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<h3><a href="index.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">calacs.e (HSTCAL)</a><ul>
<li><a class="reference internal" href="#running-calacs">Running CALACS</a><ul>
<li><a class="reference internal" href="#where-to-find-calacs">Where to Find CALACS</a></li>
<li><a class="reference internal" href="#usage">Usage</a></li>
<li><a class="reference internal" href="#command-line-options">Command Line Options</a></li>
<li><a class="reference internal" href="#parallel-processing-with-openmp">Parallel Processing with OpenMP</a></li>
<li><a class="reference internal" href="#batch-calacs">Batch CALACS</a></li>
</ul>
</li>
<li><a class="reference internal" href="#biascorr">BIASCORR</a></li>
<li><a class="reference internal" href="#unit-conversion-to-electrons">Unit Conversion to Electrons</a></li>
<li><a class="reference internal" href="#blevcorr">BLEVCORR</a></li>
<li><a class="reference internal" href="#pixel-based-cte-correction-pctecorr">Pixel-Based CTE Correction (PCTECORR)</a><ul>
<li><a class="reference internal" href="#required-keywords">Required Keywords</a></li>
<li><a class="reference internal" href="#optional-keywords">Optional Keywords</a></li>
</ul>
</li>
<li><a class="reference internal" href="#dark-current-subtraction-darkcorr">Dark Current Subtraction (DARKCORR)</a></li>
<li><a class="reference internal" href="#post-flash-correction-flshcorr">Post-Flash Correction (FLSHCORR)</a></li>
<li><a class="reference internal" href="#flatcorr">FLATCORR</a></li>
<li><a class="reference internal" href="#photometry-keywords-photcorr">Photometry Keywords (PHOTCORR)</a></li>
<li><a class="reference internal" href="#calacs-output">CALACS Output</a></li>
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<div class="section" id="calacs-e-hstcal">
<h1>calacs.e (HSTCAL)<a class="headerlink" href="#calacs-e-hstcal" title="Permalink to this headline">¶</a></h1>
<p>A detailed description of this new and improved CALACS will be available
in a future publication of ACS Data Handbook. In the meantime, if you have
questions not answered in this documentation, please contact STScI Help Desk
(help[at]stsci.edu).</p>
<div class="section" id="running-calacs">
<h2>Running CALACS<a class="headerlink" href="#running-calacs" title="Permalink to this headline">¶</a></h2>
<div class="section" id="where-to-find-calacs">
<h3>Where to Find CALACS<a class="headerlink" href="#where-to-find-calacs" title="Permalink to this headline">¶</a></h3>
<p>CALACS is now part of HSTCAL package, which can be downloaded from</p>
<p><a class="reference external" href="http://www.stsci.edu/institute/software_hardware/stsdas/download-stsdas">http://www.stsci.edu/institute/software_hardware/stsdas/download-stsdas</a></p>
</div>
<div class="section" id="usage">
<h3>Usage<a class="headerlink" href="#usage" title="Permalink to this headline">¶</a></h3>
<p>From the command line:</p>
<div class="highlight-python"><pre>calacs.e jb1f89eaq_raw.fits [command line options]</pre>
</div>
</div>
<div class="section" id="command-line-options">
<h3>Command Line Options<a class="headerlink" href="#command-line-options" title="Permalink to this headline">¶</a></h3>
<p>CALACS supports several command line options:</p>
<ul class="simple">
<li>-t<ul>
<li>Print verbose time stamps.</li>
</ul>
</li>
<li>-s<ul>
<li>Save temporary files.</li>
</ul>
</li>
<li>-v<ul>
<li>Turn on verbose output.</li>
</ul>
</li>
<li>-d<ul>
<li>Turn on debug output.</li>
</ul>
</li>
<li>-q<ul>
<li>Turn on quiet output.</li>
</ul>
</li>
<li>-1<ul>
<li>Turn off parallel processing for PCTECORR. Try this option if you encounter
problems running CALACS with PCTECORR=PERFORM.</li>
</ul>
</li>
</ul>
</div>
<div class="section" id="parallel-processing-with-openmp">
<h3>Parallel Processing with OpenMP<a class="headerlink" href="#parallel-processing-with-openmp" title="Permalink to this headline">¶</a></h3>
<p>By default, CALACS will attempt to perform PCTECORR using all available CPUs on
your machine. You can set the maximum number of CPUs available for CALACS by
setting the <tt class="docutils literal"><span class="pre">OMP_NUM_THREADS</span></tt> environmental variable.</p>
<p>In tcsh:</p>
<div class="highlight-python"><pre>setenv OMP_NUM_THREADS 2</pre>
