Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_30_second_exp_2_winners.thumb.jpg.b5430b40547c40d344fd4493776ab99f.jpg

Sign in to follow this  
alanjgreen

First Light: 20" f3.6 Lukehurst Dobsonian

Recommended Posts

First light: 20” f3.6 Lukehurst Dobsonian

Date: 2 April 2017. Time: 2130-0200.

Focal length: Native 1814mm, +Paracorr2 (x1.15) 2120mm, +MarkV (x1.7 Newtonian GPC) 3083mm

 

Finally, got a real first light last night. The conditions were not ideal with a 40% moon and some high level cloud but they were good enough to get everything setup...

I had already tested the Nexus the previous day and after changing a plus(+) to a minus(–) in the Sky Safari encoder settings had got the push-to system tested out using some false alignments.

First job was to set the Baader Skysurfer 5 up using Polaris. It took quite a large adjustment of the finder to get it centred, there was just enough adjustment available for success. Must be the amount of aperture that necessitated the large adjustment needed?

Anyway, once that was done I connected Sky Safari to the Nexus and aligned on Polaris. I slewed over to Algieba in Leo and centred in the red-dot finder. It was in the FOV so nudged it to the centre and hit the Align in the app.

Now as I move the scope, I can see Sky Safari following me around the sky – great!

Nudging note: It isn’t easy! I know that I will pick this up over a few session but most times I moved it the wrong way only to go “Doh!” and move it the other way. It was much easier to get it right when nudging while watching the IPad screen than nudging while peering through the eyepiece.

Collimation note: The defocus star presented a nice set of rings although brighter stars were flaring around the edges (atmospheric conditions I assume). Collimation with the Glatter laser & Tublug is simple!

As the moon was still too high I moved onto some eyepiece focus checks. The point of the test was to be able to get past the focus point of the eyepiece and not worry about the power/image content.

-          3x Ethos & Paracorr2 = check :)

-          MarkV bino & Pan24, Delos 17.3, Delos 10, Delite 7 = check :)

I have about half inch in-focus remaining with the Binos in use and more than an inch of out-focus with the Ethos/Paracorr2, so I am happy with that!

I found the bino was giving a darker background than the Ethos so I stuck with the Pan24 and binos and moved on to view some galaxies (x128 magnification).

Sky Note: As I am short sighted and view without glasses I see the sky out of focus but I could see that the still thin clouds were thicker than before.

M51

Using the Nexus push-to I nudged my way over to M51 and found it on the edge of FOV when the Nexus was showing it as centred. I could see two bright cores and some dusty circles around the main galaxy. Not bad for a milky moon lit sky and more than I expected.

Sky Safari note: I had read up that Sky Safari keeps the last two alignment points from the push-to and that it’s a good idea to align to something in the area that you are observing so I centred M51 and clicking Align in the app. From that point I found several galaxies in the area and they were reasonably centred in Sky Safari at the same time. So, I am happy with that. I was able to identify several galaxies that I came upon using Sky Safari which is what I had hoped for.

M101

I could see the core and one blotchy area to the side. There was a lot of swirly gas that I see with averted vision. Again, not bad for a moony sky!

M97 owl neb

Easy, nice clear circular patch. I didn’t bother with more mag for the “eyes” as the conditions were not worth it.

NGC4631 whale

Easy, nice long streak of grey dust.

NGC4565 needle

Bright core & long streaks to either side. Streaks were longer with averted.

NGC4244 silver needle

Long faint streak observed.

Cocoon Galaxies

Both galaxies seen. One bigger than the other. Smaller one improved with averted.

M94

Nice bright core and circular surrounding dust.

M63

Core with surrounding dust. Less bright that M94.

NGC4449

Easy, nice squarish shaped galaxy.

M106

Core with surrounding dust disk.

NGC4051

Faint core. Faint dust circle. Averted needed.

NGC4088

Faint galaxy, but a good size.

M13 globular

I viewed M13 with the Ethos10mm and was able to resolve some of the stars. It is quite low and I was not getting full aperture due to the shed walls.

Comet C/2015 V2 Johnson

Easily located with the help of Nexus! In the Ethos21 it was easily seen but pretty small.

Comet 41P/Tuttle-Giacobini-Kresak

Bigger that Johnson but more diffuse. Again, the conditions meant that I wasn’t bothering to change magnifications/eyepieces much!

By now the clouds were thicker still. I could see the main stars and the next level too, but even with the moon nearly gone, the images were not improving so I decided to call it a night.

