almcl

Thank you both Wim and Paul!

Most reassuring!

r dust bunny) :

For a few years I have been trying to get an image of each item in the Messier catalogue.  This has proved quite challenging for the more southerly targets, many of which never get more than 15° above the horizon here at 52½° N.  Sometimes they are even lower if one waits for astronomical dark.

So, last weekend, there was the promise of a clear night with little wind at the barren, exposed moorland site that is the nearest thing to a dark sky site nearby.

One slight issue: it was full moon. Only an idiot would try to capture a DSO under those conditions, right? 

So the AZEQ6, tripod and SW190 MN got put in the car along with laptop, old car battery, folding chairs and assorted masks, dew heaters &c. 

Arriving at the dark site my usual pitch was already occupied (not sure if he was an astronomer) so I had to look elsewhere.  I found somewhere but had the disadvantage of not being quite sure where north was.

Somehow the mount got levelled, sort of polar aligned and calibrated. A fiery full moon rose above the heather and imaging started.

I think that the second of the admittedly very low targets probably ranks as the most boring Messier object ever.  M73 consists of four stars which may or may not be a cluster (open clusters don’t do much for me, generally) and according to a recent paper the four stars are all going in different directions, are at wildly different distances and therefore are merely an asterism. 

So, was it worth it?  I am not sure, here’s one result (and yes, I do know about the monster dust bunny) :

When this happened to my TS optics OAG, the advice from the supplier was that I could use epoxy resin (JB Weld, Araldite or similar) to re-glue it.

Although the camera it was used with has now been retired, it seems to have lasted well in the subsequent 3 years. Mind you I had the whole of one face of the prism available, yours looks to have a little less surface for the adhesive? 

Don't know the direct answer to your question, but if you want to locate WR 134 in CduC or Stellarium one of its alternative designations such as HD191765 will find it OK.

Hi Ciarán

I have the ZWO V2 OAG and use it with an ASI 120 MM, but not sure I have understood which dimension you need (just a bit slow this morning).

If it's the one shown in the image below, then the thread depth is 5.19 mm.  If that isn't what you need, let me know (perhaps by noting on the image) which one?

Wow, that's interesting. 

Had a look at the Skywave website and am totally baffled as to what it does and how one would use it, but if you need an estimate of seeing, the Meteoblue Astronomy forecast provides an estimate of the seeing for a given location.  Not sure how accurate it is, its cloud amounts frequently seem rather pessimistic, but it might be worth a try?

I found dropping the handle back into the bolt once PA was done solved most of the collision issues, but the real game changer was the

'Sky-Watcher EQ6 Extension Tube for NEQ6 / EQ6-R / AZ-EQ6' Here

I can now image well past the meridian without the OTA colliding with the tripod legs, or indeed anything else.

Not sure if it helps, but there was a thread about this on the ASTAP forum a little while ago:

https://sourceforge.net/p/astap-program/discussion/general/thread/51b633e3ea/

ASTAP certainly doesn't make this easy, and when I need to do it, I use DSS.

Just to round this off, two items arrived in the mail this morning and look as though either one will do the job just fine:

So, just over a week from order to reception, Royal Mail 2nd class delivery.  Quicker options were available, but I was in no rush, so this suited fine.

Definitely one to bookmark for the future.

Click on your name 'HarryLP'  - should be top right on your screen.

In the drop down window that opens click on account settings, in the left hand part of the window, click on signature then type in what you want.

1 hour ago, Aramcheck said:

 

In order for the OAG prism to be clear of the camera sensor the camera orientation is limited, so I suspect it'll be a case of keeping it one position in relation to the guidescope.

If you're using an OAG you don't need a guidescope do you? Keeping the OAG prism aligned with the long side of the ASI2600 sensor allows it to pushed into the light beam further, which may be helpful.

1 hour ago, Aramcheck said:

The first question then is, if I want to rotate the whole assembly to either obtain better target framing, or to find a guide star, will I have to redo the guide calibration?

Afraid so, each time the camera guider assembly rotates the orientation changes so a recal is necessary.

1 hour ago, Aramcheck said:

Also - last night after focusing the main camera/scope, the guide camera distance didn't seem to make much difference to the view of the star in the guide camera or star profile image in PHD2. I understand that it should be set parfocal with the main camera, but how critical is the distance & how do you tell if I can't see it very well in PHD2?

