Capturing and processing solar images using native Linux software

Astronomers who routinely use Linux, frequently make use of a mix of Windows and Linux software to achieve their results.

AstroDMx Capture is an image capture program developed by Nicola Mackin that has versions for Linux (including the Raspberry Pi), macOS and Windows. This is the software that we use to capture SER files of planetary, solar and lunar data. It is also the software that we use to capture FITS and TIF long-exposure data of deep-sky objects. AstroDMx Capture was originally developed to provide stable and fast image capture for Linux, but has since been developed into a platform-independent program that is under constant development and refinement.

After the capture of a SER file for example, it can be stacked in Autostakkert! or sometimes Registax 5.1 running at native speeds in the Windows compatibility layer Wine. the name 'Wine' is a recursive acronym for 'Wine Is Not an Emulator'. No emulation or virtualisation is involved. What happens is that software calls to the Windows API are translated on the fly into POSIX calls (the system of compatibility for all UNIX and UNIX like operating systems) which are then executed by the POSIX compliant operating system (in this case Linux). Wine is very good and is improving all the time as it continues to be developed. However, not every Windows program will run easily in Wine.

One example of a Windows program that is difficult to get to run in Wine is Microsoft ICE (Image Composite Editor), an image stitching program second to none, that can be used to mosaic overlapping image panels, seamlessly into a larger composite image. It was a free offering from Microsoft for many years, but has now been withdrawn for no apparent reason, and with no replacement. Unless you already have it downloaded, the latest version of ICE is unobtainable. An earlier version of Microsoft Image Composite Editor 1.4.4 is at the time of writing, still downloadable from oldversion.com. Arguably, this was a nicer version of the software in that it was not replete with adverts. It is not straightforward to get this software to run in Wine and involves the construction of a Wine 'vat' or 'bottle' to contain everything that is needed.

Windows programs such as Registax 5.1 and Iris run well in Wine and can be used for wavelet processing of a solar, lunar or planetary image after stacking. For some reason Registax 6 does not always run properly in Wine.

Post processing can be done in the Gimp, a cross platform image processor that contains most of the functionality of Photoshop plus a plethora of plugins that increase its power.

For this demonstration we shall use the raw H-alpha data from May 14th and White light data from May 17th.

Everything can be done with native Linux applications

A Solarmax II 60, BF15 H-alpha scope was mounted on an  iOptron Cube Pro AZ mount. An SV305M Pro monochrome CMOS camera was placed at the focus and AstroDMx Capture for Linux was used to capture two overlapping 2000-frame SER files of the solar disk.

Screenshot of AstroDMx Capture for Linux capturing H-alpha solar data for one image pane

Siril was used to register, and stack the best 1801 images from the registered 2000-frame SER file

Screenshot of Siril stacking the best 1801 registered images

the same was done for the other overlapping pane.

The two panes for the final mosaic

Hugin Panorama creator was then used to stitch the two panes of the final mosaic image.

Screenshot showing the two images loaded into Hugin

The two images moved into their relative positions in the final mosaic

Choosing alignment points for the two overlapping panes. As the alignment points are chosen they are automatically position refined by Hugin

The final Hugin stage before the stitching process is completed

Siril is then used again, but this time to wavelet process and deconvolve the final image to sharpen it

Wavelets processor selected

Wavelets applied

Deconvolution applied

The resulting image was then post-processed and reoriented in the Gimp 2.10

Final H-alpha image

Full Size image

Processing White light Bridge camera images with Siril

Equipment used

A Panasonic DMC-FZ72 Bridge camera with 60 x optical zoom and fitted with a Baader solar filter was placed on a static, sturdy tripod and 131 images of the Sun were captured.

The images were precisely cropped in AstroCrop to facilitate their eventual stacking.

Selecting the region to precisely crop in all of the images

AstroCrop progress

The images were then registered in Siril and the best 125 images were stacked

The resulting image was then wavelet processed and then deconvolved  in Siril as previously shown, to sharpen it

The resulting image was then post-processed and reoriented in the Gimp 2.10

Final White Light image

Full Size image

It is clear that what can be done in Windows, or in Linux, using Windows programs running in Wine, can also be done equally effectively using native Linux applications.

AstroCrop and AstroDMx Capture can be downloaded HERE.

The Sun in Ca K-line, H-alpha and White light on May 14th 2022

Ca K-line light

A CaK PST was mounted on an iOptron Cube Pro AZ mount and an SV305 Pro monochrome camera was placed at the focus. Overlapping, 2000-frame SER files were captured of two halves of the Sun. 

Click on an image to get a closer view

Screenshot of AstroDMx Capture for Linux capturing Ca K-line SER file data

The best 65% of the frames were stacked in Autostakkert!, wavelet processed in Registax 5.1 and post-processed in the Gimp 2.10.

The Sun in Ca K-line light

H-alpha light

A Solarmax II 60, BF15 H-alpha scope was mounted on an iOptron Cube Pro AZ mount and an SV305 Pro monochrome camera was placed at the focus. Overlapping, 2000-frame SER files were captured of two halves of the Sun. The best 65% of the frames were stacked in Autostakkert!, wavelet processed in Registax 5.1 and post-processed in the Gimp 2.10.

The Sun in H-alpha light

White Light

A Panasonic Lumix DMCFZ72, 60x optical zoom bridge camera fitted with a Baader solar filter and mounted on a static tripod was used to capture 135 images of the Sun. The mages were precisely cropped in AstroCrop, Stacked in Autostakkert!, wavelet processed in Registax 5.1 and post processed in the Gimp 2.10.

The Sun in White light

The images were colourised mildly to represent the part of the spectrum being used to capture the image.

AstroCrop and AstroDMx Capture can be downloaded HERE.

AstroCrop is available for Windows and Linux. AstroDMx Capture is available for Windows, macOS, and Linux including the Raspberry Pi.

Lunar Studies with AstroDMx Capture, a Skymax 127 and a ZWO ASI178MC

A motorfocus modified Skywatcher Skymax 127 f/11.8 Maksutov was mounted on a Celestron AVX mount and a ZWO ASI178MC camera was placed at the focus.

AstroDMx Capture for Linux running on a Linux Mint laptop was used to capture 1200-frame SER files of different regions of the 77.7% waxing Moon. 

Screenshot of AstroDMx Capture for Linux capturing a Lunar SER file

AstroDMx Capture has customisable reticles that can be placed on the preview screen at arbitrary positions to help with manual tracking should the Moon tend to slowly drift in the fields of view. This minimises the useless edge regions that occur if drifting takes place.

Screenshot showing the reticle placed over a feature for manual tracking

The best 85% of frames in each of the SER files were stacked in Autostakkert! and wavelet processed in Registax 5.1, both running in Wine. The final images were post processed in the Gimp 2.10.

Results

Click on an image and click again to get a closer view.

Give the large images time to download after clicking.

Tycho region

Plato region

Copernicus region

Ptolemaeus, Alphonsus Arzachel region

Mare Tranquilitatis, Palus Somni region

The ZWO ASI178MC camera is a good match for the Skymax 127 Maksutov and AstroDMxCapture makes the capturing of SER files a simple matter. It is also possible, if preferred, to capture AVI files but the more modern and simpler SER file is to be preferred. One reason is that, if required, 16 bit SER files can be captured, which is not possible with AVIs. The customisable reticle is a very useful feature as it can be used to delimit the edges of the preview image in addition to facilitating manual guiding of lunar, solar and planetary imaging sessions.

AstroDMx Capture can be downloaded HERE.

AstroDMx Capture is available for Windows, macOS, Linux including Raspberry Pi OS and ChromeOS.