Due to the position of the scope within the shed, I was unable to point at the moon & Jupiter. I have repositioned it this morning (for next time) based on my experiences. David supplied a set of wheelbarrow handles with the scope which are easy to connect and make shuffling the scope around the shed possible.

 

Conclusions.

1. Very happy that I can reach focus will all my eyepieces & binos :)

2. Nexus is simple to get aligned and without it I would not have found very much to observe! Happy with that too :)

3. Surprised that the larger galaxies were visible (and pretty decent) under the moony sky, wasn’t expecting that but I don’t go out usually until the moon has departed :)

 

Comments welcome,

Alan

  • Like 12

Share this post


Link to post
Share on other sites

Nice report Alan - good start with the big new scope !

I managed to see quite a few galaxies last night as well last night - better than I had expected.

 

Share this post


Link to post
Share on other sites

Sounds like you had a great night. The scope seems quite capable.

Share this post


Link to post
Share on other sites

Great report, and good to be seeing details in galaxies despite the moon.

I am trying not to develop aperture envy.

 

Share this post


Link to post
Share on other sites

Brilliant report some great objects there. ( I must not succumb to aperture fever )

Share this post


Link to post
Share on other sites

very nice report with the big scope. M13 will only get better once the wall is knocked down. In my slightly smaller scope it is stunning. Often wish I had gone for the 20 inch which I could have at the time.

Alan

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By markastro
      Hi,
       
          Looking for a 12" DOB (or larger) which can be transported to Prestwick, Ayrshire. Any brand, as long as the telescope is optically sound and in good working order. I'm a reliable buyer who has bought and sold on this site before.
       
      Thanks,
       
      Mark
    • By Ships and Stars
      Hi all,
      Last night was the best night of astronomy I've had in my short time delving into this passion. It was simply incredible. Fortunately my dear friends the midgies have departed Scotland for another season. This means I can now stand at the scope without ingesting a lungful of tiny biting insects and concentrate on what I am observing. Always a plus!
      Two nights ago I went to my local dark spot with my 200p SW reflector. It was wonderful. LP map shows Bortle 4, but I would actually say it was a 3 or possibly a 'bright 2' when the lights go down a bit in the wee hours.
      Last night, I took the 20" dob and parked up. I am finding it easier and easier to move this beast around, but it's still a little bit of work to set up at the end of the day (literally). It can't all be so easy!
      I'm fairly new to astronomy and my scopes haven't seen a huge amount of use. After several failed attempts to get the GOTO working, I finally sussed it last night. It was just a few simple things really - small errors on my part such as a misplaced washer which blocked the azimuth from using its full range of motion, combined with a limited view at home which prevented me from doing a successful align. A huge relief to get the GOTO up and running, but I now feel a bit like I'm cheating!
      I don't feel guilty enough to not use the GOTO however😁 Frankly, it's brilliant and was putting objects bang in the centre of the EP.
      I arrived about 6pm yesterday so plenty of time to set up. I left my counterweights at home and thus ended up strapping a small vinyl bag of tools and tyre jack to the underside of the mirror box with a tie-down. Worked really well actually! Can fine tune by removing a spanner or two.
      A few drops of rain blew through just before dusk but then rapidly cleared off, so all systems go.
      I tripped over the power cord after my first successful align. And then did it again a minute later after my second align! Will need to tidy that arrangement up or put some of my glow tape on the cable. Plenty of practice then doing an alignment, haha.
      M57 Ring Nebula for starters, I've been playing with my Baader 36mm aspheric quite a lot lately, I like the wide views. The Ring was fairly small through the 36mm but bright and crisply defined with an apparent faint blue tint. I then swapped to the 21mm Ethos and OIII which stayed in the focuser most of the night. 
      Next stop was NGC6960, Western Veil Nebula or 'Witch's Broom Nebula' which was mind-blowing. It appeared as a silvery apparition which threaded right across the sky and extended well past the FOV from the 21mm Ethos. Scanning along its wispy tentacles was amazing. There's something unnerving about viewing it, it gives me goose-pimples, just otherworldly. The Eastern Veil and Pickering's Triangle in the central area were also clearly prominent, albeit slightly less luminous than 6960. The Veil was also clearly visible without the OIII, but with much more 'background noise', i.e. stars competing for attention.
      Following this, I slewed over to the Cocoon Nebula, but only saw a very dark lane practically void of stars. That was interesting in itself as it was so apparent by virtue of its darkness.. I don't know if I bumped the scope alignment of if I was just too impatient to punch another object in to the handset, but didn't spend a huge amount of time chasing it. In hindsight, I think I slewed to the wrong end of the dark lane. I'll find it next go.
      I then lined up on the Crescent Nebula which was easily visible, lots of fine filamentary details observable after some time studying it. A beauty.
      Next was Dumbbell Nebula which practically looked 3D through the big dob, just jumped right out at me. Another simply amazing sight. I spent quite a long time staring at it and could easily see the entire shape and structure extending from the 'Apple Core'. I remarked last night it looked like it was hanging inches in front of the scope. That's sheer aperture working I suppose!
      At the end, I spent some time just slewing around and having a mesmerising look across the sky, just taking in the depth and variable magnitude of stars that a big scope can display. I was already running on three hours' sleep from the previous night and by this time, I was starting to crash but was on a natural high. I crashed into the bed happily.
      Can't wait for another clear night with the big dob. I was a bit worried a few weeks ago that I'd bought something I didn't have the time or skill to fully appreciate, but getting the GOTO up and running and being able to rapidly slew to various objects really put things into perspective. My 200p is a wonderful, portable scope, but in comparison, 20" of aperture is simply a completely different level. It is like the difference between a small grainy 640px video and high definition 4k with the brightness cranked right up.
      Tonight I shall stay in, sleep well and dream about how much discarded glass is needed to cast a 36" mirror blank and how many years it would take me to figure it...
       
      Clear skies all
       
       
       
       

    • By Michele Scotti
      Hi everybody,
      i'd like to share with you the design, making and progress of a project my astro club endeavoring to. I'll post here relevant info in a run-up  to where we got to so far.
       
      Here is the mission: 800mm in diameter. That's it. A lot of inspiration out there but it needs to be able to do science. So it's a relatively fast Newtonian capable of tracking for tens of minutes.
      So we realized that we were facing 2 projects in one. The mirror on one side and the mount on the other. Shall we start with the mount? What's the best compromise in terms of ease to build and cheap components and the chance to have a stiff yet light structure. An alt-az, like the biggest telescope! - or rather a glorified dobsonian in this case.
       
      Ambitious? Definitely
      Any comment/suggestion is welcome!

    • By Piero
      Very happy with it! Wish the sky were clear, but as we all know, when we buy astro equipment, it's cloudy! Argh!
      The telescope was collected from David Lukehurst at noon and then we travelled back to Cambridge. 
      John Nichol primary mirror: 37mm thickness, Suprax. Hilux coated. Optics 1/8 PV wavefront  1/27 wave RMS. Strehl .95. Secondary mirror: 62mm MA.
      Here a few photos:



       



       

       
       



       


    • By alanjgreen
      Date: Tuesday 29th Jan 2019. 2015-2315hrs
      Scope: 20” f3.6 Lukehurst Dob with Paracorr (fl = 2089mm & f4.1).
      Night Vision: PVS-14 with Photonis 4g INTENS.
      Eyepieces: Plossl 55mm (f2 x38), Panoptic 35mm (f3 x60).
      Filters: Chroma 5nm Ha filter.
      Moon: 0%
       
      Make Hay While The Sun Shines.
      The Weather forecast changed and was now showing as two clear cold nights coming my way. I have had a couple of sessions already but we all know that you must “make hay while the moon is away” in this game!
      My plan was to hit Orion hard and make up for the disappointment of the windy night last Sunday which kept me inside until Orion had passed the drop-down side of the shed.
      Tonight I also planned to bring the Panoptic 35mm into play for a little more magnification (x60) on my chosen Ha nebula targets.
       
