Thursday, 13 May 2021

Setting up AstroDMx Capture for Windows and Deep Sky Stacker Live (DSSL) to work with each other.

The object of this exercise is to live stack images being captured by AstroDMx Capture for Windows.

The procedure is simple, but it will help to have it shown step by step.

Click on an image to get a closer view

Preparing the ground

This needs to be done on the same date that the imaging is going to be done.

First of all, set up two folders on the desktop (They could be anywhere, but the desktop is convenient). The folders are called Input and Stack Output (You can call them what you want, but meaningful names help).

Launch AstroDMx Capture for Windows.

Then click on Options and Setup Output format.

Change the  Save Folder to Input on the desktop

To set up everything properly we need AstroDMx Capture to save just one file into the Input folder. We have called this file (Object Name) First. The file index will be set to 1. Make sure that the Save Image Sets into Separate Directories remains UNCHECKED Click on OK.

Then click on Capture. The Capture dialogue is invoked. You will see that the Object is called First. Set the Frame Limit to 1.

In the Capture dialogue that has just been set up, click on the Capture button.

This will create a sub-folder labelled with today’s date in the Input folder on the desktop. Within that folder, the captured file will be placed. Because the Save Image Sets into Separate Directories box was unchecked, an information box will appear to remind you of this. Just click on OK in the information box.

The single image called First will be saved in the date-stamped folder within the Input folder on the desktop, and a message will appear saying the the capture is Complete.

If you open the Input folder, you will see that it now contains the date-stamped folder in which the image has been saved. This folder is the one that DSSL will monitor for new files appearing so that it can stack them.

Open this date-stamped folder and delete the files that have been saved there.

The date-stamped folder will then be empty and ready to receive captured images of an astronomical object.

Doing the Live Stacking

When imaging is shortly to begin, launch DSSL and click on the Settings tab.

Click on <Click Here to select the output folder> and navigate to the Stack Output folder on the desktop. Click on OK.

Then Click on Apply Changes.

At the very top  of the DSSL application window, to the right of Monitoring, Click on <Click here to select the Monitored Folder>.

Then navigate to the Input folder on the desktop and the date-stamped folder within it. This is the folder into which AstroDMx Capture will deposit the captured images.

It will be noted that in the settings box, the default is not to start stacking until 5 images are in the monitored folder. This so that when 5 images are available, DSSL will be able to select the best to use as a reference.

When capturing has begun, you can open the date-stamped folder within the Input folder and watch the images arrive. As soon as the first image arrives in the folder, click on the triangular Monitor button in DSSL. As soon as 5 images have arrived in the folder, Click on the circular Stack button in DSSL and the live stacking will begin.

You can then click on the Stacked Image tab and the image will be displayed. You will need to stretch the image using the controls at the top-right of the Stacked Image window until you are satisfied with the appearance of the stacked image. It should be noted that this does not affect the stacked image data and is to optimise the image for viewing only.

When all of the images have been captured then the Stacked image can be saved to file.

DSSL is intended for use in the field to watch the progression of the stacking of captured images. It uses the same stacking engine as DSS but does not have the facility to dark-frame or flat-field correct the images before stacking. All it does is to cosmetically  remove hot pixels.

However, when used in conjunction with AstroDMx Capture for Windows as shown here, advantage can be taken of AstroDMx Capture’s ability to do live dark-frame and/or flat-field correction.

This means that the resulting stacked image can be dark-frame calibrated during the capture process, so it is suitable for further processing.

Live dark-frame and flat field calibration with FITS images will soon be implemented in AstroDMx Capture.

Screenshot of an actual imaging session.

In this case, DSSL was in dark mode. Dark mode is useful for imaging but for this article it was turned off so that the writing would be easier to read.

Just beneath the Stacked Image tab can be seen Click here to save the stacked image to file. If this is clicked then the stacked image can be saved to file.

At the top-right of the DSSL Stacked Image window are the sliders for stretching the Live-Stacked image for optimal viewing.