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alanjgreen

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alanjgreen last won the day on January 17

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  1. Time does not stand still... It has been 17 months since I wrote the original version of the above named article and there have been a few changes in the intervening time period… 1. I now have 17 months more a-focal experience of using a telescope with a night vision device attached directly to the eyepiece. 2. A new forum has been created for the discussion of such “Electronic Assisted” observing equipment on this website. So I decided to revise my article and post it in this new “most applicable” forum. Let us start with the basics… What is a-focal observing? “a-focal observing” simply means that the night vision device is attached directly to an eyepiece (after the focal point of the telescope). You are placing the night vision device’s objective at the exit pupil point in the light path. The easiest way to achieve this is the use the “TNV-14 Eyepiece Adapter” (available from Tele Vue). This adapter has threads on either side to connect (1) any Dioptrx accepting Tele Vue eyepiece to (2) a PVS-14 Night Vision device. http://www.televue.com/engine/TV3b_page.asp?id=36 Here is a picture of a Tele Vue 55mm Plossl connected to a PVS-14 using the TNV-14 adapter. To perform “a-focal” observing we need to simply insert this “stack” into any telescope focuser. If the attached eyepiece can achieve focus then there will be a focused image available to view in the PVS-14. Here we see the stack attached to my 20” dobsonian and my 107mm Borg refractor… What are the advantages of a-focal? The biggest advantage is that you WILL be able to reach focus in any scope. Unlike other options you are simply placing the night vision at the point of the exit pupil. For Newtonians, this is a big point. Fundamentals of a-focal observing. Now we are past the basics, we have some slight more complicated “fundamentals” to get our heads around… 1. The PVS-14 night vision device is designed to work at a focal ratio of f1.2 (which is very fast). To get the most from the device then we need to aim to send light from the eyepiece as fast as possible to take maximum advantage of the night vision device. A faster focal ratio results in a brighter image, a slower focal ratio results in a dimmer image. - Here we have been given a “lucky break”. Because the PVS-14 has an effective focal length of around 26mm, if we use any eyepiece with a focal length greater than 26mm then the “effective” focal ratio of our system gets “magically” increased. [I will show how we calculate this effective focal ratio shortly but think of this on a par with adding a focal reducer into the light train]. Unfortunately, any eyepiece with a focal length less than 26mm will decrease this “effective” focal ratio of our system. 2. The PVS-14 has a fixed forty (40) degree field of view. It does not matter how wide field our eyepiece is, the night vision device will only ever show the centre forty degrees. This means that you don’t need 100 degree Ethos or 82 degree Nagler eyepieces, narrower field of view Plossl, Panoptics & DeLite’s will be fine. - Again, don’t panic! There will be so much to see in the forty degrees that it will feel like 100 degrees. I have come from 100 degree eyepieces and I have never once wondered where my huge FOV went 3. Eyepiece eye relief is important. You need eyepieces with enough eye relief to match the distance from the top lens surface of the eyepiece to the position of the night vision objective lens. Too much or too little eye relief will result in loss or distortion to the outer edges. What is the minimum set of eyepieces that I need? I use a total of four (4) Tele Vue eyepieces with my Night Vision device: 1. Tele Vue 55mm Plossl. This is my main work horse eyepiece. I use this eyepiece for >90% of my observing time. The reason it is my most used eyepiece is that it gives my telescopes the fastest possible “effective focal ratio” (which results in the brightest possible image at the eyepiece). In simple terms think of this eyepiece as being able to double the speed of your telescope (like a 0.5x reducer). I use this eyepiece for nebulae, galaxies & open clusters. 2. Tele Vue 35mm Panoptic. I use this eyepiece occasionally when I want more magnification but still want a bright accelerated image (it acts like a 0.7x reducer for the effective focal ratio). An alternative to this eyepiece would be the Panoptic 41mm - I use the 35mm because it’s half the weight of the 41mm! I use this eyepiece for nebulas, galaxies, comets, large open clusters. 3. Tele Vue Panoptic 27mm. I use this eyepiece again for greater magnification, usually for supernovae, globulars, comets & open clusters. I do not use this for nebulas and galaxies as the effective focal ratio is now too low and details are becoming lost at the eyepiece. 