</div>
<p>In bash:</p>
<div class="highlight-python"><pre>export OMP_NUM_THREADS=2</pre>
</div>
</div>
<div class="section" id="batch-calacs">
<h3>Batch CALACS<a class="headerlink" href="#batch-calacs" title="Permalink to this headline">¶</a></h3>
<p>The recommended method for running CALACS in batch mode is to use Python and
the <em class="xref py py-obj">acstools</em> package in <a class="reference external" href="http://www.stsci.edu/institute/software_hardware/stsdas/download-stsdas">STSDAS distribution</a>.</p>
<p>For example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">acstools</span> <span class="kn">import</span> <span class="n">calacs</span>
<span class="kn">import</span> <span class="nn">glob</span>
<span class="k">for</span> <span class="n">fits</span> <span class="ow">in</span> <span class="n">glob</span><span class="o">.</span><span class="n">iglob</span><span class="p">(</span><span class="s">'j*_raw.fits'</span><span class="p">):</span>
<span class="n">calacs</span><span class="o">.</span><span class="n">calacs</span><span class="p">(</span><span class="n">fits</span><span class="p">)</span>
</pre></div>
</div>
</div>
</div>
<div class="section" id="biascorr">
<h2>BIASCORR<a class="headerlink" href="#biascorr" title="Permalink to this headline">¶</a></h2>
<p>BIASCORR is now performed before BLEVCORR. This should not significantly affect
science results. This change was necessary to accomodate BIASFILE subtraction in
DN with the rest of the calculations done in ELECTRONS.</p>
</div>
<div class="section" id="unit-conversion-to-electrons">
<h2>Unit Conversion to Electrons<a class="headerlink" href="#unit-conversion-to-electrons" title="Permalink to this headline">¶</a></h2>
<p>The image is multiplied by gain right after BIASCORR, converting it to
ELECTRONS. This step is no longer embedded within FLATCORR.</p>
</div>
<div class="section" id="blevcorr">
<h2>BLEVCORR<a class="headerlink" href="#blevcorr" title="Permalink to this headline">¶</a></h2>
<p>BLEVCORR is now performed after BIASCORR. Calculations are done in ELECTRONS.</p>
<p>For post-SM4 full-frame WFC exposures, it also includes:</p>
<blockquote>
<div><ul class="simple">
<li>de-striping to remove stripes introduced by new hardware installed during
SM-4 (J. Anderson; ACS ISR 2011-05); and</li>
<li>if JWROTYPE=DS_int and CCDGAIN=2, also correct for bias shift
(ACS ISR 2012-02) and cross-talk (N. Grogin; ACS ISR 2010-02).</li>
</ul>
</div></blockquote>
</div>
<div class="section" id="pixel-based-cte-correction-pctecorr">
<h2>Pixel-Based CTE Correction (PCTECORR)<a class="headerlink" href="#pixel-based-cte-correction-pctecorr" title="Permalink to this headline">¶</a></h2>
<p>For all full-frame WFC exposures, pixel-based CTE correction (ACS ISR 2010-03
and 2012-03) is applied at the end of the ACSCCD series; i.e., after BLEVCORR.</p>
<p>Because the CTE correction is applied before DARKCORR and FLSHCORR, it is
necessary to use a CTE-corrected dark (DRKCFILE) and post-flash (FLSCFILE) if
the PCTECORR step is enabled.</p>
<p>Parameters characterizing the CTE correction are stored in a reference table,
PCTETAB.</p>
<div class="section" id="required-keywords">
<h3>Required Keywords<a class="headerlink" href="#required-keywords" title="Permalink to this headline">¶</a></h3>
<p>Running CALACS with pixel-based CTE correction requires the following header
keywords:</p>
<ul class="simple">
<li>PCTECORR<ul>
<li>By default, set to PERFORM for all full-frame WFC exposures.</li>
</ul>
</li>
<li>PCTETAB<ul>
<li>Reference table containing CTE correction parameters. By default, it should
be in the <tt class="docutils literal"><span class="pre">jref</span></tt> directory and have the suffix <tt class="docutils literal"><span class="pre">_cte.fits</span></tt>.</li>
</ul>
</li>
<li>DRKCFILE<ul>
<li>Similar to DARKFILE but with CTE correction performed. By default, it should
be in the <tt class="docutils literal"><span class="pre">jref</span></tt> directory and have the suffix <tt class="docutils literal"><span class="pre">_dkc.fits</span></tt>. This is
necessary because PCTECORR is done before DARKCORR.</li>
</ul>
</li>
<li>FLSCFILE (if FLSHCORR=PERFORM)<ul>
<li>Similar to FLSHFILE but with CTE correction performed. By default, it should
