Select the desired CCD/DSLR and Filter Wheel (if available) for capture. Set CCD temperature and filter settings.

Set all capture parameters as detailed below. Once set, you can capture a preview by click on Preview or add a job to the sequence queue.

Settings for specifying where captured images are saved to, and how to generate unique file names in addition to upload mode settings.

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.

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 in the sequence queue to add it to the queue.

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 Start Sequence to begin executing the jobs. A job state changes from Idle to In Progress and finally to Complete 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 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 . Please beware that all image progress counts are reset as well. To preview an image in KStars FITS Viewer, click the Preview button.

Sequence queues can be saved as an XML file with extension .esq (Ekos Sequence Queue). To load a sequence queue, click the open document button . Please note that it will replace any current sequence queues in Ekos.

To edit a job, double click it. You will notice the add button now changed to check mark button . 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.

If your camera supports live video feed, then you can click the Live Video button to start streaming. The video stream window enables recording and subframing of the video stream. For more information, check the video below:

Click the filter icon 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.

Configure settings for each filter individually:

Let's take an example. Suppose the capture sequence is running and the current filter is Green, 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:

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.

Field Rotators are supported in INDI & Ekos. The rotator angle is the raw angle reported by the rotator and is not necessary the Position Angle. A Position Angle of zero indicates that the frame top (indicated by small arrow) is pointing directly at the pole. The position angle is expressed as E of N (East of North), so 90 degrees PA indicates the frame top points 90 degrees away (counter-clockwise) from the pole. Check examples for various PAs.

To calibrate the Position Angle (PA), capture and solve an image in the Ekos Align module. An offset and a multiplier 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 Sync FOV to PA to rotate the current Field of View (FOV) indicator on the Sky Map with the PA value as you change it in the dialog.

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.

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.

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.

In order to focus an image, Ekos needs to establish a numerical method for gauging how good your focus is. It's easy when you look at an image and can see it as unfocused, as the human eye is very good at detecting that, but how can Ekos possibly know that?

There are multiple methods. One is to calculate the Full Width at Half Maximum (FHWM) of a star profile within an image, and then adjust the focus until an optimal (narrower) FWHM is reached. The problem with FWHM is that it assumes the initial focus position to be close to the critical focus. Additionally, FWHM does not perform very well under low-intensity fluxes. An Alternative method is Half-Flux-Radius (HFR), which is a measure of the width in pixels counting from the center of the star until the accumulated intensity is half of the total flux of the star. HFR proved to be much more stable in conditions where you might have unfavorable sky conditions, when the brightness profile of the stars is low, and when the starting position of the focus is far from the optimal focus.

After Ekos processes an image, it selects either a single star and starts measuring its HFR, or it selects a set of stars matching the criteria that have been set and calculates an average HFR. It can automatically select stars, or you can select a single star manually. It is recommended to allow Ekos to select a set of stars.

Ekos supports 4 different focus algorithms: Iterative, Polynominal, Linear and Linear 1 Pass.

The Optical Train group displays the currently selected Optical Train. By default this will be the primary imaging train, but other trains can be selected. The group consists of:

All INDI-compatible focusers are supported. It is recommended to use absolute focusers for the best results since their absolute position is known on power up. In INDI, the focuser zero position is when the drawtube is fully retracted. When focusing outwards, the focuser position increases, while it decreases when focusing inwards. The following focuser types are supported:

Start off by selecting the Focuser from the dropdown.

For absolute focusers, you can set the ticks count in the Initial Steps Size field in the Mechanics tab. For absolute and relative focusers, the step size is in units of ticks and for simple, or time based, focusers, the step size is in milliseconds. The In and Out buttons can then be used to move the focuser by this number of ticks.

The Steps fields will initially contain the starting point in ticks for the focuser. As the focuser moves, the left field will update to reflect the focuser's current position. The right field will initially contain the starting position of the focuser but will update each time a successful Autofocus run completes, to keep a last good focus position. In addition you can set the right field to whatever value you like, and use the Goto button to move the focuser to this position.

The Goto Focus Position button moves the focuser to the position in the righthand Steps field.

The Stop Focuser Motion button stops the in-progress focuser motion.

The Auto Focus button starts an Autofocus run. The Stop button is used to stop the run.

The Capture Image button will take a frame based on the current settings in the CCD and Filter Wheel group. The Start Framing button will start repeatedly capturing frames until the Stop button is pressed.

