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    This is a sample of an inexpensive observatory size mount. Each is semi-custom made to your specifications. Each old style pillow block mount can come with state of the art electronics, motors and ultra high resolution encoders on each axis. These mounts can easily be used for astrophotography. Various shaft and plate sizes can be ordered to suit your optics. The 2 images below are of a 2" shaft mount. 

    Specifications for this mount:

    Weighs ~500 lbs total. Dec. axis comes off for shipping and set up. 
    A pier was included. 9.250 OD, 1"  wall,  24" tall, all steel. 
    Steel fins will be added to the permanent pier once a height is determined by the customer. 
    3" diameter ground and polished steel R.A. shaft coupled to a 15.5" x 1" Al. worm gear.
    2" diameter Dec. ground and polished steel Dec. shaft coupled to a 12" x 1" Al. worm gear.
    Worm mounting bearings are tapered Timken, .625" ID.
    Precision steel pillow blocks on each axis. 
    Mount structure is all steel. .750" thick R.A. plate, 1/2" Dec.
    Covers are 1/4" thick black textured ABS plastic. Black spray paint for plastic will cover most scratches ! 
    Weight capacity is over 175 lbs., tested. Optics and mountings included in the weight capacity.
    Electronics are a Sidereal technology servo controller and motors. The controller is inside the R.A. cover. Should the electronics fail, user replacement is quick and simple. No need to send the mount somewhere !
    Operated on 12-24 volts DC. 
    Software is FREE, updates are FREE
    ASCOM compliant.  XP compliant software.
    Autoguiding works well with a Meade DSI Pro and Ph.D. software. 
    All standard functions of typical GoTo mounts are included in the software. See the servo page on this web site.
    Will work with easily GoTo My PC remotely.
    Point and click GoTo's with most planetariums. See video's at the bottom of this page.
    Further information about the controller is also available on this page.
    The top optical mounting plate is currently a 8" x 1" steel disc. Customer can specify something different at no charge. 
    A wireless handpad is available. 

    Periodic Error Elimination

    P.E. is controlled by Tick Management or a "P.E. Eliminator" from the computer. Tested levels are under 1 arc second per worm revolution. This is a mechanical and software solution to P.E., not the traditional hand guided button capture and replay. It is also not traditional AutoGuiding. There is a 10,000 tick encoder, driven by a 1/4 shaft that is friction driven by a 7" disc. This gives the controller over 300,000 ticks per revolution of the R.A. axis. The controller and software then work their magic to amplify those and virtually eliminate P.E. There are PemPro graphs below. 
    Typical PEC can be used in the software in addition to the P.E. Eliminator. PemPro numbers can be input as well. 
    Standard autoguiding via ASCOM or relays can be used at the same time as the P.E. Eliminator. 

    Point XP Screen Shot

    This is part of the reason for the accuracy. After an offset initialization, ( point and click on a star) you start adding in "cal stars".  These are just plain stars that are centered on the CCD chip if you are imaging or in the eyepiece is you are doing a visual only session.  After about 5 of them, accuracy is such that polar alignment drift is nearly canceled out,  mount fabrication errors are compensated for etc.  Pointing accuracy will put a star near center of a CCD chip. The better the separation of the cal stars, the better the accuracy.  This is all done automatically. You need not even look at the PxP screen, just click on the button from the main screen when the star is centered. The recommended number of cal stars for the very best accuracy over the entire sky is 18. Accuracy is dramatically improved after 5 however. 

    With these cal stars, Polar alignment does not have to be "perfect" anymore. Some of the polar alignment routines in other programs are rather lengthy and time consuming. With PxP, that can be eliminated. Each axis will be used when tracking. 

    With this mount, which is designed to be permanently mounted, a PxP run can be done once, saved to the controller itself, and forgot about.  Fabrication errors, polar alignment errors, OTA errors etc. are all compensated for.  Accuracy will depend on how well the pier is mounted and what the collimation is after you do the PxP run. 

    There is a park function to save your last position as well. 

    Here is a 300 second (5 minutes) unguided, no PEC, image taken on 10-27-2008. Scope is a F/5, 6", 750 mm F/L newt. Camera is just a DSI Pro 1. Software used is Nebulosity. I did "clean it up" a little, but I am no expert on imaging.  Mount is polar aligned to better than 5 arc minutes according to PemPro. An Ultra Block filter was on the CCD. There were only 10 cal stars used to align the mount. Location was a suburb of Dallas, lots of light pollution. 


     
     

    This is M11 taken on 10-03-208. Exposure time is 45 seconds. 15 Cal stars used. 6" newt, f/5, in heavy light pollution, no PEC, no autoguiding, Meade DSI Pro, Nebulosity camera software, minimal editing of image.
     


     
     

    PemPro Periodic Error Charts

    These were taken on 9-24-2008. The mount was roughly polar aligned and initialized. The star used was one in Lyra, Sheliak.  Tick management was turned on and working, apparently, very  well. The same equipment used in the video test was used again. 

    PE curve screen shot from 9-30-2008. 
    PE curve screen shot from 9-30-2008. 

    PE raw data screen shot  from 10-30-2008. 
    This is a screen capture of 8 (?) worm turns. Each line is a turn of the worm. Each worm turn is about 3 minutes. It is raw data, corrected for a slight drift. 
     
     
     

    Video of the mount tracking on a star (wmv)

    The video was done using a camera in video mode facing the laptop screen. The software/equipment used: 
    6" Newt, 750mm F/L
    Meade DSI Pro CCD
    K3CCD Tools software
    Beginning of vid is chopped off (no tripod for the camera)
    Re-testing with PemPro will be done shortly  software updates were needed ). 
    Video is 18 megs and in .wmv format. Most computers can play this file type.

    A tracking video on YouTube (boring)

    A video of the laptop screen while doing a few GoTo's on  YouTube

    On this night it was later discovered that there was some dirt on the encoder disc. Accuracy isn't as good as usual. 
    The planetarium is Sky Charts and is free. The camera software is Nebulosity. The servo software is free with the controller to. 6" Newt, 750mm F/L, Meade DSI Pro CCD.

    A long video of the laptop screen while doing GoTo's on  YouTube

    In this video, the polar alignment is off  70 arc minutes according to PemPro.  Azimuth polar alignment was accurate at the single digit arc second level.  I'll make another one tonight with the polar alignment as accurate as possible. Polar alignment numbers are from the polar alignment wizard in PemPro. 
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     

Servo electronics and software by Dan Gray
Mount design by Lenord Stage
GoTo & Tracking Systems
 5000 Green Hollow Dr.
Arlington Texas 76017-5910
(817) 468-0154