HiPERCAM

 

HiPERCAM is a state-of-the-art high-speed, multi-band imaging photometer operating in the optical wavelength range, designed and constructed by the University of Sheffield, University of Warwick and University of Durham, to be used as a visitor instrument at GTC.

HiPERCAM is a high-speed camera for the study of rapid variability in the Universe. It will be able to image simultaneously in 5 optical channels - u' g' r' i' z' - at rates of over 1000 frames per second. The detectors will have a FoV of 3.9 arcmin and will employ custom-made frame-transfer CCDs, with 4 low noise outputs (2.5e-) and temperatures lower than 180K cooling giving essentially zero dark current. The two reddest CCDs will be deep-depletion devices with anti-etaloning, providing high quantum efficiencies across the optical spectrum with no fringing. The instrument will also incorporate scintillation noise correction via the conjugate-plane photometry technique.

Being a visitor instruments, this web page gives a minimum amount of informations. Users are invited to visit the full HiPERCAM web site maintained by University of Warwick


 

icon Index


 

icon Observing Modes

icon Imaging

HiPERCAM will be able to image simultaneously in 5 channels (u , g , r , i , z), rather than the 3 channels of ULTRACAM. HiPERCAM will be able to frame at (windowed) rates of well over 1 kHz, rather than the maximum of ∼300 Hz available with ULTRACAM. HiPERCAM will use detectors cooled to 180 K (much colder than ULTRACAM’s), with deep-depletion CCDs in the red channels, each equipped with anti-etaloning, resulting in much lower dark current, higher QE and lower fringing than ULTRACAM. Hence, as well as high-speed work, HiPERCAM will be ideal for scientific applications requiring deep (i.e. long exposure), single-shot spectral-energy distributions (SEDs), such as supernova light-curves, gamma-ray bursts and other transients. HiPERCAM will also be the first instrument to incorporate our novel scintillation-noise cor- rection technique, known as conjugate-plane photometry, significantly reducing noise in light curves of bright objects, such as transiting exoplanets. Furthermore, HiPERCAM will have a field of view of 3.9’ on the GTC, 50% more than that of ULTRACAM on the VLT. This will ensure more comparison stars are available for differential photometry, allowing us to observe brighter targets, such as the host stars of transiting exoplanets. In short, HiPERCAM will provide an order-of-magnitude improvement over ULTRACAM, thereby revolutionising the field of high-speed optical astrophysics. Operationally, HiPERCAM will adopt the successful ULTRACAM model. Hence, HiPERCAM will be a visitor instrument for the first few years of operation, with first light likely to be in Summer 2017 on the 4.2 m WHT on La Palma. After commissioning and first use on the WHT, it HiPERCAM will be moved to GTC in order to maximally exploit the revolutionary design of the instrument.



Feature Value
Number of simulnatenous colours 5 (u' g' r' i' z')
Readout noise 2.5e- at 200kHz
CCD temperature 180 K
Dark current 1e-/pix/hr
Longest exposure time 1800s
Highest frame rate >1000 Hz
FOV on GTC 3.9'
Probability of r'=11 95%
Scintillation correction Yes
Dummy CCD outputs Yes
Deep depletion Yes
QE at 700/800/900/1000nm 92%/87%/58%
Fringer suppression CCDs Yes
Fringe amplitude at 900nm <1%



HiPERCAM

Position of the five SDSS bands u'g'r'i'z'


HiPERCAM

The exposure time required to obtain a signal-to-noise ratio of 5 with HiPERCAM on the WHT (blue, lower curve) and GTC (red, upper curve), plotted as a function of g magnitude. The calculations assume La Palma dark time, 0.8” seeing, airmass 1, and that the HiPERCAM optics have 10% better throughput in g than ULTRACAM.

 

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icon Technical Details

HiPERCAM has an all-reflective optical system, consisting of 8 diamond-turned aluminum mirrors. Light enters the HiPERCAM cryo/vacuum space via an Infrasil entrance window. A linear slide at the telescope focal plane positions the Half-Wave Plate (HWP) and polarimetry/spectroscopy mask in/out of the beam. Two fold mirrors direct light into a 2-mirror collimator system which produces an image of the GTC secondary at the pupil location. In this region, HiPERCAM has selectable filters, a selectable Lyot mask for reduced background, and a selectable grism/prism wheel. The light then passes to the 4-mirror camera system. These are 16th-order polynomial aspheres, optimized to minimize the aberrations over the HiPERCAM field of view on the GTC. The camera focuses the light on a HAWAII-2RG 2048x2048-pixel detector array from Teledyne Imaging Systems.



