I'm moving toward integrating all the functionality to accommodate most telescope control and imaging needs. After autoguiding is done, I'll work to support autonomous operation. Sky Planetarium already has a BASIC programming language built-in, I just need to expand it to handle telescope control, camera control, etc. I still need to add code to time-stamp the internal fits images as they arrive from the cameras.

6/12/13 Discussion. Just thought I'd give a short explanation of how this feature works, since its release in Sky Planetarium isn't too far off. Several equations are used to correct for the geometrical shortcomings of the telescope/mount system. A series of coefficients (all in arc-sec units) give a measure of the size and direction of each correction. The first listed is [DO]: Declination axis to Optical axis non-perpendicularity. The next [PD]: Polar axis to Declination axis non-perpendicularity. And next [PZ]: Polar axis NCP aZimuthal misalignment. [PE]: Polar axis NCP Elevation misalignment. [TF]: Tube Flexture. [FF]: Fork Flexture (if relevent). And [DF]: Declination axis Flexture. The other terms are offsets for HA and Dec on each side of the meridian. Speaking of hour-angles (HA), this works in HA - not right-ascension (RA). You can use RA's, if you enter the LST in the box provided, but it's best to work in HA's (HA=LST-RA) and keep the LST set to "00:00:00". The measurements from gotos, added via the [Add Goto] button, are in the local apparant coordinate system (and include refraction.) Additional stars can be added even if Goto Assist is on since it records the pre-corrected goto location.
1) Make sure you're polar aligned and do a one-star align with your mount.
2) Do a series of gotos and guide to center each star then press the [Add Goto] button, use several stars on each side of the meridian.
3) When done (2), set all of the sliders all the way in. Zero all of the values in the parameter space.
4) Adjust the values in the [WO, h] [WO, d] [EO, h] [EO, d] fields to bring the "After" stars into roughly the center of the graphic. Use the [Comb for best Solution] button to see the results.
5) Open the first four pairs of sliders. Press the [Comb for best Solution] button several times. Things should improve.
6) Close the first four pairs of sliders and open the last two pairs (that apply) and comb the values.
7) Repeat the process (4-6) with the Fine box checked. Don't be afraid to try some values and see how it affects the convergence.
8) If everything went well, you should have a pointing model that works.
9) Close the Goto Assist dialog. Check the [Use Goto Assist] box (ASCOM Telescope Control dialog) and left-click on the map to do goto's as you would always do. The corrected location will be sent to the mount. The telescope location bullseye that appears on the map also gets an additional red ring to indicate the corrected location.

I haven't tried this yet, but... If you have a portable setup, most of these values shouldn't change when you setup again and one could clear the "Data from goto attempts" and set the sliders all the way in for everything. Do a goto near the zenith and add the data, open up the PE slider to have it solve for Polar Elevation. Do a goto near a point opposite the pole in the southern sky and do the same for PZ.
6/11/13 Update. I did a series of goto accuracy measurements on both sides of the meridian. In the image below you can see how Sky Planetarium solves for a pointing model. These results are encouraging, Losmandy quotes the "Tpoint like" Gemini system as capable of 3' performance, so Goto Assist seems to be working as expected. I still need to do more testing though, another night of putting the model through it's paces and gathering some data should help reveal what I've really got. Goto Assist will work with any goto equipped equatorial Fork or GEM mount (it's not tied to OnStep). The attached mount shouldn't use any pointing correction of it's own - if you use Goto Assist just do a one-star align. My CCD fov is represented by the rectangle in the "After" graphic (which is 2x magnified compared to the before graphic).


5/31/13 First successful test of goto assist. I did a series of gotos all over the western sky, hand-tuning the pointing equation parameters' along the way. By the end of the night I was operating in the ±10' range (which easily puts everything in my tiny CCD fov). I've implemented a system to help search for the pointing equation parameters for a set of goto results, but I still need a way to quickly insert the goto coordinates (and corrected coordinates) into the solver to facilitate quick modeling sessions. With further tuning/modeling, I'm certain that it can do better. I'd really like to get to the <2' level which would speed up getting to target and help enable unattended operation. Still need to see how it works in the eastern sky, since the geometries change. Should be ok, and if all else fails I could simply use a seperate model for each side of the meridian.

5/9/13 Added support for ASCOM's NOVAS. The existing keplarian orbital routines will still function in ASCOM's absence (in-fact their orbital elements were also updated to improve accuracy). With NOVAS the accuracy of planetary and lunar coordinates are vastly improved.
5/8/13 Local Topocentric coordinates of stars and deep sky objects now incorporate annual aberration to bring coordinates to within about ±10 arc-sec.

