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cwis

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  1. Have a read of this: https://calgary.rasc.ca/seeing.htm On a perfect still clear night, the stars through the telescope look like blobs, with a ring round them. You may see more than one ring, I never have. It's basically a diffraction pattern. The larger diameter the telescope, the smaller the blobs and rings for the same magnification, as the resolution of the telescope increases it resolves the point light source of the stars more accurately, if you will. And of course they will be brighter. On more normal nights with poor seeing, the wibble from the atmosphere interferes with the starlight and the patterns start to move - the blob wiggles about and the rings break and reform. That page I linked has very accurate simulations and tables showing various scales for estimating seeing - others may disagree but what I expect in the UK when I step outside on an average clear night is a Pickering 4 or 5 - or "Poor" seeing. This btw will make Jupiter look like it's on fire as your description states - so you were using too much magnification for the seeing you were experiencing. Winding back the mag decreases the wobble and sharpens the image. But it obviously makes everything smaller! @sorrimen makes some very good points about exit pupil too but you're probably too young to have to deal with too many floaters etc so this probably isn't the issue you were experiencing. What 5mm eyepiece did you try, out of interest? It wasn't a Plossl was it?
  2. I'm in a BortIe 5 area and went from a 5 inch newt on a goto to a 10 inch dob so I might have some useful input... Yup - it's better. Much better. More light, more resolution. Sharper larger planets. Barges on Jupiter! Big red spot! Deeper resolution of clusters! Colour in clusters! Amazing moon! Craters less than 3km across! E and F in Orion! When the sky is perfect that is... So most of the time it's better. Slightly better. Only slightly. Andromeda is still a smudge. It's a bigger brighter smudge. Get a really clear dark night and you see some structure. 5 nights in the last year perhaps? I can split the double double with my 5 inch on a good night. On an average or poor night the 10 inch struggles with it... It's all about the seeing. The maximum practical resolution of my 10 inch is 500x I think. In a vacuum. On the average evening it's more like 150-180 depending on your target. Planets 200 maybe? I think I've used more than 250 on Jupiter once in the last 2 viewing seasons, and more than 300 on the moon exactly once ever. Stick a reasonably high mag eyepiece in your current telescope - say 200 times. Look at a bright star. Can you see the Airy disk? No? Just a wobbly squiggle in the sky? Your telescope is better than the seeing at that point then. A bigger one won't help...
  3. That telescope will squash the tripod that came with your Bresser flat! A better tripod and mount will cost more than the 'scope. If you want a bigger telecope, relatively cheaply, the answer is a Dobsonian. Bresser make some really good ones that may be available in your location: https://www.astroshop.eu/telescopes/bresser-dobson-telescope-n-200-1200-messier-hexafoc-dob/p,47842 They have nice large focus tubes and decent focus mechanisms that will carry your camera easily. Although a tracking mount is best for photograpy, a few people do even deep sky photograpy with a Dobsonian...
  4. This is probably cheating.... Cheapy binocular objective lens screwed into a 3d printed adapter with a budget prism from a Meade ST80. I'd like a lightweight RACI so this was a test - seems to work OK! I'm on the look out for a second hand crosshair eyepiece and I'll then shim it to get the focus correct. MK2 will have the dovetail to fit to the scope printed in...
  5. No worries! I'm now looking lustfully as the orrerys on the Cochranes - they are magical things...
  6. I didn't have to write a program - here's an online model: http://cosinekitty.com/solar_system.html Untick realtime update, set Cartesian coodinates to Helicentric, Angular Coordinates to Ecliptic. Then stick your date in to get the numbers you want in the Ecl. Long. column. I tested it against the table in your Cochranes link against a couple of years and got the same numbers.
  7. Ah I see! Yes - that helps!
  8. Hello! Would the angles be relative to the position of the Earth? It looks like something you could calculate fairly easily using Python and Skyfield - the program would only be about 7 lines long! I can help if you like? If you give me an existing calculation for a day I can understand what you want and also sanitly check any numbers I get before I bother you...
