|59 Elpis||968 Petuni||25 Phocaea||490 Verita|
Recent advances in software have brought asteroid identification within the reach of amateur users with computerized telescopes and ccd imagers.
The following discussion is limited to the Meade LX200 series of telescopes and computers capable of running 32-bit Windows (Windows 9x/NT/2000/XP).
Commercial software used for this project includes the following:
|ACP Observatory Control||by DC-3 Dreams (telescope control)|
|MaxIm DL/CCD||by Cyanogen Productions (ccd imager control)|
|PinPoint Astrometry Engine||by DC-3 Dreams (plate solution)|
The general process is as follows:
The user assembles a list of sky positions that he/she wants to check for asteroids. The telescope is set up normally, aligned, and synchronized in the normal fashion. The ccd imager is installed and focused in the same general portion of the sky that the user wants to image.
The user runs the script included with Astronomer's Control Panel (ACP) or runs a custom program to read the list of objects and steer the telescope to the first object. (From this point on, the operation is completely "hands off").
The ccd imager is directed to take a short image (perhaps 30 seconds). The resulting plate is solved by PinPoint, yielding the precise coordinates of the image; the telescope position is updated (synchronized) to this new position. The telescope is then micro-slewed to the precise desired coordinates, if necessary.
The ccd imager is directed to take one or more images of normal exposure length; the length of the exposure is primarily determined by the precision of the telescope's tracking capability. Some mounts will only track well enough to image for 60 seconds; some will track adequately for four minutes or more. We suggest the use of a compressor/field flattener for the following reasons:- Increased field of view (cover a larger portion of the sky)
Note: The ccd imager will also take dark frames as specified by the user. Key Point: it is NOT necessary to subtract dark frames before processing images with the PinPoint Astrometry Engine; it works very well on raw images, saving considerable time and trouble.
The telescope is then directed to slew to the next object in the list, where the pointing/positioning/imaging cycle is repeated, until all of the objects in the list have been imaged once.
The telescope is then directed to return to the first object in the list and take a second set of images.
The telescope is then directed to return to the first object in the list and take a third set of images.
The imaging run is then completed; the telescope is parked and the imager is automatically shut down.
Once the images are captured, the plates are solved by PinPoint to add World Coordinate System information, which identifies the precise centerpoint of the image, the plate scale in arc-seconds per pixel, and the mag zero point, making the images suitable for direct astrometric purposes.
Sets of three images taken of the same region of the sky are then processed to identify asteroids. PinPoint performs this formerly-onerous task quickly and efficiently, even generating a report for submission to the Minor Planet Center. Although the default settings will work very well for most situations, the user has complete control over all settings.
Although PinPoint includes a script which will solve sets of three plates to identify asteroids, I have provided an application that will facilitate the process.
The following screen shot shows PPAstro, a Windows application written in Borland Delphi that uses the PinPoint Astrometry Engine to solve FITS images and to identify asteroids:
PPAstro runs under Windows 9x/NT/2000/XP and essentially encapsulates the functionality of the sample scripts provided with PinPoint while providing a convenient user interface with extensive error trapping. PinPoint is a native 32-bit Windows application, and it is quite fast.
PPAstro also provides easy access to the wide variety of settings over which the user has control if he or she wants to deviate from the default settings.
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