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Messages - bulrichl

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1
General / Re: Error: Parsing EGAIN . . .
« on: 2019 December 13 14:50:55 »
As far as I know neither EGAIN nor ISO is evaluated by a PixInsight process. The processing should be performed correctly.

Bernd

2
General / Re: Error: Parsing EGAIN . . .
« on: 2019 December 12 13:12:15 »
This is an improper usage of the FITS keyword "EGAIN".

From FITS File Header Definition (from https://diffractionlimited.com/help/maximdl/FITS_File_Header_Definitions.htm ):

...
EGAIN – electronic gain in photoelectrons per ADU.
...
ISOSPEED – ISO camera setting, if camera uses ISO speeds.
...

Please ask Software Bisque for using the correct FITS keyword.

Bernd

3
Gallery / Soul Nebula (IC 1848)
« on: 2019 December 11 05:26:02 »
This is the first image that I want to show in this forum. Emission nebuala IC 1848, in Cassiopeia, also known as Soul Nebula. Captured with a Takahashi FSQ 106 and ZWO ASI071, gain 90, offset 65, T = -10 °C, 154 x 5 min = 12 h 50 min from my terrace in Tijarafe, La Palma at 19th, 26th und 29th November 2019.

https://www.dropbox.com/s/tycm3i0mqwh2wgk/IC1848.jpg

Complete processing with PixInsight, THE excellent software for the processing of astro images. At this point I want to express my gratitude to Juan Conejero for creating this wonderful program.

Bernd

4
General / Re: Error in WBBP
« on: 2019 December 08 07:49:28 »
... and when you typed this error message (Invalid platform 'version' attribute value '1.8.8-1: 1.8.8-2 ') into the search function of this forum, you would find the solution:

https://pixinsight.com/forum/index.php?topic=14341

Bernd

5
General / Re: Dark subtraction problems...
« on: 2019 December 08 02:06:59 »
I am supposing that your MasterDark is the plain integration of the dark frames, and that the flat frames were calibrated with the MasterBias, then integrated to the MasterFlat.

Your settings for the calibration of the light frames were:

-------------------------------------
Section 'Master Bias' enabled
MasterBias selected
Option 'Calibrate' disabled

Section 'Master Dark' enabled
MasterDark selected
Both options 'Calibrate' and 'Optimize' enabled

Section 'Master Flat' enabled
MasterFlat selected
Option 'Calibrate' disabled
-------------------------------------

That means, dark frame optimization was performed. For the calibration of the light frames a Master Bias was used. In the first step of the calibration process, the Master Bias was subtracted both from the target light frame and from the MasterDark. Then the correlation factor k0 for the calibrated MasterDark was determined and the product of k0 and the calibrated MasterDark was subtracted from the difference of the target light frame and the MasterBias. Finally this result was divided by the MasterFlat and multiplied by the mean of the MasterFlat.


Your settings for the calibration of the light frames are OK in section 'Master Flat'. Now please try the following:

-------------------------------------
Section 'Master Bias' disabled

Section 'Master Dark' enabled
MasterDark selected
Both options 'Calibrate' and 'Optimize' disabled

Section 'Master Flat' enabled
MasterFlat selected
Option 'Calibrate' disabled
-------------------------------------

That means, no dark frame optimization will be performed: For the calibration of the light frames no Master Bias is used. In the first step of the calibration process, the MasterDark is subtracted from the target light frame. Then the result is divided by the MasterFlat and multiplied by the mean of the MasterFlat.

Explanation:
Some CMOS sensors show strong "amplifier glow". The IMX183 exhibits particularly strong amp glow. This artifact is not strictly proportional to the exposure time. This is the reason that the amp glow is not completely removed in the calibration step when dark frame optimization is enabled.

Please let me know whether this helps.

Bernd

6
General / Re: Dark subtraction problems...
« on: 2019 December 07 10:19:01 »
Load one of the calibrated light frames and take a look at the FITS header (in the menu: FILE/FITSHeader). The section that begins with "COMMENT     Calibration with PixInsight 1.8.8" contains the settings for ImageCalibration. Take a screen shot and show it.

Bernd

7
General / Re: Interesting calibration problem
« on: 2019 December 07 10:05:25 »
I fear that this will not succeed. I see the artifact (in the zone 1250 - 1950 pixels away from the upper border) only in your light frame. In the MasterBias and in the MasterDark, there is a different artifact (similar as in the light frame, but only in a zone 0 - 140 pixels away from the upper border).

I also tried calibrating only with MasterDark (no 'Optimize', no 'Calibrate') and MasterFlat -- expectedly the artifacts remain the same.

Perhaps this is a Residual Bulk Image (RBI) which could be avoided by a NIR preflash? (I don't have experience with this effect, so this is speculative.)

Bernd

8
General / Re: Dark subtraction problems...
« on: 2019 December 07 08:38:17 »
Do the dark frames match the light frames (exposure time, gain, offset and temperature), how did you make the MasterDark and what were your settings for the image calibration of the light frames?

