Xecon's work in the area of Astronomical Computing currently focuses on excercises being performed at the Hobbs Observatory (750) located in Fall Creek, Wisconsin.
The first project taken up at the Hobbs Observatory was the development of a steering and tracking control program StarTrac for the 61cm, alti-azimuth, Newtonian Reflecting Telescope. The objective ofthis effort was to develop a computer controlled drive program that could be used for general telescope operations as well as for a specialized astronomical sky-search project soon to be conducted by the writer.
The StarTrac program is implemented to run on a standard personal computer (PC) that is forced to operate in a real-time mode. The StarTrac PC ties in with three seperate microprocessor controllers located at the telescope proper that drive the azimuth, elevation, and field de-rotation axis respectively. The azimuth and elevation motor controllers were built by the CompuMotor Corporation and the field de-rotation controller was built by Xecon. The StarTrac control computer is also connected to a second PC that contains an astronmical data base GUIDE, and to a third PC that operates the CCD Camera System. StarTrac accepts positional information in the form of the objects right ascension and declination from either the PC keyboard, a scripted control program, or the GUIDE data base. It then performs the required equatorial-to-horizon coordinate conversion and slews the telescope to the selected object. The object is then continuously tracked by recomputing its new position every two-seconds and sending appropriate velocity update commands to each of the respective motor controllers.
General Specifications of the Hobbs 24" Telescope System can be seen by clicking on the specifications hyperlink.
For those interested, the basic equatorial-to-horizon, horizon-to-equatorial, and field de-rotation equations used by this program may be seen by clicking on the equations hyperlink.
SkySerch is a proprietary program written to assist the operator in performing a semi-automatic search for new Astronomical Objects, including Asteroids, Comets, and Extra-Galactic Super Novae. This program permits the operator to select one of three different types of systematic telescope scan procedures to mechanize the search process. These scanning mechanisms then call on the core StarTrac control algorithms to move the telescope. The program also automatically interacts with the XECON CCD Camera system to take images of the objects being observed.
The first search technique essentially employs an x-y raster scan to observe a given area of the sky. The starting location (ra/dec) of the image, the size and the direction of scan, the method of re-trace, the dwell time on the image, and the telescope settling time between images may all be set independently in the program. This scanning technique is primarily used to search a given sky region for new objects such as Asteroids or Comets.
The second search technique uses a scripted text driver to tell the program where to point the telescope. Here again the object location (ra/dec), image dwell times, and inter-object delay times may be independently prescribed in the scripted text file. This scan technique is primarily used to search a large number of non-contiguous locations for extra-galactic super novae.
The third search technique employs a process sometimes referred to as drift-scan or TDI (timed delay integration). Here the telescope and the field rotator are initially positioned so as to allow the rotation of the Earth to automatically implement the scanning of the image across the CCD sensor. This scan technique requires the use of a specially designed CCD Camera whose image can be shifted out along the right-ascension axis at the rate of the Earth's rotation. The resulting image consists of a strip whose width is equal to the 'y' dimension of the CCD sensor and whose length is equivalent to the time interval of data collection.
A brief description of this project is provided under SkySearch.
This program accepts electronically digitized (CCD) images as its input and permits the user to display, analyze and perform various signal processing functions on them using a standard IBM type Personal Computer.
Set-up controls allow the program to accept input images with several different data formats (including FITS). It will currently process CCD images sized at 576 x 384 pixels - 12 bit A/D (Thomson chip), or 1024 x 1024 pixels - 16bit A/D (SITe TK1024 or SI-003A chips).
The program first computes a histogram of each image and presents the user with a statistical summary of critical parameters. The image may then be displayed in a number of optional formats using either automatic or user defined slice and range levels. Magnifying (or Zooming) of selected image areas is also permitted. A number of signal processing algorithms are provided to either enhance, smooth or otherwise manipulate various aspects of the image under investigation.
The program is also designed to assist the user in the alignment of sequential images taken at different chronological points in time. After the alignment process is completed, the operator is then allowed to blink these images so as to detect moving objects. If the images are properly encoded and labelled, such as from the SkySerch program, the entire review process will be semi-automatically handled by the program thereby simplifying the entire process.
A detailed description of this program may be seen by clicking on Astro-Imaging Analyst.
One of the goals of the SkySerch effort is to eventually be able to detect new objects on the fly. To assist in this process the AIA program will incorporate a unique image compression algorithm that is expected to achieve very significant compression ratios. Compressed images will then be used in later sessions as a template for comparison with the newly received search images. The image compression and detection algorithms are currently in the process of being designed.