4. Tele Vue DeLite 18.2mm. This is my least used eyepiece (as its focal length is smaller than the 26mm of the night vision device). In use, it has the effect of slowing my effective focal ratio and producing a dimmer image. It does however produce about the maximum useable magnification with my night vision a-focal setup and I have been successful using it for faint tiny supernovae and bright globular clusters. What about the huge exit pupils? [Exit pupil is the width of the light beam being emitted from the top of the eyepiece and traditionally astronomers baulk at anything wider that the width of the astronomers own eye pupil as it is not possible for our eye to consume the whole of the light beam] [Exit pupil is calculated as the eyepiece focal length divided by the telescope focal ratio so a 55mm Plossl in an f4 scope will produce a light beam 13.75mm wide] As the night vision objective lens is 20mm wide then it can take all that light in and process it with room to spare! Whilst your eye pupil would be flooded and loads of light wasted, no light is wasted in this case. But as the eyepiece focal lengths get shorter (and the exit pupils get smaller too), the night vision device soon starts to become starved of light. How do I calculate this “eyepiece focal ratio” exactly? Now seems the right time to show the maths to calculate the “effective” focal ratio of your telescope/night vision setup: Effective focal ratio = NVD / (EPFL / TFR) where NVD = night vision device focal length = 26mm EPFL = eyepiece focal length TFR = telescope focal ratio As an example, if we have a telescope with a focal ratio of f4, the 55mm Plossl will produce an “effective” focal ratio of f1.9. [Effective focal ratio = 26/ (55/4) =1.9] Does the focal ratio of my scope actually change? The answer is NO. These changes in “effective” focal ratio that I mention only happen inside the night vision device. If your scope is f4 then it will remain f4. Is a-focal observing, low magnification observing? Simple answer = Yes it is. You need to get as much light as possible into the night vision device as fast as you can get it to go. All of the photons that you can get into the device will be amplified by the night vision device enabling you to see views containing previously unseen detail. In some cases, the amount of new detail on offer will be overwhelming! At first, you will want to change eyepieces to achieve greater magnification but you soon discover that you actually see less detail (due to loss of effective focal ratio and exit pupil) so you soon return to the longer focal length eyepieces. How do I calculate the magnification that each eyepiece will give me? There is no change here. Take your telescope focal length and divide by eyepiece focal length. If your scope has a focal length of 1800mm then you would get the following magnifications from my eyepiece set: - 55mm Plossl (1800/55 = x33) - 35mm Panoptic (1800/35 = x52) - 27mm Panoptic (1800/27 = x67) - 18.2mm DeLite (1800/18.2 = x99) How do I calculate the TFOV? I used Sky Safari for this. I setup my eyepieces in the “equipment” section using a setting of 40 degrees for the fov and it did the rest… Can I use a coma corrector with night vision? If your telescope has a fast focal ratio and you find that you need a coma corrector now then you will still need it for use with night vision. I used a Tele Vue Paracorr2 with my 20” dobsonian before I had night vision and I am still using it with Night Vision. In a big reflector, the best place for filters in the light path remains on the bottom of the Paracorr. What about filters? This brings us nicely onto every astronomers “favourite” topic – filters! When combined with filters, night vision devices can allow us to not only see what was not visible before but also to steal back some darkness by blocking out our old enemy, the moon! In the Cumbrian countryside, the night sky has an SQL of around 21.6, class 4 Bortle. Please take this into account when reading my experiences as your SQM may not be the same as mine. 1. General observing – For general observing, I do not use any filters as the best results are achieved by letting all the light into the night vision device. The PVS-14 has manual GAIN which means there is a knob that can be turned to decrease the gain and darken the image at the eyepiece – this is the only filter that I use in general observing. Moon – If the moon is up then I add a Baader 610nm Red filter into the light path. This is a good filter for reducing the effects of the moon on the sky background. It can also be effective if viewing low to the horizon where light pollution can be an issue. 2. Filters for observing Nebulae For nebulae viewing, a narrowband Ha filter in mandatory. I have tried 12nm, 6nm and 5nm and my preferred choice of bandwidth is the 5nm. As this filter is the “key” to seeing nebula then please do not scrimp of a “cheapie”. If you want to get the maximum from your expensive night vision device then only consider top brands such as Chroma, Astrodon, Astronomik or Baader. I am currently using a Chroma 5nm Ha narrowband filter. Your choice of Ha narrowband filter will directly affect whether you see some of the fainter nebulae objects or you do not see them! 3. Filters for observing Galaxies For galaxy viewing, there is no filter that can improve the unfiltered view. However, if the moon is up then I use either the Baader 610nm red filter or an Astronomik UHC Visual