Some of the focus algorithms will attempt to cope with being started away from the point of optimum focus, but for predictable results, it is best to start from a position of being approximately in focus. For first time setup, Start Framing can be used along with the In and Out buttons to adjust the focus position to roughly minimize the HFR of the stars in the captured images. When Framing is used in this way, the V-Curve graph changes to show a time series of frames and their associated HFRs. This makes the framing process much easier to perform.

If you are completely new to astronomy, it is always a good idea to get familiar with your equipment in daylight. This includes getting the approximate focus position on a distant object. This will provide a good starting position for focusing on stars when nighttime comes.

This section of parameters deals with the Camera and Filter settings to use when focusing.

The top row of controls allows CCD parameters to be set.

The next row of controls allows Camera parameters to be set. Choose a value from the binning dropdown and then set either the camera gain or ISO.

The third row of controls deals with the Temperature Source and Filter, if there is one:

Next are 3 tabbed panes of parameters. These parameters are retained between sessions. First up is the Settings pane.

This is the Focus Process parameters pane.

This is the Focus Mechanics parameters pane.

The focus display, displays a FITS viewer window onto the frame taken during the focus process. It displays the Annulus values superimposed on the image. All the stars detected by Ekos based on the selected parameters, have their HFR value displayed next to the associated star.

The window supports the following FITS viewer options (at the top of the window):

The V-Curve displays focuser position (x-axis) versus Half-Flux-Radius (HFR) (y-axis). Each datapoint is drawn on the graph and represented by a circle with a number representing the datapoint. How many datapoints are taken and how the focuser moves is determined by the parameters chosen.

For certain algorithms, Ekos will also draw a curve of best fit through the datapoints. If Use Weights is selected then error bars are indicated on each datapoint that correspond to the standard deviation in measured HFR value.

Under the V-Curve a number of parameters are displayed:

When framing, the graph format changes to that of a "time series" where horizontal axis denotes the frame number. This is to aid you in the framing process as you can see how HFR changes between frames.

The relative profile is a graph that displays the relative HFR values plotted against each other. Lower HFR values correspond to narrower shapes and vice-versa. The solid red curve is the profile of the current HFR value, while the dotted green curve is for the previous HFR value. Finally, the magenta curve denotes the first measured HFR. This enables you to judge how well the Autofocus process improved the relative focus quality.

The exact settings that work best for a given astronomical setup need to be worked out by the user using trial and error, but this section gives some pointers. It uses the Linear 1 Pass algorithm:

The Coefficient of Determination, or R², is calculated in order to give a measure of how well the fitted curve matches the datapoints. More information is available here. This is an experimental feature that is available for the Linear 1 Pass focus algorithm. In essence, R² gives a value between 0 and 1, with 1 meaning a perfect fit where all datapoints sit on the curve, and 0 meaning that there is no correlation between the datapoints and the curve. The user should experiment with their equipment to see what values they can obtain, but as a guide, a value above, say 0.8 would be a good fit.

There is an option to set an “R² Limit” in the Settings tab of the Focus window that is compared to the calculated R² after the auto focus run has completed. If the limit value has not been achieved, then the auto focus is rerun.

Setting an R² Limit could be useful for unattended observation if the focus run produces a bad result for a 1-off reason. Obviously if the reason is not transitory then rerunning will not improve anything.

If the R² Limit is not achieved and the focus process is rerun, and again fails to achieve the R² Limit, then the focus run is marked as successful to avoid the process getting stuck rerunning auto focus forever.

This feature is turned off by setting the R² Limit to 0.

The Levenberg-Marquardt (LM) algorithm is used to solve non-linear least squares problems. The GNU Science Library provides an implementation of the solver. These resources provide more details:

The Levenberg-Marquardt algorithm is a new feature added for the Linear 1 Pass focus algorithm. It is a non-linear least-squares solver and thus suitable for many different equations. The basic idea is to adjust the equation y = f(x,P) so that the computed y values are as close as possible to the y values of the datapoints provided, so that the resultant curve fits the data as best as it can. P is a set of parameters that are varied by the solver in order to find the best fit. The solver measures how far away the curve is at each data point, squares the result and adds them all up. This is the number to be minimized, let's call it S. The solver is supplied with an initial guess for the parameters, P. It calculates S, makes an adjustment to P and calculates a new S1. Provided S1 < S then we are moving in the right direction. It iterates through the procedure until:

The solver is capable of solving either an unweighted or weighted set of datapoints. In essence, an unweighted set of data gives equal weight to each datapoint when trying to fit a curve. An alternative is to weight each datapoint with a measure that corresponds to how accurate the measurement of the datapoint actually is. In our case this is the variance of star HFRs associated with the datapoint. The variance is the standard deviation squared.

