The StellarMate Plus Manual
216 / 341
indeed have impressive equipment and dedicated observatories worth tens of the
thousands of dollars. Nevertheless, many amateurs can obtain stellar wide-field
images by combining smaller images into a single grand mosaic.
We are often limited by our camera+telescope Field of View (FOV). By increasing
FOV by means of a focal reducer or a shorter tube, we gain a larger sky coverage
at the expense of spatial resolution. At the same time, many attractive wide-field
targets span multiple FOVs across the sky. Without any changes to your
astrophotography gear, it is possible to create a super mosaic
image stitched together from several smaller images. There are two major steps
to accomplish a super mosaic image:
1. Capture multiple images spanning the target with some overlap between
images. The overlap is necessary to enable the processing software from
aligning and joining the sub-images.
2. Process the images and stitch them into a super mosaic image.
The 2nd step is handled by image processing applications such as PixInsight,
among others, and will not be the topic of discussion here. The first step can be
accomplished in Ekos Scheduler where it creates a mosaic suitable for your
equipment and in accordance with the desired field of view. Not only Ekos
creates the mosaic panels for your target, but it also constructs the
corresponding observatory jobs required to capture all the images. This greatly
facilitates the logistics of capturing many images with different filters and
calibration frames across a wide area of the sky.
Before starting the Mosaic Job Creator in Ekos Scheduler, you need to select a
target and a sequence file. The Sequence File contains all the information
necessary to capture an image including exposure time, filters, temperature
setting, etc. Start the Mosaic Job Creator by clicking on the icon next to
the Find button in Ekos Module.
On first use, you need to enter your equipment settings including your telescope
focal length in addition to camera's width, height, and pixel dimensions. Finally,
you need to enter the rotation of the camera with respect to north or the position
angle. If you don't know this value, start Ekos and slew to your desired target
then use the Align module to solve the image and obtain the position angle.
Next, enter the desired number of horizontal and vertical panels (e.g. 2x2,
3x3, etc.) and then click Update. The target FOV shall be calculated given the
number of panels and your camera's FOV and the mosaic overlap shall be
displayed. By default, the percentage of the overlap among images is 5%, but you
can change this value to your desired value. You can also move the complete
mosaic structure around to fine tune the position of the mosaic panels. When
satisfied, click Create Jobs and Ekos shall create an observation job and a
corresponding customized sequence file for each panel. All the jobs shall be
saved to an Ekos Scheduler List (.esl) file that you can load on any suitable
observing night and it will pick off where you left. Before starting the Mosaic Job
Creator, check that all the observation job conditions, constraints, and
startup/shutdown procedures are as per your requirements since these settings
To Next Page
Loading...
