Bugs: wavdetect

The radius, "R" column, in the output source list is computed as the standard deviation of the source pixels along the semi-major and semi-minor axes. If the pixels that make up a source are aligned along a single X column or Y row or it is simply a delta function (single pixel) then the standard deviation is 0. A small value, based on the image blocking, is used in this case to provide some visual indication of the sources existence.

For a source to be considered real, it must be found to be significant when it is smoothed at a wavelet scale larger than the PSF. Consider two sources: one with 5 counts and one with 100 counts, each in a single pixel. It will take only a small wavelet scale to smooth out the 5 counts before it would no longer be considered significant whereas it would take a much larger wavelet scale to smooth out the 100 counts before it would no longer be considered significant. In either case, the source ellipse is based on the smallest wavelet scale it was found to be significant (whether that scale is smaller than the PSF or not). This ensure that the best source position is returned and allows close pairs to be identified.

The input wavelet scales are independent, orthogonal basis functions that describe the local structure on the scale of each wavelet. Within a single wavelet scale, sources must not overlap but since each wavelet scale represents an independent spatial scale, the same pixels can contribute to multiple sources. This is the very nature of a wavelet decomposition. (The Fourier analog is that all pixels contribute at each frequency.) The output cell image, whose pixel values represent which source a pixel "belongs to", cannot truly capture this and only represents the last (usually largest) wavelet scale.

Wavdetect is not a photometric tool; it is a source detection tool. The derived properties including location, counts, and sizes are provisional estimates. Users must perform full analysis on sources to determine reliable results.

In general, autonaming only works for simple cases.

The tool does not add a history entry to the output file header, which means the dmhistory tool cannot be used to recall the command.

/soft/ciao/binexe/wavdetect: line
234: 6881 Abort trap: 6 wrecon log=$wd_log
...
wrecon failed 
or

wrecon (CIAO): ERROR: Bad file name in flux stack on line 1

: Bad file descriptor
# 5679: wrecon (1) is: exit_upon_error->NULL
wrecon failed

wavdetect creates temporary files with names like wdname_xxx_yyy, where xxx and yyy are "(int)scale*10"; scale '2 4.5 16' creates filenames with "020 045 160".

If the scale values are greater than 100, the xxx and yyy values become four digits instead of three. This may cause the string buffer to overflow and the tool to fail.