Currently the solver is used to fit either a parabolic or a hyperbolic curve.

Ekos Guide Module enables autoguiding capability using either the powerful built-in guider, or at your option, external guiding via PHD2 or lin_guider. Using the internal guiding, guider CCD frames are captured and sent to Ekos for analysis. Depending on the deviations of the guide star from its lock position, guiding pulses corrections are sent to your mount Via any device that supports ST4 ports. Alternatively, you may send the corrections to your mount directly, if supported by the mount driver. Most of the GUI options in the Guide Module are well documented so just hover your mouse over an item and a tooltip will popup with helpful information.

To perform guiding, you need to select a Guider CCD in Ekos Profile Setup. The telescope aperture and focal length must be set in the telescope driver. If the Guider CCD is attached to a separate Guide Scope, you must also set the Guide Scope's Focal Length and Aperture. You can set these values under the Options tab of the telescope driver or from the Mount module. Autoguiding is a two-step process: Calibration & Guiding.

During the two processes, you must set the following:

Dark frames are immensely helpful in reducing noises in your guide frames. It is highly recommended to take dark frames before you begin and calibration or guiding procedure. To take a dark frame, check the Dark checkbox and then click Capture. For the first time this is performed, Ekos will ask you about your camera shutter. If your camera does not have a shutter, then Ekos will warn you anytime you take a dark frame to cover your camera/telescope before proceeding with the capture. On the other hand, if the camera already includes a shutter, then Ekos will directly proceed with taking the dark frame. All dark frames are automatically saved to Ekos Dark Frame Library. By default, the Dark Library keeps reusing dark frames for 30 days after which it will capture new dark frames. This value is configurable and can be adjusted in Ekos settings in the KStars settings dialog.

It is recommended to take dark frames covering several binning and exposure values so that they may be reused transparently by Ekos whenever needed.

In the calibration phase, you need to capture an image, select a guide star, and click Guide to begin the calibration process. If calibration was already completed successfully before, then the autoguiding process shall begin immediately, otherwise, it would start the calibration process. If Auto Star is checked, then you are only required to click Capture and Ekos will automatically select the best-fit guide star in the image and continues the calibration process automatically. If Auto Star is disabled, Ekos will try to automatically highlight the best guide star in the field. You need to confirm or change the selection before you can start the calibration process. The calibration options are:

The reticle position is the guide star position selected by you (or by the auto selection) in the captured guider image. You should select a star that is not close to the edge. If the image is not clear, you may select different Effects to enhance it.

Ekos begins the calibration process by sending pulses to move the mount in RA and DEC. If the calibration process fails due to short drift, try increasing the pulse duration. To clear calibration, click the trash bin icon next to the Guide button.

Once the calibration process is completed successfully, the guiding shall begin automatically hereafter. The guiding performance is displayed in the Drift Graphics region where Green reflects deviations in RA and Blue deviations in DEC. The colors of the RA/DE lines can be changed in KStars color scheme in KStars settings dialog. The vertical axis denotes the deviation in arcsecs from the guide star central position and the horizontal axis denotes time. You can hover over the line to get the exact deviation at this particular point in time. Furthermore, you can also zoom and drag/pan the graph to inspect a specific region of the graph.

Ekos can utilize multiple algorithms to determine the center of mass of the guide star. By default, the smart algorithm is suited best for most situation. The fast algorithm is based on HFR calculations. You can try switching guiding algorithms if Ekos cannot keep of the guide star within the guiding square properly.

The info region displays information on the telescope & FOV, in addition to the deviations from the guide star along with the correction pulses sent to the mount. The RMS value for each axis is displayed along with the total RMS value in arcsecs. The internal guider employs PID controller to correct the mount tracking. Currently, the only the proportional and integral gains are utilized within the algorithm, so adjusting it should affect the length of the generated pulses sent to the mount in milliseconds.

