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0001 <sect2 id="ekos-capture">
0002     <title>Capture</title>
0003     <indexterm>
0004         <primary>Tools</primary>
0005         <secondary>Ekos</secondary>
0006         <tertiary>Capture</tertiary>
0007     </indexterm>
0008     <screenshot>
0009         <screeninfo>
0010             Ekos Capture
0011         </screeninfo>
0012         <mediaobject>
0013             <imageobject>
0014                 <imagedata fileref="ekos_capture.png" format="PNG"/>
0015             </imageobject>
0016             <textobject>
0017                 <phrase>Ekos Capture</phrase>
0018             </textobject>
0019         </mediaobject>
0020     </screenshot>
0021     <para>
0022         The Capture Module is your primary image and video acquisition module in Ekos. It enables you to capture single (Preview), multiple images (Sequence Queue), or record <ulink url="https://sites.google.com/site/astropipp/ser-player">SER</ulink> videos along with a selection of filter wheel and rotator, if available.
0023     </para>
0024     <sect3 id="capture-ccd-filter-wheel">
0025         <title>CCD &amp; Filter Wheel Group</title>
0026         <para>
0027             Select the desired CCD/DSLR and Filter Wheel (if available) for capture. Set CCD temperature and filter settings.
0028         </para>
0029         <itemizedlist>
0030             <listitem>
0031                 <para>
0032                     <guilabel>CCD</guilabel>: Select the active CCD camera. If your camera has a guide head, you can select it from here as well.
0033                 </para>
0034             </listitem>
0035             <listitem>
0036                 <para>
0037                     <guilabel>FW</guilabel>: Select the active Filter Wheel device. If your camera has a built-in filter wheel, the device would be the same as the camera.
0038                 </para>
0039             </listitem>
0040             <listitem>
0041                 <para>
0042                     <guilabel>Cooler</guilabel>: Toggle Cooler On/Off. Set the desired temperature, if your camera is equipped with a cooler. Check the option to force temperature setting before any capture. Capture process is only started after the measured temperature is within requested temperature tolerance. The <emphasis>default</emphasis> tolerance is 0.1 degrees Celsius but can be adjusted in <guilabel>Capture</guilabel> options under Ekos configuration.
0043                 </para>
0044             </listitem>
0045         </itemizedlist>
0046     </sect3>
0047     <sect3 id="capture-settings">
0048         <title>Capture Settings</title>
0049         <screenshot>
0050             <screeninfo>
0051                 Capture Settings
0052             </screeninfo>
0053             <mediaobject>
0054                 <imageobject>
0055                     <imagedata fileref="capture_settings.png" format="PNG"/>
0056                 </imageobject>
0057                 <textobject>
0058                     <phrase>Capture Settings</phrase>
0059                 </textobject>
0060             </mediaobject>
0061         </screenshot>
0062         <para>
0063             Set all capture parameters as detailed below. Once set, you can capture a preview by click on <guibutton>Preview</guibutton> or add a job to the sequence queue.
0064         </para>
0065         <itemizedlist>
0066             <listitem>
0067                 <para>
0068                     <guilabel>Exposure</guilabel>: Specify exposure duration in seconds.
0069                 </para>
0070             </listitem>
0071             <listitem>
0072                 <para>
0073                     <guilabel>Filter</guilabel>: Specify the desired filter.
0074                 </para>
0075             </listitem>
0076             <listitem>
0077                 <para>
0078                     <guilabel>Count</guilabel>: Number of images to capture
0079                 </para>
0080             </listitem>
0081             <listitem>
0082                 <para>
0083                     <guilabel>Delay</guilabel>: Delay in seconds between image captures.
0084                 </para>
0085             </listitem>
0086             <listitem>
0087                 <para>
0088                     <guilabel>Type</guilabel>: Specify the type of desired CCD frame. Options are <guimenuitem>Light</guimenuitem>, <guimenuitem>Dark</guimenuitem>, <guimenuitem>Bias</guimenuitem>, and <guimenuitem>Flat</guimenuitem> frames.
