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Messages - Terry Danks

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General / Re: Ha Calibration Woes . . .
« on: 2019 March 28 18:13:56 »
Only in the almost vanishingly rare cases when PS2 fails do I go to the failover astrometry plate solver. That cannot be the source of my subs going from FLIPPED=F to FLIPPED=T as I've just used PS2 since it became avaliable in SGP.

It will take some work on my part to determine the date when this strange change from F to T took place. OK. Did it.
All my subs taken on and prior to Mar 26, 2016 are "FLIPPED F."
All taken subsequent to that date are "FLIPPED T."
The break occurred between sessions on Mar. 26, 2016 and April 5, 2016. It occurred despite both sessions being SGP v. I can think of no change in routine, software or hardware that would account for the change. It seems curious, but irrelevant to the calibration problem recently encountered.

Yes, I should be able to come up with master darks created several years ago but only the master. I will not have the individual dark subs from which the old masters were integrated.

General / Re: Ha Calibration Woes . . .
« on: 2019 March 28 10:39:13 »
Thanks, Bernd and Adam. I remain mystified as to the reason for the change from F to T for the flipped keyword in ALL my images now . I have seen Bernd's post to the SGP forum as well.

I am using the latest version of SGP, BTW. Just that those subs were not taken since my last update. The latest version is still giving me FLIPPED=T, for no reason I can ascertain. This includes subs taken in the past 12 hours from SGP v.
And I remain unclear as to whether this flipped business can be the source of my lousy Ha calibrations of late and my need to add a pedestal while calibrating. I gather from Bernd's latest post, likely not.

All hardware remains the same other than going to a newer Win10 laptop for data acquisition.

General / Re: Ha Calibration Woes . . .
« on: 2019 March 25 19:33:19 »
Well, I'm learning stuff here for sure.

Regarding the flipped notation. That puzzled me as it was my intent to upload a file as it came from the camera.
I am imaging as I write this and it seems all my subs, as they come from the STL, now have Flipped=T! I went back and looked at some from a couple of years ago and they had Flipped=F.
When this happened, I have no idea. And I have no idea as to why it happened either. Or if I should do anything about it?

I was not aware that I could use a 10 minute dark for a 30 minute sub. Do I understand correctly that you are telling me that is what "optimize darks" actually does. It would be great to not have to take 30 minute darks for my NB!

All my subs, including darks, flats and bias frames are taken at -20C.

General / Re: Ha Calibration Woes . . .
« on: 2019 March 25 05:32:36 »
Hi Adam:

Yes, it is correct that my LRGB calibrations are fine but, no, it is NOT correct that the same darks were used to do so. The LRGB subs are 10 minutes duration. The Ha subs are 30 minutes. So, different darks.

But we have moved well beyond those anyway as the problem persists both with . . .

Totally new master darks integrated from fits files as they come from the camera and
A fresh install of PI. In fact, two fresh installs, v. 1448 and 1457.

I have uploaded the master calibration files to Dropbox. Also one of the uncalibrated fits lights, and the lousy calibrated file that resulted from the run.
Link . . .

General / Re: Ha Calibration Woes . . .
« on: 2019 March 24 11:13:30 »
I'm out of my depth here.
I "went back to basics." By that I mean . . .

1/I uninstalled PI v. 1457.
2/ I reinstalled a previous version, v. 1448.
3/ I loaded the BPP with .fits files as they come from the camera, for all frames, lights, darks, flats and bias frames.
4/ I then ran the BPP twice. Once with the "up-bottom FITS" box checked and again with it unchecked.

Same result each time. It was evident, from the break in the column defect, that checking/unchecking the "up-bottom FITS" box DID "vertically mirror" the resulting master dark. New masters were created on each run. Still, the resulting calibrated sub looked the same, i.e. severely clipped.

Attached is a single calibrated Ha frame, with the histogram displaying the stretch from the STF default. Also attached is the same single un-calibrated sub with its histogram from the STF default.

Not sure what to make of Bernd's suggestion? After I double click on Format Explorer/FITS. I attach that panel also. That panel is identical to that on both the machine with the current version of PI and the old machine with an ancient version.

General / Re: Ha Calibration Woes . . .
« on: 2019 March 23 16:47:02 »
Thanks guys. I am getting confused. I DID notice in my previous post that the master darks from the new vs the old versions of PI were of differing orientation. (Never though I'd actually be glad my STL developed its first column defect last summer!)

But I don't know why this is only a problem on the two machines that are running up-to-date versions of PI and not on the old machine running a very old version?

Also, I tried flipping the dark and re calibrating. Sorry to say I got the same result, i.e., horribly dark, clipped calibrated subs.
I have attached two panels. One with the master dark as produced by the latest version of PI compared to a single sub and another run with the master flipped to match the sub orientation.
Same poor result for each effort.

Finally, I checked and see that the master dark produced on the new machines for my 10 min LRGB subs is also flipped when compared to the lights . . . but my lights calibrate well.
Totally confused.  :'(

General / Re: Ha Calibration Woes . . .
« on: 2019 March 23 12:54:09 »
Hi Adam:

Attached is a screenshot of the two master darks.
The .xisf is, of course, produced on one of the machines running the latest version of PI.
The .fits master was produced on the older machine that still gives me good calibrated Ha subs.