11/7/12 Bug fixes: Autoguiding now works with On-Step. Autostar will need testing again as much has changed, but I'm optimistic about it working correctly. I still need to add code to sequence the exposures between guiding commands. I might also add a control to insert a delay between the arrival of images, I noticed that for short exposures (i.e. on a bright guide star) the guiding corrections happen more rapidly than is necessary. Once I code and test these two things I'll probably call this feature done.
10/23/12 Improvements: Autoguiding is now retooled to use pulse-guiding during both the calibration phase and actual guiding. This should be compatible with more mounts and allows for future compatibility improvements without changing the autoguiding code. I also took another look at how the flow of images arrives and decided to seperate the image acquisition from the calibration/guiding logic. This lets the images and sequence logic operate in a more time consistant way.
9/25/12 Autoguiding: Sky planetarium can now autoguide: Autoguiding starts with the selection (click and drag) of a reasonably bright (single) star from an image. Once a good star is selected, calibration can start. Calibration moves the telescope around and measures the direction and rate of motion in R.A. and Dec. Camera orientation, mirrored/inverted images, and Declination backlash are all compensated for automatically. To tune the guiding I added a few controls to adjust the "proportional response" and "integration rate" to minimize guiding error. The system works very well and I expect good results when imaging with this. (Once I start to tackle the autonomous operation features, I'll have to add to this the ability to identify and select a guide star automatically.)

1/15/13 - Fixed FITS 16 bit integer bug, added compatibility 16 bit integer format (truncated to a 0 to 32767 range). This allows FITS integer files to work correctly with more software, i.e. Meade Envisage, Autostar IP, IRIS. Normally, Sky would write these FITS image files with the -32768 to 32767 range and use a BZERO of 32768 to faithfully record the 16 bit unsigned integer data. Why this isn't the practice amongst these software packages is beyond me.
10/23/12 Improvements: When adding the cross-hair/magnification features I introduced a bug that would cause Sky to revert back to the prior image in the sequence when each new image arrived. Also, this introduced additional overhead to the imaging process. I fixed this problem and also made changes to tighten up the timing while pulling images down from the camera and handing them off to the imaging console, etc.
Imaging Console: The imaging console previews your ASCOM Supported Camera, Meade DSI, Web Camera, or an image from a file. The preview image can be sized up/down or zoomed in for fine focusing. All Meade DSI cameras should work, but the image (FITS) will be in raw B&W format. DSI color images aren't directly supported and the FITS file generated would need to be post-processed to "Debayer" it. ASCOM Camera support includes the ability to work with cameras returning either B&W or RGB Color images with pixel formats of short and int. Also available are three different cross-hair overlays to help with centering objects. Next, the histogram shows you where your image brightness resides and allows you to set the black & white points to visualize the data. Finally, the imaging console has controls to nudge the telescope and to adjust the focus.
Imaging acquisition allows for the length of exposure, number of exposures, and filters to be used (including ASCOM focus offsets). These can all be set ahead of time and images will be numbered and named to indicate the settings used during the capture sequence. File formats supported include 16 and 32-bit FITS, JPEG, and BMP.
10/16/12: Sky can now colorize (De-Mosaicing) images in the CMYG and CMYG2 formats.
10/11/12: Sky can now colorize (De-Bayering) images in the RGGB format.
9/10/12 ASCOM Cameras: I just finished adding support for ASCOM cameras. It works fine with the ASCOM simulators, but I don't actually have a real camera with a ASCOM driver to test. The nice thing about having ASCOM camera support is that potientially any astronomical camera can now be made to work with Sky Planetarium. See below for more information on the extent of ASCOM camera support.

1/15/13 - Switched to .jpg image format for faster uploads.
This works by either handing off images to an Astrometry.net installation on a seperate computer (or virtual machine) for plate-solving or using nova.astrometry.net to do the solving online. If/when the solve is successful the results are picked up and used to improve telescope pointing. The camera can be shared by both the imaging console and the plate-solving sub-system. Sky supports several different pointing modes for plate-solving. When you select an object on the map and do a goto, the telescope will be moved to that location. Once the goto is completed, an image is taken and passed off to be solved. If successfully solved, one of the following actions can be happen:
1. None, a marker will appear on the map to indicate the true telescope position.
2. Goto offset location (RA/Dec) to center object.
3. Sync to correct the mount's (RA/Dec) and another Goto to center object.
4. Guide to offset location (RA/Dec) to center object.

5/7/13 Added support for sending telescope mounts coordinates precessed to B1950, J2000, or J2050 (in addition to Topocentric). More robust ASCOM mount refraction support detection/setting.
10/23/12 Improvements: I added a menu item to "sync here" to help with telescope alignment. I also added another menu item that only works with my On-Step. This adds a "align here" menu item that accepts the current location during one/two/three star alignment.
Telescope Driver: I implemented the ASCOM telescope driver (v3) for my On-Step telescope hardware. Additional features to support On-Step were added to Sky Planetarium. Where possible, I used the ASCOM interface to accomplish tasks and much of the support added (for example parking) should be compatible with other drivers. Still, some features are On-Step specific, in particular those features for aligning the telescope.

I implemented the ASCOM filter wheel driver for my custom DSI-II Pro camera controller hardware and added support for ASCOM filter wheels in Sky Planetarium. The driver also supports calibration of the filter wheel and camera CCD temperature regulation. The support I added in Sky Planetarium allows you to select the filter of your choice. Or, it can cycle through all of the filters gathering a series of images automatically.

I implemented the ASCOM focuser driver for my custom focus controller hardware and added support for ASCOM focusers in Sky Planetarium. The driver has backlash compensation and can operate in relative or (pseudo) absolute mode. The support I added in Sky Planetarium works with both relative and absolute focusers. Filter wheel focus offsets are also supported in absolute mode.