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    The aluminium tripods that come with a majority of beginner and mid-range scopes have had a bad name for years as being poorly made, sloppy and people have tried various ways to make them sturdier such as filling the legs with sand, lead shot, or even expanding foam. 
    I just read an account the other day of where a person was fitting steel rebar into the legs to see if it will help…
    The only problem with these solutions is that you end up with a very heavy cumbersome tripod that is really no better than what it was when the modifications were started. 
    I will show you what I do with these to help take the shakes out of them. 
    The tripod modifications can be done to any of these aluminium tripods and not limited to adapting the SLT mount.

    Before starting the modifications, read the instructions thoroughly! If there is any part you are not sure of feel free to PM me.

    The tripods are manufactured cheaply and are not a precision work of art but can be fixed to be quite usable for only a few dollars.
    There are 3 different pivot points on the tripod that total 21 different places that the tripod can move so these can all be stiffened up.

    Tools required:
    Robertson or Phillips screwdriver
    Drill and ¼” and 1/8” drill bits
    Skilsaw
    Hacksaw or angle grinder
    Fine flat file
    White glue
    Paint or varnish of choice
    Socket/ combination wrench if using nylocks

    All the needed supplies should be available at a local hardware store. 
    18- #6 flat washers
    18- #8 x 3/8” sheet metal screws
    3- 1/4” x 3 1/2” bolts
    3- 1/4” wing nuts or nylock nuts (preference)
    6- 1/4” x 1” flat washers
    6- 3/16” x 1” bolts
    6- 3/16” wing nuts or nylock nuts
    12- 3/16” x ¾ or 1” flat washers 
    1- 1/8” x ¾” aluminium flat bar (need about 9”)
    Container for all the old bolts and screws

    Note: If you wish to paint your tripod and mount I recommend a degreaser and an aluminium etching primer to help the paint adhere to the aluminium parts. 

    For this I will show what I did to adapt the aluminium tripod to a Celestron SLT hub/mount.

    The supplied screws/ bolts holding everything together are cheaply made and it does not take much to strip these so all the hardware will be replaced with better quality. 

    Start by taking the tripod legs off of the hub and set the hub aside as it will not be reused. 
    Take the legs apart and remove all the factory screws/ bolts holding the cast metal pieces together. 
    Check all of the plastic end pieces in the legs to make sure they are tight. 
    If not they will need to be removed for now. You may wish to mark all the pieces so they go back together on the same leg but it is not essential. 

    If you are going to paint your tripod/ mount now is the time to do it and give it a full day or two to properly dry. 
    Use either #220 grit sandpaper or a course scotchbrite pad to scuff the metal to help it adhere to the parts. 
    Do not forget to scuff the primer before painting! 

    Now that you are ready to put the tripod back together we will stiffen up any of the plastic leg inserts if they were loose. 
    The only piece you do not want to do this to is the top cap for the center leg. 
    Do not install this cap or the center tray support brackets at this time. 

    Put a bead of white glue around the inside of the leg where the insert goes and then push the insert into place. Using the new #8 x 3/8” (6 per leg set) screws, snug all the parts up. 

    Picture 1:
     

    Set aside and let the glue harden.
    The #8 screws are slightly larger than the original size and will snug up nicely. You can see the difference in the photo above.

    I tend to reuse the lower single leg bolts as they are usually fine for this job. I use the glue on the insert and then the bolt.

    Before you reinstall the cast lower leg pieces run your finger around the hole that the center leg slides through, if there are any rough or sharp spots file them down smooth. 

    Now that everything is dry start reassembly by installing the side legs and then slide the center leg up through the bottom. 
    Set the legs aside for now. 

    Now we get to the fun part, power tools!

    Using the 1/4” drill bit enlarge the holes on the SLT mount hub to match the larger hole in the tripod legs. Once done set this part aside. 

    The next step is modifying the center tray supports.
    The supplied tripod tray is a flimsy piece of stamped metal and using the 3 original screws and wing nuts leaves much to be desired for tripod stability!
    Using 6 bolts in the tray will hold the legs firmly in place and not allow any play.

    Using the drill and the ¼” drill bit, drill a hole at the furthest end of the slot and another half the distance of the support. 

    Picture 2:
     

    Now to make the new center tray. This tray will spread the legs out a bit more making alarger ground triangle which helps with stability. 
    I used a piece of 3/8” plywood with dimensions of 15 3/4” on the flat side and 13 5/8” flat to peak. Your 2 holes should be approximately 2 ½” and 5” from the peak. 
    Drill ¼” holes and set aside for now.

    TIP: Use the tray support as a template to mark out the holes to ensure alignment.

    Picture 3:
     

    Using the aluminium flat bar cut 3 pieces 2 3/4” long. Use the file to smooth and round off the edges of the piece. (I used the edge of a quarter as a template to round off the corners.)

    Now to reassemble the tripod! 

    Take a leg assembly and lay it flat on your work surface, insert the center leg cap at this time but do not screw it into place. 
    Take one of the flat bar pieces and lay it across the legs butted up against the lip of the center cap and mark out the location of the screw hole on the flatbar. 
    Using the 1/8” drill bit make a hole and then install this with the center cap.
    If you have ever noticed on these tripods, as soon as you put some weight on them the center leg tends to slide/ lean inwards which causes only a small part of the leg to actually be making full contact. This flatbar brace will keep the center leg inline with the other legs when the scope is mounted. 

    Picture 4:
     

    Optional: I drill a second hole and rivet it into place so that the flatbar cannot loosen off and the cap can still be unscrewed and removed if needed. (3/16” drill bit and 1/8” rivet)

    Once the flatbar is attached turn the leg section over and it is time to install the tray brace. 
    Screw one of the pin brackets onto the leg and then insert the pin. 
    Put 3 of the #6 flat washers on the pin and then slide the tray bracket on (flat side up). Install 3 more #6 flat washers and then the other pin bracket. Screw bracket into place. 
    The tray support bracket should be nice and snug between the brackets now and there will be no slop for it to slide around on the pin. 
    Repeat for other legs. 