filter. If you are viewing tiny smudges then either are okay, if you are viewing larger galaxies with spiral arms, then I find that the Astronomik UHC Visual filter gives slightly more spiral arms than the 610nm red. Both beat unfiltered viewing if the moon is up. @GavStar is using a “Baader IR pass” (685nm) filter from his city location for all non-Nebula targets to cut out the light pollution. Which night vision units can I connect to my telescope for “a-focal” observing? As a UK based astronomer there are very few options for us to purchase a Night Vision Device with the latest military specifications. The Tele Vue adapter works with the PVS-14 night vision device so this led me in that direction. I purchased my PVS-14 from www.actinblack.com based in Luxembourg. Please do read my article on “Understanding Night Vision Tube Specs a little better” and do be prepared to wait a month or two for actinblack to get a new batch of tubes into stock (from which you can then pick the best one for astronomy use). I had to wait two months for a new batch of Photonis tubes to come into stock before I was sent three tube specification sheets to choose from via email. Having selected my tube then it was delivered to me in under a week from placing the order. Which telescope do I need for Night Vision? This is a good question and one that will be debated long into the future. My opinion is that the best telescopes for a-focal night vision use are telescopes with fast focal ratio. I am using an f3.6 dobsonian and an f5.6 refractor. Our goal is to achieve the brightest possible image at the eyepiece and focal ratio is the key to achieve that. As we can see from above, there is a rather restricted set of eyepieces needed for night vision astronomy but if we pair these eyepieces with telescopes of varying focal lengths then we can get a wide range of actual field of views and magnifications. This drove my minimal set to two telescopes, one long focal length dobsonian with good aperture and largest possible magnifications (with long focal length eyepieces) and one short focal length refractor for wide field with decent apperture (> 4") and light enough for travel. What can I see using Night Vision a-focally? At this point, I want to point you to some of the many posts from @GavStar available on this website. His images do reflect what I can see visually with my two setups. Let me go on to summarize what I have been seeing in the last 17 months since the initial article. Nebulae I have now almost completed the full Sharpless catalog (303 of 313 objects). The only ones that I have not seen are the ones that are too low to my horizon! Galaxies I am working through the 200 brightest galaxies available in the skies above us. This project is more than half way complete and so far I have observed the spiral arms of 68 galaxies with direct vision. Supernovae Last year I viewed 17 supernovae, down to a magnitude of 16.8 Globular Clusters I have so far failed to give sufficient time to Globulars, but their brightness means that I have been able to see some of the smallest and faintest on offer above us. I will get to these once my Galaxy project is completed. Comets Night Vision works well on comets, in a side-by-side test with traditional eyepieces, I saw better results with the night vision device. Open Clusters Night Vision gives great results with open clusters. The smallest ones just jump out at the eyepiece as you nudge around. Planets Failure – night vision is no good for planets. They are too bright. Moon Failure – night vision is no good for the moon. It is too bright. Here are a few links to some of my reports (there are many more if you use the search facility)... Do you still use eyepieces for observing? My eyepiece case has been mostly sold off now. I have a set of short focal length DeLite eyepieces for planetary and I have some eyepiece pairs for solar observing with my Lunt LS60. I use eyepieces to complete the 2-star alignments of my telescopes then it’s become automatic to just switch straight to the Tele Vue Plossl and my night vision to get into my nights observing. With the GAIN turned down it really is no different to using an eyepiece and you just see so much more… Hope this helps somebody, Alan
  2. Date: Monday 7th October 2019. 2340-0350hrs. 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). Filters: Chroma 5nm Ha filter, Astronomik UHC, Baader 610nm Red. Moon: 70% (until 0100am) Introduction With the full moon quickly approaching, the chances of getting outside under a dark sky are diminishing rapidly (for the next two weeks anyway). Last night was forecast clear and by 10pm it was 80% clear with a big old moon shining brightly in the south at about 40 degrees above the horizon. I checked the clearoutside website and saw the moon setting time was 1am so decided to wait a while before going outside… By 2320, I checked again and could see the Moon was behind some clouds so decided to head outside. After spending the last few months in the rear corner of the shed, I had yesterday re-located the big dob more centrally so I could access Cassiopeia (overhead) unimpeded by the shed roof apex. It took me 10 minutes to get the big dob