M33 0.75x0.75 deg combined 6cm+20cm (2015 January 28)

• The 6cm+20cm image is used to detect sources, which are then fitted with elliptical Gaussian source models to determine sizes, positions, and peak and integrated flux densities. For most islands a constant background offset is also fitted (although that is omitted when it causes convergence problems).
• A multi-resolution (median pyramid) image processing algorithm was used both for source detection and to subtract the background from the image to make the source detection threshold more uniform. The images without background subtraction can be compared to see the effect.
• The image with the Gaussian source models from the catalog subtracted can be used to identify sources where the Gaussian fits are poor. The catalog also includes integrated and peak fluxes for the island, which are noisier than the fits but work better when the source is not approximately Gaussian.
• The images with islands overlaid show the positions of the sources. Red islands have source entries in the catalog; green islands either are too faint (less than 4-sigma or failed in fitting, usually because the region was crowded.
• Only a single Gaussian component was fitted to each island. This is sometimes not very good when islands touch or overlap. I can eventually improve this by doing simultaneous fitting to neighboring islands. It is not hard (although getting convergence is harder), but I have not had time to do it yet.
• You can change the size of the displayed image (2700 is full resolution with 1 arcsec pixels). Click the blink button to blink between images. It cycles through all the images that have the "Include in blink" column checked. The FITS links allow downloading the images (and note that there are links above for the catalog). The text catalog has some information on the contents, but there is not yet a real readme file. The Display link brings up the HLA interactive display, which allows panning, zooming, changing the contrast, and overlaying some external catalogs.
• The DSS and Subaru images are matched optical images. There is clearly excellent agreement in the optical and radio morphologies for H II regions.

Other versions of the data:
C-configuration observations (low-resolution)
BC-configuration observations (2013Jan08 version)
BC-configuration observations (2012Nov18 version)