Introduction

Computerized telescopes for amateur astronomers have been around since Advance Technology Instruments introduced the Computer Aided Telescope or CAT in 1987. This first generation Computerized Telescope was expensive, difficult to use and not very reliable. It was not a market success. That had to wait until 1992 when Meade introduced the second generation Computerized Telescope, the LX200. The idea of being able to select a deep sky object from a data base, press a key and have the telescope automatically point at that object appeals to many amateurs. This appeal has made the LX200 a very popular product especially to the new generation of technology oriented amateur astronomers with spare cash in their wallets. The Vixen SkySensor 2000 is the first of the third generation of Computerized Telescopes. After a decade of development, the promise of the Computerized Telescope has been fully realized.

 The $988 SkySensor 2000, introduced in the USA by Orion in August 1997, transforms the venerable Super Polaris and newer Great Polaris German Equatorial Mounts into high performance computerized telescopes. A long last, the amateur astronomer who prefers the sturdy and traditional German Equatorial Mount can also have a computerized telescope. He can also have a computerized telescope that not only points with exceptional accuracy but also can track comets and satellites.

 Installation and Setup

The SkySensor 2000 comes nicely packaged in a small box containing the SkySensor Computer, motors, cables, miscellaneous parts and a well written and laid out 114 page manual. A one-page installation guide and included tools make the installation of the product a quick and simple task. The unit uses a 12-Volt external power supply. A battery pack for holding eight, D type batteries is included; however, I strongly recommend looking at other power supply options. Once you have the unit powered, the manual leads you through some simple operations for setting the time, date and location information and also for testing the motor installation. As you learn more about the SkySensor, you will find there is a richly featured Setup Menu allowing control of many parameters. However, right now after the simple introductory setup, the sky is waiting.

 Getting Started

The mount should be set up with a rough polar alignment, but don't worry too much about this. The SkySensor 2000 shrugs at even the grossest polar misalignment and still provides exceptional pointing and tracking accuracy. It can also help you get to a good Polar Alignment if your need it for imaging. The first display you will see when turning the SkySensor 2000 power on is a request to position the OTA at declination zero with the objective facing west. This necessary step allows the SkySensor to know the exact orientation of the OTA and thus avoid the various possible mount collision possibilities. After you have done this and pressed ENTER, you can start the alignment process.

 Alignment

Aligning the SkySensor 2000 requires pointing the telescope at three different objects and pressing the ALIGN key. This operation can be super simple and a lot of fun if you are roughly polar aligned. Using the PREVIOUS and NEXT keys select an alignment object from the library of bright Reference Stars, Planets or the Moon. You really do not need to know the sky very well to make a good selection since you will only be presented with those objects that are currently above the horizon. Once you have selected an object, press the GOTO key. The telescope will slew around at a maximum speed of 1200x sidereal and stop somewhere in the vicinity of the selected object. Using the four motor direction keys, guide the object to the center of your eye piece. Press the ALIGN key and repeat with two more objects.

The final quality of the alignment does depend upon selecting well-positioned objects; however the SkySensor 2000 will help you through this task with various messages and instructions. It is also important that you do your part by precisely centering the object before pressing the align key. A good alignment results in excellent pointing accuracy. I have found that SkySensor can position any object in the eye piece field of view at 130x after a good alignment session.

Another very important aspect of good alignment is good tracking. I have obsereved that my particular Super Polaris mount in combination with the the SkySensor 2000 produces excellent tracking results. I have measured the periodic error at less than 5 arc seconds without PEC activated and zero declination drift even with a casual polar alignment. Proof of these calims in embodied in some astrophotos I recently took.

 Object Libraries and GOTO

One of the first things I did with my freshly aligned SkySensor 2000 was to use it to hunt down M31. Since I am very familiar with this beautiful galaxy, I knew I could not be easily fooled. The PREVIOUS and NEXT keys were used to locate the Messier Library and the ENTER key pressed to select it. At this point, I could again use the PREVIOUS and NEXT keys to step through the library and be shown only those objects above the horizon. I could also directly enter the object number via the keypad. When you enter the object number, SkySensor will display that object even if it not above the horizon; however, it will not let you GOTO the object if it is below the horizon. In this case, I entered "31", pressed ENTER. The display showed me that M31 had been selected. I then pressed the GOTO key.