0089                 </para>
0090             </listitem>
0091             <listitem>
0092                 <para>
0093                     <guilabel>ISO</guilabel>: For DSLR cameras, specify the ISO value.
0094                 </para>
0095             </listitem>
0096             <listitem>
0097                 <para>
0098                     <guilabel>Format</guilabel>: Specify capture save format. For all CCDs, only <guimenuitem>FITS</guimenuitem> option is available. For DSLR cameras, you can an additional option to save in <guimenuitem>Native</guimenuitem> format (&eg; RAW or JPEG).
0099                 </para>
0100             </listitem>
0101             <listitem>
0102                 <para>
0103                     <guilabel>Custom Properties</guilabel>: Set extended properties available in the camera to the job settings.
0104                 </para>
0105             </listitem>
0106             <listitem>
0107                 <para>
0108                     <guilabel>Calibration</guilabel>: For Dark &amp;s; Flat frames, you can set additional options explained in the <link linkend="capture-calibration-frames">Calibration Frames section below</link>.
0109                 </para>
0110             </listitem>
0111             <listitem>
0112                 <para>
0113                     <guilabel>Frame</guilabel>: Specify the left (X), top (Y), width (W), and height (H) of the desired CCD frame. If you changed the frame dimensions, you can reset it to default values by clicking on the reset button.
0114                 </para>
0115             </listitem>
0116             <listitem>
0117                 <para>
0118                     <guilabel>Binning</guilabel>: Specify horizontal (X) and vertical (Y) binning.
0119                 </para>
0120             </listitem>
0121         </itemizedlist>
0122         <sect4 id="capture-custom-properties">
0123             <title>Custom Properties</title>
0124             <para>
0125                 Many cameras offer additional properties that cannot be directly set in the capture settings using the common control. The capture controls described above represent the most common settings shared among different cameras, but each camera is unique and may offer its own extended properties. While you can use INDI Control Panel to set any property in the driver; it is important to be able to set such property for each job in the sequence. When you click <guibutton>Custom Properties</guibutton>, a dialog is shown divided into <guilabel>Available Properties</guilabel> and <guilabel>Job Properties</guilabel>. When you move an <guilabel>Available Properties</guilabel> to the <guilabel>Job Property</guilabel> list, its current value can be recorded once you click <guibutton>Apply</guibutton>. When you add a job to the <guilabel>Sequence Queue</guilabel>, the properties values selected in the <guilabel>Job Properties</guilabel> list shall be recorded and saved.
0126             </para>
0127             <para>
0128                 The following video explains this concept is more detail with a live example:
0129             </para>
0130             <mediaobject>
0131                 <videoobject>
0132                     <videodata contentdepth="450" contentwidth="800" fileref="https://www.stellarmate.com/images/fss/videos/custom_properties.mp4"/>
0133                 </videoobject>
0134                 <caption>
0135                     <para>
0136                         <phrase>Custom Properties feature</phrase>
0137                     </para>
0138                 </caption>
0139             </mediaobject>
0140         </sect4>
0141     </sect3>
0142 
0143     <sect3 id="capture-file-settings">
0144         <title>File Settings</title>
0145 
0146         <screenshot>
0147             <screeninfo>
0148                 File Settings
0149             </screeninfo>
0150             <mediaobject>
0151                 <imageobject>
0152                     <imagedata fileref="file_settings.png" format="PNG"/>
0153                 </imageobject>
0154                 <textobject>
0155                     <phrase>File Settings</phrase>
0156                 </textobject>
0157             </mediaobject>
0158         </screenshot>
0159         <para>
0160             Settings for specifying where captured images are saved to, and how to generate unique file names in addition to upload mode settings.
0161         </para>
0162         <itemizedlist>
0163             <listitem>
0164                 <para>
0165                     <guilabel>Target</guilabel>: The name of the celestial target to be captured &eg; M42. Can be preloaded by the Scheduler Module and by selection with KStars.
0166                 </para>
0167             </listitem>
0168             <listitem>
0169                 <para>
0170                     <guilabel>Format</guilabel>: The Format string defines the path and filename of the captured images by the use of placeholder tags that are filled in with the selected item of data at save time.
0171                 </para>
0172                 <para>
0173                     A tag is identified by the % character. All tags have a single letter short form, and a self descriptive long form.
0174                 </para>
0175                 <para>
0176                     Arbitrary text may also be included within the Format string, <emphasis role="bold">except the % and \ characters.</emphasis> The / path character can be used to define arbitrary directories.
0177                 </para>
0178                 <para>
0179                     Note: Tags are case sensitive in both their short and long forms.
0180                 </para>
0181                 <para>
0182                     Available placeholder tags:
0183                 </para>
0184                 <itemizedlist>
0185                     <listitem>
0186                         <para>
0187                             <emphasis role="bold">%f</emphasis> or <emphasis role="bold">%filename</emphasis>: The name of the sequence .esq file, without extension.
0188                         </para>
0189                     </listitem>
0190                     <listitem>
0191                         <para>
0192                             <emphasis role="bold">%D</emphasis> or <emphasis role="bold">%Datetime</emphasis>: The current time and date <emphasis role="bold">when the file is saved. Only use this tag in the filename portion of the format, not in the path portion.</emphasis>
0193                         </para>
0194                     </listitem>
0195                     <listitem>
0196                         <para>
0197                             <emphasis role="bold">%T</emphasis> or <emphasis role="bold">%Type</emphasis>: The frame type &eg; 'Light', 'Bias', 'Dark', 'Flat'...
0198                         </para>
0199                     </listitem>
0200                     <listitem>
0201                         <para>
0202                             <emphasis role="bold">%e</emphasis> or <emphasis role="bold">%exposure</emphasis>: The exposure duration in seconds.
0203                         </para>
0204                     </listitem>
0205                     <listitem>
0206                         <para>
0207                             <emphasis role="bold">%F</emphasis> or <emphasis role="bold">%Filter</emphasis>: The active filter name.
0208                         </para>
0209                     </listitem>
0210                     <listitem>
0211                         <para>
0212                             <emphasis role="bold">%t</emphasis> or <emphasis role="bold">%target</emphasis>: The Target name.
0213                         </para>
0214                     </listitem>
0215                     <listitem>
0216                         <para>
0217                             <emphasis role="bold">%s*</emphasis> or <emphasis role="bold">%sequence*</emphasis>: The image sequence identifier where * is the number of digits used (1-9). <emphasis role="bold">This tag is mandatory and must be the last element in the format.</emphasis>
0218                         </para>
0219                     </listitem>
0220                 </itemizedlist>
0221             </listitem>
0222             <listitem>
0223                 <para>
0224                     <guilabel>Directory Browse Button</guilabel>: Opens a browse dialog to allow selection of the directory location used in the Format string. Use when first defining a Capture job.
0225                 </para>
0226             </listitem>
0227             <listitem>
0228                 <para>
0229                     <guilabel>Preview</guilabel>: Shows a preview of the resulting filename according to the Format string and other job settings.
0230                 </para>
0231                 <para>
0232                     Placeholder tags that are specified by the sequence .seq file can only be displayed once the sequence file has been saved. 
0233                 </para>
0234                 <para>
0235                     The Datetime tag is previewed with the current system time and will be replaced by the time at point of image save.
0236                 </para>
0237                 <para>
0238                     The sequence tag is always previewed as image 1 in the  sequence and will be automatically incremented when the job is in progress.
