Moravian Instruments G1-1200 CCD ASTROPhoto GUIDING & Imaging Camera with Sony ICX445 CCD

Moravian Instruments G1-1200 CCD Camera with Sony ICX445ALA/ICX445AQA CCD Sensor and COOLING FAN, 1/3" Progressive Scan CCD 1296 x 966 pixels, CS-thread lens adapter, CS to 1.25" focuser adapter.

This is the latest G1 camera from Moravian Instruments and is ideal for imaging the Moon, planets and bright deep-sky objects. High sensitivity, low noise, fast image download, electronic shutter and integratedautoguider__� port also allow G0 and G1 cameras to guide astronomical telescope mounts. Thanks to their capability to integrate light G1 cameras can guide the mount also using dim stars, invisible for common TV and web cameras. Robust construction, small dimensions, easy manipulation and powerful software make G1 cameras ideally suited for beginner astrophotographers.

The Sony ICX445/ICX445AQA CCD detector, used in this camera, is produced using EXview HAD technology and offers high quantum efficiency, comparable to cameras employing much more expensive ICX285 CCD. The 1/3" detector format (4.9 x 3.6 mm) as well as small pixels (3.75 x 3.75 _¦m) suit to short focal length guiding telescopes. G1-1200 is also good for capturing Moon and planets.

Physical dimensions of the Sony ICX445/ICX445AQA CCD detector, used in G1-1200 cameras, correspond to G1-0300 or G1-0800 cameras. But G1-1200 has 1.2 millions pixels measuring only 3.75 x 3.75 _¦m. The EXview HAD CCD production technology, ensuring high quantum efficiency especially in near infra-red portion of the spectrum, is particularly important for usage in astronomy when capturing dim stars or other objects.

Despite relatively small physical dimension of the CCD chip itself, the package is too large to be used in the round head of G0 cameras. So the 1200 model is available only in somewhat larger head of G1 cameras (similarly to G1-1400 model).

G0 and G1 cameras use Sony ICX CCD detectors with progressive read. All models are available in both monochrome and color versions. The camera is powered from the USB so it is connected to the PC/laptop via a single cable. StandardAutoguider__� port allows the camera to directly control a telescope mount. Physical appearance of G0 cameras is similar to an ordinary 1.25" eyepiece. The G1 camera head is somewhat bigger, because it contains a cooling fan, which significantly reduces CCD dark current. G1 cameras are also equipped with standard CS-thread adapter, so they are compatible with various CCTV lenses, microscopes and other devices.

• Sensor: Sony ICX445ALA/ICX445AQA CCD
• Colour filter: none
• Resolution: 1296 x 966 pixels
• Quantum Efficiency:  above 50%
• Pixel Size: 3.75 x 3.75 “_m
• Imaging Area: 4.9 x 3.75 mm
• Interface:  USB 2.0 (USB 1.1 compatible)
• Download time: appr. 0.05s with USB2.0 host (with a USB1.1 host download time can be significantly longer)
• Cooling: no cooling

GENERAL INFORMATION ABOUT MORAVIAN INSTRUMENTS G0 AND G1 CAMERAS

G0 and G1 cameras use Sony ICX CCD detectors with progressive read. All models are available in both monochrome and color versions. The camera is powered from the USB so it is connected to the PC/laptop via a single cable. StandardAutoguider__� port allows the camera to directly control a telescope mount. Physical appearance of G0 cameras is similar to an ordinary 1.25" eyepiece. The G1 camera head is somewhat bigger, because it contains a cooling fan, which significantly reduces CCD dark current. G1 cameras are also equipped with standard CS-thread adapter, so they are compatible with various CCTV lenses, microscopes and other devices.

G0 and G1 cameras are very compact, lightweight and easy to operate. The user only needs to insert it into telescope focuser, plug the USB cable to the computer and it works.

Sensitivity is an important feature of any guider. It must provide images of guiding star(s) with sufficient S/N ratio in rather short time to ensure perfect guiding. The necessity to accumulate light for many tens of seconds or even minutes is often unacceptable for high quality guider. This is why the G1 cameras utilize sensitive Sony ICX CCDs.

Sony EXview HAD CCDs have better than 50% quantum efficiency and low read noise.
G1 cameras support 16-bits digitization, significantly enhancing the dynamic range.
Strong anti-blooming protection keeps even bright stars round, without blooming streaks.
G1 cameras also provide very fas readout___pixel digitization speed reaches 8 MPx/s in fast read mode.
G1 cameras ensure very low read noise in slow read mode.

Both G0 and G1 series of CCD cameras contain similar electronics, same CCD detectors and provide similar functionality. The difference is mainly in mechanical construction and in cooling.

