Thoughts on which imaging rigs to concentrate on

[Gina]

Now integrating pixel rows - this takes a while...

I noticed that the settings were different from those used in BPP.  So, all-in-all I would expect an improved result.

[Gina]

Finished and master bias saved as XISF.  Now running to 600 set.  Put these into the 500GB SSD rather than using the HD.  Processing is faster with 6 frames in 5s.  Now stacking pixels.

Here are the two screenshots of the process for 300 and 600 bias frames.  I wonder why the 300 set uses 63 concurrent pixel stacks whereas the 600 uses only 31.

 

[Gina]

OH!!!  The processing has finished but no images on screen   I did the same as last time so I don't know what I did wrong.  I guess I can try running it again...

[Gina]

Run again and it retrieved files from cache saving a lot of time but we'll see if it displays anything...

[Gina]

Still nothing

[Gina]

I've got bigger worries though - much bigger   The boiler in my Rayburn has sprung a leak and I've got a big mopping up job to do then see what I can do about it.  Meanwhile I have some (much lesser) electric heating and have ordered a fan heater form Amazon for delivery tomorrow.  I've got a convection heater in the observatory too - I'll bring that in.

[Horwig]

GINA!!!! My heart goes out to you, I've had a feeling of deja vous reading your post,  just went through to my office in the house an hour ago, where my portable kit was sitting on the floor, and the central heating pipes on the floor above were dumping dirty water everywhere through the downlighter holes in the ceiling, telescope and camera splattered in inhibitor, must have just started, probably only a pint or so of water over the wooden floor, but no great damage, dehumidifier from the obsy now on other duties, that ceiling comes down tomorrow!

Kit has now dried out, but inhibitor brown on takahashi green is not a good colour combination

Best of luck with the Rayburn, my thoughts are with you

 

Huw

[ChrisLX200]

That's bad luck guys    hope it's a simple fix. Not what you want at any time of year but especially now as it's just starting to get colder.

ChrisH

[Gina]

Thank you very much Huw   Commiserations to you too - hope you get things sorted out soon   Funny how pipes and boilers spring leaks in autumn but I guess it makes sense as things will have been corroding merrily during the summer then when the cold weather arrives and we get the fires going and the central heating and stir it all up.

I have another, smaller water problem to sort out too.  The torrential rain last night almost flooded to observatory - the lower level regular sump pump had stopped working but thankfully the emergency higher level pump had kicked in and stopped the water rising too high.  I think the lower pump has silted up and got bunged up so I'll be sorting that out before long.

[Gina]

Thank you Chris too   I think the Rayburn is probably a lost cause as it's 20 years old but I shall get professional advice.

[Horwig]

1 minute ago, Gina said:

Thank you Chris too   I think the Rayburn is probably a lost cause as it's 20 years old but I shall get professional advice.

shouldn't think that 20 years is old in Rayburn terms, don't they go on for ever?

[Gina]

Just have to see - I'll keep my fingers crossed.  It may be that the boiler can be replaced.

[Horwig]

I used to have an AGA, when we replaced it 13 years ago, I couldn't believe how basic it was, everything was replaceable, I sold it to an AGA recon man, and he paid good money for it, enough for us to buy a new Rangemster electric range cooker.

I personally thought the hundredweight of scrap he removed from our house was worth £50 at most.

best of luck with it

[Gina]

Thank you Huw   I think this Rayburn must weigh several hundredweight   I remember when three men delivered it and maneuvered it into place on rollers!

[Horwig]

The man who came to collect the cooker turned up in a postman Pat van, the AGA was taken to bits where it stood, the only full size panel was the top plate, the front was in sections, the back was a sheet of mild steel which he folded to put in the van, and all the inside gubbins were covered in thick rust, and all the internal spaces filled with vermiculite insulation, really was a mess.

There I am cleaning the current mess, and the ASC is showing nice clear sky, someone must have it in for me tonight

Edited November 20, 2016 by Horwig

[ChrisLX200]

1 hour ago, Horwig said:

shouldn't think that 20 years is old in Rayburn terms, don't they go on for ever?

My gas boiler is more than 25years old, I thought about replacing it when I had a leak earlier in the year and advice (from a plumber) was  - don't bother, old ones are easy to repair but new ones don't last anywhere near as long! The problem with mine was the seal around a steel plate had just rotted, the bolted-on plate covered a core hole in the cast iron boiler. The leak though had dripped onto the main circuit board which died as a consequence, yet I managed to get a replacement cheaply off Ebay. The only other problem I've had with it over the years is a vacuum switch which turns on the gas valve only when the extractor fan is running - I bought a spare off Ebay only to find it was a thin plastic pipe to the valve which had split. I'll save the spare valve in case I need it over the next 25 years...   Oh, and a few years ago I had to put some engine oil onto the bearings of the extractor fan motor as it had begun to squeak..

