657x5 multi-band SDSS galaxy images from the RC3 catalog, with morphological information
The archive below contains
a subset of the RC3 catalog observed with the Sloan Digital Sky Survey (SDSS) release 2 in ASCII format. Morphological types and Hubble types are listed for each galaxy.
images in FITS format extracted from the SDSS release 2 in the 5 bands u',g',r',i' and z'.
- The original images were acquired using the SkyView web-service at 512x512, 0.4'' resolution. SDSS release 3 was not available at SkyView at this time. The resampling provided by the SkyView engine is quite crude (nearest neighbour interpolation was the only one working in batch mode when we did the download), which explains the artifacts visible in the images. The SkyView team has been notified, and we expect to have data with a much better quality in the next release.
- A dozen of galaxies with very incomplete coverage or with large positional offsets were excluded from both the catalog and the set of images.
- All images were automatically background-subtracted using SExtractor.
- All galaxies were then automatically rescaled to 256x256 (using SWarp with bilinear resampling), in such a way that the blue isophote at mu=25 mag.arcsec-2 fits right into the frame. This was done by setting the output pixel scale to 6.0*dexp(log D25)/256 (log D25 is given in the RC3 catalog). This is certainly a bit too narrow, and more margin will most likely be added in the next release.
- Last but not least, TIFF colour images were generated with STIFF and pasted together using montage to generate a beautiful poster!
Important: this preliminary set of small galaxy images is intended to be used for testing purposes, mostly image decomposition and galaxy classification through machine learning. All images have been background-subtracted and brought to a common scale to simplify dimensional reduction. But this means that the Point Spread Function varies a lot from one image to the next. Please note that these data are currently for use within the EFIGI collaboration only, and should not be redistributed without prior consent of the author (E.B.).
|Download: || |
| | PGC-1.0.1.tar.gz
| | Poster