These are the results of experiments to test whether AstroDMx Capture for Linux can be used in the Linux virtual environment on a Chromebook.
Under the hood, Chrome OS is in fact, a Linux distribution, but it has been locked down in a number of ways that prevent the running of standard Linux desktop applications. Ironically, Chrome OS is a distribution of Linux that needs to run another Linux distribution inside a virtual machine, in order to run Linux apps. Google’s motivation for doing things in this way is to make Chromebooks essentially Cloud based computers, and also to give them extra security.
Chrome OS first started offering support for Linux apps in October 2018 with Chrome 69, as a beta project. The feature left the beta channel in May 2021 with version 91 of Chrome OS and moved over into the stable channel. It offers access to a Linux terminal, which developers can use to run command line tools. The feature also allows full-fledged Linux apps to be installed and launched alongside other apps.
Linux runs inside a container as a virtual machine called Crostini. The Linux within the virtual machine has improved USB device support, but this, for the Google developers, is still a work in progress.
Chrome OS now has a faster update process that updates the Linux container at the same time as Chrome OS itself, and has better support for USB devices. However, there is clearly some way to go on this.
In a separate blog article, we shall explain how to install Linux on a Chromebook and how to install AstroDMx Capture for Linux. We shall also show how to set up the feature that allows AstroDMx Capture to see and connect to your SVBONY SV305 series camera.
The cameras that we used successfully for these tests were the SVBONY SV305 and the SV305 Pro.
We found in our initial tests that a number of astronomy cameras are recognised as USB devices, which can be connected to Linux, but some are not seen properly as cameras and if they are seen, they either won’t connect to AstroDMx Capture for Linux or won’t stream properly. However, the SV305 series of cameras can be connected to Linux and are seen as cameras, and they stream data properly in AstroDMx Capture for Linux. The SV305 series cameras can then be used normally whether they are USB 2.0 or USB 3.0 cameras.
At the moment we don’t know why the SVBONY SV305 and SV305 Pro cameras are the only astronomy cameras that we have tried that will work with AstroDMx Capture for Linux (for Chrome OS). At the present time one can only speculate that this may have something to do with the USB implementation in the camera. Whatever the reason, it is good to know that the SV305 series of cameras can be used in Chromebooks for imaging.
Nicola has now made some changes and AstroDMx Capture looks and feels just as it does on the other operating systems.
There are obviously many more tests to be performed before the Chrome OS version of AstroDMx Capture can be released.
Due to the inclement weather we have had to use our bench-testing procedures. This involves using a research grade microscope to which is attached an SV305 or SV305 Pro camera. For fast exposures, normal microscope illumination is used. For long exposures, the microscope is darkened with a lights-out canopy, the illumination is turned down to minimum and a double layer of white plasticard is placed over the light source to further reduce the level of illumination. With this system, 8-bit and 16-bit image capture can be tested.
Click on an image to get a closer view
8-bit short exposures
Screenshot of AstroDMx Capture for Linux (Chrome OS) capturing 20ms, 8-bit tiff images of a TS stem through a microscope
16-bit long exposures
Screenshot of AstroDMx Capture for Linux (Chrome OS) capturing 30s, 16-bit tiff images of a LS section of a root-tip, through a microscope.
Tests have shown that SER files, BMP and FITS files can also be captured.
We have also installed the Gimp, SER Player and Siril; and they all run properly. This means that we have all of the tools for capturing, processing and stacking images, all within Linux on the Chromebook.
Chromebooks exist with a wide range of capabilities, and it follows that more powerful Chromebooks, with better x86-64 processors and more storage will be at an advantage. It must also be remembered that Linux is running in a virtual machine, which consequently, has performance penalties associated with the virtualisation.
So, at the moment, we can say that it is possible to do astronomical imaging using a modern Chromebook running a Linux virtual machine, AstroDMx Capture for Linux and an SVBONY, SV305 series camera.
It should be noted that the current release version of AstroDMx Capture for Linux will not work properly on Linux in a Chromebook. A special version is required and Nicola will release it in due course, when we have done more testing.