ChrisH

[Gina]

Your ASC has a nice FOV Huw

[Horwig]

1 hour ago, Gina said:

Your ASC has a nice FOV Huw

Thanks Gina, it's nothing clever, a QHY5LII-C with the Fuji zoom I've always used, but I've sorted the pc and powering, it's now rock solid, and SharpCap allows me to use a real dark library. Tonight, in clear periods I could pick up the Heart and Soul nebulae and M31 without too much effort, the camera is quite sensitive to Ha.

Best of luck for tomorrow and the Rayburn. I've drained the heating system here, ceiling coming down ion the morning, hopefully, only a section, I've a good idea where the problem lies, I used push fit plastic when I did the heating here eight years ago, bet a push fit elbow has crept. Am I glad that the bathroom I just re-fitted this year was all done in copper.

Huw

[Gina]

Thank you

Ah yes    I'm thinking of going back to those for a daytime ASC - you seem to have got yours well enough sorted out for night use   Great stuff

Edited November 20, 2016 by Gina

[wimvb]

10 hours ago, Gina said:

I gather fixed pattern noise is handled by bias frames. 

I agree with your reasoning about number of darks.  Yes, this book is based on either DSLR cameras or CCD astro cameras - the ZWO cameras designed for astro use are a pretty new innovation and a different beasty from either, so a bit of "intuition" is needed in interpreting the information.  This is a new experience for me after a year or so of DSLR imaging followed by a couple of years of high quality astro CCD imaging.  Big and noisy to small and quiet and now to big and less noisy.

So latest thoughts are - several hundred biases, maybe 50 or so darks and as many decent lights as possible.  I see it's unnecessary to take special darks for flats as the "Optimize" parameter can be used to correct for the shorter time used for flats but I'm not sure this will work with the lower gain used when taking flats - I don't remember reading anything about this.

Read pattern "noise" is handled by bias, but hot or warm pixels are not, since they need the time to accumulate.

My understanding is that a read pattern in bias frames is most likely very close in signal strength to electronic noise (= random). Therefore, using a lot of bias frames will bing the noise level down and reveal the read pattern.

In dark frames, the read pattern is going to be calibrated out by the master bias. But a variation in sensitivity between pixels can also show up as a fixed pattern. Because of that, it won't be calibrated/stacked out. It is similar to truly hot pixels. If this is the case, no number of dark frames will correct this.

I agree with you about the number of calibration frames. I also don't take dark flat frames (or should that be flat dark frames?  )

7 hours ago, Gina said:

Finished and master bias saved as XISF.  Now running to 600 set.  Put these into the 500GB SSD rather than using the HD.  Processing is faster with 6 frames in 5s.  Now stacking pixels.

Here are the two screenshots of the process for 300 and 600 bias frames.  I wonder why the 300 set uses 63 concurrent pixel stacks whereas the 600 uses only 31.

 

What has me puzzled here is the line
Pixel combination .......... disabled

In the image integration dialog, combination is either average, median, maximum or minimum.

Never seen this line. I can't even reproduce it

[Horwig]

2 minutes ago, Gina said:

Ah yes    I'm thinking of going back to those for a daytime ASC - you seem to have got yours well enough sorted out for night use   Great stuff

Thanks Gina, focus is not good, I've not done anything clever to fine focus it, but colour is superb, Orion is now rising over the roof, and I can see the bright red splash of the Orion Nebula.

The exposures vary between i/1000th for daytime use, with gain at minimum, up to 30 secs at max gain for clear night time skies, with darks.

Sorry, this is going well OT

Huw

[Gina]

Thanks Wim I'll see if I can track down the Pixel combination business tomorrow.   I think hot pixels etc. are handled by Cosmetic Correction

[wimvb]

Glad to be of help. I hope you get your boiler fixed soon.

 

Cheers,

[Gina]

Thanks again   I've been in touch with one plumber but they are booked up until after Christmas   I spoke to the main plumbers wife and he is going to phone me back later today.  He may be able to recommend another plumber.  I've spoken to one of my farmer friends and he thinks that they should be able to replace the boiler - some of his family have had a similar problem and the boiler was replaced.  So I'm feeling a bit more optimistic than I did yesterday.

Running PI again and I found the problem with the Pixel combination - "Generate integrated image" was turned off.  So how I got an image for the 300 biases I don't know.

[Gina]

That's better   Auto-stretched image.