    Picture 5:
     

    So now the tripod should almost be done, take the mount hub and install the new 1/4” x 3 1/2” bolt.
    At a minimum you should have a flat washer under the bolt head and one under the wing nut.
    Check the gaps between the legs and hub to make sure they are in full contact with each other. 
    If there are gaps between the legs and hub use 1 or 2 appropriate thickness washers to fill the gap.
    Plastic report covers can be cut to make washers if the gap is small.
    You want the legs parallel but not squeezed to the point you cannot adjust the center leg smoothly.
    Use a 1/4” x 1” flat washer and then your choice of either a wing nut or nylock to tighten things up.

    Tighten until the leg is stiff but can swing without fighting it. 
    Repeat for the other legs. 
    You should now have a complete tripod minus the tray. 

    Final step is to install the tripod tray using 2- 3/16” x 1” bolts and 4 flat washers for each leg. 
    I use one washer on top of the tray and one underneath the bracket so you can tighten these up very well with the wing nuts or nylocks. 

    Picture 6:
     

    You should now be the proud owner of a very stiff aluminium tripod that no longer has a bad case of slop/ shakes when you put your scope on it. 
     

    Picture 1.jpg

    Picture 2.jpg

    Picture 3.jpg

    Picture 4.jpg

    Picture 5.jpg

    Picture 6.jpg

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    I've been mainly working on the stack inspector this week. The idea is to be able to quickly inspect the entire stack, rejecting bad subs (this also applies to calibration frames, though fuller support for calibration is the main task for next week). The stack inspector also allows animation of the subs and/or stack, making it easy to diagnose tracking issues etc. There's the option to restack based on an arbitrary sub in case the keyframe chosen isn't too good. One thing I'm finding a great surprise when going back through some of my old captures is the proportion of 'bad' subs that nevertheless get stacked into something reasonable.

    Here's a 2:22 minute video of the tool (.mov or mp4, both heavily compressed) in operation just to give a quick look at some of this functionality.

    joc1.mov

    joc1.mp4

    [0-40s] The first part shows a single sub and demonstrates the operation of the B(lack) and W(hite) point sliders; then the stretch is changed to linear and back to x/x+c demonstrating the way the latter can produce a nice range of effects even with a fixed white point. The 'p' slider is the free parameter in the stretch (for more complex stretches there are more than one available parameters). The 'fine' slider is also shown. This is more of a ratchet in that it springs back to its central position when released. It is used for very fine modification of the critical black point in either direction about its current value.

    [40-45s] All this is based on a single sub but there is actually a stack present and the next part demonstrates the live stack. In practice one can either watch the subs as they come in, or watch the stack building up, or indeed (as we see later in the video) some combination of the two.

    [46-60s] We then see the pan, zoom and rotate controls. On a touch-based device such as an iPad one can also zoom and rotate using the usual two finger gestures ;-) although the rotate lever provides more control, ensuring that the rotate is about the current centre of the displayed image.

    [1:01-1:10] You'll notice some dark pixels due to poor dark frames (there is some basic calibration built in to the current version). These are effectively removed using the median stacking method. Since the tool holds the entire stack in memory it is possible to perform arbitrary stack combination methods in near real-time. I intend to add sigma-clipping and other approaches.

    [1:11-1:25] There is an invert option which is really useful for seeing faint details, largely because we are more tolerant of noise in these inverted images. I demonstrate this by moving the stretch parameter to near its maximum setting, introducing more faint detail and noise. which nevertheless is tolerable. 

    [1:25:] The final part demonstrates the stack inspector. This provides a quick way to examine all the subs in the current object and to reject any bad cases. The first part shows me stepping through the stack looking at individual subs. From [1:44] I show stack animation -- essentially cycling through the subs repeatedly. The slider controls the speed of animation. The bad pixels are clear. All the controls are operative during the animation process (zoom etc). From [1:56] I select the stack view, which results in a stabilised image showing the build up of the stack (note the movement of the cold pixels -- we are still in inverse mode). Stack recombination is happening N times a second here. I then show the stack method changed to median during the animation. This slows things down a bit but is still reasonably fast, at least for my sensor. From [2:09] I show one of the combined display methods, in this case with the progressive stack in the centre and the individual subs in the outer 'anillo'. The amount of inter-frame movement is quite surprising. Finally I demonstrate the additional options on the stack inspector. These will be elaborated further...

  1. Having played with water cooling for astro cameras and seen this applied to 3D printers instead of fan and fins for cooling hotends but at high cost, I though I would like to try myself.  I have reasonable DIY skills :D  Some filament types benefit from a heated chamber and warm air is not so good for cooling.  This is one example where water cooling is particularly beneficial.  Another benefit should be reduced weight for the X carriage permitting faster acceleration and deceleration for fast printing.

  2. Toot and I had a great time in Norwich last night. Dr Michael Foale CBE gave a talk about his life as an astronaut to a packed audience at the University of East Anglia. What an accomplished, kind and measured man. A couple of hours in his company passed very quickly. He has great interpersonal skills and although we only spoke to him very briefly, both my partner and I felt we had 'met him' rather than just 'heard him' speak. 

    What an exciting, if not at times scary, life and career he has had?

    Highlights include:

    • a spacewalk to upgrade the Hubble Space Telescope's computer from a 386 to a 486 ( I had one of each but I only had to fetch them from Currys)
    • stopping the MIR space station from spinning out of control after it had been hit by a supply vessel
    • commanding the International Space Station

    There were many children in the audience who were very interested in space and science. Dr Foale encouraged them to do what they were good at, pursue their dreams and not to be deterred by setbacks.  He paid particular care to encourage girls to pursue careers in science and aerospace.

