Deep sky stacker user guide

DeepSkyStacker Live User's Manual

Introduction

What is DeepSkyStacker Live?
DeepSkyStacker Live is designed to be used in the field during an imaging session for the following tasks:

• Aligning and stacking the images as they are captured.
• Computing and showing statistics on the incoming images (FWHM, number of detected stars, drifting. )
• Showing the stacked image
• Issuing warnings when some conditions are met like when the drifting is greater than some user defined value

DeepSkyStacker Live is compatible with any capturing device (DSLR, CCD Camera) and any software as long as the captured images are created in a folder and are of a recognized file format (FITS, TIFF, JPEG and most RAW images from DSLRs).

Side note: DeepSkyStacker Live is not replacing DeepSkyStacker.
They are using the same engine but DeepSkyStacker Live does not have all the features that are needed to create images that can be post-processed accurately.
For example it is not possible to calibrate the images (dark and bias subtraction and flat division) or to use the most advanced stacking methods (kappa sigma or adaptive weighted average) with DeepSkyStacker Live.

DeepSkyStacker Live User Interface

Like DeepSkyStacker the user interface of DeepSkyStacker Live is quite simple and intuitive and all the main features and commands are readily available.

On top of the screen three buttons are used to start monitoring, start stacking and stop.

The bottom part is used to monitor the progress during the imagining session from different point of views:

• The stacked image
• The last image
• Graphs showing various statistics
• The Image list
• The log

The last tab is used to set the parameters controlling the behavior of DeepSkyStacker Live.

Quick Start
Your laptop is all set for the night imaging session, the CCD or DSLR capture software is up and running.

Start DeepSkyStacker Live, click on the Stack button, and select the monitored folder. That's it!

From now on all the images created in the monitored folder will be registered, aligned and stacked unless they match some specific condition that you have set in the Settings tab.

Of course you can change the settings while DeepSkyStacker Live is monitoring the incoming files.

Settings
First of all, DeepSkyStacker Live is sharing all the settings concerning image decoding, star detection threshold, alignment methods and background calibration options with DeepSkyStacker. To change these values you must use DeepSkyStacker.
The only difference is that AHD and Bayer Drizzle are automatically transformed to bilinear interpolation.

The Settings tab is used to define when the incoming images will be stacked, when to issue a warning and how the warnings are issued.

Stacking options
Don't stack until at least xxx images are available
This option may be used to wait for a minimum number of images before deciding which image will be used as the reference frame.
When the minimum number of images is available DeepSkyStacker Live will use the one with the highest score as the reference frame.
This option is especially useful if you are taking short exposures and if you are not sure that all you light frames are good enough.

Warn/Don't stack options
These options are self explanatory and can be used to set various conditions for which an image should not be stacked and/or a warning should be issued.
It is possible to set conditions on:

• The score
• The number of detected stars
• The FWHM (Full Width Half Maximum)
• The drifting (dX or dY)
• The rotation angle
• The Sky Background

Warnings
When a warning condition is detected it is possible to be noticed using four different ways:

• Sound: the classic bip of the computer
• Flash application: DeepSkyStacker Live is flashing 4 times
• Create a warning file: a file named DSSLiveWarning.txt containing the warning message is created in the folder of your choice. It can be a local folder or a network folder. If the file already exists the new warning message is appended to it.
• Send email: an email containing the warning message is send to the address of your choice.
  In the email configuration dialog box you can choose to send a email only for the first warning. In this case as soon as an email has been sent a reset button will appear to let you reset the email internal counter.

Stacked Image creation
The stacked image is only created in memory and is not saved by default.
This option may be used to create a file containing the stacked image each time xxx images are added to the stack.

The stacked image is saved in a file named Autostack.tif in the folder of your choice. If the file already exists it is overwritten.
It is always a 16 bit TIFF image and depending on the incoming images it can be color or grayscale.

Graphs
For each image DeepSkyStacker Live is using the following symbols:

• A green circle for each processed image
• An orange circle behind the green circle: a warning condition is met
• A red triangle on top of the green circle: a don't stack condition is met
• A green square is used in the dX/dY and Angle graphs to represent the reference frame

About the dX/dY graph: the red line is representing dX and the blue line is representing dY.

When an image is not stackable it does not appear in the dX/dY and Angle graphs.

Technical information
DeepSkyStacker Live is using the Average stacking method (this is the only method that can be used when the number of images is not known in advance).
Since no calibration is possible a simple hot pixels detection and removal is used on the incoming light frames before stacking them.
You can see the hot pixels in the Last Image tab, but they should be removed in the Stacked Image.

Contrary to DeepSkyStacker, DeepSkyStacker Live is using one processor for all the background tasks (loading, registering, stacking) even if more than one is available.