0239                 </para>
0240             </listitem>
0241             <listitem>
0242                 <para>
0243                     <guilabel>Upload</guilabel>: Select how captured images are uploaded:
0244                 </para>
0245                 <orderedlist>
0246                     <listitem>
0247                         <para>
0248                             <guilabel>Client</guilabel>: Captured images are only uploaded to Ekos and saved to the local directory specified above.</para>
0249                     </listitem>
0250                     <listitem>
0251                         <para>
0252                             <guilabel>Local</guilabel>: Captured images are only saved locally on the remote computer.</para>
0253                     </listitem>
0254                     <listitem>
0255                         <para>
0256                             <guilabel>Both</guilabel>: Captured images are saved on the remote device <emphasis role="bold">and</emphasis> uploaded to Ekos.</para>
0257                     </listitem>
0258                 </orderedlist>
0259                 <para>
0260                     When selecting <guimenuitem>Local</guimenuitem> or <guimenuitem>Both</guimenuitem>, you must specify the remote directory where the remote images are saved to. By default, all captured images are uploaded to Ekos.
0261                 </para>
0262             </listitem>
0263             <listitem>
0264                 <para>
0265                     <guilabel>Remote</guilabel>: When selecting either <guimenuitem>Local</guimenuitem> or <guimenuitem>Both</guimenuitem> modes above, you must specify the remote directory where remote images are saved to.
0266                 </para>
0267             </listitem>
0268             <listitem>
0269                 <para>
0270                     <guilabel>Preview</guilabel>: Shows a preview of the resulting filename according the provided path job settings. The file name format for saving remotely is pre-defined, placeholder tags may not be used. The file sequence number is always previewed as image 1 in the  sequence and will be automatically incremented when the job is in progress.
0271                 </para>
0272             </listitem>
0273         </itemizedlist>
0274     </sect3>
0275 
0276     <sect3 id="capture-limit-settings">
0277         <title>Limit Settings</title>
0278 
0279         <screenshot>
0280             <screeninfo>
0281                 Limit Settings
0282             </screeninfo>
0283             <mediaobject>
0284                 <imageobject>
0285                     <imagedata fileref="limit_settings.png" format="PNG"/>
0286                 </imageobject>
0287                 <textobject>
0288                     <phrase>Limit Settings</phrase>
0289                 </textobject>
0290             </mediaobject>
0291         </screenshot>
0292         <para>
0293             Limit settings are applicable to all the images in the sequence queue. When a limit is exceeded, Ekos shall command the appropriate action to remedy the situation as explained below.
0294         </para>
0295         <itemizedlist>
0296             <listitem>
0297                 <para>
0298                     <guilabel>Guiding Deviation</guilabel>: If checked, it enforces a limit of maximum allowable guiding deviation for the exposure, if autoguiding is used. If the guiding deviation exceeds this limit in arcseconds, it aborts the exposure sequence. It will automatically resume the exposure sequence again once the guiding deviation goes below this limit.</para>
0299             </listitem>
0300             <listitem>
0301                 <para>
0302                     <guilabel>Autofocus if HFR &gt;</guilabel>: If autofocus is enabled in the <link linkend="ekos-focus">focus module</link> and at least one autofocus operation was completed successfully, you can set the maximum acceptable HFR value. If this option is enabled then between consecutive exposures, the HFR value is recalculated, and if found to exceed the maximum acceptable HFR value, then an autofocus operation is automatically triggered. If the autofocus operation is completed successfully, the sequence queue resumes, otherwise, the job is aborted.</para>
0303             </listitem>
0304             <listitem>
0305                 <para>
0306                     <guilabel>Meridian Flip</guilabel>: If supported by the mount, set the hour angle limit (in hours) before a <ulink url="https://astronomy.mdodd.com/gem_movement.html">meridian flip</ulink> is commanded. For example, if you set the meridian flip duration to 0.1 hours, Ekos shall wait until the mount passes the meridian by 0.1 hours (6 minutes), then it commands the mount to perform a meridian flip. After the meridian flip is complete, Ekos re-aligns using astrometry.net (if <link linkend="ekos-align">the alignment</link> was used) and resumes guiding (if it was started before) and then resumes the capture process automatically.</para>
0307             </listitem>
0308         </itemizedlist>
0309     </sect3>
0310 
0311     <sect3 id="capture-sequence-queue">
0312         <title>Sequence Queue</title>
0313 
0314         <para>
0315             Sequence Queue is the primary hub of the Ekos Capture Module. This is where you can plan and execute jobs using the sequence queue built-in powerful editor. To add a job, simply select all the parameters from the capture and file settings as indicated above. Once you selected your desired parameters, click on the add button <inlinemediaobject><imageobject><imagedata fileref="list-add.png" format="PNG"/></imageobject></inlinemediaobject> in the sequence queue to add it to the queue.
