there is something rewarding in the challenge of meticuously recording and calculating distances and angles and sizes and separations – even if the experience can sometimes be frustrating and that these numbers have already be worked out for you. I have found the Micro Guide to be a useful resource for not only testing patience and recording skills, or the acuity of vision but also an aid in astronomical study. Like sketching or logging, the astro-metric eyepiece helps increase observing skills for it forces you to take note rather than just casually glancing. Indirectly, it helps increase knowledge about the objects you are looking at, for it is necessary to research such variables as size, distance, separations and position angles and by researching these variables and actively working with them, overtime you are gradually able to estimate such things in the field. Finally, it also acts as an impetus to structure a part of your observing session. After a good month with the eyepiece, working with the Sun and objects of the Solar System, I also feel I have come to appreciate a lot more such diverse factors as the quality of my optics and observing site, the effects of atmospheric seeing, sky glow, astronomical and mathematical data, patience, fatigue, mental disposition, and so on. Such insights will not only deepen your understanding of stargazing but also in coming to understand a little more about yourself – which afterall, must be one of the most important goals set out for us.
  5. 1 point
    I'm hoping this is my final and hence "Ultimate" generation of all sky cameras. Based on the ASI185MC CMOS astro camera and Fujinon fish-eye lens of 1.4mm focal length and f1.8. Image capture is provided by a Raspberry Pi 3 in conjunction with INDI drivers. This is used with KStars/Ekos client software running on a Linux Mint desktop indoors. Communication is via Wi-Fi. The astro camera is an uncooled version but I have added a Peltier TEC cooler. This cools the camera down to something like -15°C for night sky imaging with longer exposures of around a minute. Daytime imaging is also covered using the camera's minimum exposure and gain. The colour camera differentiates between dark clouds and blue sky and also shows the colours of stars at night. This Blog will describe the construction of the hardware and the special driver coding used to control dew heater, camera cooling and focussing.
  6. 1 point
    I've offered to give a talk with pictures to our local social group and thought a Blog on here would be a good place to prepare and assemble it. Also, I would welcome any comments and suggestions. I have a few ideas and will see how it progresses. I will probably take me several days to get my initial ideas sorted out.
  7. 1 point
    After tinkering with the smaller K40 we decided it wasn't quite up to our needs and decided a small upgrade would be more beneficial in the long run. A 12 hour drive and overnight stay in the Lake District later and we arrived back home with a larger 50W machine, a second hand 80W CO2 tube and upgraded power supply. The 80w upgrade will have to wait as we want this machine cutting asap. It's all set up and running now, but waiting on some extras to make the process a little healthier and cleaner. New extraction system (a bouncy castle blower), a water chiller, new focus lens, and a load of stock is due to arrive (3mm plywood, mdf and slate coasters) Took a while to get aligned, but is cutting 4mm MDF in one pass now so happy with that. Once this is up and running fully I can concentrate my efforts on finishing up the CNC build.
  8. 1 point
    So, been another busy week, but not so much travel – just been pottering around the local area which makes a nice change! Also means I get home at a reasonable hour! Had a good weekend – my 10 year old son and I went to the Donnington Car Museum for a look around. He is mad about F1, and when we saw two of Senna’s cars, he was over the moon! I read that it is closing down for good on November 5th, as they can’t afford to keep it open any more – such a shame, as there is so much history there. Anywho – on to other things. The weather has been fairly kind this past week, but it wasn’t until the end of last week I managed to get out under the starts with my 20x80’s. it was my first look at the moon through them, and I was very pleased with the view – the moon as just coming up to half full, and the detail along the terminator was crisp and sharp. I was able to make out Mare Imbrium. It was half illuminated, and some of the mountain peaks on the far side where just starting to be hit with sunlight. Further down, there were two craters in amazing relief – I think they were Eratosthenes on the left, and Copernicus to the right. Copernicus as in deep shadow, apart from the far left crater wall, which was bathed in sunlight. Overall, I was really pleased with the views, and have decided to learn as much about the Moon as I can, in readiness of the Explorer 150PL I shall be getting at Christmas. Further afield, I kept getting pulled back to the area around Cassiopeia, and Andromeda. I still don’t know what I am looking at really, but once back in the house, I am using Stellarium to work it out!! I found two clusters, close together below Cassiopeia – turns out it was N884 and N869, and each showed a mass of stars. I went back again to M45 to marvel at the sea of stars I could see. It is still fairly low from where I am, so hopefully the view will improve in the coming months. Next out, I want to try finding some globular clusters, such as M13. Time to start ticking off the Messier objects I think! Looks like it will be good again tonight, up till about midnight, but the Moon is nearly full, which might makes things tricky – we shall see!
  9. 1 point
    'Calculating the Cosmos' by Ian Stewart and 'The Universe Next Door' a New Scientist compilation are both extremely enjoyable reads and have kept me going in between the'dark clear nights' here on the east coast. So having time on my hands this summer, I prepared a digital image and poem in 'homage' to two of my favourite pursuits: reading books on cosmology I barely understand and eating shellfish most people tend to avoid. 'Winkles in the fabric of Space-Time' - mixed media - George Roberts - June 2018 "If there were winkles in the fabric of Space-Time At the Planck scale squid and plaice would rhyme If the Universe and Albert Einstein could spin on one sharp pin Might each sardine simultaneously be alive and dead in it's tin? Perhaps dark matter would even cease to matter? If cod, god and gravity were resolved in batter". George Roberts from the book 'A Brief History of Gastropods'
  10. 1 point
    I sometimes find it hard to comprehend the sheer scale and size of SGL these days. From its humble beginnings when a couple of guys were sharing some time on a yahoo group to what we have today - an active community. What this place means to so many people is something that for me i find difficult to put into words. When SGL is off line for any reason i feel left out somehow. When SGL's imagers share their great work i feel humbled at the aesthetically pleasing images they produce, knowing that there is a scientific usage and background behind each one to back it up. The observing reports are fantastic, the equipment discussion and advice that is freely handed out is second to none. And then there is the SP to look forward to. Its hard to think of a way in which this place could get any better. The surprising thing is that SGL does get better all the time. Makes you feel all warm and fuzzy inside...
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