Saturday, 25 November 2023
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One of my favourite datasets from this year was the Pier 5 M81-M82-IFN competition set a few months back, and I recently had the idea to try reprocessing the dataset with a 2x drizzle integration, focusing more on showcasing details in the galaxies themselves rather than the IFN in the full field.

Pier 5 is extremely fast: (5.94/2.8)^2 / (3.76/2)^2 - 1 = 27% faster than a RASA running the ubiquitous 3.76um pixels for instance. Together with the fact that the OSC camera gives three times as many light frames per group than you would get with mono, all indications are that P5 should be ideally suited to drizzle integration.

Resulting resolution is ~ 1.22"/px, which is well sampled for the aperture and well suited to imaging medium-sized galaxies. Although I've never tried a 3x drizzle, that might also be an interesting possibility for a large enough dataset on smaller targets.

Anyway, hopefully a convincing case that P5 need not be standing idle this galaxy season :)

3 months ago
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#6807
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Looks good, its a fantastic pier for larger galaxies, clusters and interesting sections of IFN containing galaxies etc etc, so I agree it should not be disregarded.

Whilst answering I thought it was about time I mentioned something else, Pier-5 has almost zero jobs put into it in the last 2 months. if Myself and Pete had not put a few old customer jobs (somebody who is no longer a member) in a few weeks ago, it would have almost zero work to do this winter.

Our admin team have been talking about it behind the scenes for some time that pier-5 is the fastest data collection system we have and its massively underutilised. Syndicate members have put almost no work in for a long time,as we have stopped letting them know that it has no working in the pier they have not bothered themselves. There have been so many nights that pier-5 has sat idle almost all night it's scary, for some context see the syndicate job list for all piers below!

Its not our job to keep the syndicate piers working, it's the members themselves who run the pier. we are now in wet season so it's a moot point for loading up the pier now but I hope members put more work in for when the better weather periods arrive!

Steve

 

 

 


Please ignore my dylexia wherever possible, just be thankful I can control my Tourettes ;)

Things to do, so little time!

Steve
Roboscopes Tea Boy


3 months ago
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#6808
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The current pier queue, is 2/3 nights of work and that's the most it has had in 2 months ....

 


Please ignore my dylexia wherever possible, just be thankful I can control my Tourettes ;)

Things to do, so little time!

Steve
Roboscopes Tea Boy


3 months ago
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#6809
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Having a full-frame-collimated Epsilon pointing at the NCP on a clear night is downright criminal...  We can only hope the Spanish government doesn't find out about this or it will only be a matter of time before they arrive to confiscate the entire pier...

On a serious note, I wonder if the issue doesn't stem from the community's underappreciation of the 2400MC?  To my mind this is the best astro camera currently available at any price point...  I know I'm in the minority here, with others pining for 100 megapixels and a 7-position filter wheel, but what I want is beeeg (CMOS) pixels; there's just something about the quality of data they produce that simply cannot be replicated through increasing the integration time by the amount indicated by the generally accepted equation...  

If the idea ever arose to swap the 6200MM on P2 for the 2400MC on P5 I would be all in...  Not that I am unhappy about the data I am currently getting from P2 I would hasten to add!

3 months ago
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#6810
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Having a full-frame-collimated Epsilon pointing at the NCP on a clear night is downright criminal...  We can only hope the Spanish government doesn't find out about this or it will only be a matter of time before they arrive to confiscate the entire pier...

On a serious note, I wonder if the issue doesn't stem from the community's underappreciation of the 2400MC?  To my mind this is the best astro camera currently available at any price point...  I know I'm in the minority here, with others pining for 100 megapixels and a 7-position filter wheel, but what I want is beeeg (CMOS) pixels; there's just something about the quality of data they produce that simply cannot be replicated through increasing the integration time by the amount indicated by the generally accepted equation...  

If the idea ever arose to swap the 6200MM on P2 for the 2400MC on P5 I would be all in...  Not that I am unhappy about the data I am currently getting from P2 I would hasten to add!

LOL, It is 100% criminal :)

The 2400 is a fantastic camera, the reason its so good is the sensible pixel sizes it has, pixel sizes are driven by other industries like photography, mobile phones etc. just because that's what's available on the market does not mean its right for our hobby. In most cases optical correction has simply is not up to these tiny pixels sizes and in reality most likely wont be for many years and by then no doubt they will be using even smaller pixels.