0316         </para>
0317         <screenshot>
0318             <screeninfo>
0319                 Sequence Queue
0320             </screeninfo>
0321             <mediaobject>
0322                 <imageobject>
0323                     <imagedata fileref="sequence_settings.png" format="PNG"/>
0324                 </imageobject>
0325                 <textobject>
0326                     <phrase>Sequence Queue</phrase>
0327                 </textobject>
0328             </mediaobject>
0329         </screenshot>
0330         <para>
0331             You can add as many jobs as desired. While it is not strictly necessary, it is preferable to add the dark and flat jobs after the light frames. Once you are done adding jobs, simply click <guilabel>Start Sequence</guilabel> <inlinemediaobject><imageobject><imagedata fileref="media-playback-start.png" format="PNG"/></imageobject></inlinemediaobject> to begin executing the jobs. A job state changes from <guilabel>Idle</guilabel> to <guilabel>In Progress</guilabel> and finally to <guilabel>Complete</guilabel> once it is done. The Sequence Queue automatically starts the next job. If a job is aborted, it may be resumed again. To pause a sequence, click the pause button <inlinemediaobject><imageobject><imagedata fileref="media-playback-pause.png" format="PNG"/></imageobject></inlinemediaobject> and the sequence will be stopped after the current capture is complete. To reset the status of all the jobs, simply click the reset button <inlinemediaobject><imageobject><imagedata fileref="view-refresh.png" format="PNG"/></imageobject></inlinemediaobject>. Please beware that all image progress counts are reset as well. To preview an image in &kstars; FITS Viewer, click the <guibutton>Preview</guibutton> button.
0332         </para>
0333         <para>
0334             Sequence queues can be saved as an &XML; file with extension <literal role="extension">.esq</literal> (Ekos Sequence Queue). To load a sequence queue, click the open document button <inlinemediaobject><imageobject><imagedata fileref="document-open.png" format="PNG"/></imageobject></inlinemediaobject>. Please note that it will replace any current sequence queues in Ekos.
0335         </para>
0336 
0337         <important>
0338             <para>
0339                 <emphasis role="bold">Job Progress</emphasis>: Ekos is designed to execute and resume the sequence over multiple nights if required. Therefore, if <guilabel>Remember Job Progress</guilabel> option is enabled in <link linkend="ekos">Ekos Options</link>, Ekos shall scan the file system to count how many images are already completed and will resume the sequence from where it was left off. If this default behavior is not desired, simply turn off <guilabel>Remember Job Progress</guilabel> under options.
0340             </para>
0341         </important>
0342 
0343         <para>
0344             To edit a job, double click it. You will notice the add button <inlinemediaobject><imageobject><imagedata fileref="list-add.png" format="PNG"/></imageobject></inlinemediaobject> now changed to check mark button <inlinemediaobject><imageobject><imagedata fileref="dialog-ok-apply.png" format="PNG"/></imageobject></inlinemediaobject>. Make your changes on the left-hand side of the CCD module and once done, click on the check mark button. To cancel a job edit, click anywhere on the empty space within the sequence queue table.