G0 cameras offer round body, which is more compact compared to G1 series, which could be important e.g. in combination with Off-Axis Guider etc.
G1 cameras are slightly bigger and heavier, but they keep the CCD detector on lower temperature thanks to embedded fan, which more than two times lowers detector dark current. They also offer CS-thread adapter and also other optional alternatives of lens adapters (Canon EOS and Nikon bayonets, T-thread etc.).

G0 and G1 cameras
Remark: Due to CCD detector package size there are no compact variant of G1-1400 model (G0-1400 camera).

G0 and G1 cameras do not require any external power supply, they are powered entirely from the host computer through the USB cable. Because the power provided by USB line is rather limited, these cameras do not use energy-hungry Peltier cooler. G1 cameras contain small fan, which helps keeping the CCD temperature on the environment temperature to significantly reduce dark current.

• G0 and G1 cameras are USB-powered devices (only 1 cable is necessary to operate).
• Absence of the Peltier cooler does not allow CCD operation temperature below ambient temperature, but fan embedded in G1 cameras keeps the CCD temperature very close.

Although modern astronomical telescope mounts support guiding through PC connection, G0 and G1 cameras incorporate standard 6-pin connector for the mount's autoguider input. Thus the computer can guide the mount through the camera even in the case there is no link between the telescope mount and the PC.
The G1 camera head is equipped with standard Autoguider connector.

Remark: The autoguider port current must not exceed 100 mA. If the mount does not treat the autoguider port aslogical input__� only, but switches the guiding motors directly by these signals, arelay box__� must be inserted between the camera and the mount. The relay box ensures switching of currents required by the mount.

SIPS (Scientific Image Processing System) control software supports both guiding through the camera port as well as through PC-to-telescope link.
Remark: G0 series of CCD cameras require SIPS v2 and higher version to operate. Camera drivers in previous versions supported only G1 series.

If drivers for third party software packages are used (MaxIm DL, AstroArt, ASCOM), it is necessary to use versions which already contain support for G0 cameras. Consult particular driver documentation for a list of supported cameras.
The Autoguider port on the G0 or G1 camera head follows the standard pinout introduced by the ST-4 guiding camera:

• 1 R.A. + (Right)
• 2 Dec + (Up)
• 3 Dec (Down)
• 4 R.A. (Left)
• 5 Common (Ground)
• 6 Not connected

G0 and G1 series of CCD cameras is intended for guiding as well as for CCD imaging, they are very capable to capture astronomical or microscopic images. G1 cameras can be used with any telescope or C/CS-mount compatible lens.
The SIPS control software treats any CCD camera as imaging device or guider. User choose which camera will be used for imaging and which will be used for guiding.

G0 and G1 Cameras Technical Specifications

CCD Chip
G0 and G1 cameras use sensitive and low noise Sony ICX CCD detectors. Sony does not publish the absolute quantum efficiency of these CCDs, but the estimated QE exceeds 50 %. The dark current and read noise of these CCDs are very low.

• Model G1-1200
• G1-1200 model uses Sony ICX445ALA CCD chip with progressive read.
• ICX445ALA CCD chip specifications
• Resolution 1296 (H) x 966 (V) pixels
• Pixel size 3.75 _¦m (H) x 3.75 _¦m (V)
• Imaging area 4.9 mm (H) x 3.6 mm (V)

Please note that Sony does not publish some key characteristics of ICX CCDs (absolute quantum efficiency, read noise, full well capacity, output node sensitivity, etc.).

Camera Electronics
16-bit A/D converter with correlated double sampling ensures high dynamic range, in fact exceeding the pixel well capacity of the CCD. Fast USB interface ensures image download time within fractions of second.
Maximum length of single USB cable usable is 5 m. This length can be extended for instance to 10 m by using single USB hub or USB active extender cable. Up to 100 m extension can be achieved with third-party extender.

G0 and G1 CCD camera electronics specifications

• ADC resolution 16 bits
• Sampling method Correlated double sampling
• Read modes fast (8 Mpx/s)
• slow, very low noise (2.5 Mpx/s)
• Sub-frame readout Yes
• Computer interface USB 2.0 High Speed
• USB 1.1 Full Speed compatible

Notes:
SIPS control software allows applying software binning if lower resolution images are desired.
Download times are valid for USB 2.0 host and may vary depending on host PC. Download times can be significantly longer when connected to USB 1.1 host.
Some electronics characteristics like system gain or system read noise cannot be determined without knowledge of some CCD parameters (e.g. output node sensitivity), which are not published by Sony.

Chip Cooling
The G0 and G1 series of CCD cameras does not use active cooling with Peltier TEC modules, so the CCD cannot be cooled below ambient temperature.

Working electronics (including the CCD chip itself) produce quite a lot of heat, which rises the camera internal temperature many degrees above ambient temperature. Because the CCD thermal noise typically doubles every 5 or 7 “_C, the thermal noise can be two or more times higher after some time of camera operation.

The G1 series of CCD cameras contain small fan, which efficiently removes the heat from the camera body and keeps the CCD temperature as close to ambient temperature as possible. The fan can be controlled from the software.

