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author | Joseph Hunkeler <jhunkeler@gmail.com> | 2015-07-08 20:46:52 -0400 |
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committer | Joseph Hunkeler <jhunkeler@gmail.com> | 2015-07-08 20:46:52 -0400 |
commit | fa080de7afc95aa1c19a6e6fc0e0708ced2eadc4 (patch) | |
tree | bdda434976bc09c864f2e4fa6f16ba1952b1e555 /noao/digiphot/apphot/doc/daofind.noao | |
download | iraf-linux-fa080de7afc95aa1c19a6e6fc0e0708ced2eadc4.tar.gz |
Initial commit
Diffstat (limited to 'noao/digiphot/apphot/doc/daofind.noao')
-rw-r--r-- | noao/digiphot/apphot/doc/daofind.noao | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/noao/digiphot/apphot/doc/daofind.noao b/noao/digiphot/apphot/doc/daofind.noao new file mode 100644 index 00000000..74cc8f00 --- /dev/null +++ b/noao/digiphot/apphot/doc/daofind.noao @@ -0,0 +1,21 @@ + + +There is a bug in the iraf/daophot ii daofind centering code which results in +incorrect fractional pixel corrections being computed for the detected objects. +This error can most easily be detected by plotting the histogram of the +fractional pixel corrections for an image with a large number of detected +objects. The histogram will be modulated at around the 20% level with "peaks" +around the 0.33 and 0.66 fractional pixel values. + +This bug is fixed for the next release of iraf and in the external addon +package digiphotx version of daofind. There is no workaround although it +should be emphasized that this bug does not affect the centers computed by +the psf fitting code in the peak, nstar, and allstar tasks. Users concerned +with precision in the daofind results should upgrade their software, or +recenter the objects with the phot "centroid" (fast) or "gauss" (more precise) +routines. + +This bug is also present in the standalone version of daophot ii. I have +reported this problem to Peter Stetson and he has fixed it. Users concerned +about this bug in the standalone version of daophot ii should obtain a fix +from Peter Stetson. |