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Topics - CraigNZ

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General / PixelMath question
« on: 2019 October 18 15:02:51 »
I have a monochrome CCD image and want to change the value of each pixel using this formula:

y = 0.99 *x + 140/x + 318.0

I tried this equation in PixelMath but it did not work:

0.99 * $T + 140/$T + 318.0

What would be the correct equation(s) to use in PixelMath?


PCL and PJSR Development / Calculate Airmass
« on: 2019 August 25 16:13:46 »
Is there a function or script that calculates the Airmass given an image.  I want to modify the aperture photometry script to calculate the airmass instead of using the value in the FITS header.  The reason is because the FITS header value is incorrect and I don't want to abandon the images.


General / BPP Export Calibration Files missing
« on: 2019 February 21 18:00:19 »
I am running PI v1.8.6 and BPP v1.47.  I am trying to save my session settings and file names and I understand there is a checkbox labeled "Export Calibration Files" .. but I cannot find it.  It is not listed in Global Options and I didn't see it listed anywhere in PI Global preferences.  Where do I find this?  Or is it possible when I installed PI in the C:\windows\Program Files folder that Windows 10 is blocking BPP from saving its settings?


General / Linux: PI does not see second drive
« on: 2018 April 22 17:37:41 »
Now that I have PI successfully running on Ubuntu 17.10 I was able to load an image from the C drive, all works great.  But my images are all on a separate drive and when I use Open the other drive is not listed.  I then ran LibreOffice and it is similar but it uses 'Other Locations' to show the drive.  PI does not offer this, is there some other way either in Linux or in PI that I can configure so PI can see the images on the other drive?

General / Linux install: run error
« on: 2018 April 22 14:39:26 »

Setup a new PC with Ubuntu 17.10, downloaded latest PI distro package for Linux and installed.  Everything went okay, but when I go to /bin and run Pixinsight I get this error message:

craig@LinuxBox1:/bin$ PixInsight
/opt/PixInsight/bin/PixInsight: /opt/PixInsight/bin/lib/ version `ZLIB_1.2.9' not found (required by /usr/lib/x86_64-linux-gnu/
/opt/PixInsight/bin/PixInsight: /opt/PixInsight/bin/lib/ version `CXXABI_1.3.11' not found (required by /usr/lib/x86_64-linux-gnu/

I thought I installed Zlib but maybe there is another problem.


General / BPP "Add Folder" option?
« on: 2018 April 09 18:31:40 »
Is there an enhancement to BPP which adds a "Add Folder" button, where all the subfolders and FITS files within those folders are added?

General / Bias,Dark,Flats artifact removal question
« on: 2018 February 01 11:26:18 »
Is there a process or script which can scan a collection of Bias, Dark or Flat frames and remove artifacts that appear in only one frame but not others.  For example, if there is a cosmic ray hit at a location on one image but does not appear on subsequent images then the damaged pixels could be repaired using the surrounding pixels or pixels from subsequent images.  This method would insure hot pixels, which appear in each image, are correctly allowed for and not simply removed.

General / Aperture Photometry error posPx is null
« on: 2018 January 01 15:54:19 »
Getting this error and am not sure what the problem is.  The log shows the image plate solved successfully, the script then downloads Vizier data from UCAC3 catalog, showing 3070 objects inside the image and 12,520 catalog stars, but then get the error:

*** Error: Failure to process image file 'F:/Temp/': TypeError: posPx is null.


General / New Readout Mode
« on: 2016 December 20 23:45:34 »
Having learned that Readout affects how a pixel value is loaded from a FITS image and displayed then we need to add a new mode: 16 (32k).  In this mode the 16 bit pixel value loaded is a signed 16 bit number with no offset.  So the range is (-32k to +32k).  It means a value of 1024 is read and displayed as 1024.

This is different from the current readout mode of 16 (65k) where a 16 bit pixel value is loaded and 32768 is added to the value and has a range of 0 to 65k.  In this case of value of 1024 is displayed as 1024 + 32768 = 33792.

General / 8 bit FITS images
« on: 2016 December 20 10:53:57 »
When I open a FITS image with BITPIX=8, the values are treated as 16 bit numbers instead of 8 bit numbers.  For instance, if I have an image where all the pixels are 64 then PI displays them as 16448.  It should be 64.

New Scripts and Modules / Networking in a Script
« on: 2016 December 07 12:48:00 »
Has anyone written a script to receive and send UDP packets?  The idea here is for one or more external programs to send 'requests' to a script running on PI.  The script would process the script (e.g., running a calibration on an image) and return a result to the requestor.  UDP is much easier to use because you do not have to setup and maintain a TCP session.

If there is no script, is the Network class in SpiderMonkey available in PI?

General / How to Add stars
« on: 2016 July 19 19:02:45 »
I am doing an artistic image which needs some stars to an otherwise black background.  I was able to use ImageSolver to register the image and the star mask generated does show lots of other stars.  Question now is how do I use this to map the stars on to the image so that they look as if imaged.  In other words, I would like them to have a FWHM shape of say 3 arcsec and show as faint and bright by boosting their appearance.  I find lots of articles on how to remove stars but not necessarily how to add them back in.

General / HDRComposition question
« on: 2016 July 17 04:18:53 »
Using a DSLR I have recorded sets of 5,10,20,40,80,160 and 320 seconds, each with 20 images and all taken at ISO 100.  The images have been calibrated, registered and integrated, so I now have a single image for each exposure time.

If I now use HDRComposition to combine them it fails after the second image with the message:

** This HDR composition cannot integrate further images - aborting process.

It works okay if I use any two images (e.g., 5 and 40 seconds).  It also works if I use any three images as long as they are less than 160 seconds in length (e.g., 5, 40 and 80).  But I cannot do any 4 images (e.g., 5, 10, 20, 40).

Does this mean there is some sort of math limit to the function?

General / Aperture Photometry question
« on: 2016 June 27 18:19:20 »
In the output Image Table there are 4 columns: CATRA, CATDEC, IMGRA, IMGDEC.  Quoting from the documentation:


Equatorial J2000 coordinates of the star as stored in the catalog.


Equatorial J2000 coordinates of the star as measured in the image. This value is calculated unprojecting the measured pixel coordinates of the star.

When converting the IMGX and IMGY pixel values to IMGRA and IMGDEC, is the proper motion of the stars used in the calculation?

General / DynamicPSF problem
« on: 2016 June 25 15:08:32 »
I am measuring the separation of visual double stars and have one star that DynamicPSF is having trouble resolving.

The location (pixels) of the first star is: 1794, 1258
The location of the second star is: 1794, 1273

The center of the stars are separated by 15 pixels.

When using STF Autostretch the stars almost touch each other (ie, the outer faint fringes of the stars are separated by 1 pixel).

When I run Dynamic PSF and click on the first star it draws a box around the correct star but puts the x on the other star.  It reports cx,cy as: 1794, 1273.

I changed the star detection search radius to 4 but it still did it.  I would have thought that it would have remained centered on the top star, the one I clicked.

The script 2DPlot clearly shows two peaks, one for each star.

Anyway to fix this so DynamicPSF will measure two distinct stars?

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