| The ST-9XE is an excellent self-guided CCD camera for those seeking a large field of view and high sensitivity, at a relatively low cost, for minor planet and supernova searches with long focal length telescopes. It uses two CCD sensors, one for imaging and one for guiding. The imaging sensor is a Kodak KAF-0261E CCD with a 512 x 512 array of 20 micron pixels. This is a Class 1 “E" CCD imaging sensor with high quantum efficiency (QE) and no column defects. The area of the array is about 80% the size of the more expensive ST-8XE and 330% the size of the array used in the ST-7XME. Anti-blooming is not available, and is essentially not needed, as each pixel’s very large full well capacity makes blooming unlikely. When the ST-9E camera was introduced, the first users’ image SBIG received was from two amateurs, Gary Hug and Graham Bell, who discovered a ~19th magnitude comet: Comet P/1999 X1 Hug-Bell. At that time, with a single exception, it was the faintest comet ever discovered by an amateur astronomer. Gary and Graham were using a 12" SCT at f/6.3. The discovery was made while blinking 6 minute exposures taken in search of an asteroid. Subsequent 10 minute and 20 minute exposures revealed the comet’s tail. Recently SBIG was informed that UK amateur, Mark Armstrong, has discovered no less than 40 supernova using three ST-9E cameras!
The second sensor is a Kodak TC-237H detector with a 657 x 495 array of 7.4 micron pixels for guiding. In the tracking configuration, the TC-237H CCD is normally binned 2x2 for increased sensitivity. You can also use the TC-237H CCD in a high resolution (unbinned) mode if desired.
The detectors are mounted in close proximity to each other within the camera body. They are focused at the same image plane. This patented guiding method allows you to focus both taking and guiding detectors simultaneously. Some competitive cameras require a separate guiding detector in a separate housing that mounts in an off-axis guider body. Such a two-housing system requires more setup time to focus each detector independently than the one-time focus of the ST-9XE. Still other cameras have one detector, but use a portion of that detector to guide while the balance of the detector collects the image. By using a separate internal CCD for guiding, the ST-9XE’s imaging CCD spends 100% of its time and quantum efficiency gathering the image, an improvement over this latter type of single chip design. You are not required to compromise by giving up half of the quantum efficiency or by making twice the exposure time as you might with other self-guiding designs.
No special orientation of the camera is needed for proper guiding with the built-in guiding detector. In tests, even when randomly pointing the telescope toward objects in relatively star-poor areas of the sky away from the Milky Way, stars on the guiding detector of the ST-9XE were bright enough to be used for guiding 95% of the time. In those few cases where a bright-enough guide star might not be immediately apparent, TheSky software from Software Bisque (TheSky Version 5, Level 2 software is supplied with the ST-9XE) can print finder charts showing the correct orientation of the guiding detector’s field of view relative to the imaging CCD’s field of view for proper guide star acquisition. Using this tool to plan your nights imaging is a very useful complement to the self-guiding feature of the camera.
Kodak classifies their imaging detectors according to the number and type of “defects" found on the chip. “CCD Point, Cluster, and Column Defects" are defined in the “Astronomical Terms" section above left. The Class 1 chip of the ST-9XE has no more than 10 point defects in its imaging area; no more than 4 cluster defects; and no column defects. The few possible point and cluster defects of the ST-9XE are easily removed from an image during processing.
Pixel binning modes (1x1, 2x2, 3x3) allow the user to match the pixel size to various telescope focal lengths. The camera includes a mechanical shutter, 16-bit analog to digital (A/D) converter, regulated temperature control, and has all of its electronics integrated into the CCD head. No separate CPU is required. Communication to your PC is through new high speed analog and digital electronics and a high speed USB 1.1 interface. Data transfer rates are up to 420,000 pixels per second, allowing a full frame download in less than one second. The standard cooling configuration is a single stage thermoelectric cooler with an active fan and a newly designed heat exchanger. It includes an inlet and outlet for water circulation should the user desire to maximize the cooling performance for hot climates. Typical air cooling without water assist is -35° C from ambient. With water assist, the cooling increases to a typical -45° C. Even without water cooling, the new single-stage cooling design offers similar performance to previous two-stage cooling with much less current draw than a two-stage cooler. It is therefore less demanding on battery capacity when operating in the field. A circulating water pump and tubing are available as optional accessories.