be in the <tt class="docutils literal"><span class="pre">jref</span></tt> directory and have the suffix <tt class="docutils literal"><span class="pre">_flsc.fits</span></tt>. This is
necessary because PCTECORR is done before FLSHCORR.</li>
</ul>
</li>
</ul>
</div>
<div class="section" id="optional-keywords">
<h3>Optional Keywords<a class="headerlink" href="#optional-keywords" title="Permalink to this headline">¶</a></h3>
<p>You may adjust some CTE correction algorithm parameters by changing the
following keywords in RAW image header. The default values are picked for
optimum results in a typical WFC full-frame exposure. Changing these values is
not recommended unless you know what you are doing.</p>
<ul class="simple">
<li>PCTENSMD<ul>
<li>Read noise mitigation mode:<ul>
<li>0 - No mitigation</li>
<li>1 - Perform noise smoothing</li>
<li>2 - No noise smoothing</li>
</ul>
</li>
<li>Overwrites NSEMODEL in PCTETAB.</li>
</ul>
</li>
<li>PCTERNCL<ul>
<li>Read noise level of image in ELECTRONS. This is not used if you specified
no mitigation in read noise mitigation mode.</li>
<li>Overwrites RN_CLIP in PCTETAB.</li>
</ul>
</li>
<li>PCTETRSH<ul>
<li>Over-subtraction correction threshold. Pixel below this value in ELECTRONS
after CTE correction is considered over-corrected and will re-corrected with
smaller correction.</li>
<li>Overwrites SUBTHRSH in PCTETAB.</li>
</ul>
</li>
<li>PCTESMIT<ul>
<li>Number of iterations of readout simulation per column.</li>
<li>Overwrites SIM_NIT in PCTETAB.</li>
</ul>
</li>
<li>PCTESHFT<ul>
<li>Number of shifts each readout simulation is broken up into.</li>
<li>Overwrites SHFT_NIT in PCTETAB.</li>
</ul>
</li>
</ul>
</div>
</div>
<div class="section" id="dark-current-subtraction-darkcorr">
<h2>Dark Current Subtraction (DARKCORR)<a class="headerlink" href="#dark-current-subtraction-darkcorr" title="Permalink to this headline">¶</a></h2>
<p>It uses DARKFILE if PCTECORR=OMIT, otherwise it uses DRKCFILE (CTE-corrected
dark reference file).</p>
<p>Dark image is now scaled by EXPTIME and FLASHDUR. For post-SM4 non-BIAS
WFC images, extra 3 seconds are also added to account for idle time before
readout. Any image with non-zero EXPTIME is considered not a BIAS.</p>
</div>
<div class="section" id="post-flash-correction-flshcorr">
<h2>Post-Flash Correction (FLSHCORR)<a class="headerlink" href="#post-flash-correction-flshcorr" title="Permalink to this headline">¶</a></h2>
<p>Post-flash correction is now performed after DARKCORR in the ACS2D step.
When FLSHCORR=PERFORM, it uses FLSHFILE if PCTECORR=OMIT, otherwise it uses
FLSCFILE (CTE-corrected post-flash reference file).</p>
</div>
<div class="section" id="flatcorr">
<h2>FLATCORR<a class="headerlink" href="#flatcorr" title="Permalink to this headline">¶</a></h2>
<p>Conversion from DN to ELECTRONS no longer depends on FLATCORR=PERFORM. Unit
conversion is done for all exposures after BIASCORR.</p>
</div>
<div class="section" id="photometry-keywords-photcorr">
<h2>Photometry Keywords (PHOTCORR)<a class="headerlink" href="#photometry-keywords-photcorr" title="Permalink to this headline">¶</a></h2>
<p>The PHOTCORR step is now performed using tables of precomputed values instead
of calls to SYNPHOT. The correct table for a given image must be specified
in the IMPHTTAB header keyword in order for CALACS to perform the PHOTCORR step.
By default, it should be in the <tt class="docutils literal"><span class="pre">jref</span></tt> directory and have the suffix
<tt class="docutils literal"><span class="pre">_imp.fits</span></tt>. Each DETECTOR uses a different table.</p>
<p>If you do not wish to use this feature, set PHOTCORR to OMIT.</p>
</div>
<div class="section" id="calacs-output">
<h2>CALACS Output<a class="headerlink" href="#calacs-output" title="Permalink to this headline">¶</a></h2>
<p>Using RAW as input:</p>
<blockquote>
<div><ul class="simple">
<li>flt.fits: Same as existing FLT.</li>
<li>flc.fits: Similar to FLT, except with pixel-based CTE correction applied.</li>
</ul>
</div></blockquote>
<p>Using ASN as input with ACSREJ:</p>
<blockquote>
<div><ul class="simple">
<li>crj.fits: Same as existing CRJ.</li>
<li>crc.fits: Similar to CRJ, except with pixel-based CTE correction applied.</li>
</ul>
</div></blockquote>
</div>
</div>
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