To enable automatic dithering between frames, make sure to check the Dither checkbox. By default, Ekos should dither (i.e. move) the guiding box by up to 3 pixels after each frame captured in Ekos Capture Module. The motion duration and direction are randomized. Since the guiding performance can oscillate immediately after dithering, you can set the appropriate Settle duration to wait after dither is complete before resuming the capture process. In rare cases where the dithering process can get stuck in an endless loop, set the appropriate Timeout to abort the process. But even if dithering fails, you can select whether this failure should terminate the autoguiding process or not. Toggle Abort Autoguide on failure to select the desired behavior.

Non-guide dithering is also supported. This is useful when no guide camera is available or when performing short exposures. In this case, the mount can be commanded to dither in a random direction for up to the pulse specified in the Non-Guide Dither Pulse option.

Ekos supports multiple guiding methods: Internal, PHD2, and LinGuider. You need to select the desired guider in your Ekos equipment profile:

You can fine-tune the guiding performance in the Control Section. The autoguide process works like a PID controller when sending correction commands to the mount. You can alter the Proportional and Integral gains to improve the guiding performance if necessary. By default, guiding corrective pulses are sent to both mount axis in all directions: positive and negative. You can fine-tune control by selecting which axis shall receive corrective guiding pulses and within each axis, you can indicate which direction (Positive) + or Negative (-) receives the guiding pulses. For example, for the Declination axis, the + direction is North and - is South.

Each mount has a particular guiding rate in (x15"/sec) and usually ranges from 0.1x, to 1.0x with 0.5x being a common value used by many mounts. The default guiding rate is 0.5x sidereal, which is equivalent to a proportional gain of 133.33. Therefore, set the guiding rate value to whatever value used by your mount, and Ekos shall display the recommended proportional gain value that you may set in the proportional gain field under the Control Parameters. Setting this value does not change your mount guiding rate! You must change your mount guiding rate either via the INDI driver, if supported, or via the hand controller.

The drift graphics is a very useful tool to monitor the guiding performance. It is a 2D plot of guiding deviations and corrections. By default, only the guiding deviations in RA and DE are displayed. The horizontal axis is the time in seconds since the autoguiding process was started while the vertical axis plots the guiding drift/deviation in arcsecs for each axis. Guiding corrections (pulses) can also be plotted in the same graph and you can enable them by checking the Corr checkbox below each Axis. The corrections are plotted as shaded areas in the background with the same color as that of the axis.

You can pan and zoom the plot, and when hovering the mouse over the graph, a tooltip is displayed containing information about this specific point in time. It contains the guiding drift and any corrections made, in addition to the local time, this event was recorded. A vertical slider to the right of the image can be used to adjust the height of the secondary Y-axis for pulses corrections.

The Trace horizontal slider at the bottom can be used to scroll through the guide history. Alternatively, you can click the Max checkbox to lock the graph onto the latest point so that the drift graphics autoscrolls. The buttons to the right of the slider are used for autoscaling the graphs, exporting the guide data to a CSV file, clearing all the guide data, and for scaling the target in the Drift Plot. Furthermore, the guide graph includes a label to indicate when a dither occurred so the user knows guiding was not bad at those points.

The colors of each axis can be customized in KStars Settings color scheme.

A bulls-eye scatter plot can be used to gauge the accuracy of the overall guiding performance. It is composed of three concentric rings of varying radii with the central green ring having a default radius of 2 arcsecs. The last RMS value is plotted as with its color reflecting which concentric ring it falls within. You can change the radius of the innermost green circle by adjusting the drift plot accuracy.

The internal guider can use predictive and adaptive guiding by enabling GPG guiding. This adaptively models the periodic error of the mount, and adds its predicted contribution to each guide pulse. Optionally, by enabling Dark Guiding, it can output the predicted corrections much faster than the guide camera exposure rate, effectively performing periodic error correction and allowing longer guide camera exposures.

You can opt to select external PHD2 application to perform guiding instead of the built-in guider.

If PHD2 is selected, the Connect and Disconnect buttons are enabled to allow you to establish a connection with the PHD2 server. You can control PHD2 exposure and DEC guide settings. When clicking Guide, PHD2 should perform all the required actions to start the guiding process. PHD2 must be started and configured before Ekos.

After launching PHD2, select your INDI equipment and set their options. From Ekos, connect to PHD2 by clicking the Connect button. On startup, Ekos will attempt to automatically connect to PHD2. Once the connection is established, you may begin the guiding immediately by click on the Guide button. PHD2 shall perform calibration if necessary. If dithering is selected, PHD2 shall be commanded to dither given the offset pixels indicated and once guiding is settled and stable, the capture process in Ekos shall resume.

