NEW OBJECTS in the OGLE-III SKY

The NEW OBJECTS in the OGLE-III SKY (NOOS) system is a real time detection system designed for detection of all kinds of objects that emerge from the deep Universe, i.e. from below our typical detection limit, and are found in the OGLE regularly monitored fields. These may be supernovae (SNe), gravitational microlensing of very faint objects, cataclysmic variables or anything else that brightens significantly.

Presently OGLE-III frequently observes 162 fields in the Galactic bulge (53 square degrees), 40 fields in the Small Magellanic Cloud (13 square degrees) and 116 fields in the Large Magellanic Cloud (38 square degrees). About 200 millions stars were detected in this area.

The NOOS system notifies about detection of a "new" object when it is found in the same location (with accuracy +/-0.5 arcsec) in three subtracted images (OGLE-III standard data photometry pipeline uses the image subtraction technique - DIA). The position must be unrelated with position of any of the known stars. Next, the visual inspection of the deep high resolution reference image and images where the candidate was detected is made to confirm that the object is not an artifact. If the candidate passes these checks, its photometry is determined starting from a dozen images before the first detection. Finally, it is included to the list of "new" objects presented here.

Based on the photometry at the peak only, it is impossible to classify the object. Therefore we strongly encourage astronomers to make follow up observations of our stars. In particular even a single spectrum should shed the light on the nature of the brightening object. Needless to say that anything that significantly brightens is potentially extremely interesting.

It is likely that many "new" objects in the halo of the Magellanic Clouds will be SNe, especially when a trace of a galaxy of a fuzzy object is seen in our deep reference image (finding chart). Also a number of microlensing events should be found this way. In the Galactic bulge the vast majority of the "new" objects will likely be microlensing events.

So far, the NOOS system has detected 17 "new" objects in OGLE-III fields in the 2004 observing season. Objects found in the previous seasons can be found here:

• 2003 season - 21 transients.

The data can also be found on OGLE Data download site or on Anonymous FTP.

There is also a mailing list providing on-line notification on the detected "new" objects. Astronomers interested in follow-up observations and willing to receive e-mail notification, should fill out subscribe/unsubscribe form. If you have any questions or comments, send us a message.

The following table contains basic parameters of the "new" objects as well as the links to the WWW pages with finding charts, light curve plots and photometric data. The photometric data are not calibrated. Because the objects emerge from background we do not convert fluxes to magnitudes to avoid numerical problems near the background. We estimate, however, that the flux of 2000.0 units corresponds roughly to I=19.75+/-0.3 mag.

The OGLE NOOS photometry is provided here for information purposes only to facilitate the follow up observations. Please contact us if you want to use the data for publication. We may require to be co-authors when our photometry is important for analysis.

When referring to the OGLE NOOS system, please cite the paper by Udalski 2003, Acta Astron., 53, 291 and provide the WWW address of the NOOS system or the OGLE WWW home page.

Andrzej Udalski and Michal Szymanski

Warsaw University Observatory

Warsaw, Poland

Last updated on Tue Dec 14 18:13:59 CET 2004