setup & connected to Sky Safari 5 (via my AstroDevices Nexus) ready for the 2-star alignment. I pushed back the shed roof and looked for alignment stars, I noticed that the Great Square was now high and Southern and the thought of M33 popped into my head. Perhaps I would chance a visit to the big galaxies (even though the moon was up). Part 1 - Galaxy Appetiser. Once 2-star alignment was completed, I fitted the PVS-14 Night Vision device to a TeleVue 55mm Plossl and put it into the focuser. I nudged over to M33 using Sky Safari as my guide and centred it up. M33 (unfiltered) – At first I could see what appeared as a large dust cloud, I looked for NGC604 out on the tip of the spiral arm but it was not easily spotted… As I continued to look, I noticed a long curved spiral arm headed south from the central core and it dawned on me that I had forgotten just how large this galaxy is at the eyepiece (even at x38 with the 55mm Plossl), as I traced the arm then I found NGC604 which was small and bright sitting next to a star! The next thing I noticed was a tiny NGC/IC patch sitting at 9’o clock from the core. I looked hard for the upper arm but there was not much showing on the upper side of the central core patch. M33 (Baader 610nm Red) – I decided to try to filter the moonlight out of the view and added the Baader Red filter to the front of my Paracorr2. Once I had refocused, I immediately noticed an improvement in the upper arm view but the lower arm seemed to be less visible than before. I could however see two clear NGC small patches in the path of the lower arm. M33 (Astronomik UHC) – I swapped filters for the Astronomik UHC visual filter which has a slightly wider bandpass than the Baader red and was rewarded with my best view. The upper arm improved once again and I could now see a faint (& large) backwards “S” curve in direct vision. M110 (Astronomik UHC) – I decided to checkout Andromeda and pushed the scope to its location. When I looked in the eyepiece, I saw a mid-size oval patch (it had to be M110). Unusually (at least as I remember it) M110 had a two-tone core, there was a bright small central piece which was surrounded by a mid-brightness halo and finally the fainter oval of the outer galaxy. This may have been my best view of M110! [It is worth noting that I changed my secondary mirror in July from 104mm to 120mm and I am seeing many objects better than I remember seeing them before so I am putting the improved M110 down to the increased secondary mirror size – the 55mm Plossl requires loads of out-focus so I decided to send a wider light cone down the focuser] M31 (Astronomik UHC) – I nudged right to M31 and found a super large central core with 2 vertical black dust lanes sitting on the LHS. I traced the dust lanes up, the first cuts across through the galaxy just after M32 whilst the second continues up to a sharper point further up. The curve of the dark lane at the upper tip seemed to curve back down out beyond M32 (as if M32 sits within the M31 disk), this dark lane quickly disappears so I could not trace it down as far as M32. Below the core, it was much harder to trace the dark lanes but I could trace the edges of the galaxy disk which were faint but noticeable. Part 2 – Search for visible nebula (not in the Sharpless catalog). My latest project is the creation of a new catalog of nebula objects that are visible with Night Vision plus Ha narrowband filter and not present in the 313 Sharpless catalog. The AG1-x catalog has 56 objects so far... With the Dob in its new central location, it was time to resume my push-pull systematic scanning of the Milky Way above me. I added the Chroma 5nm Ha narrowband filter to the Paracorr2. Unfortunately, I could not easily access my planned starting point as Cygnus was now quite westerly and the shed wall was blocking plenty of the primary mirror in that direction. I reset my starting point higher towards the zenith but still westerly and started to scan backwards…up then forwards… up NGC 7008 – I found a tiny bright “flying saucer” which I identified as NGC7008 by glancing at Sky Safari. GSC 4258-1810 – At this location there is a small patch which Sky Safari seemed to indicate might be galaxy NGC6952. But as I looked around the fov, I found that I could see a second patch (the galaxy). Checking the internet, I see that NGC6952 is also classified as NGC6951, I can see an image of NGC6951 where there is nebula visible to the side. TYC 3194-1302-1 – At this star location, I found two bright “angel wings”. They were mid-size in the fov and were bright. Nudging around, I could see that they were part of a much larger structure (which turned out to be sh2-119). NGC 7048 – I found a small bright circle at this location. A planetary nebula. It was very interesting many shimmering lines and variations seen within the small visible circle. Sh2-129 – Next I bumped into a beautiful thick curved section with nice detailing on the edges of the large nebula. Checking Sky Safari, I found it to be sh2-129. It’s a lovely object (one half is similar to the Witch’s Broom in the Veil) while the second curve is much less defined but wide and easily seen/traced. IC1396 – Next, I bumped into an old