Ekos Alignment Module enables highly accurate GOTOs to within sub-arcseconds accuracy and can measure and correct polar alignment errors. This is possible thanks to the astrometry.net solver. Ekos begins by capturing an image of a star field, feeding that image to astrometry.net solver, and getting the central coordinates (RA, DEC) of the image. The solver essentially performs a pattern recognition against a catalog of millions of stars. Once the coordinates are determined, the true pointing of the telescope is known.

Often, there is a discrepancy between where the telescope thinks it is looking at and where it is truly pointing. The magnitude of this discrepancy can range from a few arcminutes to a couple of degrees. Ekos can then correct the discrepancy by either syncing to the new coordinates, or by slewing the mount to the desired target originally requested.

Furthermore, Ekos provides a Polar Alignment Assistant Tool to correct polar alignment errors. It takes three images, slewing between the images, and calculates the offset between the mount axis and polar axis. It feeds back to the user the altitude and azimuth adjustments needed to align these axes. These images are typically taken near the celestial pole (Close to Polaris for Northern Hemisphere) but can work well taken from anywhere, usually starting near the meridian and slewing either East or West.

At a minimum, you need a CCD/Webcam and a telescope that supports Slew & Sync commands. Most popular commercial telescope nowadays support such commands.

For the Ekos Alignment Module to work, you have an option of either utilizing the online astrometry.net solver, offline, or remote solver:

If you are planning to use Offline astrometry then you need to download astrometry.net application.

For offline (and remote) solvers, index files are necessary for the solver to work. The complete collection of index files is huge (over 30 GB), but you only need to download what is necessary for your equipment setup. Index files are sorted by the Field-Of-View (FOV) range they cover. There are two methods to fetch the necessary index files: The new download support in Align module, and the old manual way.

Automatic Download

Automatic download is only available for Ekos users on Linux® & Mac® OS. For Windows® users, please download ANSVR solver.

To access the download page, click the Options button in the Align module and then select Astrometry Index Files tab. The page displays the current FOV of your current setup and below it a list of available and installed index files. Three icons are used to designate the importance of index files given your current setup as follows:

• Required

• Recommended

• Optional

You must download all the required files, and if you have plenty of hard drive space left, you can also download the recommended indexes. If an index file is installed, the checkmark shall be checked, otherwise check it to download the relevant index file. Please only download one file at a time, especially for larger files. You might be prompted to enter the administrator password (default in StellarMate is smate) to install the files. Once you installed all the required files, you can begin using the offline astrometry.net solver immediately.

Ekos Align Module offers multiple functions to aid you in achieving accurate GOTOs. Start with your mount in home position with the telescope tube looking directly at the celestial pole. For users in Northern Hemisphere, point the telescope as close as possible to Polaris. It is not necessary to perform 2 or 3 star alignments, but it can be useful for some mount types. Make sure your camera is focused and stars are resolved.

Before you begin the alignment process, select the desired CCD & Telescope. You can explore astrometry.net options that are passed to the astrometry.net solver each time an image is captured:

By default, the solver will search all over the sky to determine the coordinates of the captured image. This can take a lot of time; therefore, in order to speed up the solver, you can restrict it to only search within a specified area in the sky designated by the RA, DEC, and Radius options above.

Options for offline and online solvers.

Most of the options are sufficient by default. If you have astrometry.net installed in a non-standard location, you can change the paths as necessary.

Ekos selects and updates the optimal options by default to accelerate the performance of the solver. You may opt to change the options that are passed to the solver in case the default options are not sufficient.

Using Ekos Alignment Module, aligning your mount using the controller's 1, 2, or 3 star alignment is not strictly necessary, though for some mounts it is recommended to perform a rough 1 or 2 star alignment before using Ekos alignment module. If you are using EQMod, you can start using Ekos alignment module right away. A typical workflow for GOTO alignment involves the following steps:

If the solver is successful, Ekos will sync and then slew to the star. The results are displayed in the Solution Results tab along with a bullseye diagram that shows the offset the reported telescope coordinates (i.e. where the telescope thinks it is looking at) vs. its actual position in the sky as determined by the solver.

