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  1. #1
    Join Date
    Jul 2012
    Northern Sweden

    Default New ACP web item: "Live" SkyChart with telescope position for ACP Web UI

    Hi guys!

    SkyChart is now replaced with 1.1 version, read new instructions below

    * Easier to modify the .asp to customize your own interface:
    * User-selectable chartsize
    * Adjustable transparency for both sky-gradient and alt-az grids
    * Improved accuracy over the whole chart
    * Improved scope-status, now including Slewing, Tracking, Stopped, Parked
    * Choose between 6 reticles (below)


    In these days of endless bad weather, I've had some time to play around with programming & learning some new things (started from zero when I got ACP last year). I've never done jscript before, & had a peek at different parts of ACP to figure out how to use it.
    Since I'm often checking my imaging-progress from my phone, I often wonder where my scope is pointing, & how far from the meridian I am... Sure, the alt / az info is all there, but since I'm pretty new in astronomy, I prefer to have it all on a nice sky-map in front of me. That's not a problem when using a computer, but when I'm on my phone, I often wish for more.

    So I decided to try & make a new tiddler for the ACP Web UI, namely a chart of the current sky above my observatory, & also a reticle where my scope is pointint. After countless of hours, the "beta" is available if you want to try it out.

    Here's an example from today, when tracking Castor, and scope-reticle showed correct position by using alt/az from the scope.
    (Click image for bigger version)

    First off, I went to to generate a reusable image-url for my location, to be used inside the tiddler.
    Then I googled around for hours, figuring out how to convert the scope alt/az into coordinates for a reticle on top of the sky-chart image. After a while I found the formula for Polar to Cartesian conversion, & how to implement them in Jscript. It took me a while to realize jscript uses radians instead of degrees when using the sin/cos functions, but I finally figured out how to overcome that too... I dissected a few ACP .asp to figure out how to create my own first .asp. I had great fun learning tons of new stuff about programming, especially since it's my first go at jscript.

    The chart generated online have some weird non-linear geometry I haven't figured out yet, the distance between altitude-circles (let's say 10°. 20°, 30°) isn't constant in the image like I would've thought, it missed the target with up to 10 degrees in the beginning, so I had to throw in a compensating formula (which isn't anywhere exact since I never put time into understanding the geometric "distortion" in the generated image... But I think my hipshot-formula does a pretty ok job now, the target stars always ends up close to the center of the reticle every time, so that's good enough for me.

    I've also created two transparent overlays that goes on top of the chart, giving the sky-chart altitude-circles/azimuth-lines & also a horizon-gradient that looks nice when the chart is black.

    Here's the installation-instructions:

    * Step1
    Place all the included files inside the "Users/Shared/Shared Documents/ACP Web Data/Doc Root/ac/"-Folder

    * Step 2
    Generate your chart: Create your star chart using the online generator at
    You can decide for your self how many stars and dso's that'll be visible, how many / what names and so on. There are 2 settings that you must set in a specific way, those are listed here:
    Date and Time : Now (MUST)
    Observing site: Coordinates for your observatory/site, be as specific as possible, fields accept ° ' " symbols (MUST)
    Remember the image-size you entered, it must be inserted in the user input section inside the skychart.asp

    The rest can be altered any way you want, including the size, I prefer to keep the chart relatively simple, since I'm occasionally uses the chart from my phone. Here's the settings I use:

    Display Options
    ( ) Ecliptic and equator
    (X) Moon and planets
    (X) Deep sky objects of magnitude "2.5" and brighter

    (X) Outlines
    ( ) Names ( )aligned with horizon? ( ) abbreviate?
    ( ) Boundaries

    Show stars brighter than magnitude "5.1"
    (X) Names for magnitude "2.5" and brighter
    ( ) Bayer/Flamsteed codes for mag. " " and brighter

    Font scale: 0.5 (to avoid cluttered chart)
    Colour scheme: Color (background is blue during daytime, black during nigh
    When you're done, click the "update" button below the generated chart. Copy the URL of the generated image (different ways depending on your browser).

    * Step 3
    Open the "skychart.asp" and edit the following fields as you like, paste your chart-URL inside the situation-marks showed below, and enter the image-size of your generated all-sky chart:

    //    ******************************************************************************************************
    //    **************************************    User Options Starts   **************************************
    //    ******************************************************************************************************
        var ChartURL = " "        // 1. Paste your chart URL inside the citation marks to the left
        ChartSize = 500        // 2. Enter the image size of the chart you created at , (minimum 100)
        ReticleStyle = 3        // 3. Selects the type of reticle for indicating scope-position, (1-6) 
        LinesOpacity = 70        // 4. Sets the opacity-percentage for the Alt/Az grid-lines overlay, (0-100)
        GradientOpacity = 60    // 5. Sets the opacity-percentage for the Sky-gradient overlay, (0-100)
    //    ******************************************************************************************************
    //    **************************************    User Options Ends   ****************************************
    //    ******************************************************************************************************
    The options can be adjusted to best suit your style. Here's a list of the available reticles that can be selected at "ReticleStyle"


    * Step 4
    Create a new tiddler named SkyChart and insert the following line inside the tiddler:
    <<RemoteContent '/ac/skychart.asp'>>
    You're done!

    I've attached a zip-archive containing the following 6 files. all to be extracted inside the 'Users/Shared/Shared Documents/ACP Web Data/Doc Root/ac/' folder:
    * skychart.asp - The brains of this item. User-options in the beginning of the file
    * gradient.png
    - Sky-gradient that goes on top of the chart, select-able transparency
    * lines.png
    - Alt / Az grid-lines that goes on top of the chart, select-able transparency
    * reticle 1.png
    - Reticle-image indicating the scope position, choose between 1-6
    * reticle 2.png - (same as above)
    * reticle 3.png - (same as above)
    * reticle 4.png - (same as above)
    * reticle 5.png - (same as above)
    * reticle 6.png - (same as above)
    * ReadMeFirst.txt -The installation-instructions listed in this thread

    Look for attached file: - containing all of the above

    Feel free to post ideas suggestions in the DC3 thread, or by sending me an email:
    Attached Files Attached Files
    Last edited by Bob Denny; Jan 9, 2015 at 17:31. Reason: [rbd] Change formatting so it is readable on both dark and light styles



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