favourite, the Elephant Trunk. I was expecting a good view with the dob relocated but what I got was a WONDERFUL view. I spent many minutes slowly combing this large object and noting the many black hydrogen holes and lanes visible seemingly all over this large bright patch. I also noted several bright highlights that stood out as brighter than the general bright background. I opened up an image of IC1396 from Sky Safari and made a second sweep across the object to check out each and every one of the black patches seen on the image. The two sections of the elephant truck were very clear and there was a third dark lane sitting alongside them that kept taking my eye too. [Time now 0140hrs – Moon has gone] TYC 3968-1328-1 – At this location, I found a faint vertical lane of nebula. It led into a curved horizontal piece higher up. Sh2-132 – Next, I bumped into a very bright and interesting nebula (Sky Safari shown sh2-132) which turned out to be the “Lion”. The bright mane section really seemed to fill the fov with some lovely black detailing and the occasional brighter line. I traced the back and then the tail, down past the hind quarters and left through the faint legs area to just about see the faint head/snout section. Nice. Sh2-135 – Bright set of “angel wings”. Sh2-134 – Covers a huge area. Not a complete structure, you just keep bumping into small sections here and there. Sh2-138 (GSC 3995-1279) – tiny patch next to a star. Sh2-139 (GSCII N0123010-13835) – small faint patch near a star. GSC3997-0919 – I found a large faint patch at this location. Sh2-152 & sh2-153 – Next, I came upon a nice nebula combo (“Whale & baby” as I call them). Sh2-154 – I thought I had found a bright new piece of nebula when I happened upon a bright star cluster with a long leading edge running behind (LHS). It was wide and very bright but Sky Safari was happy to inform me that it was sh2-154! Cave – I saw the Cave nearby on the IPad and nudged over. Wow, maybe my best view. Not because the Cave was good. The Cave was the Cave but because of all the extra nebula that was visible out to both sides over large distances. There were some nice black cut-outs within this expanded large area. [Time now 0217hrs] NGC7380 Wizard – The Wizard is my next unplanned target. Instantly recognizable. Bright and beautiful with so many intricate details to examine, it really takes a few minutes to do it justice. As I drink up its finery, I am drawn to a large black “t-shirt” section that is standing out just to the LHS of the Wizard, so black, its keeps drawing my eye… Bubble – Wowsers, I had a great view (my best ever) of the Bubble last new moon, it was memorable not for the bubble itself but just for the huge “head” and “torso” of the “Gladiator” that filled the FOV. My luck was in, the full Gladiator was back and I spent a few minutes taking it all in. Its strange that 12 months ago, the joy was seeing the “bubble” but now the bubble is just seen as part of this larger Gladiator and does not really stand out from the remainder of this large beautiful area! Sh2-158, sh2-159, sh2-157, sh2-161 & sh2-163 – I move around this rich area of nebulosity. Sh2-157 (the pincers) is always worth a lingering visit, there is some exquisite detail in the wide head section and it’s always nice to bump into the tiny star clusters out at the “sharp” end. Sh2-161 is the Sharpless designation for this whole area encompassing all these smaller brighter objects, as you nudge around then you can still find smaller separate unclassified nebula sections that belong to sh2-161. ARO115 – I scan around and bump into a tiny faint patch, Sky Safari says “ARO 115”. Sh2-165, sh2-170 – After passing by sh2-165, I find sh2-170 which is in my “best of Sharpless” list. It’s a beautiful mid-size patch with a central black patch with two “eye like” stars within. The black patch is surrounded by a wide nebula halo. Nice. Part 3 – It’s late, time for some “bright” eye candy… Pacman – Another recent Wowser from new moon revisited. I am not disappointed! The black lane looks like an upside down “sleek black cat” with 2 pointy ears. The nebula to the LHS is huge and almost white with brightness whereas there is “not a lot” to the RHS of the black cat. The outer edges are a fainter shade and extend way out to the LHS. The lower edge is a lovely multi-shaded section that really attracts my eye. Heart – With the dob relocated, I can now reach the Heart & Soul. And I am not disappointed except for the fact that it’s just so big, it really is a nudge-nudge challenge to get around the whole object and not miss anything! The “mole head” is upside down but I see a small patch just to the side and a black hole section. It looks like “the mole is trying to post a small patch into a round bucket”. Over in the central “bright city” section, I see many shimmering small curvy lanes, it’s hard to count them as they overlap and shimmer over each other. I notice many small Sharpless objects dotted around the outer edges “like little boats anchored just off the beach” but I am too short of energy to note and name them individually. Soul – I centre the head and instantly notice that it has a black eye section and a jagged mouth section