General / Re: Ha Calibration Woes . . .
« on: 2019 March 22 18:14:04 »
Sorry, Rob, but I don't understand the question. "i16?"

I took the subs, flats, bias and darks directly as they came from the SBIG STL into the old version of PI and all is well.
I believe all are 16 bit ".fits" files.

Taking these very same files into the latest version of PI produces the wonky calibration.
Attached is a single sub put through both the old PI and the latest version. No CC on either and default STF for both.

General / Re: Ha Calibration Woes . . .
« on: 2019 March 22 07:23:38 »
Many thanks again, Rob and thanks too, Adam.
Camera is an SBIG STL CCD.

I have now involved three machines. Two running the latest versions of PI. These two both have this weird problem.

The third machine has "Stone Age" PI on it, v. Obviously, this machine is rarely used any longer for anything, but still works.

First problem with it was that it predates .xisf. Furthermore, PI's Batch Format Conversion will not convert my .xisf masters to .fits. So I loaded the original calibration subs (.fits) into the "Stone Age" version of PI and . . . voila! The Ha calibration seems fine!

Now, I could have somehow, inadvertently messed up a setting in my main machine, thereby causing this. But I see no likelihood of similarly messing up my second machine?

And calibration is fine on the third machine, the one with the ancient version of PI.

As I've stated earlier, I've already tried producing new masters on the two machines running the latest PI version in case my masters somehow "tuned bad," but get the same lousy calibrations after doing so. But all is fine on the machine running the ancient version of PI.

So, I'm flummoxed.  :-\

General / Re: Ha Calibration Woes . . .
« on: 2019 March 21 16:30:22 »
Many thanks for helping me out yet again, Rob.

Adding a pedestal (1000!) worked. The subs though have a tremendous gradient (see attached).
DBE pretty much wipes that out but this all leaves me puzzled as to what in hades I've done to cause this to be necessary?
It also means abandoning the Batch Preprocessor completely and calibrating and applying a defect map manually.  (Poor me!  :tongue: )
As I stated in my first post, this is the first time any of this has happened and there must be something I've done to cause it. Same Ha frames 4 days ago were fine going through the Preprocessor and having it apply the defect map.

General / Ha Calibration Woes . . .
« on: 2019 March 21 14:32:39 »
I am experiencing problems calibration all Ha frames.

Two things . . .

1/ Only Ha frames are giving me grief. LRGB calibrations are fine, and . . .
2/ I went back and redid some Ha frames I just calibrated a few days ago with no problems but now they come out terribly!

This is on two machines. Same "new problem" on both.

Attached is a screenshot with the "good" calibration on the left and the "bad" on the right. Default STF settings on both. All backgrounds in calibrated Ha frames are now clipped, or almost clipped.

I have used the Batch Preprocessor, set to "Calibrate only. I have also tried producing new flats, darks and bias frames in case my masters had somehow become corrupted, but I still get these very dark calibrated frames.

To my knowledge, I have not changed any settings on either machine but am at a loss as to what is causing this sudden misbehaviour.
Any suggestions?

General / SFS: Subs taken through cloud vs clear, dark sky?
« on: 2019 February 28 05:57:02 »
Last night I know there was thin, high cirrus cloud about. When I checked the subs against those taken another night, when it was clear, I expected to see figures in the SFS that would allow me to distinguish "bad" subs, i.e., those taken through the cloud, from the "good" subs, taken in a clear sky.
I saw nothing in the FWHM, Ecc, or SNR figures that pointed to the "cloudy subs" being better, or worse than the "clear" subs.
This does not seem logical and I am puzzled.

Is there really a significant advantage to using weighting expressions calculated by the SFS and written into the fits headers over the weighting the Image Integration Process does on its own when noise evaluation is active?

My concern: It seems there is a possibility that any expression I formulate to weight subs may well be less sophisticated than those used by the far more competent programmers who wrote the Integration Process in the first place, opening the likelihood of my doing more harm than good?

Again, dld, many thinks for getting me to better appreciate what these expressions are actually doing.
I am still being very unsophisticated in formulating my expressions but a weighting based on both FWHM and SNR values, without producing negative numbers, is being accomplished and the resulting integrations are successful. How much better these integrations are, if better at all, then just letting the Image Integration tool have at the subs, is a mystery.  :)
Eccentricities are a constant bugbear for me and seem strictly seeing-related. I have already used SFS to eliminate any subs with Ecc > 0.600 and have been doing so for a couple of years now. So, I have not attempted an expression to take ecc into account during the weighting calculations.

Thanks very much for the replies.
I cribbed the weighting expression from the SFS documentation.
Clearly it can, and does every time, return some negative values.
It is 2*(FWHMSigma / -3)+(SNRWeightSigma / 3)

Not sure why most of the weighting examples in the documentation return negative values with no mention that these can not be used with Image Integration.
But now that I understand the effect of negative values, I can adapt the expressions to avoid this happening.

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