Each time the solver is executed and returns successful results, Ekos can run on the following actions:

When setting up a German Equatorial Mount (GEM) for imaging, a critical aspect of capturing long-exposure images is to ensure proper polar alignment. A GEM mount has two axis: Right Ascension (RA) axis and Declination (DE) axis. Ideally, the RA axis should be aligned with the celestial sphere polar axis. A mount's job is to track the star's motion around the sky, from the moment they rise at the eastern horizon, all the way up across the median, and westward until they set.

In long exposure imaging, a camera is attached to the telescope where the image sensor captures incoming photons from a particular area in the sky. The incident photons have to strike the same photo-site over and over again if we are to gather a clear and crisp image. Of course, actual photons do not behave in this way: optics, atmosphere, seeing quality all scatter and refract photons in one way or another. Furthermore, photons do not arrive uniformly but follow a Poisson distribution. For point-like sources like stars, a point spread function describes how photons are spatially distributed across the pixels. Nevertheless, the overall idea we want to keep the source photons hitting the same pixels. Otherwise, we might end up with an image plagued with various trail artifacts.

Since mounts are not perfect, they cannot perfectly keep track of object as it transits across the sky. This can stem from many factors, one of which is the misalignment of the mount's Right Ascension axis with respect to the celestial pole axis. Polar alignment removes one of the biggest sources of tracking errors in the mount, but other sources of error still play a factor. If properly aligned, some mounts can track an object for a few minutes with the only deviation of 1-2 arcsec RMS.

However, unless you have a top of the line mount, then you'd probably want to use an autoguider to keep the same star locked in the same position over time. Despite all of this, if the axis of the mount is not properly aligned with the celestial pole, then even a mechanically-perfect mount would lose tracking with time. Tracking errors are proportional to the magnitude of the misalignment. It is therefore very important for long exposure imaging to get the mount polar aligned to reduce any residual errors as it spans across the sky.

Before starting the process, point the mount as close as possible to the celestial pole with the counterweights down. If you are living in the Northern Hemisphere, point it as close as possible to Polaris. If Polaris is not visible (e.g. blocked by trees or buildings) you may point elsewhere, preferably near the Meridian. Make sure there is at least 30-60 degrees of sky viewable in an arc East or West of the Meridian from the position you choose. Select the direction of free sky, the number of degrees for each of two slews, the mount slew speed, and whether the mount will be slewing automatically (recommended) or manually.

The tool works by capturing and solving three images. After capturing each, the mount rotates by the fixed amount you entered and another image is captured and solved. If you chose manual, you will need to slew the mount by roughly the angle chosen.

Plate Solve Correction Scheme

The images below show the workflow when the Plate Solve correction technique is used. The image below shows a display after the 3 measurement images are captured and solved. It shows an error of almost 18' in altitude and that the mount's axis needs to be moved up. Similarly it shows an azimuth error of almost 15' and that the axis needs to be moved to the right (as viewed from behind the telescope).

If your error is low enough (e.g. less than an arc-minute) then you don't need to make any adjustments. Simply press stop and you're done.

If you will be making corrections to your mount's axis, you should select the adjustment approach (we're using Plate Solve in this example), and how often the system should recapture images to re-measure the polar alignment error. The refresh interval should be frequent, but it doesn't make sense to make it faster that your CPU can capture and plate-solve the images. We're using 2s in this example. Then press the Refresh button to begin the correction process.

The system will capture images, and re-estimate the polar alignment error after each image. You can try to reduce the error by adjusting the Altitude and Azimuth correction knobs on your mount. The image below shows the screen after the altitude error has been almost zeroed. See the difference between the Measured Error row, which shows the originally measured error after the original 3 captures, and the Updated Error row which shows the current error estimate.

Below the user has also adjust Azimuth to reduce the error further. Now the error is very low and the process is done. The user should press the stop button.

Ekos Scheduler is an indispensable arsenal in building your robotic observatory. A Robotic observatory is an observatory composed of several subsystems that are orchestrated together to achieve a set of scientific objectives without human intervention. It is the only Ekos module that does not require Ekos to be started as it is utilized to start and stop Ekos. It is designed to be straightforward and intuitive. However, the scheduler should only be used after you mastered Ekos and knows all the quirks of your equipment. Since the complete process is automated, including focus, guiding, and meridian flip, all equipment should be thoroughly used with Ekos and all their parameters and settings adjusted to achieve the best result.