cutting back into the head. (I can’t remember these but it’s been a year!). I notice a small black hole within the arm/elbow section too. Monkeys Head – Bright and picturesque. I scan around but don’t notice anything that I have not seen before. M1 Crab – The crab is a strange object and improves the longer you look at it. It starts out as a patch with shimmering lanes inside. But if you stop and look the lanes turn into five bubbles that shimmer and jump around as you look at them. This object seems to be “alive”. IC410 – Wowsers. It’s the “Stay Puft Marshmallow Man” from Ghostbusters . A large “Mr. Fluffy” face fills the FOV. It’s so white and it has two black eyes and a black nose hole. Two small bright curvy “tadpoles” sit nearby. California – After visiting the Spider and the Fly, I head over to the California nebula. I am rewarded with a final “best ever” viewing for the night. Wow, I have never seen IC1499 like this! The nebula is literally 3D at the eyepiece. I have to step back and process what I am seeing before heading back to my periscope to spend some time enjoying the view. The sides are seen as white hot almost horizontal lanes then the inner section just seems to fall into the eyepiece which my brain perceives it as steep curving section in then back out at the other side. The small black eye just stands out centrally. I head out to the LHS where the California has a bright “crown” section and look up for the “flap” which is bright and clear. I trace out into deep space of both ends as the nebula seems to never end but just fade away fainter and fainter until it’s gone from view. Epilogue. By now, clouds are coming and going as is the view from the eyepiece. I check the time -0345- and decide that I have had a great night and I will get the roof closed just in case there is a “shower”. I am not too cold, which makes a nice change from last new moon when I felt frozen at the end of my last marathon session. This had prompted me to get out my full winter wardrobe of thick observing clothes and I was happy that I made the right choice. There was a bit of dew when I turned the light on and I had to towel the UTA dry before I packed up and turned on the de-humidifier. Thoughts of the observer. I had not planned on any galaxy viewing so it was nice to get back into them after what seems like 6 months of nebulas. I was pleased with what I saw given that there was plenty of moon about. Do try out your old “Astronomik UHC” as a moon blocker if you have one! I found 6 non-Sharpless nebula and added them into the fledgling “AG1-x” catalog ready for confirmation revisits (I now have a tentative 63 entries). It’s clear from last night sweeping of Cassiopeia, there is nowhere near as much of the Milky Way visible in this area when compared to Cygnus so I will need to work harder and longer to find new (to me) stuff to observe. I can see Orion moving South and now have a burning desire to test out the bigger secondary on the many bright nebula waiting for me in that area of the sky… Hope you had a clear night too. Alan.
  3. Peter, Thanks for all your help in getting me started into the world of Ha observing ! All those observed in the 4" Borg (marked "B") should be doable. Those seen only in the 20" (marked "D" and no "B"), you may need to borrow Gavin's 16" ... Alan
  4. Introduction Having just published my "Best of Sharpless" object list... Here is a full list of the 313 Sharpless objects together with their location information (based on nearest star from Sky Safari) and with a GOTO reference for your mounts (I was using a SynScan handset). For those astronomers out there with a Ha narrowband filter and an urge to get images of "something new" or "something different" then here is something to get your teeth into! I have just spent the last 16 months exploring 303 of 313 Sharpless objects and I had a great time, there are some very rarely observed objects in this list What follows is a data table of all 313 Sharpless objects. For each object the table shows: Sharpless Reference, Observed? (1=YES), Best Of? (1=YES), Physical Size, Scope Used (B=Borg107FL, D=20” Dob), SS Star Ref (An object that I located manually at this star position), Goto ref (Closest SAO, NGC, M object for Goto mounts), Catalog Name (The more famous objects already have a name) In SS? (1= object in Sky Safari, 0=No) Note (details Sky Safari/Bracken errors) Here is the raw excel file: sharpless targets v8.xlsx Hope this helps you find and observe one or more of these wonderful nebula Clear Skies, Alan