0345         </para>
0346         <para>
0347             If your camera supports live video feed, then you can click the <guibutton>Live Video</guibutton> button to start streaming. The video stream window enables recording and subframing of the video stream. For more information, check the video below:
0348         </para>
0349         <mediaobject>
0350             <videoobject>
0351                 <videodata contentdepth="315" contentwidth="560" fileref="https://www.youtube.com/embed/qRsAqTL4ZZI"/>
0352             </videoobject>
0353             <caption>
0354                 <para>
0355                     <phrase>Recording feature</phrase>
0356                 </para>
0357             </caption>
0358         </mediaobject>
0359     </sect3>
0360 
0361     <sect3 id="capture-filter-settings">
0362         <title>Filter Settings</title>
0363 
0364         <screenshot>
0365             <screeninfo>
0366                 Filter Queue
0367             </screeninfo>
0368             <mediaobject>
0369                 <imageobject>
0370                     <imagedata fileref="filter_settings.png" format="PNG"/>
0371                 </imageobject>
0372                 <textobject>
0373                     <phrase>Filter Queue</phrase>
0374                 </textobject>
0375             </mediaobject>
0376         </screenshot>
0377 
0378         <para>
0379             Click the filter icon <inlinemediaobject><imageobject><imagedata fileref="view-filter.png" format="PNG"/></imageobject></inlinemediaobject> next to the filter wheel selection box to open the filter settings dialog. If you are using filters that are not parafocal with each other and require a specific amount of focus offsets in order to get them into proper then set all the relative focus offsets in the dialog.
0380         </para>
0381         <para>
0382             Configure settings for each filter individually:
0383         </para>
0384         <orderedlist>
0385             <listitem>
0386                 <para>
0387                     <guilabel>Filter</guilabel>: Filter Name.
0388                 </para>
0389             </listitem>
0390             <listitem>
0391                 <para>
0392                     <guilabel>Exposure</guilabel>: Set exposure time used when performing focus under this filter. By default, it is set to 1 second.
0393                 </para>
0394             </listitem>
0395             <listitem>
0396                 <para>
0397                     <guilabel>Offset</guilabel>: Set relative offsets. Ekos will command a focus offset change if there is a difference between the current and target filter offsets. For example, given the values in the example image, if the current filter is set to <emphasis>Red</emphasis> and next filter is <emphasis>Green</emphasis>, then Ekos shall command the focuser to Focus In by +300 ticks. Relative positive focus offsets denote Focus Out while negative values denote Focus In.
0398                 </para>
0399             </listitem>
0400             <listitem>
0401                 <para>
0402                     <guilabel>Auto Focus</guilabel>: Check this option to initial AutoFocus process whenever the filter is changed to this filter.
0403                 </para>
0404             </listitem>
0405             <listitem>
0406                 <para>
0407                     <guilabel>Lock Filter</guilabel>: Set which filter should be set and <emphasis>locked</emphasis> when performing autofocus for this filter.
0408                 </para>
0409             </listitem>
0410         </orderedlist>
0411         <para>
0412             Let's take an example. Suppose the capture sequence is running and the current filter is <guilabel>Green</guilabel>, so the relative offset is already set to +300. The next image in the sequence uses Hydrogen Alpha (H_Alpha) so before Ekos captures the next frame, the following actions take place:
0413         </para>
0414         <itemizedlist>
0415             <listitem>
0416                 <para>
0417                     Since Luminosity is specified as the locked filter and auto-focus is checked, the filter is changed to Luminosity.
0418                 </para>
0419             </listitem>
0420             <listitem>
0421                 <para>
0422                     A focus offset is -300 is applied since the prior filter <guilabel>Green</guilabel> was moved +300 previously.
0423                 </para>
0424             </listitem>
0425             <listitem>
0426                 <para>
0427                     Auto Focus process is initiated.
0428                 </para>
0429             </listitem>
0430             <listitem>
0431                 <para>
0432                     Once Auto Focus is complete, the filter is changed to H_Alpha.
0433                 </para>
0434             </listitem>
0435             <listitem>
0436                 <para>
0437                     A focus offset of -1200 is applied.
0438                 </para>
0439             </listitem>
0440             <listitem>
0441                 <para>
0442                     Capture sequence is resumed.
0443                 </para>
0444             </listitem>
0445         </itemizedlist>
0446     </sect3>
0447 
0448     <sect3 id="capture-fits-viewer">
0449         <title>FITS Viewer</title>
0450 
0451         <para>
0452             Captured images are displayed in &kstars; FITS Viewer tool, and also in the summary screen. Set options related to how the images are displayed in the viewer.
