This program was designed to assist in the astronomical work being done at the Hobbs Observatory (750) in Fall Creek, Wisconsin. At the beginning of 1999 the SkySerch program at Hobbs used a Photometrics Star 1 CCD camera to do the astronomical imaging. This device produced a 576 x 384 image operating at 12-bits per pixel. The sky coverage of this 23 micron device was about 15 x 10 arc minutes. To assist in this effort, Xecon Engineers began the development of a new imaging and data reduction package called Astro Imaging Analyst. Although initially the program was designed to operate only with the Photometrics camera, we were anticipating the incorporation of a new CCD camera and associated software into the system at some point in the coming year. This new camera, to be constructed around a thinned back illuminated SITE TK1024 CCD chip, would provide a sky coverage of nearly 28 arc minutes squared, or over five times the area of the older device. This project took on additional significance early in 2001 when it appeared that the new camera system would not be forthcoming. At that time Xecon engineers commenced the design and development of a new camera using the same SITE TK1024 CCD imaging chip. (A description of that camera design can be seen by clicking on the hyperlink XEP12K.) The camera hardware build was completed in the fall of that year. We then decided to proceed with an upgrade to the image data reduction and analysis program so that it could accomodate both cameras. Also at this time an extensive number of new options and features were added. These were completed early this year (2002). The output of that effort is the current (3.1) version of Astro Imaging Analyst. A brief description follows.
This program accepts digitized electronic (CCD) images at its input and allows the user to display and performs various classes of signal processing functions on them. At the opening of the program the user selects the basic camera type that will be employed during the session. Currently the program will accept CCD images from either a Photometics Star1 Camera (576 x 384 12-bit pixels), or a Xecon/SITE camera (1024 x 1024 16-bit pixels). At program load an automatic set-up of the following machine state parameters is performed: Input Image File Format, Image File Location/Directory, Display Size & Orientation, Auto Display Level Set, Palette Selection, Sequencing Method and Pre-processing Method. Each of these initial set-up conditions may be changed via a user MENU - this is an "example" AIA menu. The program is started by calling up an image to be processed. For each image selected the program first performs a statistical analysis of the data set and presents the user with a summary display of critical parameters. Using these data points, the operator may then display or further process the image under investigation. An example use of this statistical data is the "auto-level set" feature which permits the program to automatically adjust display range and slice levels so as to achieve a realistic presentation. (A manually controlled setting of the display range and slice levels is also provided.)
The following is a general list of functions and processes that may be performed by this program: Summary Display of Image Statistics and Histogram Presentation. Image Filtering, Stacking, Merging, Scaling, Masking, Flat-fieliding, Alignment, and Blinking. Individual Star Centroiding, Flux Integration and Astrometry Calculations. Detailed Image Zooming, and Pixel Examination. Selection of Palette types for special display presentations. Multiple Display Orientations so as to accomodate visual comparisons with other program outputs. Each of the above functions may be selected or controlled via a user menu.
Several image compression schemes, including the Space Telescope Science Institute HCompress routine, will be added in the near future.
Operating System: As currently compiled, the AIA program is designed to be used on an IBM style PC employing a DOS operating system. It will work on a Microsoft Windows machine by forcing it into the DOS mode [Press F8 at Start Up and then select the DOS prompt]. This program was written in standard ANSI "C" code. Windows and mouse support have been coded with proprietary "C Windows" software. They do not use the MicroSoft Windowing system. At sometime in the future the intent is to port this program to "X Windows" and the LINUX operating system.
CPU, Hard Disk and Display Card: For best performance and speed it is recommended to run this program on at least a Pentium class machine. It will also run adequately on a fast (800MHz) Celeron machine. The program requires hard disk space for the executable, several support files, as well as run time buffers for images and statistical data. When running large (1024 x 1024) images up to 9 Megabytes of disk space will be needed by the program. This is in ADDITION to the users space devoted to image input and output files. Again from a speed standpoint, it is best to run the program with a LARGE (multi-platter) hard disk. The PC on which this program is installed should preferably have a Super VGA Card that can display a 1280 x 1024 image in the 256 color mode. If multiple frame image blinking is required this card should have at least 8 MBytes of Video RAM. The program will work with a lesser VGA card (minimum 1024 x 768 256 color display, 4 MB Video RAM), but with a substantially reduced capabiltiy.
Camera, Image File Formats: As indicated previously the program will operate with images taken by either a Photometrics Star1 or a Xecon/SITE CCD camera.
The Photometrics Star1 camera system produces an image that has 576x384 12-bit pixels. This program will accept the following three PM image file formats: A Photometrics produced file that consists of a 160 byte header followed by 442,368 bytes of image data. A Xecon/PM/SkySerch produced file that contains 442,368 bytes of image data with no header. A FITS data file with NAXIS1 = 384, and NAXIS2 = 576 included in the standard header with accompanying data in the FITS format.
The Xecon/SITE camera system outputs a data file that is 1024 x 1024 x 16-bits in size (2,097,152 bytes). Any 1024 x 1024 16-bit image may be presented to the program in raw form as long as no header is present and the data arrives in the "little endian" (Intel) format. For example, if images have been accumulated in the TDI (Drift Scan) mode, they must be broken down into 1024x1024 word parcels before being input to the program. The program will also accept FITS formatted data files that have both NAXIS1 and NAXIS2 equal to 1024. Both header and data MUST be in the standard FITS format, i.e. a 2880 byte header followed by 2,097,152 bytes of "big endian" data.
Statistics: Mean, Median, Variance, and Standard Deviation. Pixel Values and Counts @ Max count, Min count, Max level, and Min level. Display of Histogram Decile Points. Detailed Histogram Display.
Filters: 2 Hi-pass, 2 Low-pass, 2 Noise Cleaners, 1 Unsharp (15x15) L.P.
Re-Scaling: Linear, Exponential, Toothed, Contoured, Stepped, HG Equalize.
Merging: Arithmetic or Stacked, Masked, Flat-Field.
Palettes: 6 total: Gray, Psuedo-color, Toned, Multi-Cycle.
Displays: Non-binned 1X, Binned 2X, with 4 possible Orientations.
Zoom/Examine: Zoom to 256X (64x64), Examine Pixels (11x11).
Centroiding: Up to 3 References; X & Y Position, Peak Pixel Value, Integrated Flux Measure.
Astrometry: RA & DEC Calculation of the Unknown, Mag. Estimate.
Alignment: Accuracy to 1 pixel V & H, with up to 6 Degrees of Field Rotation.
Blinking: Up to 6 images (Dependant on VGA card memory).
Several example AIA image presentation types may be seen by clicking on:
