Changes between Version 5 and Version 6 of Stack

Timestamp:

Mar 6, 2011, 12:59:54 PM (15 years ago)

Author:

eugene

Comment:

--

Stack

@@ -19 +19 @@
 === Stack Zero Points ===
 
-Here is a description of how the stack zero points are determined at set:
+Here is a description of how the stack zero points are determined and set:
 
  * in ppStackInputPhotometer
@@ -25 +25 @@
  * in ppStackSources: 
    * extract the reported zero points for each exposure
-   * if all are valid (not NAN), use these as the zero points
-   * otherwise use airmass and exposure time to generate a nominal offset [this explains some jumps: if any image was missing the zero point, the stack would end up with a reference zero point of essentially 25.0 -- from the ppStack recipe file -- otherwise it would be essentially the zero point of the given filter (relative to grizy.synth)].
+     * if all are valid (not NAN), use these as the zero points
+     * otherwise use the recipe values (25.0 at the time of this writing)
+       * this explains some jumps: if any image was missing the zero point, the stack would end up with a reference zero point of essentially 25.0 -- from the ppStack recipe file -- otherwise it would be essentially the zero point of the given filter (relative to grizy.synth).
    * if (ppStack:MATCH.ZERO.POINTS), use relative photometry to set the zero point:
-      * pmSourceMatchRelphot returns the set of transparencies that minimize the chisq [is this forced to have a mean of 0.0? or keep photometric images at 0.0?]
+      * pmSourceMatchRelphot returns the set of transparencies that minimize the chisq [the 'photometric clump' is set to 0.0 offset]
       * transparency is defined as: M_app = m_inst + zp + c1 * airmass + 2.5log(t) - transparency
       * the transparencies are applied to the reported zero points