  5. Introduction I purchased a Night Vision Monocular in April 2018 to attach to my TeleVue eyepieces and use for astronomy purposes. Initially I purchased an Astronomik 6nm Ha filter (I later switched to a Chroma 5nm Ha filter) to allow me improved views of many visible nebula but I discovered that I now had access to a whole new world of previously invisible (to me) nebula. I discovered that many of these were in the “Sharpless” catalog and began a journey to see how many of the 313 catalog objects that I could find/observe. I wrote an article in the Webb “Deep Sky Observer” (Issue 181) detailing my joy and initial efforts to observe the Sharpless objects using my Night Vision Monocular. Last week, I observed my 303rd Sharpless object. Of the ten outstanding, one does not exist (sh2-214) and nine and very low on my Southern summer horizon (and will be left for a Greek holiday sometime in the future!) so I am ready to publish my findings in the hope that they may assist others who take the same route in the future. Finding the Sharpless Objects Before you can observe an object, you need to find it and get it into the eyepiece (obvious)… My main scope is a 20” push-to Dobsonian which I attach to Sky Safari 5 Pro and push to my chosen targets. I soon discovered that the Sky Safari database only contains 249 entries and a small number of these are in fact erroneous or duplicates. In all, I have had to locate 75 Sharpless objects manually… I would like to call out the book “The Astrophotography Sky Atlas” by Charles Bracken at this point, as my search would have soon been abandoned if it had not been for this book and its great tables of Sharpless object data (at the back). With this data and the galaxymap online explorer, I was able to use sky co-ordinates to find nearby stars (in Sky Safari) and then hunt around that area to finally find and record an accurate positional star. Many Sharpless objects are huge and so I also employed a second widefield scope, a Borg 107FL, which I paired with a Skywatcher AZGTi GOTO mount with SynScan handset. As I found the Sharpless objects, I recorded the nearest SAO catalog star and then used this for the GOTO mount to get the Borg107FL on target. Unfortunately, I discovered that the SynScan handset does not hold the full SAO catalog, so once again there was some “on the fly” rework needed to get the nearest SAO that was in the handset identified and recorded! The Best of the Sharpless catalog Many of the Sharpless objects were underwhelming at the eyepiece (when compared to objects like the Rosette, Gamma Cygni or the Orion nebula) but when you consider how faint and small some of these objects are then there is more to this than just the “visual beauty” perceived at the eyepiece. However, there is no denying that many Sharpless objects are very beautiful at the eyepiece and in many cases are equal or even better that the better known and more photographed Messier nebula objects. I am therefore publishing my “Best Of Sharpless” list, it is entirely based on my own perceptions so feel free to disagree with the objects that I have selected, I will not be offended. My goal is to inspire just one person (who has an Ha filter) to turn their scope to one or more of these objects and for them to observe an object that they have never seen before! What follows is a data table of 115 Sharpless objects (the best of according to me). For each object the table shows: Sharpless Reference, Physical Size, Scope Used (B=Borg 107FL, D=20” Dob), SS Star Ref (An object that I located manually at this star position), Goto ref (Closest SAO, NGC, M object for Goto mounts), Catalog Name (The more famous objects already have a name) Here is the raw excel file, Best Of Sharpless v1.xlsx If you have an Ha filter then I encourage you to give them a try! Alan
  6. Good luck, you won’t find any as I won’t be posting in this section. Sad but true. Alan
  7. I am afraid that this was covered two weeks back when it all got a bit ugly in a “please make them go away” posting by a seasoned observer which resulted in NV users being banned from posting in the general observing forums. The last thing I want is an NV only forum, with 4 NV users in the UK we may as well just arrange to meet directly down the pub! HTH your understanding. Alan
  8. It appears that we NV users are supposed to join in discussions on "live stacking" and other things that are of no interest to us whatsoever! I wont be bothering.
  9. As a visual only observer, I have no idea what live stacking is! My observing does not involve the use of cameras, software or computers so I cannot answer your question! I use an NV device attached to various Televue eyepieces directly at the telescope which I view as “visual” astronomy and I do not see it as the same as EAA at all! I am sure the live stackers and EAAers that will post in this new forum have no interest in NV as they are into the “software” and “cameras” that I assume you use with this “live stacking”. In my view these are not at all the same as NV but I am in the minority (who seem to governed by "senior observers" on this forum who don’t like/want to read about what they cannot see (they see it as "oneupmanship" - it has already been stated by one senior observer that my observing reports posts are just my attempt to "put one over on them"). They just want the NV posts in a side forum where they can be easily avoided and it seems the mods are of the same mind. It’s all very sad really! But back to your question, I am sure an EAA guy will come along and answer your question but that is not me
  10. I agree with Gavin. I have no intention of posting in EAVVAAA or whatever you call it. I am a visual observer too! Alan
  11. Discovered 12 March. Mag 15.1, type unknown (tbd) http://www.rochesterastronomy.org/novae.html#2019bsd Could be one to watch as it should brighten further... shame it is so poorly positioned at this time of year Alan
