almcl

at the scale your screenshot shows, you might not see RA wobble. Try reducing the Y axis figure to 2 and seeing what the RA line is doing? I fed your image to nova.astrometry.net and after it solved the image http://nova.astrometry.net/user_images/2965169#annotated (took a few minutes) I followed the link to the Worldwide Telescope. The submitted image is overlaid on the view and the RA and Dec axes can be superimposed from the sidebar. For amusement (can you tell it's overcast here?) I also got All Sky Plate solver to run it, using a guess for the focal length and image scale but its result (after 76 seconds) isn't as easy to read on my monitor (although it's great for solving in the field as it doesn't need an internet connection).

Can't answer that one, I am afraid, but it happened to me after some weeks of blameless guiding, suddenly, there it was. It might have been 'mirror flop', or guide scope flexure or a combination. If the PHD2 graph is solid for an image with bad stars, my money is on one or both of the two foregoing. Incidentally, now that I've had a chance to plate solve your image of the Veil, it looks as though the two bottom images are erring in Dec, while top left has jumped in RA: Balancing'east heavy' can be tricky close to the zenith (if that is where the scope was pointing) and can produce this effect, but so too can failing to rebalance after a meridian flip (ask me how I know!)

If the guiding graphs are good with no sudden excursions, and the scatter plot in PHD2 is reasonably round yet you get star trails, flex between guide scope and imaging scope is a possibility. You mention guide scope rings, are these the ones with plastic tipped locating screws? If so, these alone are sufficient to introduce the sort of flex displayed in your post above. Solid guide scope rings might help, or, better, switching to an Off-Axis Guider (there are Canon specific ones) would help to eliminate flexure between guide scope and imager. An OAG will also help if the mirror is moving in its cell as, for example, when the scope tracks through or close to the zenith. Can you post a guidelog from a session where you got the weird stars?

Thanks, Steve. Going to need a couple more clear nights (at least) and a lot more processing, but it is an interesting area:

Very nice image, Steve, thanks so much for posting. It inspired me to have ago at the area in wide field Ha and as you say, there's a lot of stuff going on there. Great fun!

Hello Martin Many thanks for that (and Pretty Deep Maps itself). Although I have a short cut to the Technical Companion on my desktop, it possibly assumes a level of knowledge that I have yet to attain - I wasn't sure which type of object to search for, but now see it is in the double (or multiple!) stars category. The Vizier link is very helpful, thanks! I am using Adobe Reader XI on a Win7 pro machine but also have Adobe Reader DC on a Win 10 home machine where PDM runs fine also. In both cases all ~7000 pdfs are in the same directory. In the past I used Foxit Reader but when that started to suffer from bloat and didn't work with PDM I switched back to Adobe Reader (on advice from your good self) and have been happily using

Sounds like you are good to go. Be interested to hear how you get on if you do decide to upgrade?

You can use the FOV calculator (http://astronomy.tools/calculators/field_of_view/) to see what the image will look like, but another thing to consider is your mount's guiding performance. At 1.38 " per pixel imaging (490 on the Espirit 100) the recommendation is to be guiding at half that so .69 " RMS error in PHD2 (if you use that). My AltAz EQ6 sometimes achieves that level of accuracy but there are also nights when it doesn't. What mount are you using currently and what sort of guiding performace does it achieve?

Thanks Francis. From that I managed to get to this page: https://www.cloudynights.com/topic/39940-catalog-names/ and the sixth post answered my immediate question.

Anyone use Martin Meredith's Pretty Deep Maps? I think it's a wonderful resource and to have it for free is amazing, but almost every time I go to look something up, I come up against an abbreviation on the chart that I have no idea of the meaning of and a Google search often doesn't turn up anything relevant. Today's poser was 'what does ARA stand for' (screen shot below - ARA 1838 was the object of interest) but in general I'd love to find an index of all the abbreviations, catalogues &c used on the chart, if anyone knows of one?

