Instruments | |
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The top floor of the observatory contains a single fork mount
supporting five telescopes: a 65 cm vacuum reflector, a 25 cm vacuum
refractor, a 20 cm refractor for H-alpha full disk observations, a 15
cm refractor for CaII K and white-light full disk observations, and a
15 cm refractor for Earthshine observations. The two vacuum telescopes
are equipped with 3 separate optical benches and a computer controlled
mirror system directs the light to these benches allowing for up to
6 experiments running quasi-simultaneously. In addition, the
65 cm telescope's Coudé-exit feeds an optical laboratory on the
floor below the telescopes.
Please note that the information provided on the instrumentation only describes a typical set-up. Since addressing a certain scientific questions might require a different set-up, all the information provided below is subject to change and should only serve as a general guide-line. |
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Full Disk Observations |
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H-alpha full disk observations:
The 20 cm refractor (known as the Singer telescope) is used with a Halle Lyot filter and an Apogee KX-4 2032 X 2032 pixel CCD camera. CaII K full disk observations: White-light full disk observations: The CaII K and white light full-disk observations are obtained with a 15 cm refracting telescope and a Kodak Megaplus 1.4i 1364 X 1035 pixel CCD camera. The CaII K images are obtained using a Daystar 1.5 Å bandpass solid Fabry-Pérot filter. |
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Observations with Moderate Spatial Resolution |
| The 25 cm telescope is normally operated with a digital magnetograph (DMG) working at 6103Å, a Zeiss Lyot filter working at H-alpha, and a Halle Lyot filter working at CaII K (3933Å). Other filters can be used depending on science requirements. |
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Observations with High Spatial Resolution |
At the moment, we reserve the 65 cm vacuum telescope for the
development of state-of-the-art equipment for solar observations such
as
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Digitizers and Cameras |
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For more than 20 years we have used a number of different digitizing
systems and digital cameras on our telescopes.
Quantex video digitizer The Quantex video digitizer was used between the early 1980s and 1997. The Quantex was originally built as a device for integrating video frames. Such devices were often used in the 1980s with guider cameras for nighttime astronomy. The Caltech solar group quickly saw the potential of a modified Quantex device as the core of a video magnetograph system. The modifcations included adding control circuits to allow adding and subtracting video frames and a direct digital readout to a PDP-11 computer. The Quantex digitized an incoming video signal with an 8-bit A/D converter and fed the result to a 12-bit memory buffer. There the frame could be added to or subtracted from the image already in the buffer. By modulating a polarization analyzer a magnetogram could be built up in the memory buffer. The digital output from the Quantex was an 8-bit image. This could be the top 8 bits from the buffer ("12-bit mode") or the 8 bits could be offset by two bits ("10-bit mode"). The "10-bit" mode was most frequently used. The magnetogram would be started by placing a 1 in the top bit to be read out (creating a blank image with pixel value 128). Then incoming video frames were added or subtracted as required. The magnetogram when it was read out of the Quantex buffer would exhibit "wrap". Originally there was not enough disk space or tape capacity to record the digital images from the Quantex. The primary output at first was to a video monitor which was then photographed by a 35 mm Mitchell film camera. As disk and tape capacity increased, eventually all of the Quantex images were also recorded digitally. The Quantex magnetograms consist of Stokes V images not divided by intensity, so are primarly useful in studying the morphology of active regions, but not field strengths. It is sometimes possible to calibrate the Quantex magnetograms, depending on what auxilliary images are available. The Quantex was also used (particularly in the 1982-1986 period) to digitize individual video frames, for the daily full disk images for example. At this time, these images were often digitized some time after the observations by using a video camera looking at a strip of film containing the original image. Eyecom video digiizer The Eyecom video digitizer was an 8-bit system used between the mid-1980s and about 1995. It was primarily used for simple video digitization, although it also had some image processing features. The digital output went to a PDP-11 computer. The Eyecom was primarily used to produce the daily full-disk images and the Ca II K line index. Datacube video image processor The Datacube was originally purchased in 1988 to provide magnetograms like the Quantex system but at a different wavelength. Output from the Datacube went to a DEC MicroVAX computer. Additional modules purchased in 1990 greatly increased its capabilities and allowed it to obtain 16-bit vector magnetograms and longitudinal magnetograms of very weak fields. The Datacube was used until 2001. Aspro video digitizer The Aspro was used in the 1994-1997(?) period to first supplement and later replace the Eyecom. It was an 8-bit video digitizer built into an IBM PC clone. OSL CCD camera The OSL CCD camera was the first digital CCD camera used at BBSO. It was built in 1988-1989 by Lockheed as a test camera for the OSL (Orbiting Solar Laboratory) project. It was one of the few astronomical CCD cameras designed from the beginning for solar work. It was used until 2005. It was used with a DEC MicroVAX computer. The original Lockheed software package was replaced in 1994(?) with new software developed at BBSO and based on the software for the Datacube VMG system.
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