FIRST SEARCHES FOR OPTICAL COUNTERPARTS TO GRAVITATIONAL-WAVE CANDIDATE EVENTS

During the LIGO and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type

Efficient search in hidden text of large DjVu documents

The paper describes an open-source tool which allows to present end-users with results of advanced language technologies. It relies on the DjVu format, which for some applications is still superior to other modern formats including PDF/A. The DjVu GPLed tools are not limited just to the DjVuLibre library, but are being supplemented by various new programs, such as pdf2djvu developed by Jakub Wilk. It allows in particular to convert to DjVu the PDF output of popular OCR programs like FineReader preserving the hidden text layer and some other features. The tool in question has been conceived by the present author and consist of a modification of the Poliqarp corpus query tool, used for National Corpus of Polish; his ideas have been very succesfully implemented by Jakub Wilk. The new system, called here simply Poliqarp for DjVu, inherits from its origin not only the powerfull search facilities based on two-level regular expressions, but also the ability to represent low-level ambiguities and other linguistic phenomena. Although at present the tool is used mainly to facilitate access to the results of dirty OCR, it is ready to handle also more sophisticated output of linguistic technologies

Efficient search in hidden text of large DjVu documents

The paper describes an open-source tool which allows to present end-users with results of advanced language technologies. It relies on the DjVu format, which for some applications is still superior to other modern formats including PDF/A. The DjVu GPLed tools are not limited just to the DjVuLibre library, but are being supplemented by various new programs, such as pdf2djvu developed by Jakub Wilk. It allows in particular to convert to DjVu the PDF output of popular OCR programs like FineReader preserving the hidden text layer and some other features. The tool in question has been conceived by the present author and consist of a modification of the Poliqarp corpus query tool, used for National Corpus of Polish; his ideas have been very succesfully implemented by Jakub Wilk. The new system, called here simply Poliqarp for DjVu, inherits from its origin not only the powerfull search facilities based on two-level regular expressions, but also the ability to represent low-level ambiguities and other linguistic phenomena. Although at present the tool is used mainly to facilitate access to the results of dirty OCR, it is ready to handle also more sophisticated output of linguistic technologies