almcl

A quick look at your guide log suggests that the orthogonality error (29° on the 1st run) is preventing a good calibration.  At least one estimate of your PA error is in excess of 25 arc minutes and it would definitely be worth reducing this and seeing if it reduces the ortho error.  Your polarscope should allow you to get within 5 arc minutes or Sharpcap or similar can do a reasonable job.

Once you have a calibration, running the guiding assistant and accepting its recommendations and then guiding for a reasonable period will show if there are any mount problems that need to be addressed.

Don't think it's a hot pixel, it changes shape over time (blow up from first and last subs):

but perhaps more tellingly, it moves between last and first frame while nothing else does:

I'll check out 447 Valentine, thanks!

Would some kind soul with minor solar system objects enabled on their planetarium prog, cast their eyes over the image below and help determine if the horizontal artefact (arrowed in green) is genuinely an asteroid/minor planet or similar?

Try as I may, I can't get Stellarium to display anything in that area.

On individual subs it is just a point source but when stacked the line shows up.  If it's an artefact I can deal with it, but if it's genuine feel it should be left there.

7 hours ago, drumsolo said:

Sorry I don't know what you mean, can you explain?

Thanks

It is suggested (in various places around the web)  that the resolution of the guiding set up shouldn't be more than 3 to 4 times that of the imaging train.  The reasoning being that  a sub pixel movement of the guide star, which PHD can usually detect, will translate into whole pixel movements on the image.  There's much debate about exactly what ratio does or doesn't work, (and PHD2 is said to be better at detecting such movement than PHD1) but when you add this to flexing between guidescope and imaging scope, mirror movement (if using a scope with a mirror) a ratio of more than 6 to one (which is what you have, if my guess about your equipment was correct) is probably going to contribute to ragged or elongated stars.

Agree that doesn't look like coma.  I use the SW coma corrector and find it does a pretty good job at correcting it (albeit at the expense of some annoying reflections on very bright stars).

Another thing in passing, guessing from the equipment in your signature, you are imaging at around 0.9"/px but guiding at over 6"/px?  This may be  contributing to the issue.

Haven't used PHD (1) for a while now, so can't remember if it corrects for when imaging declination is different from calibration dec. 

PHD2 saves logs which can be analysed after the event to see what was going on using PHD logviewer which is handy, but unfortunately doesn't work with the PHD1 logs.

In addition there's an active PHD2 forum where the developers give advice and help on solving guiding problems.

Haven't used it myself in anger, but I've an idea that Sequator might be worth a look for what you're seeking to do.

Have a look at the snapshot page?

Almost all the elongation seems to be along the RA axis,  if so it's a tracking/guiding problem.  (Image below of your crop over laid on WWT map.)

What did your guiding program report as the RA oscillation?  If the reported error is small it might be caused by differential flex on your guide scope.  But if a largish error is reported then other aspects of the mount mechanics may need investigating.

It would help to know what equipment you're using?

If a reflector, do you have a coma corrector?  If so, which one and at  what spacing?  

What camera, and how is it attached?

How are you focussing, Bahtinov, manual or auto focus?

whoops! double post. Sorry!

190 sounds about right.

Without a coma corrector you're imaging at  0.89 "/px so, by the time you have debayered this will be  equivalent to 0.88"/px, so you'll ultimately want to guide at about 1 arc sec.  Won't be possible every night (tonight is looking a bit windy here) but some nights that should be doable according to my logs from 4 years ago.

I used an EQ5 with a SW200p and Canon DSLR for a while, and although results weren't always brilliant and I agree it's not an ideal combination, it could usually manage more than 40 seconds.

A good PA helps, a good balance (slightly east heavy) is also useful.  Getting the right figures into PHD2 is essential, what figure did you enter for the focal length of you guide scope? 

Can you post a PHD2 guide log file plus details of your imaging camera?

The largish black spots are likely caused by dust somewhere in the imaging train a few mm in front of the camera sensor.  If you are taking flats (without disturbing the imaging train after your lights) they should help get rid of those.

You may have some 'walking noise' and dithering might help with this, assuming you are guiding?  

Not entirely sure if I've interpreted misting correctly, but if it's the light to dark cast from left to right then that may be a light gradient.  Not sure how Gimp users deal with that (don't have it myself) but hopefully one will be along shortly to tell us?

You select a target in Stellarium and ask it to 'goto' that target. 

Stellarium moves the scope to where it thinks the target is. 

You take an image and, If you are platesolving within APT, once it has solved, click the sync button. 

This repositions where Stellarium thinks it is pointing.  You can then either reselect the goto in Stellarium and it will move the scope to the (more accurate) target position or you can use the goto++ feature in APT.  This needs  a bit of setting up and, for me, usually takes a bit longer.

17 minutes ago, philhilo said:

Startools user, very interested. I have been trying to use it as the easiest processing software, but I cant seem to find a good tutorial on an up to date version preferably with some demo data. Is my data good or bad, I have no idea, put unknown data into unknown process and see what happens? Did you just play with it or is there a really good tutorial, so often they say do this and look at the change, but it looks the same. The wipe module baffles me presently, I hit the big buttons to see what looks best.