G0 as well as G1 cameras also include the embedded temperature sensor, which measures the current CCD temperature. This feature enables controlling of the CCD temperature and ensuring the used dark frame was taken in the same or similar temperature as the light exposure etc.

Power supply
G0 and G1 cameras are powered from the USB cable. No external power supply is necessary.
The current limit for single USB device is 500 mA from 5 V supply. The current required by G0 and G1 cameras varies depending on the camera operation mode. The following table summarizes camera consumption. Either way, cameras do not reach the allowed 500 mA limit, defined in the USB specification.

• G0 and G1 cameras power requirements
• Camera operation mode Required current
• Idle, fan off 185 mA
• Idle, fan on 260 mA
• Image digitization, fan off 285 mA
• Image digitization, fan on 360 mA

Notes:
If the camera is connected through unpowered USB hub, the current available for the connected devices can be as low as 100 mA, which is insufficient. Always use powered USB hubs when using G1 cameras.
Note the so-calledactive USB extender cable__� is in fact nothing more than standard USB cable with a hub with single USB connector on the far side. Such hub consumes some energy and may not work with G1 cameras.
Some USB cables incorporate very thin power lines with relatively high resistance. If the USB device consumes several hundreds miliampers, the voltage drop on such cable can be around one Volt. Although the G1 camera should work, some features may be negatively affected. Always make sure the used USB cable is as short as possible and with low-resistance power lines.

G1 Camera Mechanical Specifications
Compact and robust camera head measures only 83 x 76 x 26 mm (approx. 3.25 x 3 x 1 inch). The head is CNC-machined from high-quality aluminum and black anodized.
The head contains CS or C-thread for connecting various CS or C lenses. The C-thread to 1.25" adapter can be screwed into the head to attach the camera to any telescope focuser accepting standard 1.25" eyepieces.
The G1 cameras use Interline Transfer CCDs and they do no contain mechanical shutter. It is necessary to cover the telescope manually to take dark or bias frame.

• Internal mechanical shutter:   No
• Shortest exposure time 0.000125 s
• Longest exposure time Limited by chip saturation only
• Head dimensions 83 mm x 76 mm x 26 mm
• Back focal distance 12.5 mm (CS-thread standard)
• 17.5 mm (C-thread standard)
• Camera head weight 0.2 kg

Notes:
Camera dimensions do not include the CS-thread adapter. This adapter depth is 6.4 mm, so the camera depth including the CS-thread adapter is 32.4 mm.

Guiding
Although the CCD cameras of G0 and G1 series are capable to capture images of various objects in astronomy, microscopy or in other applications of low-light conditions imaging, they are primarily intended as telescope mount guiders for scientific-grade G2, G3 and G4 and also for other imaging devices.
The G0 or G1 camera can work asremote guider head__� for any CCD camera, including the Gx series. The fact that it is not connected to the Gx camera head itself by some proprietary cable, but directly to the USB port of host PC, brings numerous advantages:

• Guiding can guide any camera or DSLR, not only the main camera type for which it is designed, like other remote guiding heads.
• There are no proprietary connectors/cables used to connect main camera with remote head. Standard USB cable is used instead.
• There is almost no limit in distance between guiding and imagine cameras. Guider can be placed to any guiding scope or to off-axis guider.
• Even if the guiding camera shares the same telescope with the main camera using off-axis guider, the light feeding the guider is deflected before it pases through the filters. So there is enough light for guiding even when the main imaging camera takes exposure through some verydark__� filters, like UV, Blue or H_Ï.
• On the other side, simple USB hub creates an integrated solution from the pair of two separate Gx and G0 or G1 cameras.

SIPS automatic guiding
There are two algorithms used in SIPS for guiding:

Single star guiding. The PC calculates the centroid of the brightest star on the image acquired by the guider. The centroid position is calculated to the fraction of pixel precision, so the guiding can be very precise even when the guider is connected to short focal length telescope.
Astrometric reduction guiding. The PC performs basically the same operation like in the case of sub-pixel matching of multiple exposures or astrometry reduction. Number of triangles are created from the brightest stars and they are matched to triangles on reference frame.
Although triangle matching requires at last three stars on the guiding image and thus is suitable either for short-focus guiders or for rich star fields, the image shift is calculated from multiple star positions and is less sensitive to random errors like seeing, radiation spikes etc.

Guider setup tab of the SIPS CCD Camera control tool
The guiding support in SIPS allows incorporating of G0 or G1 camera Autoguider port, which is de-facto standard and compatible with various autoguiders/telescope mounts. SIPS can also guide through telescope link (e.g. through the Meade LX-200 or Celestron Nexstar protocol) so no autoguider cable may be necessary. But the specialized device like G1 guider camera can usually control the mount with much better precision compared to relatively limited time resolution of an application running on the standard PC.