      An Initial Run with the 55mm Plossl.
      I had myself setup (in the shed) and aligned (Nexus 2-star) by 2015hrs and loaded the Chroma 5nm Ha CCD filter onto the Paracorr2. Then inserted the 55mm Plossl and attached the PVS-14 Night Vision Device to it using the TNVC a-focal astronomy adapter.
      Flaming Star – First up was the Flaming star. It provided a decent view with some wispy fine detail including the two right angles of the back corner and multiple bright fuzzy lines at varying angles within). The 3D view of “my best outing” was not repeated on this occasion so I determined that the sky was not “at its best”.
      IC410/417 – I nudged over to IC410 which was looking good with three black holes on one side and another large black hole on the other side. The nebula was more lush than the Flaming star and I enjoyed the view. Over to IC417 where the “spider” was visible but again not “at its best”.
      M1 Crab – I headed down to the Crab and was rewarded by 5 nice ovals shapes interlinked in a bubble like structure. It took time and averted to tease out the outer bubbles whereas the central bubbles were much easier.
      NGC2174 Monkeys Head – Over to the Monkeys Head and I was greeted with a very bright and “in your face” view of a neanderthal man. The edges of the facial features showed several bright areas. There was a tiny nebula spot set away from the mouth and a bright spot around the “ear”. The larger right patch to the neck (that I have seen previously) was there but took some averted to see it.
      Sh2-269 – small bright “angels wings” shape.
      Sh2-267 – medium sized faintish patch.
      Sh2-268 – Faint and large. Like an upside-down pear drop. I could see black detailing inside around a line of bright stars.
      Sh2-270 – FAIL. I am missing this Sharpless object and I failed to find it once again! I found a “candidate” but internet research this morning says that it was not it. I have compared sky safari location to an image and it seems they are slightly out so I have added a marked into sky safari ready for my next attempt. This object is only 1’ x 1’ size so maybe I need more magnification?
      HorseHead IC434 – Up to IC434 and Wow it’s really wide and bright.  I nudged above Alnitak and there was a lovely shapely horse head. The head showed the snout and neck but I was also attracted to the bright white line that was running through IC434 as it was really standing out. As I nudged around, it really was amazing to see just how long and wide IC434 actually is. The whole of this region is just full of a faint nebulosity glow.
      Flame – I nudged down to the Flame and at last it was a view to savour. My last couple of visits have been underwhelming but tonight it was standing out bold as brass. I could make out many wispy black details to the RHS and see the small black circle to the LHS. It really was nice but I had to go back to the horsey as it was probably “beating it” for loveliness tonight!
      M42 – Fantastic. I swore out loud as M42 swung into view. God its bright and God its lovely. The swirling, looping nebula behind the fish head is overwhelming. The ray of black hydrogen spewing out of the mouth of the fish head is like an “oil leak”. There is so much to see that I settle in on my chair and let it float across my fov several times as I try to tease out a detail that I have not noticed before. Tonight I settled on a couple of black areas to the LHS lower of the fish head. I even though that I could see the Candle Star sitting in the fishes mouth. I could see all 4 trapezium stars clearly so maybe the transparency was improving…
      Running Man NGC1975 – Time to get into Orion and start with my on-going challenge to see the Running Man. I am gradually building up more mental notes to help with seeing this difficult target. I could easily see a very bright patch sitting over three stars below M43. I could see a black finger coming down the LHS of the 3 stars. I got distracted by further nebulosity down underneath an open cluster below and became confused as to where the black legs of the running man actually are?
      Sh2-278 – Triangular kite shaped nebula but faint and time needed to get to grips with it.
       
      Time to Increase the Magnification with the 35mm Panoptic.
      The image presented by the 55mm Plossl (when used with Night Vision and a fast focal ratio scope) leaves a lot to be desired especially around the edges of the fov. The 35mm Panoptic does not suffer from these issues and provides a sharp edge-to-edge view. However, the 35mm only acts as a 0.7x reducer so some image brightness is lost compared to the 55mm Plossl. Therefore, you need to use more “gain” (a knob on the PVS-14) to compensate for the darker image. From my experience the 55mm Plossl seems to always win out because the brighter image just shows more stuff and I just ignore the outer edges of the FOV.
       
