So is this a fits bug or as I expect not enough memory, but Kstars 2019-05-30T13:10:05Z is crashing when while running the simulators, guiding and opening a fits file, I would have thought that 1 G RAM and 1 G swap space would have been sufficient. To demonstrate this, I open a previously generated Nikon Z7 90.9M fits file. The logs don't provide much info. A gdb session is shown below.

Currently the way I use Kstars is to turn off auto viewing of fits files and use VNC to control the RPi3B+ session and save the files to the client. Alternately, if running from a Mac -> RPi3B+ remotely, I can't plate-solve on the Mac as it appears to timeout getting the file from the rpi3B+ (USB 3 camera -> USB 2 Pi and 2.4 Ghz wi-fi). Perhaps a 4G ODROID-N2 is in order

I may not be using gdb correctly, as I can't get a backtrace, as shown below.

stellarmate@stellarmate:~$ gdb -ex run --args kstars
GNU gdb (Ubuntu 8.1-0ubuntu3) 8.1.0.20180409-git
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "arm-linux-gnueabihf".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from kstars...Reading symbols from /usr/lib/debug/.build-id/88/bd3986ae34bf498ad5d2cfe4abfed9db3c6961.debug...done.
done.
Starting program: /usr/bin/kstars
Cannot parse expression `.L1207 4@r4'.
warning: Probes-based dynamic linker interface failed.
Reverting to original interface.

[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/arm-linux-gnueabihf/libthread_db.so.1".
[New Thread 0x71316370 (LWP 5858)]
libEGL warning: DRI2: failed to authenticate
[New Thread 0x6d10e370 (LWP 5859)]
[New Thread 0x6c7ff370 (LWP 5860)]
[New Thread 0x6bdff370 (LWP 5861)]
[New Thread 0x6b3ff370 (LWP 5862)]
[New Thread 0x6a2e4370 (LWP 5863)]
[New Thread 0x698ff370 (LWP 5864)]
[New Thread 0x68eff370 (LWP 5865)]
[New Thread 0x686fe370 (LWP 5866)]
org.kde.kstars: Welcome to KStars 3.2.3
org.kde.kstars: Build: 2019-05-30T13:10:05Z
...

org.kde.kstars.ekos.guide: "DEC drifting forward..."
[Thread 0x3bc6b370 (LWP 5978) exited]
[Thread 0x4e996370 (LWP 5977) exited]
org.kde.kstars.fits: Loading FITS file "/home/stellarmate/Pictures/test/Light/Light_003.fits"
org.kde.kstars.fits: Loading FITS file "/tmp/fitsKe5855.fits"
[Thread 0x63341370 (LWP 5964) exited]
[New Thread 0x53a47370 (LWP 5983)]
[New Thread 0x3bc6b370 (LWP 5984)]
[New Thread 0x63341370 (LWP 5985)]
[Thread 0x3bc6b370 (LWP 5984) exited]
[Thread 0x53a47370 (LWP 5983) exited]
org.kde.kstars.fits: Loading FITS file "/tmp/fitsBS5855.fits"
[Thread 0x450ee370 (LWP 5973) exited]
[New Thread 0x3c8ed370 (LWP 5989)]
[New Thread 0x3bc6b370 (LWP 5990)]
[New Thread 0x450ee370 (LWP 5991)]
[Thread 0x450ee370 (LWP 5991) exited]
[Thread 0x3bc6b370 (LWP 5990) exited]
[Thread 0x3c8ed370 (LWP 5989) exited]
[Thread 0x63341370 (LWP 5985) exited]
[Thread 0x4e859370 (LWP 5979) exited]
[Thread 0x5ba27370 (LWP 5969) exited]
[Thread 0x5521c370 (LWP 5951) exited]
[Thread 0x6150d370 (LWP 5885) exited]
[Thread 0x61d0e370 (LWP 5884) exited]
[Thread 0x62b40370 (LWP 5883) exited]
[Thread 0x686fe370 (LWP 5881) exited]
[Thread 0x63de7370 (LWP 5872) exited]
[Thread 0x64fd8370 (LWP 5871) exited]
[Thread 0x66322370 (LWP 5870) exited]
[Thread 0x66b23370 (LWP 5869) exited]
[Thread 0x67324370 (LWP 5868) exited]
[Thread 0x67daf370 (LWP 5867) exited]
[Thread 0x68eff370 (LWP 5865) exited]
[Thread 0x698ff370 (LWP 5864) exited]
[Thread 0x6a2e4370 (LWP 5863) exited]
[Thread 0x6b3ff370 (LWP 5862) exited]
[Thread 0x6bdff370 (LWP 5861) exited]
[Thread 0x6c7ff370 (LWP 5860) exited]
[Thread 0x6d10e370 (LWP 5859) exited]
[Thread 0x71316370 (LWP 5858) exited]

Program terminated with signal SIGKILL, Killed.
The program no longer exists.
(gdb) bt
No stack.

Thanks

Auto debayer & auto 3D && auto WCS turned off?

You nailed it. Auto Debayer was turned on. Turning that off, avoids the crash. Thanks!