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Astrotortilla faux par

Nathan_Pembs

By Nathan_Pembs
in Discussions - Software

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Nathan_Pembs

Nathan_Pembs

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Was a wonderfully clear night last night, Milky Way was like a glowing blanket across the sky and the ISS zipped over in the early hours.

Anyway, I digress, I was trying out Astrotortilla for the first time, on what I believe we're quite easy targets for a first go (Ring Nebula, NGC7000 etc).

After capturing through Nebulosity fine, the plate solving seemed to take an absolute age leading me to just abort it every time. After a lot of head scratching and the night wasted, I realised I'd not put in the min/max degrees for fov with my setup and it was still on the default 0 and 179.....so mad with myself!!

I'm guessing that there was just too much of the index to search and solve??

Also, do I need to be guiding during all this or can AT plate solve with some slight star trailing?

Many thanks :)

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PhotoGav

PhotoGav

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Ouch, a shame to waste good clear skies, but every problem is a learning opportunity (that's what my therapist has taught me to say...!).

Have you followed the set up tutorial to the letter from here: http://lightvortexastronomy.blogspot.co.uk/2013/08/tutorial-imaging-setting-up-and-using.html ? It really will get it all working properly if you follow it all. The only thing that I have changed from the 'default' settings as recommended by that tutorial is 'Search Radius' which I have reduced to 6 - that seems to speed things up a bit.

No, you shouldn't be guiding when using AT - it will plate solve and then move the scope to correct for the pointing error, so you don't want to be guiding.

As for star trailing... I use an exposure time of 10 seconds for the ED80 and 20 seconds for the C8, and there is no trailing at that short an exposure. What exposure were you using?

I find that the first solve takes quite a while (maybe 300 seconds), then, leaving AT open all the time, subsequent solves are much faster, down to 30 or 40 seconds or even less.

Do persist though, once up and running it's the finest piece of software and will help you massively.

Good luck.

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Nathan_Pembs

Nathan_Pembs

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Yes very maddening to waste such a good night, but with this hobby I've decided to tell myself "there'll be other nights" when things don't go to plan lol

I have actually read through that tutorial after downloading AT but I'd gone away to do something else (crying baby probably) and not changed everything in the setup, such as the fov degrees. Last night I had a feeling the figures weren't right but just couldn't see it haha.

Using 10 sec exposures, which NEb 3 captured fine.....AT status said "Field 1 could not solve index_1450 object 20-30" or similar?

Think I got to over 500s and gave up once lol

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PhotoGav

PhotoGav

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Yes very maddening to waste such a good night, but with this hobby I've decided to tell myself "there'll be other nights" when things don't go to plan lol

I have actually read through that tutorial after downloading AT but I'd gone away to do something else (crying baby probably) and not changed everything in the setup, such as the fov degrees. Last night I had a feeling the figures weren't right but just couldn't see it haha.

Using 10 sec exposures, which NEb 3 captured fine.....AT status said "Field 1 could not solve index_1450 object 20-30" or similar?

Think I got to over 500s and gave up once lol

Sounds like it is just a simple tweak to the numbers and it will be humming along. Look forward to hearing it's your new favourite thing very soon!

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Thalestris24

Thalestris24

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Hi

Well, as I recall, you can just watch AT when it's solving and see which index it uses to get a successful solution. You can probably calculate which one it uses from your fov. For instance, the max fov for my QHY8L is 1.85 deg = 111 arcmins. This corresponds to index 4211 which covers 85-120 arcmins. I'm not sure if I actually need them there but I also have 4210 and 4212 in the Cygwin data folder. All others that I've downloaded I've put in a separate folder. Could be on separate drive, I guess. Anyway, they are there if I need them for a different camera/scope setup. 4211 will also cover me for my 1100d should I happen to want to use it.

Assuming you have AT and Cygwin installed on your C: drive, the index files are stored in: Cygwin\usr\share\astrometry\data\

Hth

Louise

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Steve 1962

Steve 1962

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Yup, Louise is absolutely correct. If you enable the Log Window before starting a solve, AT will tell you which index it solves with. I've put all of my unused indexes in a sub folder which I created in the folder Louise has described - AT just ignores them and the process speeds up enormously.