  9. Can confirm! This idiot just got some funny looks out in the street...
  10. Hi all, to close off this topic nicely, I wrote Brendan a simple Python program to get the data he needed, which I've enclosed in case anyone else finds it handy! I've commented it fairly extensively so it's probably a nice base for hacking about with even if you're a newcomer to Python (which I am too!) During the course of my research I found the source that I think Brendan's original web source was using - it's the JPL Horizon app, and access is free: https://ssd.jpl.nasa.gov/horizons/app.html#/ API access is also free... I think the issue Brendan had was caused by the parser on the website he was using not being set up to deal will NULL fields from the JPL API - the previous value in that field was printed instead. Tut tut! The Python program uses the module skyfield as mentioned in a previous post. If anyone wants to mess with the program (assuming windows): Install Python https://www.python.org/downloads/windows/ Once done: In a cmd window type "pip install skyfield" and hit enter (this downloads and installs the module required by the program and supporting modules). Download the program from this post and stick it in a folder. Navigate to the folder with your cmd window and type "domaths.py" and hit enter to run it. It will output to the screen - redirect to a file in the same directory like this: "domaths.py > afile.csv" Currently it will print out a year's worth of data, and the location for moonrise calculations etc is set to my house - both can easily be changed by editing the program in a text editor and saving it: Change this line to match your location: yourhouse = api.wgs84.latlon(+51.6441483, 0.7694381) Change this line to change the number of days: datelist = list((base + delta *x for x in range(1,365))) If anyone wants assistance or questions about this program answering - ask! domaths.py
  11. I've had one a few years and print bits and bobs in ABS. @adyj1 is correct though - it ends up being another hobby. I've replaced the hotend, the control board, the bearings, the bed, built an enclosure, run it over the network with a Raspberry Pi.... Now it's dialled in it is pretty much plug and play - I have to fiddle a bit to get dimensionally accurate pieces for push fitting bearings or pcb boards, but that's my fault for using ABS. It's a slippery slope though... Now I want a lathe. And a mill....
  12. Oh yeah - and could you chuck me an extract of your spreadsheet so I know what I'm trying to produce?
  13. Hmmm. Does this data look valid? It's calculated between timenow and timelater (24 hours from now) for the moon. I THINK it's in GMT but the time settings are obviously critical in this and I'm trying to get my head round them... Not sure the location is set correctly in my Pi and I'll need to do that to get a valid datetime object. I'm just cutting and pasting various examples in the docs at the mo - fastest way to gain understanding! timenow 2022-02-22 17:49 timelater 2022-02-23 17:49 2022-02-23 00:47 Rise 2022-02-23 09:34 Set ['Meridian transit', 'Antimeridian transit'] ['2022-02-23 05:16', '2022-02-23 17:44'] Ra now 15h 04m 07.35s Dec now -16deg 38' 03.1" Moon phase now: 254.5 degrees If I get sensible numbers I know I have the datetime correct and I can sort out the rest of the calcs and format the output for you! It looks like the data comes back in arrays thanks to numpy so that should be pretty easy. Edited to add - locations is (+51.6441483, 0.7694381)
  14. Well I'm kind of forcing myself to learn Python at the moment so an interesting short task is probably ideal. Let's start with moonrise and moonset and I'll add the rest of the columns - those two look the hardest believe it or not. The charts go to 2050 by the way... I'll fire up my python environment (Raspberry zero!) and get started. I may be able to find somewhere to host it online too - may be handy!
  15. Funnily enough I was looking at at Python module that can calculate that sort of thing earlier today. https://rhodesmill.org/skyfield/ https://rhodesmill.org/skyfield/almanac.html#risings-and-settings Want me to have delve for you? I'm not a Python person but it seems simple enough for what you want it to do...
  16. To push back a bit in the other direction with your concerns about the optics... I got a 130mm F5 goto newt as my first scope, and after 6 months or so I "upgraded" to a 250mm F5 dob. I say "upgraded" in quotes because upgraded would normally mean I replaced one scope with another - of course not, I now have two scopes! (Actually 4 but that's another story...) Obviously it then became all about the new scope, and the 130 was neglected. Then one night I dragged my "old" 130 out for a session - I needed goto to find some target or other. I was amazed how competant it was! Yes the views were dimmer, or smaller, or less sharp than the dob, (or all three!) but not by as much as I remembered - it held up very well in comparison. So maybe the jump in performance isn't as great as you were expecting? It may not be such a jump in badly LP skies with average UK seeing... Try to play towards some of the inherent strengths of the larger scope notwithstanding your LP - higher mag views of the planets (not long to wait now!), or split some tight doubles - you may then see it pull away from your smaller scope in perceived performance...