    He very kindly - let anyone who wanted to - have their photograph taken with him. A long queue of excited children formed down one side of the Lecture Hall.

    "Dr Foale, I could tell you that the photograph is for my grandchildren, but really its for me"  said a very excited and pleased old man.

    If you get a chance to hear him speak and/or go to events organised by ISSET or a 'Pint of Science'  - go for it!

    Toot Dr Michael Foale CBE and Papa crop.png

  3. In an earlier post I examined the noise in single dark frames over a range of exposure times.  My conclusion was that the Nikon D7500 was a lower noise camera than the D5300.  This was also backed up by an examination of master bias frames that again strongly favoured the D7500.

    However ...

    The first image I attempted to produce with the D7500 exhibited very strong streaks in the noise.

    5a4d7733d427e_Galaxy_NGC_1365_Oct_2017_100pcCrop-IPADPro-compressed.thumb.jpg.18041249e7d07d813d6d7aff262acc13.jpg

    5a4d781b23bf6_Galaxy_NGC_1365_Oct_2017_100pcCrop-IPADPronoise.thumb.jpg.4bbe1718af4186a65f611cd7c5516ad4.jpg

    I had been in the habit of not using dark subtraction with the D5300 as it has very low thermal pattern noise.  Accordingly, I again only used bias and flat frame calibration in the workflow that produced the above images.  

    Whilst the streaks are due to patterns in the noise being spread across the image due to errors in the application of dithering during tracking, it did indicate that the D7500 did have significant thermal pattern noise.  I found this surprising because the noise in individual frames ( when looked at in isolation ) seems to be completely random.  I thought that perhaps my memory had failed me and maybe the D5300 has the same level of pattern noise but my memory was being tricked.  That is, all my recent images with the D5300 were taken at lowish air temperatures ( ~5 deg or so ) whereas the image above was captured on warm nights ( low 20s ) and so maybe the D5300 would be just as bad at higher temperatures.   

    To test this I produced bias corrected master darks for both the D7500 and D5300 from images all taken at around 20 deg or just over. 

    The images below have all been stretched using the same screenTransferFunction applied to the Pixinsight histogram tool.  The results are striking ...

    D5300 master dark ( 47 subs, bias corrected ) - red channel:

    5a4d7c06d91e1_D530047integration_CFA0_R_small.jpg.e0a09fbfa623e7641252ca8611e30d02.jpg

    D7500 master dark ( 281 subs, bias corrected ) - red channel:

    5a4d7c30ede0b_D7500281integration_CFA0_Rsmall.jpg.65fd1ddc6f1598cb1f6c9497e4c981f0.jpg

    D5300 master dark 100% centre crop - red channel:

    5a4d7c298011c_D530047integration_CFA0_R_100pccentrecrop.jpg.608f678dc78cef5474f4fb8da0045a54.jpg

    D7500 master dark 100% centre crop - red channel:

    5a4d7c215701e_D7500281integration_CFA0_R100pccentrecrop.jpg.610e2669d6fbcd092d25e67f7b430527.jpg

    And the histograms of the full size images ( red channels ) ...

    D5300 master dark ( red channel ) histogram:

    5a4d7c193d62c_D530047integration_CFA0_R_hist.thumb.jpg.e62b42cec1f256d7b5a06dbc7f65d48b.jpg

    D7500 master dark ( red channel ) histogram:

    5a4d7c1423da3_D7500281integration_CFA0_Rhist.thumb.jpg.d0e579c13ce8468de6daac2171ffbe28.jpg

    The Pixinsight statistics tool calculates the following:

    D5300:  mean 2.3,  standard deviation 9.3
    D7500:  mean 7.5,  standard deviation 20.8

    -------------

    Analysis:

    The images and histograms clearly show that the D7500 has higher pattern noise than the D5300.  In particular, from the histograms, 0.1% ( 6,286 ) of D5300 pixels are more  than 44 ADU whereas, for the D7500 this figure is 27 times as great at 2.7% ( 141,305 pixels ).  Furthermore, the master dark for the D5300 was only produced using 47 images -v- 281 for the D7500 so I would expect that this difference would be even higher with more D5300 frames. 

    On the other hand, whilst not shown in the histograms above, my D5300 does have more 'very hot' pixels than the D7500 ( 579 pixels greater than 400 ADU -v- 10 pixels greater than 400 ADU ).  However, these hot pixels are very easily removed via dithering during tracking and sigma clipping when integrating.  The very large number of warm pixels however are very difficult to remove as dithering just places different warm pixels on top of each other.

    I went back and examined the 'random' noise seen in the individual D7500 dark frames ... and yes they do look random when seen individually, however, when flicking between a number of frames it is clear that the 'random' pattern is repeated in each frame! 

    Conclusion:

    My D7500 has very significant thermal pattern noise, albeit randomly distributed in a fixed pattern.

     

    ............

     

    Next steps (?)

    - I could use in dark subtraction during calibration to reduce the impact of pattern noise - however, as my camera is not cooled and the night's temperatures are constantly changing, any master dark will not closely align to the actual thermal pattern noise and as such dark subtraction may help but will not solve the problem

    - Using in-camera dark subtraction ( Nikon's long exposure noise reduction feature ) would almost completely remove the pattern noise from each frame.  However, due to the extra random noise being introduced by subtracting another noisy dark frame from each light frame, as well as the reduction in total light frames by 2, the resultant images will suffer from higher levels of random noise.  So whilst this would be an improvement with respect to the pattern noise, it is not a complete solution.

    - Third option, sell the D7500 and go back to using the D5300 ... :undecided:

  4. This is a tutorial explaining how to install the Ubuntu Mate operating system and astro software onto a micro SD card to use in a Raspberry Pi for astro imaging and control of the relevant hardware.

