Equipment and user competence test

[Mr Thingy]

I've just completed and set up my AP rig, so with a few hours of clear skies last night I decided to run an equipment and software test (and user competence test!).

There was a full moon and my time was limited,  but nevertheless, I'm very pleased with the result.

I couldn't get platesolving to work, so I had to manually locate the target, which was very difficult with M31 near the meridian. Turns out I hadn't installed the platesolving database. That ate a large amount of my time.

I also had difficulties with PHD2 so, rather than spend more of my limited time solving that, I opted to go unguided.

In the end I only managed 10 x 90 sec lights, plus 5 darks and a few bias frames, as time ran out, but nevertheless I'm pleased.

My goal for AP was never to make beautiful pictures but resolve those faint fuzzies I've looked at for years and bring them into something more tangible and really understand what I am seeing. It's not the same looking at some else's images, however beautiful they may be, and creating your own image really links you to that astronomical object.

I'm pleased with the polar alignment and being able to do 90 sec subs unguided. Focus needs improvement, I need to fix get PHD2 running and I seem to have a little tilt to fix. I also notice a weird dark circle in my lights (at about the 1 o/c position from the nucleus) - any ideas what has caused that? I've not inspected my optical train but can't fathom what has caused that.

My next piece of research needs to be image processing!

Anyway, a reasonable foundation to start my journey.

Kit: HEQ5 Pro; Evostar 72ED; ZWO ASI 183 GT; Evoguide 50ED; ZWO ASI 120 MM.

Image capture software: NINA

-Thingy-

Edited December 28, 2020 by Mr Thingy

[geeklee]

Great start @Mr Thingy You did the right thing on the night - with so many new things or new processes to follow, if something isn't working and you can still carry on without it... then do that!  Things tend to make more sense when you don't feel under pressure to get it working so you can capture images.  Hopefully next time out (or before if it's that type of problem) you can resolve the PHD2 issue.

6 minutes ago, Mr Thingy said:

I also notice a weird dark circle in my lights (at about the 1 o/c position from the nucleus) - any ideas what has caused that? I've not inspected my optical train but can't fathom what has caused that.

Looks like a dust mote - Flats will take of this.  If you still have everything connected, you may still be able to take the flats and capture that dust mote in the same place.

Some gentle processing may stop the core blowing out and remember to try and avoid clipping the background (it looks close to, if not at that point in the image above).

[Mr Thingy]

10 minutes ago, geeklee said:

Great start @Mr Thingy You did the right thing on the night - with so many new things or new processes to follow, if something isn't working and you can still carry on without it... then do that!  Things tend to make more sense when you don't feel under pressure to get it working so you can capture images.  Hopefully next time out (or before if it's that type of problem) you can resolve the PHD2 issue.

Looks like a dust mote - Flats will take of this.  If you still have everything connected, you may still be able to take the flats and capture that dust mote in the same place.

Some gentle processing may stop the core blowing out and remember to try and avoid clipping the background (it looks close to, if not at that point in the image above).

Thanks for your comments and advice.

I didn't realise a dust mote could make such a big dark circle. Good to know. I decided not to take flats due to time and as I assumed dust wouldn't make such an impact 🤭... Live and learn! I've since rotated the camera so I can't get any flats now. Nevermind. 

[geeklee]

59 minutes ago, Mr Thingy said:

I didn't realise a dust mote could make such a big dark circle. Good to know. I decided not to take flats due to time and as I assumed dust wouldn't make such an impact 🤭

I've been there 😁  I'm now ultra careful and "rocket blower" anything before closing up in the imaging train - just in case I miss the chance for flats as I setup and tear down each time.  It also gives me a better chance of taking flats "on the bench" on a cloudy night!  IIRC, the size is where in the optical train they are - the distance from chip.  There's a calculator out there online that can help with this - but I can't find it right now 🤔

59 minutes ago, Mr Thingy said:

I've since rotated the camera so I can't get any flats now. Nevermind. 

If you were so inclined, I think some careful masking could reduce it enough in post processing but sounds like onwards and upwards is your logical next step!

Look forward to your future images 👍

Edited December 28, 2020 by geeklee

[wimvb]

16 hours ago, geeklee said:

There's a calculator out there online that can help with this - but I can't find it right now 🤔

Diameter of mote/aperture =distance from sensor/focal length

Where all units must be the same. Diameter of mote = nr of pixels across x pixel size. Motes that are smaller are usually on the camera cover glass. This mote is very likely on the filter.

[rickwayne]

Wow, that is an AMAZING first image. It's really unfortunate that there are so many things we can't test or debug without using up dark-sky time, eh? I don't know if your setup will do this, but if you can feed your plate-solving software one of the lights from this session, that should let you test it in the daytime. Usually it's one of four things:

1. The field of view numbers aren't close enough to the real thing
2. The image scale number (arcseconds per pixel) is off
3. The initial coordinates fed to the solver are wrong
4. The solver can't find its index files, or not all of them are present

Most solvers can do a "blind" solve with no coordinates at all, but it takes longer and is more likely to gack.

How far did you manage to get with PHD? 

