GuidePump ~ The Complete Autoguider System

Yep - we actually really (no... really!) we do mean complete!  No loud statements about how great some autoguider camera is, or how cool some guidescope is, you must have noticed they do not mention how you have to buy those separately, figure-out how to mate them with some obscure chance of getting a useful guide response resolution if it works at all with the f-ratio, and a useable field-of-view from it also scientifically (good luck and hope you have high-level college math!), then buy expensive parts to mount all that stuff, you have to buy an expensive electronic ST4 translation cord to connect to your mount before you actually get the intended result signal to the motors (oh... you didn't know?), and did they mention how you are on your own from there and how hard it really is to find a guide star and hold it still with their proposed ring mount accessories?


What now?  Well... first you should get one on order fast because these are REALLY getting popular quick and the lead time is running around 4-8 weeks already.  The GP5 is just $299 introductory price, this may not last very long with a free ST4 cable and LED signal indicators included on it,  and only $20 domestic shipping fully insured (overseas is $60us shipping).  A stealthy semi-flat black gun, it's the ultimate photon-piston!  The cam-end does look like a high performance engine piston and so we call it ... "Guide Pump".  This entire set costs about as much as an entry-level guider camera alone!!


Q: What is an 'autoguider' ?
A: It does automatically the same as you would with a second telescope mounted on your main one, using a cross-hair illuminated reticle you would open the shutter on your imaging camera and, with extreme care, control your telescope via this crosshair by manually 'guiding/correcting' errors in your drive and gears as time passes with the use of your hand control or slo-mo controls.  It has been quite common in the past to do this manually and experienced users know of the great pain it can produce in both eyestrain and spinal cord fatigue (I once knew a man who did hours-long film exposures... knew him ONCE!).  Today the problem is more centered around automated control of the telescope position (.5 to 1.5 arcseconds in this case) while the operator pays attention to their main imaging camera and its myriad details needed to stack-up that series of 'Great-Shots' when a good night comes along.

Q:  What is "ST4"?
A:  A 6-pin telephone type receptacle in your telescope drive control or in the mount.  It is intended for connecting a cord from an autoguider such as this one.  SBIG (Santa Barbera Instrument Group) created this interface long ago and it has been used universally as a 'de-facto' standard ever since for telescope fine-adjustment drive conrol on-the-fly during photo exposing.  All mainstream manufacturers use this jack (typically labeled 'CCD') on their mounts or hand controls when they offer autoguiding functions for their telescopes... one exception is the Mead Autostar controllers and for this we add the ST4 connection to that hand control separately if desired.  You will receive an informative data sheet with GuidePump detailing the use and the exact signal wires and pinout-numbers of cords used for this standard.  It is intended to be simple so most cords and autoguiders just plug-in to the telescope mount or hand control.  We include the details just in case you are the kind of person who will rig things and alter for your own building purposes, or adapt to other cameras and mounts, add extenders or used parts etc.

Q:  Where is the rack and pinion or other focus mechanism?
A:  We designed this for perma-focus since the main problem with autoguider scopes is the focuser mechanism.  All focusers have a slight amount of 'play' that causes problems with holding micron-size pixels on a camera chip rigidly motionless when the telescope shifts slowly its position while tracking (gravity shifts and structural flexings), and thermal changes during exposures are also thwarting your rock-solid intention.  Many people find focus on a scope they intend only for guiding - then fill their focuser mechanisms with glue to stop these problems!  We machine it and bond tight without any focus rack, but do provide a tensioned fine focus knob seen at the rear of the GuidePump camera cell to take up thermal expansions as well as allow small focus shifting for 'blob' guiding purposes (the best way to get a star center calculated from pixel squares is to make it non-point-like, aka: blob).

Q:  What are the spec's?
A:  Tech2000 part# GP5...  0.5-degree diagonal field-of-view (a full Moon diameter!).  Sub-pixel resolution yields well under 2 arcsecond guide resolution (0.5 to 1.5 arcseconds typ.), the sky conditions will rarely yield that well.  In engineering we must weigh FOV vs. resolution so we pick resolution first since it is the entire purpose of autoguiding - the largish .5-degree field-of-view is just a bonus.  It could be larger but that would compromise the guiding resolution - a NoNo!  No power supply is needed as this unit is completely self-contained. Drive correction repetition rate can be down to fractional second periods which is great for deleting the need for PEC training as it will follow gear errors rapidly by itself.  Just over a LB and 16" in length.  Live video (AVI) and still frame record ability (for the science - this is a Guider - NOT an imager). A 1-year warranty and 30-day moneyback guarantee assure complete confidence.  Guider camera cord is 6-foot heavy-duty USB.  ST4 cord on the parallel port cable is 7-foot using the industry-standard (SBIG) ST4 connection 6-wire phone plug with gold pated contacts for zero corrosion worry outdoors.  These can be extended with commonly-available extensions if desired with little compromise to signal integrity (if you use extension cords they should have visibly gold-plated contacts and that is the norm - always use 1:1 wire pass-thru so that wire colors are always maintained in proper connector position - normal phone cords and couplers reverse the wire color connection sequence!).  If your PC has no parallel 25-pin printer port connector then use the adapter for USB described below, or an adapter for PCcard slots-to-parallel port conversion - these are also widely available.  The software supplied on this CD-ROM also can optionally connect to your mount for guiding signals if  your mount uses the ASCOM protocall and has the autoguide or Pulse-Guide feature - in that case you would not need to use any separate ST4 cord at all!