With Ekos, the user can utilize the powerful sequence queue to image batches of images for a particular target. In simple setups, the user is expected to focus the CCD, align the mount, frame the target, and start guiding before initiating the capture process. For more complex observatory environments, there are usually predefined custom procedures to be executed to prepare the observatory for imaging, and another set of procedures on shutdown. The user may plan to image one or more targets during the night and expects data to be ready by morning. In KStars, tools such as the Observation Planner and What's up Tonight help the user in selecting candidates for imaging. After selecting the desired candidates, the user can add them to the Ekos Scheduler list for evaluation. The user may also add the targets directly in Ekos scheduler or select a FITS file of a previous image.

Ekos Scheduler provides a simple interface to aid the user in setting the conditions and constraints required for an observation job. Each observation job is composed of the following:

You must select the Target and Sequence before you can add a job to the Scheduler. When the scheduler starts, it evaluates all jobs in accord to the conditions and constraints specified and attempts to select the best job to execute. Selection of the job depends on a simple heuristic algorithm that scores each job given the conditions and constraints, each of which is weighted accordingly. If two targets have identical conditions and constraints, usually the higher priority target followed by higher altitude target is selected for execution. If no candidates are available at the current time, the scheduler goes into sleep mode and wakes up when the next job is ready for execution.

The description above only tackles the Data Acquisition stage of the observatory workflow. The overall procedure typically utilized in an observatory can be summarized in three primary stages:

Startup procedure is unique to each observatory but may include:

Ekos Scheduler only initiates the startup procedure once the startup time for the first observation job is close (default lead time is 5 minutes before startup time). Once the startup procedure is completed successfully, the scheduler picks the observation job target and starts the sequence process. If a startup script is specified, it shall be executed first.

Depending the on the user selection, the typical workflow proceeds as follows:

Once the observation job is completed successfully, the scheduler selects the next target. If the next target scheduled time is not due yet, the mount is parked until the target is ready. Furthermore, if the next scheduled target is not due for a user-configurable time limit, the scheduler performs a preemptive shutdown to preserve resources and performs the startup procedure again when the target is due.

If an unrecoverable error occurs, the observatory initiates shutdown procedure. If there is a shutdown script, it will be executed last.

The following video demonstrates an earlier version of the scheduler, but the basic principles still apply today:

Another critical feature of any remotely operated robotic observatory is weather monitoring. For weather updates, Ekos relies on the selected INDI weather driver to continuously monitor the weather conditions. For simplicity sake, the weather conditions can be summed in three states:

Due to the uniqueness of each observatory, Ekos enables the user to select startup and shutdown scripts. The scripts take care of any necessary procedures that must take place on startup and shutdown stages. On startup, Ekos executes the startup scripts and only proceeds to the remainder of the startup procedure (unpark dome/unpark mount) if the script completes successfully. Conversely, the shutdown procedure begins with parking the mount & dome before executing the shutdown script as the final procedure.

Startup and shutdown scripts can be written any language that can be executed on the local machine. It must return 0 to report success, any other exist value is considered an error indicator. The script's standard output is also directed to Ekos logger window. The following is an sample demo startup script in Python:

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os
import time
import sys

print "Turning on observatory equipment..."
sys.stdout.flush()

time.sleep(5)

print "Checking safety switches..."
sys.stdout.flush()

time.sleep(5)

print "All systems are GO"
sys.stdout.flush()

exit(0)
        

The startup and shutdown scripts must be executable in order for Ekos to invoke them (e.g. use chmod +x startup_script.py to mark the script as executable). Ekos Scheduler enables truly simple robotic operation without the need of any human intervention in any step of the process. Without human presence, it becomes increasingly critical to gracefully recover from failures in any stage of the observation run. Using Plasma™ notifications, the user can configure audible alarms and email notifications for the various events in the scheduler.

Hubble-like super wide field images of galaxies and nebulae are truly awe-inspiring, and while it takes great skills to obtain such images and process them; many notable names in the field of astrophotography employ gear that is not vastly different from yours or mine. I emphasize vastly because some do indeed have impressive equipment and dedicated observatories worth tens of the thousands of dollars. Nevertheless, many amateurs can obtain stellar wide-field images by combining smaller images into a single grand mosaic.