  17. Interesting - now £125! The AA 24mm UFF was £135 when I bought one 18 months ago. Must be responding to the introduction of the Svbony UFF clones. - they don't do a 24mm yet though. I really rate my 24mm UFF (not that I have much experience!)
  18. Bit of a delay in posting this - I'm serious considering whether or not to continue with the blog as I feel a bit conspicuous doing it! Never mind. I'm sure very few in the UK missed the clear skies over the past few days.... Got outside about 2130 - the dob had been out there a couple of hours with dust caps on cooling. It was cold and dry and still. No dew on grass or 'scope - weird. Moon: Peeking outside just before I went out there I'd accused LSW (Long Suffering Wife) of leaving a light on somewhere - we rig the house for darkness at the back if I'm going to be observing as the kitchen and bathroom lights in particular light up the back garden like it's daylight. LSW protested her innocence - it was a VERY bright moon. So I looked at the moon. I've never really properly looked before - I think I pointed my first telescope at it a few times but never the dob. Crikey. It moves FAST and is so bright. I didn't use a moon filter as I wanted the bright moon to stop down my eye a bit and remove astigmatism and this seemed to have worked - I ended up with VERY crisp views and noticeably dimmer vision out of the one eye afterwards! I'd checked collimation earlier and found it was bang on - as long as I put the 2 inch to 1.25 inch adapter flat in the focuser (it looked like it had moved a bit - wups!) The conditions easily took the 10mm UFF barlowed to give 254x magnification. One crater stood out as it was near the terminator - Gassendi. I could clearly see the rilles and tiny hummocks on the crater floor and a small crater about 120 degrees from Gassendi A - according to maps it's about 2-3Km across which is amazing be able to see at something like 385000Km distance. I did have to blink a number of times to make sure it wasn't a floater. Looking away and allowing some night vision back I was amazed how much nebulosity was visible in Orion with the moon so near by. I had a quick peek for E and F in the Trap - both visible (F intermittant) at 127x - E just visible at 70x. I'm guessing the moon was washing F out at lower mags. Castor: I seem to be revisiting sights I first looked at when I got my first telescope! This was the star that told me I had a problem with collimation as the barlowed 10mm kit eyepiece I received with the 130ps showed a pair of seagulls rather than a double star. This time round a nice pair of almost resolved Airy disks showed at higher magnifications, but the split was obvious at 50x magnification. I wasn't aware that I may also be able to spot Castor C (I think - anyone confirm?) - something to look out for next time. Mintaka: I was using Turn Left as a source of easy doubles so I picked off a few in or near Orion. Easy split as expected at 50x. The smaller star is supposed to be clearly blue - not to my eyes - perhaps I was still a bit blind from the moon or maybe it's just my yellowed, aging eyes... Meissa: 24mm didn't show the split - a barlowed 18mm did though and moments of calmness showed clear Airy disks and diffraction rings - I so very rarely see them. Sirius: Bright! Too low in the sky to even attempt a split - the star was a mess of shapes and colours under magnification - it looked like a multicoloured sparkler! I thought I saw glimpses of a dim twinkle to one side of it a few times - it turned out to be a reflection of either my pupil or retina! Turned in at 23:15 - didn't feel like I'd actually been out more than a few minutes!
  19. I use SS6 Pro on an S6 - it runs fine but the downloads/updates of files if you've not started it for a while take AGES. I just fired it up a few times and closed it down and eventually it shows fewer files to download and the process completes. Make sure you're on your Wifi - some of the files are HUGE and look out for alerts and confirmation boxes from the google store app etc as this can hang the process. One dialog box in particular I remember I had to answer but it only showed on the status bar - it didn't pop up. I forget what it was asking - sorry! Having said that: my phone ONLY has SS6 and SynScan on it (it's an old phone I use just for astro stuff) so if you've less storage space available maybe it will run even slower.. If you persist with the S6 fire up SS6 every week or so to let it update - even if it's cloudy!
