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jambouk

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About jambouk

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    Red Dwarf

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    Nottingham
  1. The starting position of the mount is generally not that important, though depends on the mount you are using.
  2. I’ve broken the optical disc on the dec motor of an old Celestron Advanced GT mount. Celestron can only provide it as part of the whole motor which will be £150 (FLO asked for me). Does anyone have any ideas of other much cheaper (circa £20) options? The disc is in three pieces and I’ve superglued it together but not sure it will work well as there are bits missing and the graduated lines don’t match up at all well.
  3. If you can’t fit it, put a wanted add on astro buy sell UK for a new mount arm, you’d probably get one for £40.
  4. A friend has just had solar panels installed, but no battery system. He is keen to look at ways to store energy produced in the day time to use at night to boil a small kettle (900W) and run the TV (200W). He is thinking of getting a large leisure battery (>180 amp hour), a pure sign wave inverter (12v DC input, 2000W), and then a charger on a timer to top up the batter in the day time, powered by solar energy. To have it set up in the garage and run the AC power the 10m under some slabs into his house to have a dedicated 3 pin socket for the "night" kettle and another one in the other room for the TV. Through various contacts the bits can be obtained cheaply, so hopefully not a massive out outlay. Has anyone else done something similar? Can anyone think of any ways to do this better without breaking the bank? Thanks. James
  5. Is there a list somewhere of the largest optical telescopes in the UK? It looks like St Andrew’s has the largest, at 0.94m (37 inch).
  6. You would need to put the scope on an equatorial mount to identify the severity of the cone error and take steps to reduce it by shinming the dovetail. Why do you think cone error is causing you problems?
  7. I would definately recommend the AZEQ6. I turn off the encoders to allow a more precise GOTO accuracy.
  8. Either set the time in the handset to the actual time, and use planetarium software to work out roughly where the stars would be in the sky and see how accurately the scopes movements are (if it says Vega is high and south, but the scope goes north and low, there is a big error); or aet the time to 9pm and try and remember where the current stars are.
  9. OK. This test can be done in the day time, in a garage etc and doesn't need a clear night. Point the polar axis roughly to the north. Make sure the scope is in the home position. Lock the clutches. Turn the mount on and enter the date and time and location. Do a three star alignment. How far out is the scope roughly (as there are no stars) from the first star? Move the scope with the handset to where you think the first alignment star would be in you could see it. Accept that position. Go to the second star. How far out roughly is the scope now? Again roughly slew to where the second star would be if you could see it. And now the third star, how far out is that roughly? If stars two and three were pretty close to where you think they should have been accept the alignment. Now what happens when you use the GOTO to go back to the first alignment star? James
  10. "It tracks perfectly and I'm convinced mechanically its sound." So the RA motor side of things is fine. "Theres no issue with the setting up , tried one, two and three star alignment, polar accuracy is ok" So communication between handset and motors OK, power must be OK, and Dec motor must be OK too. This doesn't leave a lot else. If you have successfully done a three star alignment, then for this particular use of the mount the date, time and location details are not an issue (these are only needed to help suggest alignment stars, and also useful if you are subsequently parking the scope and then wanting to wake it up again another time without doing any further alignment). Things I'm thinking: If your polar alignment is WAY off, and there is a delay between doing a star alignment and using the GOTO the targets could have moved. What is the focal length of your scope? If it is over 1000mm, and/or you are using a high power eye piece, then it isn't uncommon for the target to be out of the field of view. How accurately are you doing your star alignment? Are you using a high power eye piece to really centre the target stars and ending with an up and right move on the key pad to do the final centering? Are you 100% sure you are centring on the stars the handset is suggesting? How bady off is the GOTO accuracy? Have you turned on the advanced filter on the handset for alignment stars? I would do that and I would only ever do a three star alignment. Are your clutches tight? Is the balance on the kit as good as you can get it? What scope is it? Is there mirror flop? Are you adding any kit to the set up after you have done a star alignment? Daft question, but are you using the same scope to do your alignment and to use your GOTO? We really need to know exactly the issue before we can help further I think. James
  11. I think it would be relatively easy to polar align in the different ways and then just run PHD2 on either the main scope or the smaller guide scope for 30 minutes and look at the errors for each method of polar aligning (and repeat 3-5 times). It would be a time-consuming project and I guess we know roughly what the data would show (PA accuracy in ascending order: by eye with polar scope < handset polar alignment routine < SharpCap < PoleMaster < drift alignment) but the magnitude of the differences between them would be interesting to know from an academic point of view, especially for the middle three methods. If I knew how PHD2 worked I might be tempted to give it a go from my back garden
  12. Ron, do you do a three star alignment with the mount after your eye ball polar alignment, if so what vales for Mel and Maz does the handset typically give you? Using the Polemaster I usually (and reliably) see values of under 3 arcminutes and often nearer 1 arcminute or less if the routine is done very carefully. I just wonder what are the typical values for eye ball method, and following a sharpcap and drift method.
  13. Has anyone done any reliable comparisons of the different methods of polar alignment (polar scope with the eye, polemaster, sharpcap method, drift aligning) and shown the reproducibility of each and the accuracy of the alignment? I'd be interested to see such data. James
  14. Using SharpCap or a PoleMaster etc gives very tight polar alignments, but I do think it is important for people to learn how to polar align with a polar scope to understand the principles polar alignment and it also helps make you think more about the celestial sphere. James
  15. Thanks for that. I'd previously thought about the cone with cone error, but not with NPE, so that is useful. Having both errors would be weird, and I guess that links back to my original thoughts of how does the software differentiate the two. Maybe the machining and assembly of modern mounts mean there really is minimal NPE, and that even if a small amount is present it is just so insignificant it probably wouldn't be noticed by the user. Maybe. James
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