Live-Stacking with AstroDMx Capture and stacking software

Live Stacking of images is a technique of value for Electronically Assisted Astronomy (EAA). EAA is of particular value for outreach work where members of the public are shown astronomical objects in real time.

Although it is possible to use EAA during astro-imaging sessions, it is not normally used in these circumstances.

EAA uses Live Stacking of images, that is, as each image (often Deep Sky images) is captured, it is stacked with the previously captured images and displayed on the computer screen. In this way, the viewer can observe the image building up on the screen and becoming less noisy with more details becoming visible.

AstroDMx Capture may well have EAA Live Stacking built into the software at some future date, but it is possible to do EAA and Live Stacking with AstroDMx Capture by using it in conjunction with Live-Stacking software in a completely seamless way.

Three programs have been tested and found to work simply and seamlessly with AstroDMx Capture for Live Stacking. They are:

Deep Sky Stacker Live 4.2.6

ASTAP version 2023.01.21

Siril-1.2.0-beta1

It is likely that one of these programs would be used routinely to stack and maybe partially process the images captured during an imaging session.

Deep Sky Stacker Live is a Windows only program.

Siril-1.2.0-beta1 is cross platform and works on Linux, macOS and Windows.

ASTAP version 2023.01.21 is cross platform and works on Linux, macOS and Windows.

All three programs work in the same way. They monitor a user specified directory (folder) and when a new image appears in that directory, it is stacked with the previous images that have appeared there. The current stacked image is displayed.

AstroDMx Capture saves its images into date-time-stamped folders by default.

Click on an image to get a closer view

The directories (folders) generated by AstroDMx Capture during an imaging session

So, for example, AstroDMx Capture created a folder on 2023-03-02.

Within that folder AstroDMx Capture created other folders that would contain the various sets of images captured. One of these folders was created at 19-48-15 when its contents started to be captured. When opened, it can be seen that it contained image files called S2HHead_000001_19-48-15_data.fits; S2HHead_000002_19-53-15_data.fits etc.

This folder was created when AstroDMx Capture started to capture the data on this object (SII on the Horsehead nebula).

It is this folder (19-48-15) that would be specified as the folder to be monitored as soon as the first image had been captured.

Whichever program that was being used would proceed to Live-Stack the images as they were captured by AstroDMx Capture and placed in the folder.

Deep Sky Stacker Live

The directory (folder) to be monitored is selected

Select the Stacked image tab. Click on the red Stack button and stacking begins.

When just the first image is captured and displayed

When all 20 of the images have been stacked and displayed

It can be seen that the 20 image stack is more defined and less noisy than the first, single image. In fact, the Signal to Noise ratio increases as the square root of the stack size.

Siril Live Stacking

The Home folder is set to the folder to be monitored.

Live Stacking is started by clicking the red button.

When the first image is captured it is displayed

After all 20 images have been captured and stacked

Again, it can be seen that the stack of 20 images is more defined and less noisy.

ASTAP Live-Stacking

The folder to be monitored is selected

The button is clicked to start Live Stacking

When the first image has been captured and displayed

After all 20 images have been captured, stacked and displayed

As before, it can be seen that the stack of 20 images is more defined and less noisy. This, of course, is why EAA is so valuable for outreach.

With ASTAP it is then important to click the button ‘Rename all files back to original’. This is because during the stacking process, the files have an underscore added to the filename extension as they are stacked. Clicking on the button removes the underscores from the filename extensions.

In each case it is a matter of moments to start the Live Stacking process. The window in which the Live-Stacked image is displayed is quite separate from the preview window of AstroDMx Capture. It is best to display this window on a separate desktop or even an external Monitor.

In this way, it is possible to simply and seamlessly Live-Stack the images being captured by AstroDMx Capture, whatever operating system is being used.