  20. After a couple of months of cloud interspersed with a few short sessions with the ST80 I finally got the chance to drag the 10 inch dob outside. Goodbye tiny pretty pinprick stars, hello big fat fluffy stars but so many, many more of you. Goodbye pleasant soft circular stars towards the periphery, hello scratchy coma! 04/01/2022 Clear Outside had been warning me about the possibility of two evenings of clear skies for a few days, so I was READY! I dropped the dob outside on the 4th while it was still light, made sure the power pack was charged for my heated vest, checked collimation (OKish - looks like secondary mirror has moved ever-so-slightly) and got out there for a couple of hours. To a large degree I was trying to remember how it all worked - I had a quick look at Orion, toured around the sky and took in the Pleiades (nicely nebulous with the dob - can't make up my mind whether that's my eyes or actually really there!) but spent most of the session on Andromeda - it was high up so nice and clear (M42 seemed quite wobbly to me at that time) and I wanted to have an extended session to see if I could finally spot M110. I've found M32 easy to spot, even with the ST80, but even with goto, never spotted M110. Also I've managed to seize my drummer's throne height adjuster so higher targets were far more comfortable. I finally managed to spot M110 with inverted vision after star hopping using the dob view in Sky Safari to place it in the centre of view in the 24mm (50x) UFF. My mistake was expecting it to be compact like M32 - it's much more diffuse and seems a lot dimmer (Bortle 5). I used my new secret weapon to increase eyepiece contrast ( a black t-shirt draped over my head) Should be easier to spot from now on! 05/01/2022 Got outside to a cold dew covered telescope - I like to let it cool slowly with the cover on - seems to attract less dew while it cools. While I was out there the dew on the grass froze - minus 2 I think. A slightly better prepared session on the second night with a repaired seat and thermal socks, double Stars bible, observing fluid (Red wine in the summer (gets warmer) and IPA or similar in the winter (happy cold). I only drank the one - the rest went in the fridge to warm up after the session!) notebook and pen! UFF Whitterings with added astigmatism: I started about 1930 and initially the seeing didn't look that good - I started at the Trapezium and they were moving about a fair bit - the E star was occasionally visible at 50x (24mm UFF). It actually felt warmer than the night before because there was no wind and I think the air was less humid - it may already have been below freezing so all the moisture was probably on the grass instead of in the air. With the 18mm UFF (70x) the E was clearer and the F was hinted at. With the 10mm UFF (127x) both E and F were occasionally clear. I noticed a smaller zone of sharpness from the 10mm than from the 18mm. I'm not sure whether this is astigmatism or coma etc but I tried the 18mm barlowed (140x) and I think it was slightly better - the zone of sharpness was larger. Or maybe it was a slightly smaller exit pupil working to supress my eye's own astigmatism. I don't know enough to be able to tell - I also find I have to be cautious with eye position with regard to star shapes too - again I'm not sure whether that's my eyes or the eyepieces... My prescription seems to be in flux at the moment (aging eyes) so maybe I need specs with smaller exit pupils now - time will tell. I'm pleased the Svbony UFF eyepieces barlow nicely (if you're careful with eye relief) - the 24mm Altair did so I had high hopes... I may pick up the 15mm to complete the set. The 10mm doesn't seem quite as good as the other two UFF designs in the sharpness zone size - nice and contrasty though. Barlowing the 10mm pushed the seeing a bit too far (254x) most of the time but when the conditions momentarily played ball both E and F showed up as nice discrete tiny dots. Plenty of doubles in and near M42 so while I was there.... Zeta Orionis: Blue Blue double easily split at 50x. I had to check with Sky Safari in dob view as I expected it to be harder - perhaps my collimation was better than I thought? Or perhaps the secret contrast weapon is helping? Struve 790: A single finder's diameter from the above. Yellow Blue pair of roughly the same apparent magnitude - a wide split even at 50x. Theta2 Orionis: This looks like a mini Orion's belt! I had no idea they were gravitationally bound. Also in view were S490B and V1073 with pleasant contrasting colours. With lower magnifications I can't help glancing to see if Trap E is visible - distracting! Struve 747 and Iota Orionis: This was my favourite view of the night - at 50x you can see the trapezium (Theta), Theta2, Iota Orionis or Hatysa and Struve 747. Struve 747 is a nice bright white white widely split double. Hatysa is my favourite type of double - closely separated and different apparent magnitudes so it looks like the smaller star is peeking out from behind the larger. I liked the view so much I stepped onto the top of a very long and slippery slope and.. Took a photo. Help! Rigel: Like Iota Orionis and Polaris my fave type of double - a nice bright primary and a shy secondary