As luck would have it, Guy posted a 'new' work flow this morning on the StarTools forum here

Happy-Kat pointed out a way to control (or at least ameliorate) noise here

Another user, RKonrad posted some videos which I found very helpful here and here. There are links to the data he used in the demos on there somewhere, as well.

You'll need to download the latest (Beta) version  1.6.392, it's stable, so should work fine.  

Be interested to hear other opinions, as I have a similar set up, albeit probably Bortle 6 skies. 

I found dithering helped a bit with walking noise, but created problems of its own (even with 20+ subs, I still ended up with clusters of hot pixels in the stacked lights).  

Darks didn't help at all when the camera was uncooled, and even after I devised a external cooler and at least stabilised the temperature, didn't help much with some vicious  amp glow, or with hot pixels.  So now I rely on StarTools' increasingly impressive noise suppression abilities and, if really necessary, painting out individual hot pixels in Photopaint. 

I got rid of walking noise by ditching the guide scope and acquiring a Canon OAG.  This, after guiding, probably made the single biggest improvement in my imaging.

Sorry, only just seen this.

Yes, I have had something similar happen. It was a while ago, so memory is a bit hazy, but think it had to do with which version of the firmware updater and/or configuration utility was used.

Perhaps worth downloading the latest version(s) and if that doesn't fix the issue, post a message over on the AstroEQ forum ?

You don't mention changing exposure length?  

What was it set to? 

I find somewhere around 1 to 2 seconds gives a result,  YMMV of course.

That new flat seems to have two extremely circular artefacts, upper right and lower left, but I wonder if they are caused by dust or by something else, perhaps a reflection or other anomaly within the imaging train?  

Without details of the imaging set up (scope, camera, filters, reducer/flattener &c) it's difficult to say but the dust might be as much as 10mm from the sensor, which seems a bit unlikely...

Could the flat have been rotated relative to the lights?

If you're happy with the result, that's probably all that matters!

However, it's always worth running the guiding assistant and accepting its recommendations at the start of a session.  It's quite good at min move (better than randomly altering it in the hope of improving things, at least).  If you have to set up and dismantle every session, it may be worth re-calibrating, too.

You have quite a bit of periodic error (image below), but PHD2 should be able to guide most of that out, although you may need to re-run the new equipment wizard and let it sort out the settings.

The first file doesn't seem to be a flat - it's got stars in it.  Is it the correct file?  If so, that may be part of the problem.  Also the two images are rotated relative to each other.

As well the 'dust bunnies' (I can see 5 or 6 rather than 2) look awfully symmetrical.  Might have another cause?  Some great data though, well worth persisting with!

2 hours ago, fireballxl5 said:

When combining data taken many months apart and so cal files (flats in particular) have been refreshed, this is not so straight forward. Whats the best process for adding data on the same target in these cases?

I find putting only the offset bias files in tab 1 and then putting first sessions lights, flats and darks (if you use them) in tab two, the lights &c from the 2nd night in tab 3 and so on works OK.  Definitely don't want individual night's calibration frames in tab 1 as they will then be applied to all tabs. 

DSS will work out the light with the highest score and use this as the reference frame to stack all the sessions. 

One caveat: the latest (beta) version of DSS sometimes creates spurious stars (some completely outside the frame) and these have to be manually deselected and some real ones used instead otherwise the stack doesn't work.

7 hours ago, kman42 said:

I am using a Helios M44-2 for my guidescope. It says 58mm on the lens, which is what I enter into PHD2. Hopefully the Russians report their lenses correctly..

That's a camera lens, right?  That focal length may relate to its use with a 35mm film or dslr camera so you may need to experiment to find out how it  works with your guide camera.

10 hours ago, kman42 said:

Hi, I am trying to get my guiding setup working properly. I am using stepper motors to drive an EQ5, via an AstroEQ box and PHD2.

Good man!  I use the same set up (AstroEQ and NEMA  steppers on an EQ5) for my widefield imaging.

Have you set up the new equipment profile with the correct figures?  I ask because a common slip is to input the wrong guidescope focal length.  This can lead to PHD2 miscalculating the number of steps.  The other thing is to nudge the scope in DEC in whichever direction it calibrates in the southern hemisphere (it's north in the northern hemisphere but not sure about the southern) until you see the selected star move, before starting a calibration.  This helps with the often quite large amount of backlash that the EQ5 can suffer from.

11 hours ago, kman42 said:

If i then start guiding, PHD2 quickly says that it was unable to make sufficient corrections in RA/DEC.

Try getting PHD2 to carry out a starcross test and see what that looks like?  That will at least confirm that it is able to move in all directions.

Thanks for posting this John and sorry I only just saw it.

You've probably worked this out already but in case not, the Mystic Mountain nebula (Herbig-Haro 901) is located at approx 10h 43m 53s  -59° 26' 59" (according to my version of Stellarium) 

Image below may make it a bit clearer(?) but if not, the images here and here (if rotated a bit) give the location.