Still got my Observers book (although not the dust jacket) but my first ever was the Golden Book of Astronomy:

We visited Wyoming last August, to a ranch running a week long 'Astronomy Retreat'. We had use of a 10" Dob, solar scopes and a 20" dob which was bought out on 3 nights. Skies were great and they even got me on a horse during the day time for the first time in my life. My avatar is a picture from one of the nights.

Yeah, that's the one. And, yes it is more of an autumn or winter target.

You may have done it already, but the Spaghetti nebula (Sh2-240) is large, faint and I found it quite challenging?

Don't know the proper answer to your question but I had to replace the lock shaft on my EQ5 a while ago and found that a length of studding of the appropriate thread size and a couple of wing nuts and washers did the job satisfactorily. Last month's S@N mag had a picture of an accessory tray supplied by Northern Optics (link). Said to be for a Celestron but looks as if it could do duty on EQ6?

I used an EQ5 with my SW 200p to take astro photos using a Canon 700d for three years before upgrading to an Alt Az EQ6. It didn't always produce great results but it quite often surprised me. For the cost of an adapter (and possibly a coma corrector) it's definitely worth having a go. Any of the photos in my album (link) with a date before October 2016 were shot from the EQ5.

Lights, trees, houses, the usual:

If you are just starting out on processing, Steve Richards' 'Dark Art or Magic Bullet' contains step by step instructions on how to use Photoshop. The book also goes into calibration frames, which can help in removing hot pixels, as well as lots of other aspects of the post processing art.

Is this the Skywatcher upgrade kit with the brass gears and steel brackets? If so, I found that occasionally the grub screws on the gears would slacken off, all by themselves. Also the positioning of the brackets and the motors on the brackets, while not readily adjustable, could make a difference to how well the system performed. Making sure everything was square on and tight helped.

It might be worth hanging a bag of sugar (or similar) off the weight bar just to check the balance - my set up may weigh more/less than yours:

I have a somewhat similar setup - 200mm Canon lens and Canon camera on an EQ5 - and like you, I found the standard counterweights too heavy. After a bit of experimenting with empty bean tins filled with lead, sand or water, I settled on a 2.0 kg counterweight (https://www.rothervalleyoptics.co.uk/bresser-counterbalance-20-kg-for-exos-1eq4.html) which balances my set up nicely. It is worth experimenting to find what weight is suitable and checking that the centre hole matches HEQ5 counterweight bar diameter. Or, if you are handy you might make one? At 200 mm focal length you may well find the mount will track accurately enough to give round stars.

Ah! Wonderful, Thanks!

Thanks all! Looks like the buck converter is the way to go and I do have an almost scrap case of exactly the sort Davey-T shows. The screw terminals and voltmeter are good, too. Can you remember where it came from? I can see similar but not-quite-the-same items on ebay, but so far the terminals are proving elusive.

A question for any electronics gurus, please? I made up a circuit, readily available on the web, using an LM7808 to convert 13.8 volts from either my stabilised mains power supply or from a 12 volt accumulator to 8 volts to use with a Canon dummy battery in my Canon 700d. It worked nicely, delivering 7.9 volts and the camera is quite happy with that. Went to try it out last week and after about 20 minutes or so everything stopped as the 15 amp power supply (which also powers the mount and the camera cooler) cut out. Further investigation showed that the small plastic case in which the LM7808 is mounted with a couple of capacitors on a strip of Veroboard was too hot to touch. So was the supply cable. Investigating with a remote infra red thermometer suggests that the LM7808 reaches 50°C within a minute or so of switching the camera on. I haven't measured the current draw, lacking a suitable spot to break into the supply cable, but guess this might be the problem? If so, is this to be expected when dropping 13.8 v to 7.9 with about (I estimate) a maximum 2 amp demand? I haven't used a heat sink as my hope was to keep everything small and light such that the whole unit could simply hang on the cable. I do have another LM7808 if it is possible that the original is defective, but would appreciate more knowledgeable input before putting my pretty limited desoldering ability to the test.

Ah, yes good point. That could certainly be contributing to the problem, couldn't it?