A average telescope has on axis spot sizes of 5-10micron and off axis it's much larger

The issue is on Pier-2 most people want mono and the 2400 is colour :(


Please ignore my dylexia wherever possible, just be thankful I can control my Tourettes ;)

Things to do, so little time!

Steve
Roboscopes Tea Boy


3 months ago
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#6814
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I like Pier 5 a lot. It has produced some of my favourite images and mosaics. I have normally used it in OSC mode, but beginning to explore the dual-band filters.

I have been inactive for a while (family health issues), but hoping to pick up the pace again.

Just submitted four jobs. 2430 and 2431 to add O3S2 to the existing HaO3 mosaic of NGC 1499 (jobs 2373 and 2374). 2432 and 2433 for a two panel mosaic of the heart and soul nebulas using both HaO3 and O3S2 filters. I did this target in narrowband way back on the old Pier 14, and am currently reprocessing the data hoping to improve it with the skills I have learned over the last couple of years (hollow laughter). It will be interesting to compare the two images.

Look for more from me shortly!

3 months ago
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#6815
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Awesome as its desperate for some jobs, sorry to hear about your troubles btw

PS add the OIII/SII to your California and see what it brings :)

 

Steve

 

 


Please ignore my dylexia wherever possible, just be thankful I can control my Tourettes ;)

Things to do, so little time!

Steve
Roboscopes Tea Boy


3 months ago
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#6816
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Awesome as its desperate for some jobs, sorry to hear about your troubles btw

PS add the OIII/SII to your California and see what it brings :)

 

Steve

 

 

That's the intention. I have also just added job 2434 SH2-157 the Lobster Claw. If I have the camera orientation right it is a very nice field of view. Again with both dual band filters. As I said I am still learning/understanding what these filters do.

Thanks for your concern. The health issue was partner's cancer treatment. All going well (thank you NHS), but massively stressful and time consuming. As far as we can tell, it was a success. So, back to real life for a while.

3 months ago
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#6817
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Hello Anunnaki, 

Regarding drizzling I'd read somewhere to drizzle OSC camera data any time you have sufficient subs. I think it said 24 or more. That's what I've done since then but for anything other than from a smaller sensor I'd only employ 1x1 to avoid working with huge file sizes. That's what I did on that set of data.

I struggled to deal with extracting the background and was left with something from which I couldn't distinguish IFN from uncorrected gradients. Hence I never entered it into the competition, but rather than waste the data I did a major crop to include just the galaxies and was satisfied with the result. On my long list of things to do is a retry with 2x2 binning, something that never occurred to me at the time but should improve the resolution. I'll also look at what other larger galaxies I have and do the same.

Appreciate you sharing that and the results you got. Drizzling 2x2 is something I need to consider doing from now on, after all when it's a galaxy cropping after integration keeps the file sizes down.

Cheers and CS, 

Ray 


Ray
Roboscopes Guinea Pig


3 months ago
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#6818
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Hey Ray :)

You will be pleased with the results of a 2x2 drizzle on your older datasets!  The file sizes are also a concern for me as I do everything on a budget laptop lol, but as the frames are "only" 24mp the resulting masters aren't that much bigger than the 62mp on P2 for instance.

I also had a nasty colour gradient initially on the master light for this one.  Two ideas for you:

1) Try (free) Siril's DBE - at least as good as PI's and much easier to use imho.  Set the view stretch to "Histogram" (which is max), manually place a few dozen sample points in the gaps you can see and hit "Compute Background".  Things are much easier to see then, and you can move the sample points around and add a few more, then repeat etc.  The whole process took about 20 minutes, not exactly fun but somewhat therapeutic lol, and the end result was almost perfect for me.

2) Calibrate the lights without flats and bias.  I do this often!  The edge-of-field light falloff is often a lot easier to deal with using DBE than the strange artifacts I get when calibrating with flats.  Dust donuts are usually a non-issue with the lights from RS (they keep their scopes pretty clean with all those maintenance trips!), while the few minor ones that remain are easily dealt with using a little clone stamping on the starless layer.

Hope this helps, CS mate :)

3 months ago
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#6819
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Thanks Anunnaki, 

Two great suggestions. I will use those when I reprocess the target in question.

When running WBPP I had never considered not using a flat during calibration but from what I've seen, and you rightly say, sometimes the flats can create problems of their own which might be worse than what they are being used to correct. :(

Again, thank you for taking the time to post your recommendations for which I'm very grateful. :)

Cheers and CS, 

Ray 

 


Ray
Roboscopes Guinea Pig


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