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About Penguin

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    Star Forming

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    Gloucestershire, South-West England
  1. Fixing these star trails?

    Thanks Bob, and I'm also very interested in your home-brew guide camera article. Definitely something to look into once I am happy with the alignment. I'm planning on following this guide to get the alignment sorted: Drift Alignment by Robert Vice since it should be easy and quick to verify if the adjustments I make are correct.
  2. Fixing these star trails?

    That's very interesting on the coma corrector! Once I have the alignment sorted out to enable longer exposures I may try that out on some brighter targets. Here's the result of tonight's investigation It's about 2 minutes of non-tracking, followed by another few minutes of tracking. I can't remember what the target star was but it was a little east of south, around 60 degrees up. It looks to me as though, when tracking, the stars are drifting up the frame. I think I will watch some polar alignment videos and try again from scratch once I have a better understanding of what is going on.
  3. Fixing these star trails?

    Thanks Nigel, I will check this on the next clear evening (which might even be tonight!). I believe I know how to do it: Orient the camera so stars drift across the long side when not tracking. Time roughly how long they take to traverse. Place a star at the starting edge and start an exposure When enough time has passed for the star to travel 1/2 way or so across the frame, start tracking Continue the exposure for the same time again That should tell me which direction is which in the frame and which direction any alignment issues are in, I think.
  4. Fixing these star trails?

    Thanks Bob. Just to be clear, there is no guiding at present. Looking closer at those individual subs, I did spot that there are two issues going on, as you have pointed out: a consistent trailing upper left to lower right throughout the frame. I assume this is polar alignment. I may need to do some physical fixes to my rig in order to sort that out, as well as learning alignment methods (see below). a 'shadow' towards the edge of the frame, particularly noticeable in the top-right and bottom-left corners where it is at 90 degrees to issue #1. I assume this is the coma you are talking about and a coma corrector will be the only way to get rid of this if I want to use the full frame. I aligned the mount quite some time ago, maybe even last year, and have not touched or done anything to check it since. I have not found an alignment guide that I can fully understand so my technique may have been way off. Also, my mounting plate is a home-made affair with a bolt as the pin that the HEQ5-Pro alignment screws push against and it's quite possible that bits may have 'moved'.
  5. Fixing these star trails?

    It occurred to me last night that not only is the posted image processed, it is also cropped! So here are two of the individual unprocessed subs, taken at 21:47 and 22:07 which may help diagnose exactly where I need to concentrate my efforts. The amount of movement between the two says 'polar alignment' to me. Flicking through the subs, there seems to be consistent drift in one direction.
  6. Fixing these star trails?

    That explains why the image didn't appear in the post, thanks.i will try to remember to post jpegs in future. No, there is no coma corrector or anything like that in the path, just the scope and camera. I had not considered collimation, will look into that as well as polar alignment and post my findings.
  7. So I have polar aligned the HEQ5 Pro as best I can on its pillar, taken 40 60-s subs of NGC 7789 through the SW150P with the 450D, stacked in DSS and processed in PixInsight and ended up with this image. It clearly has elongated stars, which I frequently get, and I think this should be my priority to sort out. I think the solution could be Guiding: would adding guiding be able to compensate for errors in balance or alignment? I have an SP900 webcam and am considering attaching it to a finder/guide scope. Is that feasible? Balance: I have not been precise with my balancing. Could this be causing the trailing? Alignment: Do I need to just spend more time and effort getting the mount aligned? NGC7789_Processed.tif
  8. Roll-away observatory plan

    Update: it has proper Police Box signs and lighting! A solar powered string of 200 LEDs that I have put behind the sign boxes and around the inside. Obviously these will be turned off while observing and I will pop something over the top light to mask that as well. My big issue now is damp: It *will* get in, particularly with the complicated roof which is flat around the edges, the hole for the pillar and my general DIY bodges. What can I do about this? I have vents behind one of the sign boxes for air-flow but I think that is probably more for summer and might need to be covered during winter? I can put a load of silica gel in there but have no idea how much I would need, how often I would have to dry it back out and whether it would work anyway!
  9. A little update: new cable arrived and seems to work much more reliably. The USB Hub is still an issue though (dodgy power connection) so I will need to sort out a new one of those as well.
  10. Thanks Alan, I hadn't thought of wiggling the cable! I will try plugging other things into the port as well but I did also try a different port to no avail.
  11. Now having my roll-away observatory operational, I am trying out controlling the scope with EQMOD and I'm having problems that I think are probably the EQDirect cable. What I have is... Laptop in the obvservatory, running Stellarium, StellariumScope and all the EQMOD stuff 3 meter USB2 cable to a powered USB2 hub strapped to the pillar. Short USB cable from the hub to a HitecAstro EQDirect box, which then has an RJ-whatever cable plugged into the HEQ5 Pro mount. It was working last week and I was able to connect to and control the scope using Stellarium from the laptop. However, at that point I was running a 2-meter USB2 from the laptop straight into the EQDirect, bypassing the hub. This evening, I fired it all up and it failed to connect to the scope. First suspects were the hub and 3m USB. First I swapped that back to last week's 2m cable. Success! It found the scope on COM2. I disconnected and tidied up the cables, then tried to reconnect. "Not found" on any port! So I tried various different cables, with and without the hub. No joy. The only thing I was not able to swap out was the EQDirect cable and box, which is old, cracked, and came with the 2nd-hand scope, so I am suspecting that. I've ordered a new EQDirect cable from FLO but is there anything else I should suspect?
  12. Roll-away observatory plan

    I could put bolts on the base, either side of the pillar and put two holes in the pillar for the bolts to slot into. I don't think that would weaken the pillar too much. Or I could put a shelf in the Tardis that would slot under the shelf that is already on the pillar. I was going to do something like that anyway for the laptop etc. Or I could lift a couple of the decking strips and bolt some hoops into the concrete that the pillar goes into in the ground and fashion something in the base to slot into those. Lots of options and I suppose I should deal with this sooner rather than later!
  13. Roll-away observatory plan

    Most important check: the scope fits! We had some rain overnight and I can see a little dampness in one corner of the ceiling but I think I can fix that. I'm going to give it a few weeks before putting the scope in there permanently.
  14. Roll-away observatory plan

    An update, now that it has been painted and glued together. It still needs a lot of work: Handles and locks. Central door strip. Ventilation (I'm planning some holes behind the top signs and a solar powered fan to encourage through-flow of air) More permanent top sign boxes. Removable floor piece to close the slot around the pillar and complete the Tardis base at the front. The light is a solar-powered garden light and looking at it last night, it'll ruin any night vision! So I need a cover I can pop over it when observing. Check its weather proofing: if it's damp and leaky inside, I can't keep the scope in it, which kind of defeats the object. Speaking of which... Put the scope on the mount and make sure the damn thing fits! Add electrics, shelving, laptop etc etc
  15. Thanks for all the advice, I'll have a think. Unfortunately, it does have to be a laptop as it will also be the family machine. To be fair, I've been using Pixinsight on my current laptop (HP 250 G1 with an I3 processor, 4GB RAM and inbuilt graphics) so pretty much anything will be an improvement!