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Nathan_Pembs

Nathan_Pembs

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Clear last night so got a chance to try out AT, it's a very fickle bit of software I must say :/

Now and again it solved but alot of the time it didn't or just froze. Seems to be alot of settings to jiggle with like sigma, star count, exposure, etc to get it working properly.

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Thalestris24

Thalestris24

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Clear last night so got a chance to try out AT, it's a very fickle bit of software I must say :/

Now and again it solved but alot of the time it didn't or just froze. Seems to be alot of settings to jiggle with like sigma, star count, exposure, etc to get it working properly.

It is temperamental - sometimes just mental! I've found I do need several indexes to be present for it to solve with my qhy8l. Another problem seems to be hot pixels. I have quite a few with my cam :( Obviously AT might think they're stars... Also LP is a big factor. I have to put my sigma right up sometimes. Also I run it with Eqmod as 'dialog based' otherwise the syncing causes problems. Maybe a newer version of AT will improve on some of it's current shortcomings - I live in hope. When it works, it's great!

Cheers

Louise

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Thalestris24

Thalestris24

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It is frustrating when others get it working and rave about it.

I think I might be capturing too many stars, usually 300+ with a 10s exposure, so I'll have to try shorter ones?

Don't worry - it took me a while and I still have some problems sometimes. Yeah try 5s. Increase sigma. Make sure you have the right indexes, make sure your fov calculation is correct. One thing to bear in mind is that it uses the current scope co-ordinates as a reference. This is why it isn't recommended to have too long an exposure time, I think.

FWIW here are my last used settings:

post-33532-0-69095000-1407161279_thumb.j

I'm using the 64-bit version.

I often vary sigma and exposure times during a session - especially now as skies aren't so dark. Your settings will likely be different.

One problem I still have is that sometimes my mount is still moving when it makes a second exposure so it has trouble solving the star trails! I'm not sure whether it's a bug in AT or a possible problem with my mount.

Hth

Louise

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PhotoGav

PhotoGav

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I find I get the best / fastest solutions when there are more stars in the shot. Over 500 is really good - I think it narrows it down to the brightest 100 anyway. For some reason it just seems better when more appear. Exposure times wise, I use around 5 seconds with the ED80 and 15 or 20 with the C8.

Keep at it - it's worth the faffing. I use AT with virtually no tweaking these days and it gets the scope on target very efficiently.

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libraryman

libraryman

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An excellent thread, i used AT and it worked a treat, unfortunately i had to reformat the drive and i lost the settings...any way following the path to the index folder i find numerous index files all with the same name i.e Index 4024-00 to 4204 -47

Is this correct?

i wonder because now when i try to solve, i sometime see 600+ sources..

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Thalestris24

Thalestris24

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Hi

Well it uses the appropriate index file to solve the image.  As mentioned above, you don't need all the index files in the data folder. The number of sources will be determined by seeing conditions, scope/lens, target, exposure time and sigma value. Check the image acquired by AT to see if it looks reasonable.

Hth

Louise

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libraryman

libraryman

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Thanks Louise, I wondered if by downloading and reinstalling several times, I had inadvertently put in multiple copies of my indexes.. I did not expect to see index 4024-00 and 46 more up to index 4024 -47!!

I just expected to see 4024 once.

I'll try to assert which one its using.

Ray

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Christopher Davenport

Christopher Davenport

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Some tips

Once AT has solved you can save the settings for that telescope / reducer / camera.

Reducing the radius to 20 helps.

Also the 50 brightest stars as above.

I find shorter exposures force it to look at brightest stars.

Most my solves happen in 30sec and I abort at 1 min.

Because it relies on where you are pointing, if you are far out it will not solve.

By manually slewing to a known point, then clear sync points and sync on known point before your first solve, will calibrate it before you start.

Edit: quite a mouthful hope it helps!

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