0453         </para>
0454         <itemizedlist>
0455             <listitem>
0456                 <para>
0457                     <guilabel>Auto Dark</guilabel>: You can capture an image and auto dark subtract it by checking this option. Note that this option is only applicable when using <guilabel>Preview</guilabel>, you cannot use it in batch mode sequence queue.
0458                 </para>
0459             </listitem>
0460             <listitem>
0461                 <para>
0462                     <guilabel>Effects</guilabel>: Image enhancement filter to be applied to the image after capture.
0463                 </para>
0464             </listitem>
0465         </itemizedlist>
0466     </sect3>
0467 
0468     <sect3 id="capture-rotation-settings">
0469         <title>Rotator Settings</title>
0470 
0471         <screenshot>
0472             <screeninfo>
0473                 Rotator Settings
0474             </screeninfo>
0475             <mediaobject>
0476                 <imageobject>
0477                     <imagedata fileref="ekos_rotator_settings.png" format="PNG"/>
0478                 </imageobject>
0479                 <textobject>
0480                     <phrase>Rotator Settings</phrase>
0481                 </textobject>
0482             </mediaobject>
0483         </screenshot>
0484 
0485         <para>
0486             Field Rotators are supported in INDI &amp; Ekos. The rotator angle is the raw angle reported by the rotator and is not necessary the <ulink url="https://en.wikipedia.org/wiki/Position_angle">Position Angle</ulink>. A Position Angle of <emphasis>zero</emphasis> indicates that the frame top (indicated by small arrow) is pointing <emphasis>directly</emphasis> at the pole. The position angle is expressed as E of N (East of North), so 90 degrees PA indicates the frame <emphasis>top</emphasis> points 90 degrees away (counter-clockwise) from the pole. Check <ulink url="https://nustarsoc.caltech.edu/NuSTAR_Public/NuSTAROperationSite/file/NuSTAR-PA.pdf">examples</ulink> for various PAs.
0487         </para>
0488         <para>
0489             To calibrate the Position Angle (PA), capture and solve an image in the <link linkend="ekos-align">Ekos Align module</link>. An <emphasis>offset</emphasis> and a <emphasis>multiplier</emphasis> are applied to the raw angle to produce the position angle. The Ekos Rotator dialog permits direct control of the raw angle and also the PA. The offset and multiplier can be changed manually to synchronize the rotator's raw angle with the actual PA. Check <guilabel>Sync FOV to PA</guilabel> to rotate the current Field of View (FOV) indicator on the Sky Map with the PA value as you change it in the dialog.
0490         </para>
0491 
0492         <mediaobject>
0493             <videoobject>
0494                 <videodata contentdepth="315" contentwidth="560" fileref="https://www.youtube.com/embed/V_hRPMlPjmA"/>
0495             </videoobject>
0496             <caption>
0497                 <para>
0498                     <phrase>Rotator settings</phrase>
0499                 </para>
0500             </caption>
0501         </mediaobject>
0502 
0503         <para>
0504             Each capture job may be assigned different rotator angles, but be aware that this would cause guiding to abort as it would lose track of the guide star when rotating. Therefore, for most sequences, the rotator angle is kept the same for all capture jobs.
0505         </para>
0506     </sect3>
0507 
0508     <sect3 id="capture-calibration-frames">
0509         <title>Calibration Frames</title>
0510 
0511         <screenshot>
0512             <screeninfo>
0513                 Calibration settings
0514             </screeninfo>
0515             <mediaobject>
0516                 <imageobject>
0517                     <imagedata fileref="calibration_settings.png" format="PNG"/>
0518                 </imageobject>
0519                 <textobject>
0520                     <phrase>Calibration settings</phrase>
0521                 </textobject>
0522             </mediaobject>
0523         </screenshot>
0524         <para>
0525             For Flat Field frames, you can set calibration options in order to automate the process. The calibration options are designed to facilitate automatic unattended flat field frame capture. It can also be used for dark and bias frames if desired. If your camera is equipped with a mechanical shutter, then it is not necessary to set calibration settings unless you want to close the dust cover to ensure no light at all passes through the optical tube. For flat fields, you must specify the flat field light source, and then specify the duration of the flat field frame. The duration can be either manual or based on ADU calculations.
