cwis

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?

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...

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...

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...

No worries! I'm now looking lustfully as the orrerys on the Cochranes - they are magical things...

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.

Ah I see! Yes - that helps!

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...

Can confirm! This idiot just got some funny looks out in the street...

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

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....

Oh yeah - and could you chuck me an extract of your spreadsheet so I know what I'm trying to produce?

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)

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!

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...