peeping out. I found out Rigel was a double last year the first night I pointed the dob at Orion. I'd looked at the Trap, meh with so so seeing and decided to try the UFF24mm barlowed and picked Rigel as a close bright target. I saw a sharply defined star and diffraction rings and a tiny perfect second dot. The seeing and transparency were amazing - the campfire smoke had blown aside and the running water I was used to looking through was still. I turned back to the Trap and saw 4x sharp stars with diffraction rings and E and F as perfect little bright dots. It was like that for a few seconds and then the seeing went back to normal - the wobbles poured back, the stars dimmed down.. Amazing while it lasted though! This year at 50x the secondary was almost lost in a diffraction spike but easily discernible. At 70x it was slightly more obvious but both the primary and secondary were dancing about. One day that seeing will return..... I came in about 2145 with a flat battery on my phone thanks to the cold and SkySafari and another one on my heated vest. I thought the thermal socks had been rubbish until I started bringing the kit in and noticed the crunchy frozen grass!
  21. Ah ha! Yes - as I adjusted focus a "ring of sharpness" moved outwards or inwards from the centre. So field curvature then. It's SO different to the dob - there the stars stay sharper (but not sharp sharp!) towards the edge but obviously get more comet shaped... Love the way the stars in the ST80 "pop" in and out of focus!
  22. More than two months after my last session, I managed to get out again for a short time (just over an hour) on M42 and the surrounding area. It's the first time this year I've looked at Orion and the first time ever with the ST80 - I didn't have the time last night to get the dob out and let it cool so I grabbed and gonned! It was windy and 20% cloud cover when I went out, so I didn't have great expectations as to transparency or seeing but with the low magnifications of the ST80 this is less of an issue anyway. It was 4 degrees so fairly chilly. I was running the AzGti on a new power source - a usb powerpack and a 9V or 12V step up voltage converter based on the LM2577 chip: Maximum load is 800mA for this chip (not sure whether on the 12V or 5V side) - I did some load tests to check and logged load during my session. Here's power utilization with a phone connected to the on board WiFI and the unit tracking: And here's the power during a maximum speed two axis movement: The usb power meter showed peak current was 650mA during the session (probably when I leaned on the telescope or something) so it looks like it will be fine. It powered the mount happily for the hour and was still showing 99% battery remaining, which is promising although probably inaccurate but not bad for 20 odd quid all in. I'm going to 3D print a holder for the battery so it slots into the battery compartment of the AzGti so the unit is completely self contained. During the session I used the following eyepieces, the two middle ones being new UFF ones by SVbony from Amazon I got during Black Friday - I got these because I liked the Altair UFF 24mm so much: Initial impressions (I'm neither experienced enough or knowledgeable enough for a review!) are that the 18mm in particular is very much more of the same - lovely sharp stars across lots of the field that soften progressively towards the edge with the ST80 (curved field?) with loads of contrast. The 10mm seemed to have a smaller sharp spot, but a similar amount of contrast - it darkened the sky over London nicely to allow the nebulosity of M42 to show up far more clearly than through the 24mm or the 18mm and the teeny, tiny trapezium (at 40x magnification) shone out beautifully. All three eyepieces are fairly picky when it comes to eye position being central, and I noticed a few times it was easy to get under the eye relief of the 18mm in the same way as the 24mm so it takes a bit of practice to see the field stop consistently - less so with the 10mm. None of the eyepieces are parfocal to me. Overall I'm really pleased - I hope the 18mm and 10mm barlow as well as the 24mm (didn't get a chance to test last night) and work well in my dob - I'm on the way to being able to retire my cheapy zoom! Seriously temped to get a better barlow (any recommendations?) and the 15mm Altair model would be after that to give me 24, 18, 15, 12, 10, 9, 7.5, 5 and 4 with my Nirvana. I'd only really want a 6mm then probably? On to the last new bit of kit (to me!) an old black t-shirt. I used it as a shroud to see how I would get on with a proper one. I liked it but I'd need a thicker one (I could see light through the fabric which was distracting) . One unexpected upside was that it was lovely and warm in there, and my 4mm Nirvana that I normally avoid using as it mists up so readily steadfastly refused to mist up! I used it to chase the E and F stars of the Trap - no luck on either but the nebulosity showed up really well under the shroud even at 100x magnification. Not sure whether to make my own or buy one. So a short, packed session on just one target - lots to take in and think about for the future and quite frankly it was great to get out there again, however fleetingly!