We are often limited by our camera+telescope Field of View (FOV). By increasing FOV by means of a focal reducer or a shorter tube, we gain a larger sky coverage at the expense of spatial resolution. At the same time, many attractive wide-field targets span multiple FOVs across the sky. Without any changes to your astrophotography gear, it is possible to create a super mosaic image stitched together from several smaller images. There are two major steps to accomplish a super mosaic image:

The 2nd step is handled by image processing applications such as PixInsight, among others, and will not be the topic of discussion here. The first step can be accomplished in Ekos Scheduler where it creates a mosaic suitable for your equipment and in accordance with the desired field of view. Not only Ekos creates the mosaic panels for your target, but it also constructs the corresponding observatory jobs required to capture all the images. This greatly facilitates the logistics of capturing many images with different filters and calibration frames across a wide area of the sky.

The Mosaic Planner in the Ekos Scheduler will create multiple Scheduler jobs based on a central target. To toggle the planner, click on the Mosaic Planner button in Ekos Scheduler or KStars INDI toolbar as illustrated in the screenshot. The planner draws the Mosaic Panel directly unto the sky map. It is recommended to enable HiPS overlay for the best experience. The planner is composed of four stages:

Click Create Jobs to generate mosaic scheduler jobs and add them to the schedule queue.

The Analyze Module records and displays what happened in an imaging session. That is, it does not control any if your imaging, but rather reviews what occurred. Sessions are stored in an analyze folder, a sister folder to the main logging folder. The .analyze files written there can be loaded into the Analyze tab to be viewed. Analyze also can display data from the current imaging session.

There are two main graphs, Timeline and Stats. They are coordinated—they always display the same time interval from the Ekos session, though the x-axis of the Timeline shows seconds elapsed from the start of the log, and Stats shows clock time. The x-axis can be zoomed in and out with the +/- buttons, as well as with standard keyboard shortcuts (e.g. zoom-in == Ctrl++) The x-axis can be panned with the scroll bar as well as with the left and right arrow keys. You can view your current imaging session, or review old sessions by loading .analyze files using the Input dropdown. Checking Full Width displays all the data, and Latest displays the most recent data (you can control the width by zooming).

The three main displays can be hidden to make more room for the other displays. There are checkboxes to the left of the section titles (Timeline, Statistics, and Details) that enable and hide the displays.

Timeline shows the major Ekos processes, and when they were active. For instance, the Capture line shows when images were taken (wither green for RGB or color-coded by the filter) and when imaging was aborted (shown as red sections). Clicking on a capture section gives information about that image, and double clicking on one brings up the image taken then in a fitsviewer, if it is available.

Clicking on a Focus segment shows focus session information and displays up the position vs HFR measurements from that session. Clicking on a Guider segment shows a drift plot from that session, (if it's guiding) and the session's RMS statistics. Other timelines show status information when clicked.

A variety of statistics can be displayed on the Statistics graph. There are too many for all to be shown in a readable way, so select among them with the checkboxes. A reasonable way to start might be to use rms, snr (using the internal guider with SEP Multistar), and hfr (if you have auto-compute HFR in the FITS options). Experiment with others.

The left axis shown is initially appropriate only for RA/DEC error, drift, RMS error, RA/DEC pulses, and HFR, plotted in arc-seconds and defaulting to a range of -2 to 5 arc-seconds. However, clicking on one of boxes below the Statistics graph (that shows a statistic's value) will set that statistic's range as the range shown on the left-axis. Double clicking on that box will bring up a menu allowing you to adjust the statistic's plotted y-range (e.g. setting it to auto, explicitly typing in the range, setting it back to its default value, and also changing the color of that statistic's plot).

The statistic shown on the left axis can also be scaled (awkwardly) using the mouse wheel. It can be panned by dragging the mouse up or down over the left axis' numbers. Clicking anywhere inside the Statistics graph fills in the values of the displayed statistics. Checking the latest box causes the most recent values (from a live session) to be the statistics displayed. This graph is zoomed and panned horizontally in coordination with the timeline.

StellarMate is shipped with a VNC Server. This enables you to access the whole StellarMate desktop remotely. To connect to VNC, you can either use a Desktop/Mobile VNC Client, or simply via any browser.

The VNC address is: https://stellarmate_hostname:6080/vnc.html

Where stellarmate_hostname is the actual hostname (or IP address) of your unit and 6080 is the port. If you do not know the unit hostname, you can find the hostname in your StellarMate App.

You can use Real VNC which is available on all platforms to access stellarmate.

Once you access StellarMate, you can use it like any full-fledged computer. The default username is stellarmate and the default password is smate.