eshy76

Just like in PI, APP (Astro Pixel Processor), allows you to weight subs by quality, including FWHM, when stacking. There is even a control to choose the percentage of subs to stack, so if you think that 10% of your subs are potentially bad, you would select 90% and would get the best 90% subs weighted by quality. This is a faster process than PI I find, as it's two settings then click, but you can always inspect the sub stats after weighting and manually remove ones you don't want in the same way if you wish. In your position that's the approach I would take and see if I was happy with the result.

All very sensible tips here. I would just add that I don't really use those exposure tables for exposure time per se - I used the underlying maths to work out what ADU I should, theoretically, be aiming for per sub. So at unity gain and default offset, the maths chucks out a minimum ADU per sub for me of about 1400. You can then use the readout in your capture software to judge the right exposure times. It's a one-time thing unless you image in different places with different skies. So I aim for this when judging exposure time, which is dependent on light pollution. With my bortle 7-8 skies this works out for me at about 30-60 seconds for RGB subs (much less for Lum) and 300 seconds for narrowband subs. Results seem good, which is, of course, the acid test!

Another vote for unity gain (139) to start off with. I've had the Pro version for nearly a year and it is only now that I am experimenting with other gain settings. As you say, the move from DSLR has many different aspects to it without complicating it by fiddling with the default gain which will give you great all round results as mentioned above. That sub exposure table/thread is a good place to start to judge sub length. Good luck! It's a great cam!

Hi everyone - it's been a while! This has been on my hard drive for almost 2 months and I finally got round to processing it...it was quite optimistic of me to try and image this from my Bortle 7-8 back garden, but I gave it a go! While the nebula itself is clear to see, all those gorgeous dust clouds surrounding it were extremely hard for me to capture from my location without a lot more integration time. I think I'll head to dark skies to capture this one next time, along with some more focal length! LRGB shot with ASI1600MM Pro and WO Z73. 2.9 hours of integration time. Full details here. Thanks for looking!

Hi there - Yoddha has been super helpful in addressing any problems I have had with APT...he helped me with the Platesolve2 approach I've settled on...I haven't really felt the need to go to blind solving yet.

Hi there - I also have not been able to get blindsolve to work in APT...so I just stopped trying. I just use Platesolve2 instead. My workflow is: 1. Turn everything on - usually my mount is in zero position here 2. Slew away from Polaris (apparently platesolving can go haywire at the pole) - I usually use the simple GoTo function in APT to pick an object for this or Cartes du Ciel - do not worry if the slew is inaccurate, you are just trying to get away from Polaris 3. Hit "Shoot" to take an image - 10 second exposure or so should be fine 4. I then click on Pointcraft and then on "Scope position" which populates the coordinates the scope thinks it's at. Then I hit "Solve" Within about 20 seconds this is successful on the first attempt and I then hit "Sync" to make sure APT is dialled in - all the Goto++ functionality works perfectly after that and subsequent "Solves" are usually successful within 10 seconds. The only step which might be superfluous is the "Scope pos" bit, you might be able to hit "Solve" directly after the initial slew. I'd love to get blindsolving working, but the above method has been foolproof for me, and given the blind solve takes longer as it's solving more of the sky I believe, I'm not sure it would necessarily be faster. Hope this helps!

Congratulations to the winners for some stunning images. This was a fun challenge!

Hi Mark - I got 2.4 hours of integration time over three nights, 89x75s at ISO400 at 135mm and 6x300s at ISO800 at 430mm. APP put it all together easily - I think the lack of noise is due to 1. Antares being overhead in Mauritius away from light pollution 2. Using dithering 3. Using quality weighted subs when stacking in APP 4. Processing technique - I used TGV Denoise and MMT in PI, with bright masks. Hope that helps. Here is a link to the higher res version: https://www.astrobin.com/356347/C/?nc=user

Mark's great pic has inspired me to post mine. Shame I only had a stock DSLR but lucky I had the Lacerta MGen to rescue my haphazard Southern Hemisphere polar alignment!

Wow Mark - I just saw this - fantastic shot! Congratulations!

Hi Steve - yes that's exactly it - Tools/APT Settings. Once you plug in figures for gain per filter (and autofocus offsets if applicable) in the dialog in your screenshot, whenever you select the filter in an imaging plan, the same gain/focus offset will be brought into the plan...very convenient once you've settled on what you want to use.