  5. Every Autumn our local pub organises a charity auction evening.  As one of the lots I offer a voucher for 'An evening of Astronomy'.  This blog shows the outcome of the last winning bid as posted on the local website, warts and all.

    Cashing in on photons

     

    A short article on an outreach at the Bishop Monkton observatory

     

    Sunday the 22nd of October 2017, a week after the annual auction at the Lamb and Flag, the owners of the Astronomy Evening voucher from 2016 made it to the observatory.  It may have taken a year to arrange but that’s nothing to the 2.3 million year old photons hitting our eyes from M31, the Andromeda galaxy.

     

    M31.jpg.4f5bc898e84d4a62cfca6cba92aeb0d9.jpg

    The author’s own image of M31, the Andromeda galaxy.

     

    This was just one of the sights I was able to show to my guests, Carole, David, Stancey and Olly.  What great companions they were too being very patient as I waffled on about the secrets Andromeda gave up to Edwin Hubble and the scientific community in the early 1920s.  Showing the attentive audience how to star hop just with their eyes from the great square of Pegasus to a large fuzzy patch overhead was all it needed. Until then most astronomers believed everything we could see was contained within our own galaxy, the Milky Way.  How much further from the truth could that have been, as we now know it is merely in our backyard in astronomical terms.

     

    Testing the sky was also on the agenda for the evening and the conditions were such that we could just make out the seven main stars of Ursa Minor with normal vision.  That equates to a magnitude 5 sky so not too bad but how much better it could be without all the untamed light around us.  Olly, pointing at the Pleiades, remarked that he always thought that was Ursa Minor. An open cluster, number 45 in Messier’s catalogue, known as the Seven Sisters or Subaru in Japan is a very young, close group of hot white/blue stars formed from the same cloud of gas.

     

    M45.jpg.dc391768fbea8957e2c6888810427c39.jpg

     

    The author’s own image of the Pleiades (M45).

     

    We had to crack on though and put to use the short, telescope driving lesson undertaken under red light and over a glass of wine earlier in the kitchen.  I wanted to make sure we didn’t miss a chance to view M13, the Great Hercules globular cluster before it sank below the rooftops.  It proved a bit of a tough nut to crack because to get the most out of it we had to use a technique called averted vision.  David realised that the large fuzzy ball in the eyepiece was made of thousands of stars, bound together by their own gravity like a swarm of bees around a honey pot.  These 12 Billion year old stars though take us back to the very start of the Universe.

     

    M13.jpg.cee8f567bd3966ec7fd2802a755b6924.jpg

    M13, the Great Hercules globular cluster (Wikipedia commons credit; rawastrodata.com).

     

    It was time to move on to some other deep sky objects so we dipped into the space between Perseus and Cassiopeia to sample the double cluster that is pretty in itself but I wanted my audience to look a bit deeper.   Our eyes are poorly equipped compared to cameras but obvious to all is a rich, orange star apparently visiting the cluster of younger members. 

     

    Colour tells us so much about a star and so we chased Cygnus the Swan across the Milky Way with both ‘scopes to pinpoint Alberio, the star designating the swan’s head.  In the ‘scope everybody detected Alberio as two stars of sharply contrasting colours, an optical double, often described as indigo and gold telling us immediately that they have markedly different surface temperatures and characteristics.  Are they gravitationally bound as a binary system? Well the jury is out on that one but current estimates have one third of all stars in the Milky Way to be true binaries.

     

    Getting towards the end of the evening it was time for a couple of more challenging objects.  Number 57 in Messier’s catalogue is described as a planetary nebula purely because when viewed in the 18th century it resembled a view of the know planets, small, round (ish) and some colour.  These objects have nothing to do with planets but are the result of the after effects of a dying star that has puffed off its last layers of gas leaving a white dwarf at the centre.  The gas is energised by the radiation from the star and takes on colours that are determine by its composition, very often the green of triply ionised oxygen.

     

    M57.jpg.a243e944fd40aacccdc5ca5f8687081f.jpg

    M57, the Ring nebula (NASA/ESA public domain)

     

    I tried hard to answer and fulfil the questions and requests from my guests and one of the first queries raised before we left the kitchen, was “Can we see any planets?”.  Unfortunately it’s pretty poor times in the UK right now for the top targets and will be for some time.  However, the two ice giants are in the southern sky so in theory are visible but crikey they are a long way off. 

     

    With Olly’s help and whilst the others warmed up in the kitchen we changed to my old Schmidt Cassegrain telescope that has a focal length of 2.3 metres to attempt this feat.  This also meant realigning the telescope mount. That took a few minutes but it was then possible to pick out Uranus, which is about 4 Earths wide at a distance of nearly 3 billion miles! It is obviously a disk that has a slight green tinge.  We also tried to view Neptune, which is a massive 4.5 billion miles away but the view was slightly obstructed by my roof!

     

    Uranus.jpg.8ec472d3dd9ec5d3905647e75f4818a1.jpg

    Uranus and Earth comparison (NASA public domain).

     

    Visitor comments

     

    Carole kindly remarked about the group’s experience of the evening and her words are below.

     

    “We had been looking forward to this evening ever since we bid for it in the auction. It took a while for us to find a time that was good for everyone and for the skies to be clear and not moonlit.  It was well worth the wait and a huge thanks to Chris for offering the event and putting on such an amazing evening. 

     

    Having only a very limited knowledge of astronomy, it was great to have Chris enthusiastically explaining to us what we were seeing.  He has an array of different telescopes and he patiently set them up in his observatory for us to get the best view of the various stars and planets. Seeing the telescopes and learning about how they are controlled to lock onto coordinates in the sky is fascinating in itself. 

     

    Chris has already described above the range of astronomical bodies we focused on in just a couple of hours. Before the evening I don’t think any of us had heard of Messier’s catalogue! There is just so much to observe and it was a treat to see two remote planets. Neptune was a bit naughty trying to hide behind the house chimney but we just about saw it. We also saw Uranus, which was a bonus. Everything else was good to see and the evening was very enjoyable so we hope to see some more at a future date.”