Q:  What are the PC minimum system requirements?
A:  Windows XP or above, 256MB ram, 1GB available harddisk.
      1-USB 2.0 port for camera connect.
      For the output signal to guide the mount choose at anytime from one of 3 possible methods:
        1) ASCOM telescope control framework if your mount has a PC connection that can use ASCOM guiding (No extra cord).
        2) 1-USB 2.0 port, plus a GPUSB adapter and an ST4 cord from (No LED indicators).
        3) Use our free parallel cable with the 4 LED signal indicators, you need a parallel port (25-pin female D-shaped connector).

Need more USB ports?  USB hubs are quite compact and make one USB port into 4 USB ports...
Tech2000# USB-HUB4 passive - $10 while they last.

Q:  Can I take off the tube assembly and rigidly mount it on a set of my rings (when I am expecting to guide only on-axis or very near-axis)?
A:  Certainly.  Tube forward body section is 52mm diameter, rear section tailstock tube is approx 60mm.

Champ... GuidePump KO's competitors.  No others have a complete set for catching fallen stars IN ANY OFF-AXIS POSITION.

6-9-07 First test fire-up using GP5
  Guider:  50x350mm tube assembly, Tech2000 Cam # SIC4700/37 (NO IR FILTER)
  Observing scope:  NF 102x600mm refractor & 6x30 crosshair finder.
  Loc: Monroeville Tech2000 shop, lots of light pollution in town, 9 mercury lights close.
  Seeing:  4 rather poor at start but improved greatly later as described below.
  Transparency:  9, a very clear day & evening. Excellent rating.
  Temp:  56  Wind:  Dead calm.

  10pm - Lined up finder, main instrument, and guider all at one mercury lamp about 150 yards distant.
  10:30 - followed Venus, fine focus, guider cam got a nearby star looking faint - seeing made it come and go.
  11:00 - Mizar & Alcor just past zenith high overhead.  Both easy by naked eye 2.3, 4.0 mag.  Cam gets the 4.0 fine & GuideDog stays locked continuously while guiding on that.  Snapped a single-frame pic shown above, the realtime frames look better.
  12:00 - Seeing is much better, probably 7.  There is a 7.6 mag star between Mizar & Alcor slightly offset (SAO 28748).  Faintly visible in the 4" but only hinted at in screen viewing though its position is evident it could readily be mistaken for noise and so that mag could never be used as a guide star with this model.  This just shows an upper-level limit faintly hinted at the 7.6 mark.
  01:00  There is a 4.8 mag star directly east of mizar about 1/2 - to one degree or so (SAO 28843).  Moved over to it & captured easily & GuideDog tracked 45 minutes never losing lock.  Its pretty faint I gotta say looking in occular on the 4" but easily seen on screen, surely red & cleanly so in occular but whiter on screen, about 2 pixels not including color ghost (IR filter is removed).  The steady air helps alot.  Can not see it naked eye even when eyes are shrouded really well like Kenny in the SouthPark television series.
  2:00  Packed & done.  3.5 hours run.  Used alot about 40 hours now, the 9V battery is near dead on Nightfire drive, noticed when LED lamp showed a distinct visible flicker, then the tracking dial control setting needed large adjustment for faster/slower in a chasing fashion as the battery re-awoke when buttons were pushed.  Pressed onward until the unit maxed-out around 40 hours use.

Summary:  A typical mag 4 guidestar will be readily useable anytime and anywhere for this entry-level system since it has a cross point off-axis mounting to aim it anywhere irregardless of where the user is located or what the user can see or where the main telescope is ponted.  Max is likely far more than above mag 5 since the 4.8 above was extremely easy on this good night with in-town conditions.  The Mizar/Alcor pair have a separation of 12' (1/5 degree).  Using a ruler and ratio measurement between them, compared to full image width, shows this unit yields very close to 1/2 degree FOV, ratiometrically less on the vertical of course.  This closely matches the calculation I used from Joos Et.-Al. in "Theoretical Physics" (footnotes not included for brevity) as y' = f tan-a that yields a 3mm image field diameter prediction, which is quite close to the actual dimension of the photodiode array width that I have measured myself directly.  Coalescence achieved!  Notably this proto camera chip is offset from true center by around 30 arcminutes which does not influence test results but does influence illumination on guide stars since the .96" focuser barrel is long and partially vignettes the aperture.  About 2 arcseconds guiding resolution should result with this 388 pixel-wide array and software like GuideDog typically will produce sub-pixel on the real-time analysis adjusting corrections thereby, then there is the dynamics of the mount which usually would make it even better due to inertial effects.  As the lowest-cost 'entry level' complete guider system, it sure worked fine for me over many hours!  I'll pick this one above the 100x600 NF refractor version anytime.  Not just on the lower price but the fact that it performs very similarly and is much more compact.  There are technical reasons for this otherwise puzzling discrepancy since you would naturally expect a 100mm aperture to beat a 50 soundly in magnitude instead of being almost the same.  OK- now you got my attention!

TECH2000 USA, 69 Ridge St. South, Monroeville, OH 44847
PH: USA 419-465-2997 FX: USA 419-465-2484
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Prices or specifications subject to change.