Since M31 was well above the horizon, the telescope began its hunt for M31. After a few moments it stopped. I looked in the EP. Yep, there was M31almost in the center of my 130x EP. I could also see M32. Just for kicks, I selected M32 and hit GOTO. The telescope twitched a little bit and M32 now appeared near the center of the EP. So far, so good. Next I selected M33. After a short slew the telescope stopped. I looked into the EP and as I suspected, M33 was not visible. My local magnitude 4 skies do not let me see M33 with the 4" refractor I was using. The field was right. If I had been doing CCD imaging, M33 would have been very close to the center of the CCD. I spent the rest of that evening slewing around and observing my favorite Messiers. SkySensor placed each one with the FOV of that 130x EP. The Messier library is just one of the many object libraries avaialable to the SkySensor 2000 user.

 Sky Tours

The next evening, I decided to take a Sky Tour. In order to avoid having the scope point at things that I could not see, I went into the Setup menu and made some changes to the object selection parameters. I decided to limit my local horizon to a minimum of 30 degrees elevation to avoid having the telescope looking into my neighbor's windows and trees. My local skies are usually limited to a visual magnitude 4, so I limited the object selections to objects of magnitude 9 and brighter. This being done, I pressed the ETC key to get the Sky Tour menu. This menu allows for the selection of the tour objects and the length of time the telescope will remain pointed at each object. This time interval can be between 1 and 999 seconds. I selected SAO and 30 seconds and then pressed ENTER to start the tour.

The SkySensor 2000 began the tour with a beep-beep-beep and a warning saying "Caution the scope will now move." After a short pause the scope was moving. The display showed me some information about the object I would soon be looking at. I found I could press the PREVIOUS and NEXT keys and learn other interesting information about the destination object. When the object was centered, the scope unceremoniously stopped for me to take a quick peek. After 30 seconds, the beep-beep-beep sounded again and the Telescope was off to the next object.

Shortly after starting this tour, I realized that I was being shown some fascinating colored and double stars that I never knew existed. I wanted to take more time to look at some of these than was being allowed by the 30 second interval. Pressing the ESC key got me out the Sky Tour mode. Press the ETC got the Sky Tour menu back. This time I selected an interval of zero seconds. When in this mode, the telescope will stay positioned on the object until ENTER is pressed. If the object was not interesting, I could press ENTER immediately. Some very interesting objects warranted further observation at a latter time. To re-visit these objects, one could write down the object number and later select it out of the library. The SkySensor 2000 provides and even better way of handling this problem in the form of User Libraries

 User Libraries

While the telescope is pointing at an interesting object, press the STORE key. The SkySensor then allows you store the object in either the USER1 or USER2 libraries. At some later point you can either do a custom Sky Tour from these libraries or directly select some particular object for direct GOTO. The User Libraries are a great tool to making a highly selective Sky Tour of fascinating objects for public viewing sessions or lectures.

The user libraries also allow you to create new references for new objects not found in an of the other databases. For example, one object that I have not yet found in the databases in the Epsilon Lyra Double-Double stars. I like to use these stars for a quick check on the seeing conditions. I pointed the telescope at the midpoint between the two star pairs and then pressed a few keys to store the current sky location in the next available user library slot. This new User object was then given the Name "EPS LYRA."

In addition to the USER1 and USER2 libraries for sky objects, there are the Land, Satellite and Comet user libraries. The Land library provides for storage of land objects. When a Land Library object is selected, the RA motor stops tracking at sidereal speed. The Satellite and Comet libraries are used to define artificial satellites and comets by orbital information. Given this information SkySensor 2000 lcan locate and track of those objects. I have used the Satellite Tracking feature to track Space Station Mir on several occasions.

 Conclusion

The SkySensor 2000 is a richly featured, easy to install, easy to use, third generation, computerized telescope positioning system for equatorially mounted small telescopes. It is capable of very accurately locating and tracking thousands of sky objects contained in its many libraries. It is also capable of tracking artificial comets and satellites. My SkySensor 2000 has given me many nights of enjoyment and will continue to be well-used tool in my observatory.