  23. That looks pretty much OK! You are looking for: 1). The secondary mirror looks like a perfect circle and is bang in the middle of the focus tube. It's a bit difficult to make out from the pic above but it might be a bit out - looks a little to the right and down from centre. But you be the judge - it could be the pic... Looks circular though - excellent! 2). The primary mirror reflection is centred so the three clips and maybe the mount for the primary (depending on how far the focus tube is racked out) is concentric with the outside of the secondary mirror I'd say - yup - looks good on that one. 3). With both the above satisfied, the black dot of the refection of the hole in the collimation cap is in the middle of the doughnut in the centre of the primary mirror. Yup on that one. So - check on point 1) - but it looks like it's fine. Personally, even if it's a bit out with point 1). I'd leave it - it's probably better than the average eyeball at this point anyway. Astrophotographers have to be far more picky with regard to collimation... Read up on doing a star test and do one next time you're out for the final check under real conditions.
  24. I'd also recommend a table top dob like Heritage 130, but for another reason. With a tripod and a telescope, you'll need a stool for you, and a taller stool for her - the eyepiece is going to be up there, somewhere, from her point of view. Or one of you will be crouching, or standing. Not ideal. With a table top dob, she can sit on the table, or put the 'scope on the floor. The eyepiece will be at her height. https://www.harrisontelescopes.co.uk/acatalog/skywatcher-heritage-130p-flextube-dobsonian-telescope.html#SID=1701 That'll show (on a good night) Saturn's rings, the great red spot on Jupiter, the ice caps on Mars, etc etc.. It's also got the aperture for some deep sky objects too. People call 8 inch Dobsonians the Transit vans of telescopes because of their all round flexibility. If so, the Heritage 130 is the Transit Connect. Not quite as capable, but easier to park.
  25. Here are some collimation scenarios for you from my 130PS Pic 1). The secondary mirror is properly aligned with the primary mirror, because the outer parts of the mirror mount (the black circle) and the three mirror clips (with two Philips screws on each) are nice and concentric in the secondary mirror, and it looks like a circle as viewed through the collimation cap. Unfortunately the primary mirror is not correctly aligned - the refection of the hole in the collimation cap (the black dot in the centre of the photo) should be inside the white doughnut in the centre of primary mirror. This would indicate the primary mirror is looking directly at the centre of the secondary mirror and therefore directly at the middle of the focus tube and the collimation cap - as you can see below, it's not. The green is a plastic bag I put the other side of the secondary mirror mount from the focuser to make the edges of the secondary mirror clear as otherwise it all gets confusing (for me!) Pic2). The secondary mirror is not correctly aligned. It looks a bit squashed (not a full circle) and the reflection of the primary mirror is not in its middle. It does point at the middle of the primary mirror, but this will not result in sharp planets in the centre of the view - there will be a sharp spot off to one side somewhere which will be a fair bit smaller... Pic 3). This is what you should expect to see. The clips in view around the outside so the primary mirror reflection is central, and the dot is in the middle of the doughnut so everything is lined up.
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