A trick I use which may help is after focussing the main camera, switch to the PHD2 view and select a star then carefully rack the focusser in or out and see what this does to the FWHM or HFD figures.  Keep a careful note of which way and how far you moved the focus.  Then return to 'imaging camera focus point' and adjust the guide camera in or out by the amount the focuser moved.  It should be possible to get pretty good stars.

1 hour ago, Aramcheck said:

PS: I'm aware that the 120MM may not be the best, but current budget didn't extend beyond the OAG & Helical focuser.

I have been using an ASI 120 mini mono for a while now on an OAG and it has never failed to find guide stars, usually a full suite of 12 are available.

5 hours ago, malc-c said:

Result.... post up a picture of the printed item when you receive it

Certainly will!

Just had a email to say it's being printed, so fingers crossed won't have to wait too long.

Brilliant, Malcolm!

Have just ordered two for an all in price of just £6 - just what was needed!

11 hours ago, malc-c said:

You can upload the stl file to that website I suggested and they will give you an instant quote.  It's cheaper to have individuals than making a spur frame with lots attached as that gets treated as one piece.

Thanks for the thoughts, Malcolm.

I think that was one of the websites I tried but their 'minimum order charge' (perfectly understandable) made them uneconomic.  I don't think there are opportunities to sell the surplus - there are precious few of these remotes in use and it tends to be the electronics that break rather than the case hardware.

Given a sufficiently thin block of plastic, I could probably sculpt something with a craft knife, files and sandpaper but think a 3D print would probably be neater!

Julian

It's a small part for a remote control (non-astro).  Original material might possibly PVC, but anything similar (nylon or a bit more rigid) would do.

It looks like this (stl file available) and is 30 mm long  and 18 mm at the widest part:

I am looking for a 3d printing service.

A while ago I used 3D Hubs but they have now changed their business model from lots of independents who could quickly make something small for little money to a more commercial approach.

Have looked at other sources, but while the cost of the part comes out at under £2 on several sites, all want a minimum order of around £40, which isn't sensible for a single part less than 30 mm long by 20 mm wide and whose stl file is only 200 kb.

I can't really justify getting a 3D printer of my own, not needing 3D printed items more than once every 4 years or so, and wonder if anyone knows of a UK based one-off service that doesn't need a commercially sensible quantity of parts?

There's a calculator here:    http://76.12.87.114/resources/dust.cfm

If you put the relevant numbers in it tells you how far above the sensor the dust is likely to be.

Just guessing, but the smaller ones *might* be on the camera window, while the bigger one might be further out?

You might find the thread here is worth a look:

1 hour ago, Rodd said:

  That is why viewing images from excellent astrophotographers can really improve ones processing. 

Indeed so, Rodd.  May I say that I also find your images inspiring and they prompt me to see if I can do better.  Although I seldom manage to achieve as good results, I much enjoy looking at what you (and others) achieve.

2 hours ago, Perrywarburton said:

Now can anyone tell me why my stars look like this? 
 

Is it this that concerns you:

which might be an object intruding into the light path

Or this:

which might be tracking error?

There's a little bit of field rotation between the before and after, but nothing a competent stacking program shouldn't be able to deal with. 

Which one are you using? 

3 hours ago, Shibby said:

This surprises me greatly. I've never had this problem.

Well, here's an example.  I count 25 hot pixels in the stacked image (grey scale) and they all stem from one in the individual light (bluish image):

Not now sure how many lights were stacked, there were 30 altogether, but at least 25 must have been used.

(Sorry to the OP for hi-jacking the thread, but this is moderately relevant to the question.)

1 hour ago, Shibby said:

I believe 16 is the "magic" number, so stacking 20 should work OK with a sigma clip stack.

Unfortunately that's not been my experience.  I have had stacks of 25 in which DSS failed miserably to remove hot pixels, despite quite large dithers every frame and just the other night it failed to Sigma clip a single satellite trail from a stack of 70.

Of course, other stacking software may perform differently...

They look like hot pixels.  

If you are not tracking, the stars progressively move across the frame and when each frame is aligned the hot pixel appears to move.

You might be able to eliminate them with a Kappa-Sigma clip stacking algorithm, but if you're using DSS you will probably need a good deal more than 20 frames for this to be effective.

Is there a reason you are using GPINT as your mount type rather than  EQMOD ASCOM HEQ5/6 ?