There’s a remote guide head port for use when imaging through a color filter wheel. A separate external guiding head eliminates the possibility of a color filter affecting the brightness of the guide star when using the camera’s internal TC-237 guiding sensor. There’s a new I²C accessory port that adds bi-directional communication capability for the coming development of a new family of “smart" accessories. A standard accessory port is also provided to maintain compatibility with the customer’s existing telescope interface cables and backwards compatibility with SBIG’s existing accessories – such as the CFW8 color filter wheel, AO-7 adaptive optics system, and a relay adapter box for telescopes that do not have a dedicated CCD guider input. The camera body has rack handles that make for easier and safer handling of the camera, particularly in cold weather when wearing gloves; a high-speed USB 1.1 interface port with a 15-foot USB cable (commonly available and relatively inexpensive third party USB extenders are available for cable runs up to several hundred feet, something not presently possible with a USB 2.0 interface); a user-rechargeable desiccant plug (there’s no need to return the camera to the factory for frosting problems); an internal shutter for automatic dark frames; a 2" nosepiece; a T-thread ring for attaching to T-mount photo accessories; a 1/4"-20 thread side plate for tripod mounting; a telescope interface cable for autoguiding; and a universal 90-240VAC power supply with a remote on/off switch. A supplied CD-ROM has sample images and software for SBIG’s CCDOPS version 5 camera control software, and Software Bisque’s CCDSoft Version 5 image processing/camera control software and TheSky version 5, level II, with telescope control for Windows. Instruction manuals are provided on the CD-ROM. You also get a separate printed camera operating manual and a custom designed Pelican hard carrying case with pre-cut foam. The custom cut foam securely holds the camera and power supply with additional spots for accessories, cables, etc. The case is dust proof, water proof, crush proof, and carries a lifetime guarantee from the case manufacturer.
Detector specifications are as follows: Imaging Detector: Kodak KAF-0261E high QE Class 1, with no column defects.
Imaging Pixel Array: 512 x 512 pixels.
Imaging Pixel Size: 20 x 20 microns.
Imaging Total Pixels: 262,000.
Imaging Full Well Capacity: ~150,000e-.
Imaging Dark Current: 4e-/pixel/second at 0 degrees C. Guiding Detector: Texas Instruments TC-237.
Guiding Pixel Array: 657 x 495 pixels.
Guiding Pixel Size: 7.4 x 7.4 microns.
Guiding Total Pixels: 325,215. Readout specifications are as follows: Shutter: electromechanical.
Exposure: 0.12 to 3600 seconds, 10ms resolution.
Correlated Double Sampling: yes.
A/D conversion: 16 bits.
A/D gain: 1.6e-/ADU.
Read noise: 15e- RMS.
Binning modes: 1x1, 2x2, 3x3.
Pixel digitization rate: up to 420,000 pixels per second.
Full frame download: <1 second. Optical specifications with 8" f/10 (2000mm focal length) scope are as follows: Field of view: 16.8 x 16.8 arc minutes.
Pixel size: 1.97 x 1.97 arc seconds. System specifications are as follows: Standard cooling: single stage thermoelectric, active fan, water assist ready, -35° C from ambient typical, air cooling only (-45° C from ambient typical with water assist).
Temperature regulation: +/-0.1 degree C.
Power requirements: 5 VDC at 1.5 amps, +/-12 VDC at 0.5 amps, power supply included.
Computer interface: USB 1.1.
Computer compatibility: Windows 98/2000/Me/XP.
Guiding: patented dual CCD self-guiding. Physical specifications are as follows: Optical head: measures 5 inches diameter x 3 inches deep (12.5 cm diameter x 7.5 cm deep), weighs 2 pounds/0.9 Kg.
CPU: no separate CPU required, all electronics integrated into optical head.
Supplied mounting methods: T-thread, 2" nosepiece.
Back focus needed: 0.92"/2.3 cm.
|
Printer friendly version
Email page link to a friend
Do you have a question about this product?
