Changes between Initial Version and Version 1 of psphot_extended_source_fit

Timestamp:

Sep 5, 2013, 2:59:42 PM (13 years ago)

Author:

bills

Comment:

--

psphot_extended_source_fit

@@ +1 @@
+= psphot Extended Source Fit Testing =
+
+This page discusses some experiments where we ran psphot on simulated images to test recent improvements to the
+psphot extended source fitting.
+
+The 40 simulated images were provided last year by Peter Draper for use in testing the psphot kron radius and magnitude
+code. They were constructed using E Bertin's SkyMaker program. 
+
+The objects of interest are simulated galaxies which are described by the following parameters
+
+{{{
+  - x y   centre of object in pixels
+  - mag   total magnitude
+  - bt    build/disk ratio
+  - br    bulge effective radii (half light arcsec)
+  - bi    bulge inclination (always 1 in this sample)
+  - ba    bulge position angle
+  - dl    disk scale length (arcsec)
+  - di    disk inclincation (always 1 in this sample)
+  - da    disk position angle
+  - z     redshift
+  - ht    hubble type  (10 for pure disks, -6 for pure bulges)
+}}}
+
+These images were run though psphot using the STACKPHOT recipe. The parameters for the set of sources psphot selected for extended source fitting were
+matched by coordinates to the list of simulated galaxies. In the following sections we examine the fits for the 3 different models.
+We concentrate mostly on the simple galaxy models, pure disks (exponential profile) and and pure bulges (de Vaucouleur 1/4 profile).
+
+== Sersic Model ==
+
+{{{
+    I(r) = I(0) exp[ -k * R ** (1 / m) ]
+
+psphot extended source parameters meausred
+   EXT_INST_MAG
+   EXT_WIDTH_MAJ
+   EXT_WIDTH_MIN
+   EXT_THETA
+   EXT_PAR_07       (0.5 / m)
+}}}
+
+Since all of the simulated galaxes in this sample have bulge inclination == 1 and disk inclination == 1,
+the major an minor axes should be equal and the angle will
+unmeasurable due to noise.
+
+=== Magnitude ==
+
+The difference between the simulated galaxy's magnitude and the sersic fit magnitude is shown in the following plot
+
+