      Flaming Star – Back to the Flaming star and I could see some nice texture and details within. The larger image scale meant more nudging was needed and I felt that I preferred the 55mm on this object.
      IC410 – Very nice and the extra brightness of the nebula meant that nothing felt lost on this target. I felt the 35mm was the winner here.
      M1 crab – A nice view. The bubbles were now a little larger but I felt that I was not seeing more than with the 55mm so I will call this one a tie.
      Fox Fur/Cone – With the 35mm loaded, I wanted to see if I could get more from the Cone than the other night. I started at the central star cluster and nebulosity was showing all around except for near the bright stars which seemed to have cleared a nice black patch over them. I nudged up and right to the Cone. It was pretty obvious as it came into view and a decent size too. It felt like it was an inch long and both sides were clearly visible running to a sharp multi colored double at the point. (With NV I cannot see colors but I can see shades and it was noticeable that the double stars were not the same color). I played with the gain control trying to get more out of the cone with not much success. It’s a difficult target and although I could see it easily, if the same view had been presented to my wife then she would have said “where is it?”. I nudged left and right in long sweeps for a while as I tried to cover the area of the Fox Fur nebula (Huge) and see the many lanes of bright nebula within. There was plenty to see but I prefer the Fox Fur view in the Borg107 where I can more easily take it all in.
      Rosette – Holy Cow, the highlight of the night! I would have to say this must have been my “best ever” view of the Rosette even allowing for the fact that I had to nudge around it thanks to the extra scale of the 35mm Panoptic. The Nebula was so lush and large. The extra magnification really allowed me to get deeper into the many intricate black lanes that run within the lower and left sides of this nebula. I found further black areas to investigate in the upper RHS. And I noticed three small nebula patches embedded within the centre star cluster (RHS) which I have not noticed previously.
      Sh2-280 – Nudge down to a large nebula patch with two black eyes. The RHS edge was brighter and also below.
      Sh2-282 – Nudge down to a triangular patch on its side. 4 stars were carving out a black area behind the tip.
      Sh2-283 – A tiny bright patch (located at star HD291952 in Sky Safari).
      IC434 – Over to view the horse head with more magnification and I was not disappointed. The Horse was there in all its glory – snout, neck and an ear. I let it drift across the view a few times. I also noticed that if I turn the “gain” down then the outer edges of the horse head took on a brighter glow? A win for the 35mm here.
      Flame – Up to the Flame which was big and bright. I think that the 55mm Plossl view was slightly more feature-ridden and the loss of focal ratio had taken something away. It still looked great though, don’t get me wrong!
      Running Man – Back to the nemesis that is “the Running Man” and unbelievably I was able to tease out some black edge detail. I could see a vertical piece LHS and a longer horizontal piece under the three stars (more RHS). The black lane seemed to reach up and touch the middle of the three stars too. Another win for the 35mm.
      M42 – You have to don’t you? A great view but with diminished resolution compared to the 55mm Plossl IMHO.
      Medusa – An easy black crescent. It had a very bright tip at the bottom and also a less bright tip at the top. The Crescent sides seemed incomplete and I chalked this as another win for the 55mm.
      Sh2-241 – A small bright patch with a central star and a black area within.
      Sh2-242 – A mid-size patch with an off-centre bright star within.
       
      What Happens when you View an Open Cluster with a 5nm Ha Filter?
      By now I was getting cold and Orion was passed the drop down side of my shed. I headed up towards the zenith and decided to view M37 with the 5nm Ha CCD filter still loaded on the Paracorr2.
       
      M37 – A lovely bright open cluster fills the fov of the 35mm Panoptic. As I turn the gain down on the NVD something interesting happens… A black lane structure appears running in some of the gaps between the stars of the cluster. It takes on an appearance more reminiscent of Caroline’s Rose with conventional eyepieces. I continue to play with the gain. It seems some stars are within nebula lanes/patches and some stars are within or next to these black (Hydrogen) lanes. I stood there pondering whether the stars were clearing the nebula to reveal the blackness or the blackness was somehow connecting lines of stars within the cluster?
      M35 – Onto another nearby cluster M35. Once again, the same thing. With the gain down then black snaking lanes appear within the cluster. But there are lanes/patches of nebulosity too (or is it reflecting dust?)
       
      IC443/444 – I finished with a short hop over to one of my favourite objects, the Jelly fish, IC443. Wow, the detail showing within the pancake of the Jellyfish was great. The flat head had two clear sides and dimmer/blacker areas within. There were some shimmering brighter bits too. The outer edges had clear definition as it steps down and curves away. I could see a single thread heading away from the pancake head towards IC444 and followed it away from IC443. I eventually ran into four thick parallel lanes of nebula near the strangely named “Tejat Posterior” star. I went back to IC443 and followed the tentacles running away to the left this time.
       
      Thoughts of the observer.
      It was nice to get some use from the Pan35 at last. I seem to robotically load up the 55mm Plossl these days. I did prove on several targets that the extra magnification of the 35mm Plossl cannot compensate for the loss of focal ratio provided by the 55mm Plossl. BUT I did also see some benefit on several targets notably the Rosette, Horse Head & Running Man. Looks like I need to use both. The dark lanes in the open clusters M37 & M35 were an unexpected bonus and I think I will be trying the 5nm Ha filter on other non-nebula targets (M45 & M13 for instance) in the near future. I have looked on the internet for some Ha images of the open clusters but nothing was immediately found that showed what I was seeing? Perhaps one of the NV phonetography guys can get a shot of this feature? Its forecast clear again tonight so I packed up early so I could get some sleep in preparation.  
      Hope you are getting some clear skies too?
      Alan
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.