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    So what have I seen through my scopes since the last blog..............zip.........nothing.....nowt....zero

    The wonderful Cornish skies have been full of clouds, when I've been awake anyway, and now the howling gales prevent even standing my scopes upright even if the clouds clear. I had one glorious night of dark skies while on a work trip to central Germany, the sky lit up with stars, unfortunately my scopes were back in Blighty. Still just staring upwards can be so rewarding.....I highly recommend it!

    So short and sweet (as my father used to say "like a roasted maggot") but I live in hope of nights out with my scopes, I did manage to buy a new 8mm BST EP which I can't wait to use.......reviews seem pretty good

    Clear skies to all

  6. Gigaclear have provided optical fibre cable to our village of Upottery in East Devon with full Fibre To The Property at 1Gb/s both download and upload.  We are the first village west of Bristol to be provided with this ultra-fast fibre broadband. 

    They provided connection to a pot (like a water D head) just outside my premises and I am arranging the fiber optical cable connection from there right into my house and to the router they have supplied.  This blog describes the process of digging a trench and laying the cable then running it into the house.

  7. Sir John Herschel at the Cape of Good Hope

    Having spent the years 1825 to 1833 cataloguing the double stars, nebulae and clusters of stars visible from Slough, in the south of England,  John Herschel, together with his family and telescopes,  set sail from Portsmouth on the 13th of November 1833 bound for Cape Town.   As detailed below, in an extract from his book, the family enjoyed a pleasant and uneventful voyage and arrived some 5 months later at Table Bay with all family and instruments in good condition.  Reading on however, one might very well think that it might not have ended so well had they but left shortly after ...

    “... (iii.) Accordingly, having- placed the instrument in question, as well as an equatorially mounted achromatic telescope of five inches aperture, and seven feet focal length, by Tulley, which had served me for the measurement of double stars in England; together with such other astronomical apparatus as I possessed, in a fitting condition for the work, and taken every precaution, by secure packing, to insure their safe arrival in an effective state, at their destination, they were conveyed (principally by water carriage) to London, and there shipped on board the Mount Stewart Elpliinstone, an East India Company's ship, Richardson,Esq. Commander, in which, having taken passage for myself and family for the Cape of Good Hope, we joined company at Portsmouth, and sailing thence on the13th November, 1833, arrived, by the blessing of Providence, safely in Table Bay, on the 15th January, 1834, and landed the next morning, after a pleasant voyage, diversified by few nautical incidents, and without seeing land in the interim. It was most fortunate that, availing himself of a very brief opportunity afforded by a favorable change of wind, our captain put to sea when he did, as we subsequently heard that, immediately after our leaving Portsmouth, and getting out to sea, an awful hurricane had occurred from the S. W. (of which we experienced nothing), followed by a series of south-west gales, which prevented any vessel sailing for six weeks. In effect, the first arrival from England, after our own, was that of the Claudine, on the 4th of April, with letters dated January 1st.(iv.) ...”

    D3862C27-4934-488C-A225-2399FB153C41.thumb.jpeg.b7596d4d6ae6e1639040fd551ee5429e.jpeg

    “Result of Astronomical Observations, Made During the Years 1834, 5, 6, 7, 8, At the Cape of Good Hope ... “ by Sir John Herschel, 1847

    John Herschel rented a property and set up the twenty foot reflector near Table Mountain, at a site, that was then, just outside of Cape Town.

    70F7AD49-B1B2-49A4-B084-F5A36B8D078C.jpeg.7494c57d1e6be4fe4650efaf1097c09b.jpeg

    The Twenty Feet Reflector at Feldhausen, Cape of Good Hope, South Africa, 1834

    This telescope was made by Herschel in England and transported, along with his other instruments, by ship to Cape Town and then inland to Feldhausen.  The telescope is a Newtonian reflector, built to William Herschel’s design, with a focal length of 20 feet and clear aperture of 18 1/4 inches ( f13 ).

    The location of the telescope was established by careful survey to be: lat 33d 55’ 56.55”,  long 22h 46’ 9.11” W ( or 18.462 deg E ). 

    0B62D033-0038-4155-978D-1CF0BBEB18C6.jpeg.01782f7486b3d064519812142c9972a2.jpeg

    The site of the great telescope was memorialised by the people of Cape Town by the erection of a granite column that is still there today.

    3993EDE7-B3B0-4154-8D57-1D90C346CF5E.jpeg.e4feceb9cf266f950625726420635999.jpeg

    A74B1EA5-CEFA-405F-8F68-E2F2EDCE263F.jpeg.802e925a156cdf2ef7922249bf5f57b3.jpeg

     

    .............

    Observations of the Sculptor Galaxy

    Amongst his many thousands of observations made from Cape Town, of nebulae, clusters of stars, double stars, the sun, etc., Sir John Herschel records that he observed V.1 ( CH10 - Caroline’s Nebula - the Sculptor Galaxy ) during two different “sweeps” and gave it the number 2345 in his South African catalogue.

    9948BFB9-C32E-4BB6-853E-B6E990F04246.thumb.jpeg.5dbd9d817df724bd75a850f7a94411a1.jpeg

    Sweeps:    646 -  20th November 1835;   733 - 12th September 1836

    At the latitude of Feldhausen, and on these dates, the Sculptor galaxy would have been at an altitude around 80 degrees above the northern horizon when near the meridian ( which was where the telescope was pointed during Herschel’s “sweeps” ). The sight afforded from this location, with the Sculptor Galaxy almost at the zenith, must have been significantly brighter and clearer than the Herschels had thus far been granted from its location way down near the horizon south of Slough.

    ..........

    Other Obsevations by John Herschel from Cape Town

    Also observed by John Herschel in 1835 were the people and animals that inhabit the moon ...