0526         </para>
0527         <orderedlist>
0528             <listitem>
0529                 <para>
0530                     Flat Field Source
0531                     <itemizedlist>
0532                         <listitem>
0533                             <para>
0534                                 <guilabel>Manual</guilabel>: The flat light source is manual.</para>
0535                         </listitem>
0536                         <listitem>
0537                             <para>
0538                                 <guilabel>Dust Cover with Built-In Flat Light</guilabel>: If using a dust cover with builtin light source (&eg; FlipFlat). For dark and bias frames, close the dust cap before proceeding. For flat frames, close the dust cap and turn on the light source.</para>
0539                         </listitem>
0540                         <listitem>
0541                             <para>
0542                                 <guilabel>Dust Cover with External Flat Light</guilabel>: If using a dust cover with an external flat light source. For dark and bias frames, close the dust cap before proceeding. For flat frames, open the dust cap and turn on the light source. The external flat light source location is presumed to be the parking location.</para>
0543                         </listitem>
0544                         <listitem>
0545                             <para>
0546                                 <guilabel>Wall</guilabel>: Light source is a panel on the observatory wall. Specify the Azimuth and Altitude coordinates of the panel and the mount shall slew there before capturing the flat field frames. If the light panel is controllable from INDI, Ekos shall turn it on/off as required.</para>
0547                         </listitem>
0548                         <listitem>
0549                             <para>
0550                                 <guilabel>Dawn/Dusk</guilabel>: Currently unsupported.</para>
0551                         </listitem>
0552                     </itemizedlist>
0553                 </para>
0554             </listitem>
0555             <listitem>
0556                 <para>
0557                     Flat Field Duration
0558                     <itemizedlist>
0559                         <listitem>
0560                             <para>
0561                                 <guilabel>Manual</guilabel>: Duration is as specified in the Sequence Queue.</para>
0562                         </listitem>
0563                         <listitem>
0564                             <para>
0565                                 <guilabel>ADU</guilabel>: Duration is variable until specified ADU is met.</para>
0566                         </listitem>
0567                     </itemizedlist>
0568                 </para>
0569             </listitem>
0570         </orderedlist>
0571         <para>
0572             Before the calibration capture process is started, you can request Ekos to park the mount and/or dome. Depending on your flat source selection above, Ekos will use the appropriate flat light source before starting flat frames capture. If ADU is specified, Ekos begins by capturing a couple of preview images to establish the curve required to achieve the desired ADU count. Once an appropriate value is calculated, another capture is taken and ADU is recounted until a satisfactory value is achieved.
0573         </para>
0574     </sect3>
0575 
0576     <sect3 id="capture-video-tutorials">
0577         <title>Video Tutorials</title>
0578 
0579         <mediaobject>
0580             <videoobject>
0581                 <videodata contentdepth="315" contentwidth="560" fileref="https://www.youtube.com/embed/Gz07j7VPnpc"/>
0582             </videoobject>
0583             <caption>
0584                 <para>
0585                     <phrase>Capture</phrase>
0586                 </para>
0587             </caption>
0588         </mediaobject>
0589 
0590         <mediaobject>
0591             <videoobject>
0592                 <videodata contentdepth="315" contentwidth="560" fileref="https://www.youtube.com/embed/yfz9_UJIvLY"/>
0593             </videoobject>
0594             <caption>
0595                 <para>
0596                     <phrase>Filter Wheels</phrase>
0597                 </para>
0598             </caption>
0599         </mediaobject>
0600     </sect3>
0601 </sect2>