Hi there - I'm on a pretty recent Ascom version, maybe not the latest one....however, the answer is in the post above this one. When I set up my filter wheel, I use APT's settings, not the Ascom settings, so Tools/APT Settings as specified by Steve. That should work.

Hi there - do you have the latest version of APT? I believe the gain per filter was only recently added. I have version 3.63. APT is not updated within the program - you have to download and install the new version over the old one. Settings survive that process! That would be my best guess.

Thank you Alan - yes, I collected the data pretty much as a side project to the tadpole/flaming star mosaic I was working on. It wasn't one of my primary targets for the winter - I was also after M45 and the Horsehead - so the data just got forgotten. But processing the clean narrowband data was a pleasure and NGC 281 itself surprised me with its pillars of dust and the little star cluster at its heart. It's a beautiful object in its own right, which I realised when I zoomed in.

And here's the original field of view

Hi everyone, This has been on my hard drive for some months, so nice to have finally got round to processing it! Shot over several nights in January in my back garden. NGC 281, also known casually as the Pacman Nebula, is a bright emission nebula and part of an H II region in the northern constellation of Cassiopeia and is part of the Milky Way's Perseus Spiral Arm. It lies about 9,500 light years from us and is 48 light years across. As the final version, I've gone for a crop, which I think holds up well, though I'll include the wider fov version in the next post. I used a more natural colour blend for this image: R = 76%*Ha + 24%*SII G = 100%*OIII B = 85%*OIII + 15%*Ha For some reason, I was not expecting much from this image, but the result looks like it will be one of my favourites...the narrowband data was really good! Captured using APT, stacked using APP and processed in Pixinsight. 5.4 hours integration time. Link to full details and higher res version. Thanks for looking!

Yep done that one too....one to add to the slapstick astro mess ups...though not as bad as taking 20 mins to realize that the cap was still on my polemaster once...the hot pixels looked like stars on the ipad screen...it took me time to figure out why they weren't moving when I rotated the RA axis....!

The way it works is that if you put a gain number in the little box on the camera tab, that will override whatever was in the Ascom driver pop up, for a single shot and for an imaging plan - *if* you haven't assigned a gain to each filter in settings. In APT's settings when you set up your filter wheel, you can add a couple of things per filter which are useful as defaults for every time each filter is used - (1) the focus offset, if you are using autofocus and (2) the gain. So I tend have 139 assigned to LRGB filters and 200 for narrowband filters for example. I then leave the little box on the camera tab blank to make sure it doesn't override the filter wheel settings I put in when an imaging plan starts. It works perfectly for me....APT's scripting is pretty powerful...I also used it to platesolve to another target (Goto++) and restart PHD guiding in the same night...worked fine. Glad it's working for you now!

Hi there - this seems very odd - I have the same camera and also use APT, and I'm pretty sure the gain can be set higher than 100. I tend to use 139.... My first reaction to your post is that you might not have the right driver selected in APT....to check, click on the "Settings" button next to the camera name at the bottom of the APT screen...then make sure the ASI-1600 is selected specifically from the driver drop down menu in the Ascom screen that pops up. Personally I tend to set the gain using the Ascom driver (in the same "Settings" pop up) and leave the gain setting blank in APT itself - this is because in my filter wheel setup, I have a different gain associated with each filter and I don't want that overridden by the manual gain setting on the camera screen. Let me know if you need me to explain the above more clearly...happy to help!

Yep another vote for SkySafari...has been my invaluable companion on imaging/observing nights in both the Northern and Southern Hemispheres. I also prefer its forward and backward time controls compared to the swiping in Stellarium (which is also a very good app).

I watched the vid and read those posts yesterday - superb! The new stuff versus what I had read before was actually getting a number for light pollution and incorporating that into the equations. It was an impressive presentation and makes me want to dig deeper into Sharpcap, if its creator is so knowledgeable. Thanks again for sharing!

Thank you!

Thank you tomato! I went straight to CMOS, so short subs is all I know...looks like Sharpcap does a lot more than just polar alignment...I need to take a closer look.

By the way, NGC 4440 was the pretty barred spiral galaxy I was referring to earlier....you will be mine one day!

Thank you! I really wanted to bring out the blues more but the data was not cooperating...in any case it's a nice data set to come back and add to. The background is a mottled black too - I actually think that is the beginnings of IFN (integrated flux nebula), but the integration time was too low and the light pollution too high to get close to bringing that out as pretty dust.