    5ECD1835-D30B-428A-B495-1739FA618A2E.jpeg.38ab350d49888de5167dc46065789b93.jpeg

    The Great Moon Hoax of 1825 - “Lunar Animals and other Objects, Discovered by Sir John Herschel in his Observatory at the Cape of Good Hope ... “

     

  8. 59b740250ae52_NGC104-47Tucanae.thumb.jpg.c5380d2368e4919288fc10bfdf181e0b.jpg

    NGC 104 ( also known as 47 Tucanae ) and NGC 121 in the constellation Tucana

    ( Please click/tap on image to enlarge page )

    ------------

    Link to image on Flickr

  9. This is basically a mechanical perpetual calendar with 3D printed plastic parts but whether I drive it from a clock with hands etc. or simply from a stepper motor remains to be decided.  The display consists of drums with numbers and letters stuck on.  Each drum is driven from specialised gears and levers.  The mechanism is designed to be visible and show the workings.

  10. Gina

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    I'm new to blogs - never used them before so I don't know what I'm doing :D  I'll just experiment and see what happens...598b5ea6b4850_GearChain01.png.dd6b21a895f7895a24ca88dc76156518.png

  11. Three months ago I remounted the EQ8 in the observatory after my friend Chris made me a pier extension to raise the mount 15 cm. Unfortunately, a combination of cloudy nights, holidays, it not getting dark until early in the morning, and my lovely wife being ill has meant that it took until tonight to get the EQ8 re-polar aligned.

    SharpCap's polar alignment tool makes this pretty easy.  I used my Lodestar x2 mounted on a 60 mm finder/guider.

    IMG_20170806_243428479_HDR.thumb.jpg.bde0975ee10075c3bfbabb12e7641b07.jpg

    I'll aim to try to see if I can get this even closer with full drift alignment on another night, but my guess that'll be close enough for now.

     

  12.  

    It’s been a frustrating couple of weeks in the life of this (very) amateur astronomer. Of course, our old sparring partner the clouds have loomed large and thick, making viewing nights few and far between, and then, when a beautiful, visibility-for-miles kind of night did come about, Herschel said a firm ‘no.’ Try as I might, I could not get the power to turn on and stay on. I tried all the tricks in my arsenal, all the high tech stuff like swearing, switching it off and on again, swearing, changing the batteries, swearing, Googling, swearing, waiting 10 minutes, and of course, swearing. I managed to stop just short of giving her a damn good thrashing, but it was a close run thing. So, a day followed of getting in touch with Celestron and my local, very patient telescope dealer, and trying to ferret out the problem. Long story short, it turned out to be the notoriously fickle battery pack, which to be fair, looks to be held together only by the power of prayer. So, a power pack was duly ordered. leaving me with an out of a action scope for a few nights.

    Last night, now in possession of a fully charged power pack, a telescope which worked and the promise of a couple of clear hours, I headed out into the garden once more. I focussed my attention on the Moon, the planets are not easily visible to me at the moment due to trees in the way-I really must invest in a chainsaw-and it was not dark enough for any deep sky viewing, but the Moon was a lovely racing gibbous, and I decided to attempt to point my bridge camera down the eyepiece and get some lunar detail shots. At first, this went about as well as you’d imagine, and blurry grey smudges were the evidence to show for it, but with a little bit of practise and a fair bit of grumbling, I managed to hone in on some detail.

     

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  13. 3rd of July 2017 / 21h30 UTC+01:00 / Stargazing Conditions: 80%

     

    After much reading and hyping myself so much, I was pretty stunned by the early notification on my phone that yesterday night could potentially be a good evening with good seeing. So I went home after work (with my phone still showing 80% of potential seeing), sat on my desk and prepared myself. I chose to watch the Moon, since I never really observed it, Jupiter, Saturn and search for the Sombrero Galaxy!

    Last week I searched for a few good atlases and stumbled unto the Interstellarum Deep Sky Atlas. A promising atlas which should arrive this week, but still would let me be without a field atlas, since it is a desk edition... After cramming in the forums I mainly found three downloadable recommendations:
    1) The Deep-Sky Atlas
    2) Deep-Sky Hunter Atlas
    3) TriAtlas
    I downloaded all of them and browsed through them, noticing that only the Deep-Sky Hunter Atlas exists in a field edition. I printed the normal Version on A3 paper to look if it fits the need and, hell yeah, I really like it so far!! Only downside (for me) at the moment, is that the constellations are in black lines in contrary to the Deep-Sky Atlas. So I think I'll print both of them, laminate them and take them with me on my sessions. (I will have to inverse the colors on the Deep-Sky Atlas though)

    To round everything up, I figured that I'll need a software too, to plan my sessions a little better and just give me the right impressions on where I will have to search in the sky. A while back I downloaded Stellarum, which seemed to be a great free app, but it simply kept crashing on my laptop... Searching for alternatives I found SkySafari 5 and Starry Night 7. Given the prices of Starry Night 7 and the fact that it isn't to be found on the AppStore, I went ahead and downloaded SkySafari 5 Pro. It is a beautifully simple app which does the job just fine and gives me the needed input to satisfy my thirst for knowledge (at least for now). At this point, I was wondering if someone knows if Starry Night 7 was up-gradable? So let's say I buy the Enthusiast Edition and wanted to up-grade to the Pro or even Pro-Plus version one day. Do I have to buy the App entirely new or does it give the opportunity to up-grade for a few bucks to the next edition?

     

    Enough rambling an off to my stargazing site!

    I arrived well early before sunset, which gave me the opportunity to once check again, if my finderscope was well aligned with the 'scope. It also gave me the chance to let my 'scope acclimatize the same way as last time and so I sat back and waited a little until the moon gained a little on contrast as the sun was setting.

