Sidik Isani

The Pan-STARRS Gigapixel Camera #1 and STARGRASP controller results and performance

The Pan-STARRS project has completed its first 1.4 gigapixel mosaic focal plane CCD camera, Gigapixel Camera #1 (GPC1). The mosaic focal plane of 60 densely packed 4k×4k MITLL CCD Orthogonal Transfer Arrays (OTAs) constitutes the Worlds largest CCD camera. The camera represents an extremely cost and time efficient effort with a less than 18 month production and integration phase and an approximate cost of

Results from the Pan-STARRS Orthogonal Transfer Array (OTA)

4 million USD (excluding NRE). The controller electronics named STARGRASP was developed to handle the 480 outputs at near 1Mpixel/sec rates with Gigabit Ethernet interfaces and can be scaled to even larger focal planes. Sophisticated functionality was developed for guide readout and on-detector tip-tilt image compensation with selectable region logic for standby or active operation, high output count, close four side buttable packaging and deep depletion construction. We will discuss the performance achieved, on-sky results, design, tools developed, shortcomings and future plans.

CFHT's SkyProbe: a real-time sky-transparency monitor

The Pan-STARRS project has completed its first 1.4 gigapixel mosaic focalplane CCD camera using 60 Orthogonal Transfer Arrays (OTAs). The devices are the second of a series of planned development lots. Several novel properties were implemented into their design including 4 phase pixels for on-detector tip-tilt image compensation, selectable region logic for standby or active operation, relatively high output amplifier count, close four side buttable packaging and deep depletion construction. The testing and operational challenges of deploying these OTAs required enhancements and new approaches to hardware and software. We compare performance achieved with that which was predicted, and discuss on-sky results, tools developed, shortcomings, and plans for future OTA features and improvements.

Design of the CFH12K: 12K x 8K CCD mosaic camera for the CFHT prime focus

We have developed a system at the Canada-France-Hawaii Telescope (CFHT), SkyProbe, which allows for the direct measurement of the true attenuation by clouds once per minute, within a percent, directly on the field pointed by the telescope. It has been possible to make this system relatively inexpensively due to the low-cost CCD cameras from the amateur market. A crucial addition to this hardware is the quite recent availability of a full-sky photometry catalog at the appropriate depth: the Tycho catalog, from the Hipparcos mission. The central element is the automatic data analysis pipeline developed at CFHT, Elixir, for the improved operation of the CFHT wide-field imagers, CFH12K and MegaCam. SkyProbe’s FITS images are processed in real-time and the pipeline output (a zero point attenuation) provides the current sky transmission to the observers and helps immediate decision making. These measurements are also attached to the archived data, adding a key criteria for future use by other astronomers.

FlyEyes: a dual CCD detector system for CFHT PUEO NUI's wavefront sensor

The CFH12K is a 12K by 8K CCD mosaic camera for the Canada- France-Hawaii Telescope (CFHT), a 3.6 m telescope located on Mauna Kea, Hawaii. The CFH12K is comprised of twelve 4K by 2K thinned backside-illuminated CCDs, arrange din a close- packed array of two rows each containing six CCDs. Located at the CFHT Prime Focus, the CFH12K provides a 42 by 28 arcminute field-of-view, 0.206 arcsecond per pixel sampling, with a resulting data file of more than 200Mbytes per image. The camera has been designed to exploit the exceptional wide-field imaging capability provided by the CFHT. At the time of its commissioning in January 1999, the CFH12K is the largest thinned close-packed CCD mosaic in astronomy. This paper describes the system architecture, and some of the relevant issues associated with the construction, evaluation, and operation of very large mosaic cameras. Emphasis is given to system design issues, illustrating the CFHT12K as part of a larger system: the CFHT.

IOTA: the array controller for a gigapixel OTCCD camera for Pan-STARRS

Until now, only avalanche photodiodes (APD) have been used as the detectors in curvature wavefront sensors in astronomy. This is due to the strict requirements of very short integration time and very low readout noise. In 1999, Beletic et al. invented a new CCD design which should achieve the same performance as APDs but with higher reliability and lower cost. In addition, this CCD has higher quantum efficiency than APD modules and larger dynamic range, eliminating the need for neutral density filters on bright objects. The CCD was designed and fabricated by MIT Lincoln Laboratory in collaboration with ESO and IfA. R. Dorn extensively tested the CCD in laboratory at ESO and proved that it achieves the predicted performance. CFHT is currently implementing this CCD on PUEO, CFHT’s Adaptive Optics system, to assess its performance for the first time in real conditions on the sky for a direct comparison with the current 19 APD detector system. In this article we present the current implementation scheme and discuss the upgrade we foresee for PUEO NUI, a 104-element high-order curvature AO system envisaged to replace the current AO system at Canada-France-Hawaii Telescope.