[Mr Thingy]

5 hours ago, rickwayne said:

Wow, that is an AMAZING first image. It's really unfortunate that there are so many things we can't test or debug without using up dark-sky time, eh? I don't know if your setup will do this, but if you can feed your plate-solving software one of the lights from this session, that should let you test it in the daytime. Usually it's one of four things:

1. The field of view numbers aren't close enough to the real thing
2. The image scale number (arcseconds per pixel) is off
3. The initial coordinates fed to the solver are wrong
4. The solver can't find its index files, or not all of them are present

Most solvers can do a "blind" solve with no coordinates at all, but it takes longer and is more likely to gack.

How far did you manage to get with PHD? 

Thanks for you kind comments.

I didn't think about testing out the platesolver with one of my lights - I will try that - Thanks for the suggestion. I realised the source of the problem, which was that I didn't have a database installed 🙈. Hopefully it will now work.

With PHD2, it seemed to keep timing out. I never saw the chart running, so I don't think it was even operational. Since my time was short I opted to go unguided,l and didn't spend any time trying to get it working. I've since done some more configuring of settings, so hopefully it will work next time 🤞

Edited December 30, 2020 by Mr Thingy

[Mr Thingy]

On 30/12/2020 at 03:52, rickwayne said:

 I don't know if your setup will do this, but if you can feed your plate-solving software one of the lights from this session, that should let you test it in the daytime.

I tried that and the platesolve worked 👍

That's one less thing to play around with next time.

I was assuming I could dispense with any star alignment process by using plate solving - is this correct or should I also perform a star alignment?

[wimvb]

32 minutes ago, Mr Thingy said:

I was assuming I could dispense with any star alignment process by using plate solving - is this correct or should I also perform a star alignment?

Correct. Just do a good polar alignment.

[Mr Thingy]

2 minutes ago, wimvb said:

Correct. Just do a good polar alignment.

Thanks for confirming. 

My polar alignment seems to have been good (once I realised that the reticule illuminates when the mount is powered 🙈).

[wimvb]

12 minutes ago, Mr Thingy said:

My polar alignment seems to have been good (once I realised that the reticule illuminates when the mount is powered 🙈).

👍🏽 Just remember that polar alignment using the polar scope will get you in the ball park, but you need to refine it. Both NINA and PHD have tools for that. Aim for a polar alignment within a few arc minutes.

[Mr Thingy]

1 hour ago, wimvb said:

👍🏽 Just remember that polar alignment using the polar scope will get you in the ball park, but you need to refine it. Both NINA and PHD have tools for that. Aim for a polar alignment within a few arc minutes.

Good to know. I assumed the polar scope alignment was enough and that the Nina PA was for use with polar cameras. I will have a play with PA in NINA. 

[rickwayne]

And of course if you really want a test that's as close as possible to what you'll actually see while imaging, there's the DARV method. I would recommend using a more interactive tool to establish a good polar alignment,  and then double-check with DARV. I use the polar alignment assistant in Ekos but it's not always super-repeatable, so it's good to have a backup check.

[Mr Thingy]

2 hours ago, rickwayne said:

And of course if you really want a test that's as close as possible to what you'll actually see while imaging, there's the DARV method. I would recommend using a more interactive tool to establish a good polar alignment,  and then double-check with DARV. I use the polar alignment assistant in Ekos but it's not always super-repeatable, so it's good to have a backup check.

I found a good video on PA in Nina. Looks relatively simple. 

[jimjam11]

Or use sharpcap which is a doddle for polar alignment using your guidescope.

No point bothering with a polarscope nowadays if you are imaging with any kind of computer because there are so many cheap, fast and better solutions. You can make this even faster by marking the location of your tripod legs after alignment so you can start from the same place every time.

[City9Town0]

+1 for Sharpcap.

[rickwayne]

To be clear, the polar alignment tools in SharpCap, or Ekos, or NINA, or a Polemaster or iOptron's iPolar for that matter, are great. Certainly much better than the polar scope in my experience, and much more efficient than the fiddle-and-check method of drift alignment.

But to confirm your polar alignment, the gold standard is actual observation of declination drift on the celestial equator.

[Mr Thingy]

2 hours ago, rickwayne said:

To be clear, the polar alignment tools in SharpCap, or Ekos, or NINA, or a Polemaster or iOptron's iPolar for that matter, are great. Certainly much better than the polar scope in my experience, and much more efficient than the fiddle-and-check method of drift alignment.

But to confirm your polar alignment, the gold standard is actual observation of declination drift on the celestial equator.

Looks like NINA has a DARV routine built in.

I was going to expwriment last night until I realised that the weather forecast tricked me ☹️.

[rickwayne]

23 hours ago, Mr Thingy said:

Looks like NINA has a DARV routine built in.

Wow, that software really has it going on, doesn't it? If I were starting out and looking for capture software I think I'd go for that first.

[Mr Thingy]

1 hour ago, rickwayne said:

Wow, that software really has it going on, doesn't it? If I were starting out and looking for capture software I think I'd go for that first.

I don't have much practical basis for comparison, but I did start out with APT and had some problems with setup, so I downloaded NINA and found it much more intuitive.

[jimjam11]

Nina is excellent and very fast which is important with a cmos camera.

An easy way of verifying your polar alignment is just to run the phd guiding assistant for a couple of minutes, it will give you an accurate value without you having to do anything! Ideally do this pointing south towards the celestial equator...