Stacking Program and FITS viewer.
ASTAP is a free stacking
program for deep sky images. This program can view and stack
astronomical FITS images using an astrometric solution. It uses
a local version of Astrometry.net or PlateSolve2 to find the astrometric solution. With the solution the
astronomical position of each pixel can be calculated.
images including Dark Frame and Flat Field correction
deep sky images based on HFD value and average value.
call to local Astrometry.net or Platesolve2 for the astrometric solution.
FITS viewer with swipe functionality.
be saved to 16 bit or float (-32) FITS file
Export to 16
or 32 bit integer TIFF files, grayscale or color or simple PNG or JPEG.
building covering large areas using the astrometric linear
ANSVR link contains a newer compilation of astrometry.net made for ASP.
It runs as a Linux program under Cygwin in MSWindows. Follow up to
installation step 9. The link you have to put in ASTAP is as follows:
Adapt "user_name" to the login name used in Windows.
Start the ASTAP program.
Enter the approximate
location of the images taken and the image dimensions unless the
location and dimension are already contained in the FITS file header.
You can test this by just opening one FITS file.
Call up the stack
window. Select the images, dark, flats, flat darks (bias)
Select the stacking
method, average or sigma-clip-average.
For OSC camera
select "Convert OSC images to colour". Select the
(4 options).. Test the required
pattern first in the viewer with a single image. The source images
should be raw (gray) without colour produced by
Press the stack button.
Save result as
FITS ( IEEE float (-32) or 16 bit format), or
export as 16 bit stretched, 16 bit or 32 bit TIFF.
The stretched export folllows the gamma and stretch setting
of the display.
reference of each pixel is the astronomical position. So stacking is
not done against a reference image but against an position array
set by the first image. If the oversize is set from the default 100
pixels to a large value lets say 2000 pixels, the array is
on all sides 2000 pixels larger then the first image. If
the first image is 2000x1500 pixels, the stacking array will be
6000 x 5500 pixels large. So any following image will be placed in this
6000x5500 pixel array. If the images are taken from
different areas of the sky, the stacking will result in a mosaic
as long the proceeding images are within this 6000x5500 pixels. Here an
example of a mosaic build:
The size can be reduced by a crop function (right mouse button) later.
Making the oversize too large could result in memory overload.
De stack menu:
The astrometry menu:
Show solving: shows the Astrometry.net solving console. You better keep this on to see what happening.
Keep console open: This should be off and is only required to see an solving error.
Search area: This can be large 10 degrees or so.
Pixel tolerance: Can be off.
Extra options: Can be blank. --downsample 2 or
--downsample 4 helps sometimes with solving. For noisy images you could
experiment with --sigma 10 or higher.
Typical cold CMOS master dark:
Application of Gaussian blur under sigma 5:
Gaussian blur under sigma 5 and
hot pixel removed:
The FITS viewer can
and add the plate solution to the FITS header. Also PNG and JPEG files
can be plate solved. The program will convert them to the FITS
format. With the batch routine several FITS image
"plate solved". The viewer can convert raw images
of sensors with a Bayer matrix to color.
ASTAP viewer screen shot:
a good plate solver but can’t write the plate solution to the
header using standard keywords. HNS_FV can call the
PlateSolve2 program and writes the found plate solution to the FITS
file header using standard keywords.
Working of the program:
Load the FITS file in the
Press the “Solve” button
Is the solution found press
principle it should be possible to rename the program as Platesolve2
and call it instead of PlateSolve2. The solution will then written
automatically to the FITS file. The
plate solution is read from the APM file produced by PlateSolve2.
There is a big variation in FITS file keywords. If this version doesn't
work, please send me the FITS file for testing.
Send a message if you like this free
program. Feel free to distribute !