CFH12K: Optimising 12 MIT/LL CCID-20 CCDs for a direct imaging application

The PanSTARRS project has undertaken an ambitious effort to develop a completely new array controller architecture that is fundamentally driven by the large 1gigapixel, low noise, high speed OTCCD mosaic requirements as well as the size, power and weight restrictions of the PanSTARRS telescope. The result is a very small form factor next generation controller scalar building block with 1 Gigabit Ethernet interfaces that will be assembled into a system that will readout 512 outputs at ~1 Megapixel sample rates on each output. The paper will also discuss critical technology and fabrication techniques such as greater than 1MHz analog to digital converters (ADCs), multiple fast sampling and digital calculation of multiple correlated samples (DMCS), ball grid array (BGA) packaged circuits, LINUX running on embedded field programmable gate arrays (FPGAs) with hard core microprocessors for the prototype currently being developed.

Conceptual design of the MOBIE imaging spectrograph for TMT

CFH12K is a 12 k by 8 k wide field imaging camera for the CFHT prime focus. The mosaic consists of twelve MIT Lincoln laboratories 2 k by 4 k thinned backside illuminated CCID20 devices. The devices’ operating parameters have been optimized to ensure the best data quality for use in broad and narrow band filter imaging mode. Adaptation to the CFHT prime focus environment included modifications to reduce the scattered light seen by the CFH12K. Science data taken by the camera has proven the success of CFHT’s new capability for 42 by 28 arcmin2 imaging with high resolution subarcsecond seeing.

GPC1 and GPC2: the Pan-STARRS 1.4 gigapixel mosaic focal plane CCD cameras with an on-sky on-CCD tip-tilt image compensation

The Multi-Object Broadband Imaging Echellette (MOBIE) is the seeing-limited, visible-wavelength imaging multiobject spectrograph (MOS) planned for first-light use on the Thirty Meter Telescope (TMT). The MOBIE project to date has been a collaboration lead by UC Observatories (CA), and including the UH Institute for Astronomy (HI), and the NAOJ (Tokyo, Japan). The current MOBIE optical design provides two color channels, spanning the 310–550nm and 550-1000nm passbands, and a combination of reflection gratings, prisms, and mirrors to enable direct imaging and three spectroscopic modes with resolutions (λ/triangle λ) of roughly 1000, 3000, and 8000 in both color channels, across a field of view that ranges from roughly 8x3 arcmin to 3x3 arcmin, depending on resolution mode. The conceptual design phase for the MOBIE instrument has been underway since 2008 and is expected to end in 2015. We report here on developments since 2010, including assembly of the current project team, instrument and camera optical designs, instrument control systems, atmospheric dispersion corrector, slit-mask exchange systems, collimator, dichroic and fold optics, dispersing and cross-dispersing optics, refracting cameras, shutters, filter exchange systems, science detector systems, and instrument structures.

MegaCam FAST: reducing data acquisition time on the Canada-France-Hawaii Telescope’s wide-field optical imager

We will report on the on-sky, on-CCD, tip-tilt image compensation performance of GPC1, the 1.4 gigapixel mosaic focal plane CCD camera for wide field surveys with a 7 square degree field of view. The camera uses 60 Orthogonal Transfer Arrays (OTAs) with a novel 4 phase pixel architecture and the STARGRASP controller for closed loop multi-guide star centroiding and image correction. The Pan-STARRS project is also constructing GPC2, the second 1.4 gigapixel camera using 64 OTAs. GPC2 will include design enhancements over GPC1 including a new generation of OTAs, titanium mosaic focal plane with adjustable three point kinematic mounts, cyro flex wiring and the recent software distributed over 32 controllers. We will discuss the design, cost, schedule, tools developed, shortcomings and future plans for the two largest digital cameras in the world.