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Topics - GaryP

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General / Which version to download for an antique system?
« on: 2019 October 01 16:50:31 »
I'm still clinging to my late 2009 iMac until it dies and running OS X 10.9.5. What is the latest version of Pixinsight that will run on it?

General / SNR
« on: 2014 August 05 21:55:56 »
I made three different stacks of IC1396 with a DSLR camera, and I want to make sure I'm working on the best stack. One of the stacks is a reregistered integration of the other two. I've been trying to figure out how to use PixInsight to determine SNR. One message from an apparent expert on the PI forum says use AvgDev for the signal and MRSNoise for the noise and then do the division.

I found AveDev in the Statistics readout. Notice there is not a whole lot of difference in the stacks. July 25 has the edge.

Table 1: AveDev from Statistics, 3 Stacks
   R   G   B
Jul 25:   1.21e-03   8.79e-04   6.86e-04
Jul 27:   1.13e-03   8.05e-04   6.37e-04
combi:   1.20e-03   8.65e-04   6.61e-04

MRSNoise is supposed to be in NoiseEvaluation, a script that just runs immediately on an open image and displays its results on the console, but I don't find anything called MRSNoise in it. Here is a readout from the console for the combined stack.


Calculating noise standard deviation...

* Channel #0
?R = 9.237e-05, N = 186299 (1.23%), J = 4

* Channel #1
?G = 7.597e-05, N = 397750 (2.62%), J = 4

* Channel #2
?B = 8.241e-05, N = 884136 (5.83%), J = 4

So maybe MRSNoise refers to the sigma values above (?sigma = mean root square). What, exactly, does N refer to? Table 2 gives the sigma values.

Table 2. Sigma values from NoiseEvaluation, three stacks

   R   G   B
Jul 25:   1.305e-04   1.079e-04   1.115e-04
Jul 27:   1.385e-04   1.137e-04   1.180e-04
combi:   9.237e-05   7.597e-05   8.241e-05

Notice the smaller noise values for the combination stack. Now we can do the arithmetic for SNR:

Table 3. Signal to noise ratios (AveDev/Sigma), three stacks

   R   G      B
Jul 25:   9.27203, 8.14643, 6.15247
Jul 27:   8.15884, 7.08004, 5.39831
combi:   12.9912, 11.3861, 8.02087

In my very limited experience, those look like plausible SNR values. We see that Jul 25 beats Jul 27 in every channel in spite of better seeing on the 27th, but the combined stack of 69 subs beats them both by a substantial amount. This is due mainly to dividing similar signal values by lower noise values in the combined stack. It may be the case that some difference in calibration parameter settings had something to due with getting those noise values down, but my records are not good enough to say.

I know little about any of this. I would like to know if what I have presented makes any sense.

General / Help needed with Aperture Photometry
« on: 2014 May 13 13:28:52 »
I'm trying to learn how to use the AperturePhotometry script. I had no fresh (or stale) CR2 images at hand, so I tried it with a stack in .fit format following the tutorial at

and the PixInsight page on the topic at

As is readily seen from the output of the Process Console, the attempt didn't work out well. I did not know what value to enter for pixel size after debayering, so I left it at "1". I entered the coordinates of M13 (from Wikipedia) and the focal length of the scope used (Stellarvue 80ED, 560 mm). Can anyone see immediately from the following data where I went wrong?

I'm wondering if the CR2 files produced by the Canon T1i lack some necessary bits of information, or if the information that they formerly contained was somehow lost in the stacking.


Reading 1 image(s):
Reading FITS: 16-bit integers, 3 channel(s), 4769x3177 pixels: done

run --execute-mode=auto "/Applications/PI-macosx-x86_64-"

Processing script file: /Applications/PI-macosx-x86_64-
** Warning [162]: /Applications/PI-macosx-x86_64-, line 1487: reference to undefined property this.parent.parent.outDir_Edit

* The image has no WCS coordinates -> SOLVING
Seed parameters for the plate solving:
   Image coordinates: RA=16 41 41.240, Dec=+36 27 35.50
   Resolution: 0.3683300111555292
Starting StarAlignment iteration

Downloading Vizier data: 36.459861&-c.r=0.585522&-c.u=deg&-out.form=|&-out.max=200000&-out=PPMXL&-out=RAJ2000&-out=DEJ2000&-out=pmRA&-out=pmDE&-out=Jmag&-out=Hmag&-out=Kmag&-out=b1mag&-out=b2mag&-out=r1mag&-out=r2mag&-out=imag&r1mag=<10
3751 bytes transferred in 1.01 s @ 3.64 KB/s
Catalog PPMXL size: 11 objects

Using Triangle similarity algorithm

StarAlignment: Processing view: stk1
Scanning star data: done
2 stars.
*** Error: /tmp/stars.csv: 2 star(s) found - need at least six stars.
<* failed *>
*** Error: The image could not be aligned with the reference star field
*** The image could not be solved.
This is usually because the initial parameters are too far from the real metadata of the image
Warning: The image could not be solved. It will be processed using the existing referentiation.
Error in image stk1: The image hasn't coordinates

Photometry process finished:
   0 of 1 images processed successfully.
   1 images with errors.
   1 errors and warnings.
Writing error log: /Users/garypalmer/Documents/ASTRONOMY/ASTROIMAGES/PHOTOMETRY/Table_Errors.txt

content of Table_Errors.txt: "stk1: The image hasn't coordinates"

When attempting to save the new integration file after ImageIntegration, I find that the items in the File menu are all inactive except for Open Recent and Clear Recent. It is possible to activate the Save and Save As menu choices by applying DynamicCrop (and undoing).