  12. I also use a v4 handset with my AZGTi and like the extended catalog available. The app has a very limited selection that is too restricted for my liking. The handset is also much more tactile and easy to use wearing gloves. I just stuck velcro on the back of the handset and wrapped some more around the legs of the tripod so it is easily docked when I need my hands free. If you want to beef it up further then I would refer you to the stronger skywatcher tripod that is available, it’s a lot stronger that the standard and still very lightweight too. https://www.firstlightoptics.com/alt-azimuth/sky-watcher-38-stainless-steel-tripod.html i also refer you to the new ADM saddle upgrade which is also a big improvement on the standard version But it’s a great little mount and made to travel with. Alan
  13. You remove nuts from fixed threads and the poles lift off. The bolt thread is a fixed part of the mirror box. The poles just have holes in to push onto the threads. Each side and pole is numbered so it’s easy to get them on the correct side. You can see the attachments and the fixed bolts in one of the pictures in this post http://www.fjastronomy.com/reviews/18-inch-f4-3-david-lukehurst-dobsonian-with-nichol-optics/ (It’s the last picture of the collapsed scope) Alan
  14. Hi Paul, The first two are "type 1a", and are both recently discovered. Type 1a have a larger brightness increase than other supernova types. We can expect them to get brighter than the quoted recent magnitude numbers. They are also good for a couple of months although the brightness fall-off is steep once maximum has been reached. see https://en.wikipedia.org/wiki/Type_Ia_supernova SN2019bic found in UGC5072 (12.7"E & 18.5"N), Type 1a supernova discovered 27/2/19, Mag 16.5 SNAT2019bpc found in UGC7744 (3.8"E & 3.4"N), Type 1a supernova discovered 7/3/19, Mag 16.1 The other common type is a "type II" (which is subdivided into II-P, II-L, II-N & II-B). These supernova gain less magnitude (from the starting point) compared to a type 1a but they have a longer "tail" and therefore survive for many months visually. https://en.wikipedia.org/wiki/Type_II_supernova I just found this on wikipedia... The last two columns are interesting, 60+19=79ish days for a type 1a & 30+150=180ish days for a type IIn. SN2019bic found in UGC5072 (12.7"E & 18.5"N), Type 1a supernova discovered 27/2/19, Mag 16.5 - 27February + 19 days = 18 March reaches PEAK Luminosity (ish) - 27February + 19 + 60 = 18 May fades to 10% luminosity SNAT2019bpc found in UGC7744 (3.8"E & 3.4"N), Type 1a supernova discovered 7/3/19, Mag 16.1 - 7March + 19 days = 26 March reaches PEAK Luminosity (ish) - 7March + 19 + 60 = 26 May fades to 10% luminosity Do you think that you can get them from town with your NV gear? Certainly, the NV kit is helping me with supernova where I am now able to get to see those around Mag 17 or less (a Mag 18 was beyond me recently), I have to use an 18.2mm eyepiece (giving x115) magnitude (any more means loss of brightness and less reach into the lower magnitudes) so this means that I may not be able to split them from the core if they are close-in. I could not get down to these levels of (lack of) brightness before when I was using traditional methods although the greater magnification I had available did give me more chance of splitting the close-in (to the galaxy core) supernova. The mind boggles when you read the distance to these galaxies (which are calculated thanks to type 1a supernova (as I am sure you know)) and think that you are witnessing events that happened millions of years ago! - UGC7744 is 74 Million light years away. (I can't find a distance for UGC5072 so maybe this is the first type 1a and they can now measure it or maybe I need to look harder!) - The other thing that makes my mind boggle is the sheer size of an explosion that lasts for months & months. Imagine the poor neighbouring stars/planets/moons being destroyed or changed forever! (Makes me think how lucky we are not too close to any giant stars). I guess that you would need to factor in the loss of scope aperture (20" - 16") and then the change in SQM (mine is 21.6) using the same method of decreasing aperture/brighter skies in the same way we would now - although it may be less affected as NV responds well to star light (or supernova light in this case). Alan
  15. FOUR new (well placed above us in the UK) supernova as follows: (1) SN2019bic found in UGC5072 (12.7"E & 18.5"N), Type 1a supernova discovered 27/2/19, Mag 16.5 http://www.rochesterastronomy.org/supernova.html?#2019bic (2) SNAT2019bpc found in UGC7744 (3.8"E & 3.4"N), Type 1a supernova discovered 7/3/19, Mag 16.1 (now 16.0) http://www.rochesterastronomy.org/supernova.html?#2019bpc (3) SNAT2019bpu found in UGC4551 (5"E & 0"S), Type ?? supernova discovered 6/3/19, Mag 14.3 http://www.rochesterastronomy.org/supernova.html?#2019bpu (4) SNAT2019bvt found in PGC061928 (4.2E & 2.3"N), Type 1a supernova discovered 17/3/19 (yesterday!), Mag 16.8 http://www.rochesterastronomy.org/supernova.html?#2019bvt Just need the moon to go away! Alan
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