documentation of ncal

docs/commands.rst

@@ -35,6 +35,7 @@
 .. |ol-makemovie| replace:: makes stills for movies from a run
 .. |ol-mstats|   replace:: list stats of multiple frames from a run
 .. |ol-mul|      replace:: multiply two frames
+.. |ol-ncal|     replace:: noise calibration
 .. |ol-nrtplot|  replace:: plot frames as they come in [matplotlib]
 .. |ol-plog|     replace:: plot output log from |reduce|
 .. |ol-redanal|  replace:: analyse a reduction log file
@@ -141,6 +142,8 @@ useful.
    +--------------+----------------+----------+----------+---------+-----------+------------+
    | |mul|        | |ol-mul|       |          |          |         |   Yes     |            |
    +--------------+----------------+----------+----------+---------+-----------+------------+
+   | |ncal|       | |ol-ncal|      | Yes      | Yes      |  Yes    |           | Yes        |
+   +--------------+----------------+----------+----------+---------+-----------+------------+
    | |nrtplot|    | |ol-nrtplot|   | Yes      | Yes      |  Yes    |           |            |
    +--------------+----------------+----------+----------+---------+-----------+------------+
    | |plog|       | |ol-plog|      | Yes      |          |  Yes    |           |            |
@@ -467,6 +470,7 @@ extension '.hcm' to distinguish them, although they are also FITS-format files.
 .. autofunction:: hipercam.scripts.makemovie
 .. autofunction:: hipercam.scripts.mstats
 .. autofunction:: hipercam.scripts.mul
+.. autofunction:: hipercam.scripts.ncal
 .. autofunction:: hipercam.scripts.nrtplot
 .. autofunction:: hipercam.scripts.plog
 .. autofunction:: hipercam.scripts.redanal

docs/globals.rst

@@ -46,6 +46,7 @@
 .. |makemovie| replace:: :func:`makemovie <hipercam.scripts.makemovie>`
 .. |mstats| replace:: :func:`mstats <hipercam.scripts.mstats>`
 .. |mul| replace:: :func:`mul <hipercam.scripts.mul>`
+.. |ncal| replace:: :func:`ncal <hipercam.scripts.ncal>`
 .. |nrtplot| replace:: :func:`nrtplot <hipercam.scripts.nrtplot>`
 .. |plog| replace:: :func:`plog <hipercam.scripts.plog>`
 .. |psf_reduce| replace:: :func:`psf_reduce <hipercam.scripts.psf_reduce>`

hipercam/scripts/ncal.py

@@ -36,8 +36,13 @@ def ncal(args=None):
     """``ncal [source] (run first last [twait tmax] | flist) trim ([ncol
     nrow]) (ccd) bias dark flat xybox read gain grain``
 
-    Calibrates noise characteristics of CCDs but plotting estimator
-    of RMS vs signal level from a series of frames.
+    Calibrates noise characteristics of CCDs by plotting estimator
+    of RMS vs signal level from a series of frames. The estimate
+    is the mean of the absolute difference between each pixel
+    and the mean of its 8 near-neighbours. This is very local and
+    fairly robust. Assuming gaussian noise, the RMS is sqrt(4*Pi/9)
+    times this value, and this is what is plotted as the RMS by this
+    routine.
 
     Parameters: