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General Information

INVENTORY has been originally designed as a medium speed and medium accuracy universal program for finding, classifying, and investigating astronomical objects on two-dimensional image frames in a way that is as automatic as possible. In a course of further development, both speed of execution and attainable precision have been improved, and the package differs from other related programs mainly by its tendency to minimise the amount of time spent by a user on interactive work at the terminal. Though it can be used for most of the relevant applications, INVENTORY is best suited for analysing numerous similar frames, like in cases of surveys or variable stars observations. It is also convenient for a first look preview of the material that will be analysed with more elaborate methods. It is not recommended for users who are not willing to give up the possibility of interactive control. A major requirement imposed on INVENTORY was that it should be able to classify detected objects into stars, galaxies, and image defects.
While it is possible to run INVENTORY for the first time without many preparations, achieving good results requires some experience. The program runs in an automatic mode when some parameters are set to proper values. Different applications may require different values for these parameters. Using INVENTORY with a new kind of material requires some preparation and trial runs are necessary for adjusting the parameters. The time spent on tuning up the program is well paid off when there is a sufficiently large number of objects and/or frames so that the use of other techniques would be much more time consuming. The tuning up may be difficult in a crowded field with many overlapping objects, or in a case where there are big bright galaxies. On the other hand the use of INVENTORY should be relatively easy when the investigated field is populated mainly by not too densely packed stars.

These photometric packages which aspire to high accuracy of results have to solve the problem of deblending of overlaping images. In its base mode INVENTORY does it in a fast but approximate way. A somewhat more accurate deblending of stellar objects using one-dimensional point spread function is now optional. Two dimensional point spread function fit, its extension to strongly undersampled images, and more precise deblending of galaxies are in preparation.

The program is functionally divided into three discrete steps. It will be possible to perform these steps using the commands: SEARCH/INV, ANALYSE/INV, and CLASSIFY/INV. The additional commands SHOW/INV and SET/INV serve for displaying and updating values of the INVENTORY keywords.

Before using INVENTORY commands it is necessary to give command SET/CONTEXT INVENT. It may be convenient to include this command into the login.prg file.

The (optional) SEARCH/INV command prepares a preliminary list of objects. The SEARCH/INV can be omitted once we have a list of objects with accurate positions in a MIDAS table format.

The ANALYSE/INV command evaluates and updates an input list of objects. It can be used in a VERIFY or NOVERIFY mode. In VERIFY mode, the ANALYSE/INV command verifies the used table of objects. Some entries are deleted but usually a larger number of new ones are added. The objects positions are improved. In NOVERIFY mode this verification process is omitted. In both modes the ANALYSE/INV command calculates several image parameters, which can be used as final results and/or as input to the CLASSIFY/INV command.

The CLASSIFY/INV command uses the output table produced by the ANALYSE/INV command for dividing the objects into stars, galaxies and spurious objects. It accepts only input of MIDAS table files that have been produced by ANALYSE/INV.

next up previous contents
Next: What Data Frames can Up: Object Search and Classification Previous: Object Search and Classification
Petra Nass