     

    The Moon

    The Moon, being a waxing gibbous, shone bright in the slightly dark blue night sky with literally NO clouds in the sky. I put my 15mm BTS eyepiece in and looked at the beautiful moonscape. It is defiantly the first time I've seen the Moon so up-close and I was in awe by it. I never imagined that it could be so nice to look at all these craters and I began to wonder where they all came from. It is simply a battlefield of craters and each and everyone has its own story to tell... after a good 30 minutes of switching between the 8mm and 15mm eyepiece and lots of "ohs" and "wows", I figured I could try and photograph the Moon with my phone through the eyepiece... what seemed to be a really stupid idea at first turned out to be a really great shot (I think?)! (very little photoshop-magic to increase contrast and sharpness)

    34872562754_71c255db04_o.jpg

     

    Jupiter

    Next on that nights list was Jupiter. I remembered the image last time I looked at it and I was thrilled to already clearly identify Europa from Io through the finderscope. I managed to see Callisto, Ganymede, Europa and Io. I think that Jupiter itself was a little less contrasty as last time BUT I think I could make out the Red Spot which really made me happy! I was so thrilled by the view I even can't write down how I felt...

    I switched from 15mm to the 8mm eyepiece and focused in... I kept focusing and focusing and focusing but nothing happened... As I looked up in the sky I was shocked... the beautiful cloudless sky had turned into a thick carpet of Cumulus Cumulonimbus... I immediately looked at the horizon on my right to see if there was a slight possibility of clear sky but the enemy had invaded the sky... To make matters even worse at that moment, I met my locations' neighbor, which is no other company then Arcelor Mittal... The sky with the clouds lit up in a bright orange from the molten metal... At that moment I knew it was over for that night...

     

    Thanks for reading

    Abe

  14. Yesterday I was bitten by kernel update (to 4.10.5) on my main computer (I use Fedora 25). The boot process would at some point just stop, with nothing suspicious in the last visible boot messages; the machine was responsive, though, and Ctrl-Alt-Del reboot was possible. Booting using the previous kernel was fine. After reviewing the boot log (where -1 means second-to-last boot, -0 would be the last (successful) boot etc.):

    journalctl -k -b -1

    it turned out there was a problem uploading firmware blob to my Radeon R7 370 (I use the standard open-source driver):

    kernel: [drm] radeon: 2048M of VRAM memory ready
    kernel: [drm] radeon: 2048M of GTT memory ready.
    kernel: [drm] Loading pitcairn Microcode
    kernel: radeon 0000:01:00.0: Direct firmware load for radeon/si58_mc.bin failed with error -2
    kernel: [drm] radeon/PITCAIRN_mc2.bin: 31100 bytes
    kernel: si_fw: mixing new and old firmware!
    kernel: [drm:si_init [radeon]] *ERROR* Failed to load firmware!
    kernel: radeon 0000:01:00.0: Fatal error during GPU init

    Indeed, for my particular Radeon model the newer kernel tries to upload si58_mc.bin, but the file was missing.

    The solution was to get the file from https://people.freedesktop.org/~agd5f/radeon_ucode/, put it in /usr/lib/firmware/radeon and regenerate initramfs images:

    dracut --regenerate-all --force

     

  15. Filroden
    Latest Entry

    Another short clear window in the early evening let me practise set up and alignment of the new AVX mount again. I ran through my new alignment process, including calibrating the StarSense to the OTA. I then repeated the process and the handset reported a final PA accuracy of 30" in Dec and 3' in RA. However, (and with clouds rapidly moving over) I managed to take another sequence of 30, 60, 90, 120 and 180 second shots to test tracking. Here's the 180s (which is heavily affected by high clouds), which is consistent with the others but shows the trailing best:

    NGC2239_H_180sec_2017-03-09_193100_1x1_-20C_fpos_5773_g300o50_0001.thumb.jpg.b72de33ed591a812a2ed86e81dd03f68.jpg

    Q1. I roughly measure the trail to be 14 pixels, or 26.6" at my pixel scale, so 0.15" per second. If correct, my maximum unguided exposure would be 13 seconds to stay within my 1.9" pixel scale. Would a PA error of 3' give this sort of trailing?

    Q2. I also noticed (or believed I noticed) that the mount seems to move when tightening the mount bolt. I think that this further tightens the accessory tray which pushes on the legs more. I noticed this when I calibrated the StarSense on Betelgeuse. Normally, my goto would then be bang on centre but when I slewed back to Betelgeuse it was a little way outside my crosshairs (using SGPro). I wonder if this is causing me problems and whether I need to attach the accessory tray at all?

    Q3. I also use anti-vibration pads beneath the tripod feet. Could they also slip when adjusting the mount?

    Q4. Whilst the length of trailing seemed proportionate to the exposure time, the direction was not always consistent, particularly in the shorter subs. I'm assuming this could be the affect of many things: PEC, wind, seeing. Is that right?

    I did get reasonable 120s exposures the previous night, so I know it's possible. However, I'm quickly concluding that having tested unguided I now need to quickly move onto a guided set up (skipping over drift aligning though I probably should learn how!). I have a ZWO OAG and ZWO ASI224 so time to bite the next complexity bullet. As it's likely to be cloudy until Monday at the earliest I can start working on that now.

    Spacing

    I think I've just got my spacing right for the ASI1600MM-C.

    IC0443_H_120sec_2017_03_08_202514_1x1_20C_fpos_5829_0001_c_mosaic.thumb.jpg.45fa105eb0038e619b47ed0f918aaeea.jpg

    Which for my reference was 66mm for the Skywatcher field flattener plus an additional 1mm for the filter (1/3rd of the 3mm filter thickness on the Astrodon 3nm HA).

    I achieved this spacing with:

    IMG_1354.thumb.JPG.c05975250ff2d2165dcbd26c913d4e01.JPG

    The OAG has a spacing of 16.5mm and comes with a M48 adaptor so I'm hoping I can just swap out the 9.0mm FLO M48 to M42 adaptor and the 7.5mm Baader T2 extension tube.

