The ADAS data reduction and analysis process
The analysis of the acquired frames is done in several steps, during the dayfollowing theobservations. Each triplet (scan or stare image) is processed with SExtractor(a public domain image processing software package developed by Emmanuel Bertinand S. Arnouts, IAP, Paris), to obtain three catalogs of positions (x,y pixelcoordinates) and magnitudes (in instrumental system) of all objects detectable bythe software. No pre-processing (flat-fielding, etc.) is done.
A second software package (called Rackis, developed by Magnus Lundström)is used to find moving objects and determine their astrometric positionsin MPC format. This is done fully automatic and run (together with the SExtractorstep) in batch mode.
Rackis produces a "blink-file" for each moving object found. In order to verifythe validity of a detected asteroid or comet, these blinks have to be examinedvisually by the operator. For this purpose a special piece of software,called Blink, was developed by Stefano Mottola. Blink allows interactivelyto distinguish real moving objects from fake ones.
Finally, the preliminary positions and the corresponding logs from the blinkingfor a whole night (or several nights for that matter) are processed with a routinecalled MPC_prep (written by Gerhard Hahn) which produces a file with thepositions to be submitted to the Minor Planet Center (M.P.C.) in Cambridge, Mass.
Normally, the blinking step is done twice, by two different observers, to safeguardfor possible misidentifications. A first check is often done during the observing night,while the preparation step for the M.P.C. is made at the IPE in Berlin. Theblink-files, together with the position-file and blink.logs are transferred to theIPE at the end of an observing night, so that a support observer at the IPE cantake over and finish the processing of the observations by sending the finalproduct via email to the M.P.C.
In addition to archiving the obtained astrometric positions, some analysis forstatistical purposes is made. For interesting discoveries (i.e. FMOs, or objectswith peculiar motion identified during the blinking procedure) orbit determinationsoftware is used to check the validity of the positions prior to their submissionto the M.P.C. Software for plotting motion vectors and ephemeris generation areavailable as identification aids and for planning follow up observations.
Updated on October 31, 2001 by Gerhard Hahn
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