Log Book Entry No.9

Created: 04 Sep 2013 18:23:45	Last Revised: 05 Sep 2013 22:16:53	PedroPaiva	Dark Analysis

Created: 04 Sep 2013 18:23:45

Last Revised: 05 Sep 2013 22:16:53

PedroPaiva

Dark Analysis

Camera: SBIG ST-8XME at 0 ºC

CCD Dark Linearity

In order to test the CCD Dark Linearity 5 frames of each were taken with filenames: darkAnalysis-XXX-EEE.fit,
XXX - image number
EEE - exposure in seconds (001 corresponds to 0.01s and 100 to 100s)

Exposures:

0.001s
0.01s
0.1s
1s
10s
100s
1000s

Processing:

The median frame for each exposure was taken (see #Master_Darks for more)
The median electron count for each frame was measured and ploted versus the exposure time

Electron Counts vs exposure time:

Master Darks

To create master Darks, the 25 frames of each were taken with filenames: darkAnalysis-XXX-EEEs.fit, and the median was taken.
XXX - image number
EEE - exposure in seconds (001 corresponds to 0.01s and 100 to 100s)

Exposures:

60s - for Luminance frames
80s - for Red frames
86s - for Green frames
109s - for Blue frames

Processing:

Full source
- dev branch -> new
In a nutshel:

    def masterFrame(expTime, type, method = 'median', fileName = None, path = None) :
        ''' Creates a Master Frame from files loaded in manager
            Files must have a valid header['EXPTIME'] '''
        allNames = _manager.imageList()
        allValid = [name for name in allNames if _manager.getImage(name)['header'].has_key('EXPTIME')]
        images = _numpy.array([_manager.getImage(name)['img'].image
                               for name in allValid if _manager.getImage(name)['header']['EXPTIME'] == expTime])
        size = len(images)
        if size:
            if method == 'mean':
                master = images.mean(axis=0)
            elif method == 'median':
                master = _numpy.median(images, axis=0)
            masterError = images.std(axis=0) / _numpy.sqrt(size)
            if not fileName:
                fileName = "master" + type + str(expTime)
            saveFits(master, fileName, path, 'Master'+type, egain=1, expTime = expTime, errors = masterError)
        else:
            print "Sorry, no files found with exposure time =", expTime

Final Images:

Obs. The scaling was made according to the camera Quantum Efficiency. Click here

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Subject	Dark Analysis
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Topic revision: r5 - 05 Sep 2013 - PedroPaiva

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