Bernd

9
General / Re: Interesting calibration problem
« on: 2019 December 07 02:36:57 »
Hi Stu,

why do you set the data range in Statistics to '14-bit [0-16383]'? The camera has a bit-depth of 16 bit.

Despite an exposure time of 30 min the signal in the Ha light frames is very low. As you can see in the histogram of your calibrated light (see appended Light_cal.JPG), the noise distibution effects that about 25 % of the pixels are clipped. In order to avoid that you should use an output pedestal in the calibration of the light frames (see the effect of an output pedestal of 100 ADU in the appended Light_cal_output_pedestal.JPG).

In the calibrated light frame I see a stripe pattern (dark vertical stripes in a zone 1250 - 1950 pixels away from the upper border). Don't know what that is.

Bernd

10
General / Re: Low gain darks not read by PI
« on: 2019 December 06 09:58:39 »
Yes, for the integration of darks, flat-darks and bias frames the setting 'Normalization' in the 'Pixel Rejection (1)' section has to be set to 'No Normalization', see Vicent Peris's excellent tutorial:

https://www.pixinsight.com/tutorials/master-frames/

Why did you say that an outlier-dark is no problem? Something obviously went wrong during the capture of dark 022, and I definitely would exclude it from the integration.

Bernd

11
General / Re: Low gain darks not read by PI
« on: 2019 December 06 09:18:45 »
With 'No Pixel Rejection', these darks are integrated flawlessly. However when I set e.g. 'Percentile Clipping', the error message appears.

On further inspection it turns out that dark 022 has a totally different median (= 4720 ADUs) than darks 020 and 021 (= 620 and 624 ADUs respectively). I guess this is the culprit. You could load all darks with 'Blink', output a Seies Analysis Report and take a look whether there are any more outliers. Exclude the deviating darks from the integration. Hope that helps.

Bernd

12
General / Re: Low gain darks not read by PI
« on: 2019 December 06 07:38:41 »
Then I guess it is advisable to upload a set of 3 dark frames which produce this error message in order that Juan can take a look at it.

Bernd

13
General / Re: Image integration error messages
« on: 2019 December 06 07:15:45 »
In order to report this you need 3 threads in the category "Announcements" which by the way is reserved for the developer of PixInsight?

This was a bug in SGP which was fixed in the SGP beta v3.1.0.211 in August 2019, see e.g. https://pixinsight.com/forum/index.php?topic=13796 . When you search in PixInsight Forum, you will find numerous threads about it.

Bernd

14
General / Re: Low gain darks not read by PI
« on: 2019 December 06 06:58:27 »
Did you also try the integration of the darks with 'Evaluate Noise' disabled?

Bernd

15
Lights were created with N.I.N.A: 1.10.0.10 (gain 120, offset 30), flat darks and flats are created with APT v.3.7.1 (gain 120, offset not written to the FITS header). We had it in another thread just recently:

It is not recommended to use different capturing software for light frames and calibration frames!

---

FlatDarks captured at 25th November 2019 (folder "/flat darks/"):

The flat darks in the folder "/flat darks/" have a median of about 77 ADUs which is not plausible at all. Presumably these frames were captured with a different (higher) offset setting than most of the other frames. Unfortunately the offset is not visible for the frames captured with APT.

Accordingly the MasterFlatDark "dark-BINNING_1-EXPTIME_3.5.xisf" has a median of 77.257.

All of these files (flat darks of 25th November 2019, MasterFlatDark and the integration of the calibrated light frames) are unusable and should be deleted.

---

FlatDarks captured at 27th November 2019 (folder "/flat darks 2019-11-27 L-enhance fw 120 sweatshirt GOOD peaks good 2.5sec (WORKS)/"):

The first file in the folder "/flat darks 2019-11-27 L-enhance fw 120 sweatshirt GOOD peaks good 2.5sec (WORKS)/", "F_5-Lenhance_2019-11-27_18-42-16_Bin1x1_2.5s__-10C.fit", is a flat frame, NOT a flat dark. It belongs to the folder "/flats-2019-11-27 L-enhance fw 120 sweatshirt GOOD peaks good 2.5sec done (WORKS)/".

The remaining 35 flat darks have a median of 1916 ADUs which is in the expected range.

---

Correct dark frames and consequently a correct MasterDark are missing.

Additional to using the incorrectly captured flat darks and the missing dark frames there are mistakes using the script Batch Preprocessing:

==================================================================================

[2019-12-04 20:08:04] ************************************************************
[2019-12-04 20:08:04] * Begin integration of dark frames
[2019-12-04 20:08:04] ************************************************************
[2019-12-04 20:08:04]
[2019-12-04 20:08:04] ImageIntegration: Global context
[2019-12-04 20:08:04]
[2019-12-04 20:08:04] Opening files:
[2019-12-04 20:08:04]
[2019-12-04 20:08:04] B:/Data/astronomy/Calibration Captures/Dark Flats/2019-11-25 L-enhance fw hyperstar 1.25 120 sweatshirt 3.5sec GOOD/F_5_2019-11-25_20-46-31_Bin1x1_3.5s__-10C.fit
[2019-12-04 20:08:04] 36 FITS keywords extracted.
[2019-12-04 20:08:04] Reading FITS image: 16-bit integers, 1 channel(s), 4144x2822 pixels: done
[2019-12-04 20:08:04] Computing image statistics: done
[2019-12-04 20:08:05] Weight          :     1.00000

...

[2019-12-04 20:08:32] ************************************************************
[2019-12-04 20:08:32] * End integration of dark frames
[2019-12-04 20:08:32] ************************************************************
[2019-12-04 20:08:32]
[2019-12-04 20:08:32] * Writing master dark frame:
[2019-12-04 20:08:32] B:/Data/astronomy/Captures/M42 Orion Nebula M42 hyperstar fw L-ehance/2019-11-25 30s 120 gain/PPoutput no darks/master/dark-BINNING_1-EXPTIME_3.5.xisf
[2019-12-04 20:08:32] Writing image 'integration': w=4144 h=2822 n=1 Gray Float32
[2019-12-04 20:08:32] 186 FITS keyword(s) embedded.
[2019-12-04 20:08:32] 16 image properties embedded.
[2019-12-04 20:08:32] Writing image 'rejection_low': w=4144 h=2822 n=1 Gray Float32
[2019-12-04 20:08:32] Writing image 'rejection_high': w=4144 h=2822 n=1 Gray Float32
[2019-12-04 20:08:33]
[2019-12-04 20:08:33] * Searching for a master flat dark frame with exposure time = 30s -- not found.
[2019-12-04 20:08:33]
[2019-12-04 20:08:33] * Calibration of flat frames skipped -- no flat darks found.
[2019-12-04 20:08:33]
[2019-12-04 20:08:33] ************************************************************
[2019-12-04 20:08:33] * Begin integration of flat frames
[2019-12-04 20:08:33] ************************************************************

...

[2019-12-04 20:09:18] ************************************************************
[2019-12-04 20:09:18] * End integration of flat frames
[2019-12-04 20:09:18] ************************************************************
[2019-12-04 20:09:18]
[2019-12-04 20:09:18] * Writing master flat frame:
[2019-12-04 20:09:18] B:/Data/astronomy/Captures/M42 Orion Nebula M42 hyperstar fw L-ehance/2019-11-25 30s 120 gain/PPoutput no darks/master/flat-FILTER_L-enhance-BINNING_1.xisf
[2019-12-04 20:09:18] Writing image 'integration': w=4144 h=2822 n=1 Gray Float32
[2019-12-04 20:09:18] 244 FITS keyword(s) embedded.
[2019-12-04 20:09:18] 16 image properties embedded.
[2019-12-04 20:09:18] Writing image 'rejection_low': w=4144 h=2822 n=1 Gray Float32
[2019-12-04 20:09:18] Writing image 'rejection_high': w=4144 h=2822 n=1 Gray Float32
[2019-12-04 20:09:18] Writing image 'slope_map': w=4144 h=2822 n=1 Gray Float32
[2019-12-04 20:09:20]
[2019-12-04 20:09:20] * Searching for a master dark frame with exposure time = 30s -- best match is 3.5s
[2019-12-04 20:09:20]
[2019-12-04 20:09:20] ************************************************************
[2019-12-04 20:09:20] * Begin calibration of light frames
[2019-12-04 20:09:20] ************************************************************

==================================================================================

According to this section of the logfile generated by BPP there are several flaws:

1) The flat darks are taken as dark frames. The "MasterDark" in fact is the MasterFlatDark.
2) Surprisingly the script searches for a MasterFlatDark with an exposure time of 30 s (this is the exposure time of the LIGHT frames, the flat frames had an exposure time of 3.5 s!). It does not find one and skips the ccalibration of the flat frames. The uncalibrated flat frames are then integrated and the result is used as the MasterFlat.
3) Then the script searches for a MasterDark with an exposure time of 30 s, finds the one with 3.5 s and takes this.

So there is big confusion. Obviously this is caused by a wrong selection of the sort of frames (light, dark, flat, flat-dark). Normally this has to be set in the capturing software and the rest is done automatically. Alternatively one can denominate the files accord to their sort of frame  (e.g. L for light, D for dark, F for Flat) and select them manually in BPP with 'Add Custom'.

The bottom line is: the flat frames were not calibrated at all. For the calibration of the light frames the MasterFlatDark made from the incorrect flat darks (instead of a MasterDark) and the "MasterFlat" (without subtraction of the bias offset) were used. The result is - not surprisingly - rubbish.

I strongly recommend you to perform the preparation of the master calibration files and the calibration of the light frames at least once separately.step by step (not with BPP but with the processes ImageIntegration, ImageCalibration, Debayer, StarAlignment). See my guide https://pixinsight.com/forum/index.php?topic=11968 for a detailed description and explanation of the preprocessing.

Bernd

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