Deep Lens Survey : Real-time Transient Detection

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CTIO, Apr 1-6 2000

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The transient detection strategy for our current run is optimized to detect stationary transients. Previous runs were performed without the advantage of having long time baselines, hence we posted many moving objects. We now have, for many of our fields, 1 month baselines, and we are currently co-adding 5 exposures together to detect dim, stationary transients such as SN and other bursting phenomena.

This page contains REAL-TIME information on detections of transient astronomical happenings from the Deep Lens Survey, currently being undertaken on the KPNO and CTIO 4-m telescopes using the wide-field MOSAIC imagers.

A by-product of this wide-field survey is the detection of transient astronomical phenomena, including Near Earth Objects (NEO), Kupier Belt Objects (KBO), Supernova (SN), and even previously unknown events which happen with such rarity that only a wide field and deep survey, such as this one, is even reasonably sensitive to them.

The table below contains recently updated information on objects detected during the course of this survey. These are extracted from the images in real-time using a combination of SExtractor for object detection and ISIS to provide differenced images, from which we are able to identify transient, or "new", objects, after filtering out spurious objects like cosmic rays. These objects have also been inspected by eye and categorized as probably real.

We include the date, DATE-ARCH, when the object was added to this archive or updated, the date the object was most recently observed DATE-OBS (MJD), and the FILTER of this observation. Additionally, we include the RA and DEC (J2000, to ~0.5'' accuracy) of the object, a preliminary categorization of the nature of the transient, and a preliminary estimate of the magnitude of the transient (+/- 0.1 mag in R and B, +/- 0.5 in V and z). Two types of images are available for download: mosaics and finding charts.

The mosaic page includes a time-series of GIFs showing 200-pixel (50") postage stamps, with time increasing from top to bottom. The discovery mosic includes a template observation on the left, discovery image in the middle, and difference image on the right. Subsequent mosaics show a similar collection of images, or the new observation image only, in the case where a subtraction image was not available. The files are generally a few hundred kilobytes. In all mosaics, East is up and North is to the right.

The finding charts are 5'x5' FITS images centered on the discovery position. The time in the header is the start of the exposure and the world coordinate system in the header is accurate to 0.5". The files are 3 MB. The images are zero-padded to maintain the object in the center even if it was near the edge of the discovery image. Your browser may not bring up saoimage/ximtool automatically on the FITS file. Right-click on the link to save to local disk.

For moving objects, a finding chart is useless, and instead we provide an ASCII list of positions and times.

RA (J2000)
DEC (J2000)
Apr 10 10:56
2000-04-05 00:55:34.1 (51639.03822569)
time series
finding chart
Apr 10 10:55
2000-04-02 06:09:52.0 (51636.260000)
time series
finding chart

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Please mail questions or comments to Andy Becker
Deep Lens Survey Transient Page
Last updated : Fri Jul 21 20:00:02 PDT 2000