    How good does a polar alignment need to be for guiding? Would it be happy with the sort of accuracy I was achieving above or would I need to drift align and improve it further? I'm hoping that a single StarSense alignment routine will get me close enough that guiding will take over (having also read that guiding seems to like an error in PA so that it only has to correct in one direction). Tune in next week for what I expect to be a frustrating first attempt :)

  16. Jim

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    Cold clear night tonight, finally got to see a few planets as a first.    Northern lights around 9 pm and Mars and Uranus came through pretty clear but the cold got to me after about a hour observing. Came out after 11 pm to watch Jupiter rise from the east.  Stayed for another hour before fingers dropped off.  I'm still learning the sky and how to use my equipment but overall I had a good night.    Hot chocolate then bed lol 

  17. M106
    Latest Entry

    i have been waiting for tonight all week, clear skies predicted and virtually no moon, slept all day so i could stay up all night, only to wake to cloud and clearskies changed from green to orange, and red for the rest of the week

    :crybaby2:

    and my pentax adapter just arrived too. sigh...

  18. From the beginning of the human race, to nearly only 400 years ago, everything we knew about space would be observed from the naked eye. Then Galileo came up with his telescope, and the world awakened. We learned Saturn had rings. Jupiter had moons. Within just a few years  of that, our entire understanding of the Universe changed. In the next few centuries, telescopes became more complex, of different sizes, lengths, and powers. Hubble is up in space, the ultimate viewing spot. Unhindered by weather, light pollution, or any other inconveniences, it is used by scientists to study the great cosmos.

    hubble_earth_sp01.jpg

    For 26 years now, the HST (Hubble Space Telescope) has been enthralling us with its spectacular images of nebulae, galaxies, and other space phenomena. However, the telescope does more than just take pictures all day for us to enjoy. The HST was a combined NASA(National Aeronautics and Space Administration) and ESA (European Space Agency) project, which went up with tons more scientific instruments than just a powerful camera.


    heic0206a.jpg


    Since being put in orbit, over 4000 astronomers have used it to publish ~13000 scientific papers on various topics. The HST is truly a marvel of civilization. When Hubble went up, it had a flawed mirror, which was sending back blurry images. After a 1993 servicing mission, the flaws were rectified, and from then, it's been taking pictures of all the amazing things we know it for. It's been used to look at other planets, their moons, further galaxies, and nebulae.

    It's been used to find water on planets, moons, and other asteroids. It's been used to map Pluto, the furthest planet from us (now a dwarf planet). NASA's New Horizons mission will rival the HST, but it will take 9 years to get close enough to Pluto to give any challenge to the HST.
    It's been used to calculate the lifespan of the universe, Hubble helped astronomers nail down the age of the universe with an accuracy of about 5 percent. Our Galaxy, the Milky Way is set to collide with the Andromeda Galaxy, speeding towards us at the speed of a bullet. We know this all thanks to Hubble.

    Quote

    "When massive stars reach the end of their lives, they explode in a fiery death known as a supernova. These violent blowouts may leave behind black holes or supercompact neutron stars even as they blow the heavy elements that form in the heart of the star through their galaxy. Hubble has helped scientists to better understand the supernova process." - Space.com

     
     

    Check out the gallery below to see what kinds of amazing pictures the HST has taken over the years, and also check out my original blog over at http://hridaysabir.blogspot.in/ to keep up with the latest topics I write on.

     

    heic0206c.jpg

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  19. What is the best I can expect to see through my skywatcher 1114p telescope and the best way to see it, i.e how to combine lenses etc

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    So I've recently purchased this little gem. It is so good! Surprisingly showing me Venus and Mars in great detail.

    The scope boasts a 4" aperture with a 400mm focal length(quite short tbh) but gets the job done with messier objects.

    it has this beautiful red finish which I shouldn't include as a feature but it sure does look gorgeous. Unfortunately it has only seen the sky once

    due to the bad weather here :clouds1::clouds2: but the views were worth it.

     Zrh8q3R.jpg

  20. My EQ-2 mount is nearing the end of its useful life. It has suffered a screw shear on the Dec. Slo-Mo controls, and now the handle of the main mount bolt has disintegrated. Although I would like to repair the mount, and keep it in operation, unfortunately, it is getting left behind in my astrophotography journey, and a replacement was due within a year or two. The recent disasters have only highlighted the need for this, and so a replacement is on its way! More next week....

     

    ===========IN MEMORIUM============

                                     EQ-2 (2012-2016).

                            A Wonderful Telescope Mount.

          Who Passed Away While Drift Aligning On The Front

              Path, And Who Will Never See The Stars Again.

                                    WE WILL MISS YOU

  21. 11 / November 18, 2016 / Home / 1955-2035 JST / Cold & clear / 15x70, 8x42

    I went outside before moonrise to find The Golfputter, and I succeeded. I saw a shooting star pass from south to north just below M31. The last 10 minutes were consumed by a conversation with the next door neighbor, who'd stepped outside for a cigarette.

    CONSTELLATIONS:          And / Ari / Aur / Cas / Cep / Per / Tri

    DEEP SKY OBJECTS:

    Kemble 1 (As/Cam)             -

    M31 (SG/And)                     -

    M33 (SG/Tri)                       Same hazy patch

    M36 (OC/Aur)                     -

    M37 (OC/Aur)                     -

    M38 (OC/Aur)                     -

    M45 (OC/Tau)                    Naked-eye only.   I doubt I'll ever resolve more than two points of light.

    Mel 20 (OC/Per)                 -

    NGC 752 (OC/And)           I liked it! It appears as a widely distributed patch of stars; I pictured them as grains of sand being disturbed by the Golfputter.

    Golfputter (As/And)          First sighting! It's distinct, but unlike Kemble's Cascade, doesn't suffer when viewed through lower magnification. 

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