HiPERCAM

Left-hand panel: Schematic of the light path through HiPERCAM, showing how the light is split into five beams by the four dichroic beamsplitters. Each beam is then re-imaged by a camera onto a CCD after passing through an SDSS u’, g’, r’, i’ or z’ filter. Right-hand panel: Detailed optical design of HiPERCAM, including the GTC collimator we shall procure (the three large elements on the left). Four of the five arms are clearly seen – the fifth comes out of the plane of the paper.



HiPERCAM

HiPERCAM single CCD configuration and readout structure



HiPERCAM

Hardware components of the HiPERCAM data acquisition system. The ESO New General detector Controller (NGC) is mounted on the instrument (left) in order to minimise the lengths of the video and clock/bias cables to the 5 HiPERCAM CCDs. The power for the NGC comes from a Power Supply Unit (PSU) mounted in the HiPERCAM electronics rack (upper right), which will be located adjacent to the instrument on the GTC elevation ring. Control of the NGC and receipt of data from the CCDs will be via a fibre running between a PC in the electronics rack (marked LLCU) and the NGC. The trigger cable running between the LLCU and the NGC will be used for GPS timestamping. The external GPS antenna (lower center) will be connected via fibre to the LLCU. Another fibre will connect the LLCU with the data reduction PC in the GTC control room (lower right).

 

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icon Observing strategy and Phase 2

We have already developed a Phase II submission system for ULTRACAM (as shown in the upper pannel of the figure below), which we shall adapt for use with HiPERCAM. The HiPERCAM team will ask the Principal Investigator of every successful telescope-time application to submit a Phase II entry for their observations, which will provide the HiPERCAM observers with all of the information they require to perform the observations in service mode.



HiPERCAM

HiPERCAM

The ULTRACAM Phase II web form (lower panel), which will form the basis of the HiPERCAM Phase II system (upper panel). The form provides the observers with all of the information they require to perform the observations in service mode. Entries include: PI contact details, link to a PDF copy of the observing proposal, target coordinates, finding charts, filters, exposure times, binning and windowing parameters, readout speeds, timing information, observing conditions required, and any additional comments.


HiPERCAM

A screenshot of the ULTRACAM finding chart and object-acquisition tool, which is similar to the tool we will be providing for HiPERCAM. The left-hand window is used to define the window parameters. The right-hand window shows the outline of the ULTRACAM CCD and allows the user to drag it around in order to locate the target and comparison stars in the 6 CCD windows. The resulting telescope right ascension, declination and rotator angle (shown in the left-hand window) are then passed to the Telescope Operator.

 

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icon HiPERCAM FITS data structure

HiPERCAM will write its data to FITS cubes, with one cube representing one run on a target. Each plane in the cube will contain data from all 5 CCDs at a particular time; since all 5 CCDs in HiPERCAM are exposed and read out simultaneously, only a single timestamp will be written for all 5 frames. The FITS cubes will also contain a full set of standard headers, such as the CCD parameters.

HiPERCAM can generate up to 4 MB of data per second. In the course of a typical night, therefore, it is possible to accumulate up to 144 GB of data, and up to 1 TB of data in the course of a typical week-long observing run.

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icon HiPERCAM data reduction

 

In order to handle the high data rates, HiPERCAM will have a dedicated pipeline data reduction system, which will be based on the successful ULTRACAM pipeline2. The data reduction pipeline will grab these frames from the data disk in the LLCU by sending HTTP requests to a file server running on the LLCU. The HiPERCAM data reduction pipeline has been designed to serve two apparently conflicting purposes. Whilst observing, it will act as a quick-look data reduction facility, with the ability to display images and generate light curves in real time, even when running at the highest data rates of up to 4 MB/s and at the highest frame rates of over 1 kHz. After observing, the pipeline will act as a fully-featured photometry reduction package, including optimal extraction.

To enable quick-look reduction whilst observing, the pipeline will keep many of its parameters hidden to the user and allow the few remaining parameters to be quickly skipped over to generate images and light curves in as short a time as possible. Conversely, when carefully reducing the data after a run, every single parameter can be tweaked in order to maximise the signal-to-noise ratio of the final data for analysis and publication.



HiPERCAM

A screenshot of the ULTRACAM pipeline data reduction system, which is similar to the software being developed for HiPERCAM. The left-hand window shows the image of the target (a are star) and bright comparison star on the three ULTRACAM CCDs. The series of circles define the software apertures used to determine the ux from the star and the sky. The right-hand window shows, from top to bottom, the diferential light curve of the target, the target x and y positions as a function of time, the sky transparency as a function of time (measured from the comparison star ux) and the seeing as a function of time (measured from the comparison star FWHM).

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icon Guaranteed Time - Reserved Targets

 

Target Name RA(2000) Dec(2000)
TBD TBD TBD

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icon HiPERCAM contact persons at GTC

 

contact email @ gtc.iac.es
David Garcia - main contact david.garcia
Nieves Castro nieves.castro

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icon More information:

 

 


Last modified: 05 April 2017