General / How best combine two stacks
« on: 2014 May 08 07:50:07 »
I have two stacks of the same subject that I would like to integrate because PI would not integrate all 72 subs in one batch on my system, as explained in a recent post. They need to be cropped a bit. My questions are:

1. Are the stacks already registered by virtue of the fact that the subs were registered?
2. Does it matter if they are cropped before or after after integration?
3. If they are preregistered and then cropped, is it necessary to reregister them before integration?

General / ImageIntegration quits on large batch in Mavericks
« on: 2014 May 07 09:30:16 »
I have 72 subexposures taken on two separate nights that I would like to integrate into a single stack. They have been calibrated and registered in PixInsight, so they all have the suffix "". I close down all running programs except the OS X ActivityMonitor. I load the files into ImageIntegration with the settings shown on the attached screenshot. I click the global icon and watch the process begin on the Process Console. In the morning the console says "Integrating channel 1 of 3, 0 --> 3177: 24%".

It apparently stopped running during the night, but my click of the mouse reawakened it. The ActivityMonitor reads 660 MB of memory. After a few minutes it moves up over 30% and the memory used drops to 300 to 400 MB levels. I return a half hour later and the screen is dead. No amount of clicking or space bar pressing revives it. I do a hard shutdown, restart, and increase the buffer size to 152. Same result.

I didn't try increasing the stack size, but perhaps I should have. I was deterred by the Activity Monitor which tells me that 3 GB of memory was in use with no programs open. I have since learned that Mavericks has it's own way of handling memory, so that might not be a problem. Before trying this, I did my best to clear the system of all unnecessary daemons, .plists, and programs. In the past I have integrated as many as 32 subs. I could integrate this set in two batches and combine them, but PI should be able to take larger bites, shouldn't it? Does anyone have an insight into this difficulty?

Off-topic / Problem running Keller video in OS X Mavericks
« on: 2014 May 04 11:35:14 »
I purchased the online version of PixInsight-I of the Keller tutorial series. When I tried to view it, the video started and after a few seconds it quit and started buffering. It never stops buffering. Then I saw the small print that it requires Internet Explorer (I have Chrome and Firefox at hand). Then I discovered that Internet Explorer doesn't run on recent versions of OS X without the aid of a virtual PC or CrossOver. Suddenly the cost of the video has doubled. My Flash player is updated and enabled. Any help here?

I hope I can get this sorted out quickly, because I was planning taking a quick look at series I and then taking advantage of the $30 special offer on the 3rd series.

General / What, exactly, are the pixel readouts?
« on: 2014 April 26 09:58:33 »
A panel at the bottom of the PixInsight workspace shows values for R, G, and B pixels that change as one moves the cursor over the image. I wonder what it is that these values represent. My T1i has a 14 bit analog to digital signal conversion. Does a reading of say, R: 0.0150 tell me that the red channel is 1.5 percent saturated? Can I infer anything regarding the number of electrons or photons that produced that reading?

<-- Like it says on the panel, a newbie.

Bug Reports / Annotation text does not appear on image
« on: 2014 April 22 11:21:58 »
I am trying to use the Annotation process to place a few labels on an image. I understand the procedure is to set the parameters in the dialog and then left click on the image. At first I had no luck seeing any text or leader on the image. Then a friend suggested setting the font size up to 72 and the color to something more visible, e.g. red. When I did that, I was able to draw a label on the screen. When I left and returned for another session, I found it no longer worked, even after restarting PI and resetting the size and color parameters to the configuration that previously worked and trying a variety of sizes and colors.

General / Annotations not happening
« on: 2014 April 18 20:31:10 »
It appears to me that most PI users use annotation to search a database to obtain labels for objects in their images. But as I look at the Annotation process window, it appears to be designed to place user-created text annotations on the image. I found some instructions that said to click on the image and one should see a display of the text from the Annotation window on the image. This is not happening here. Am I misreading the function of the Annotation process?

PI version

I would like to be able to delete selected samples. I noticed in one of Harry's videos that he used the delete key. That doesn't work for me. The little red X at the bottom of the DBE dialog deletes all the samples. Is there a way to delete just the selected sample?

General / Frustrated by active dynamic interface
« on: 2014 April 03 09:00:49 »
When I start a new process and attempt to apply it, I often encounter the error message: "This file being used by an active dynamic interface". Some explanation would be welcome. The problem was also noted by @bitli, who received no answer, back in 2012 I think.

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