Liverpool Telescope Technical Note 1: Telescope and IO:O Throughput

We measure the absolute photon efficiency of the Liverpool Telescope using observations of photometric standard stars and a throughput model of the IO:O instrument. Over a period of 1 year following mirror re-coating the telescope transmission is in the range 73-79% over 4000-10000 Angstroms. Transmission in the u'-band (~3500 Angstroms) is slightly lower at 65%. Immediately following mirror re-coating the throughput is shown to be consistent within 4% to predictions for two reflections from bare-aluminium-coated optics. The telescope throughput (two reflections) degrades at a rate ~0.0002 mag/day. Also presented are the effective wavelengths and widths for the u',g',r',i',z',B,V broad-band filters, taking into account all optical components of the system

Using Wireless Sensor Networks for Aged Care: The Patient's Perspective

This paper presents the findings of a qualitative study on the perceptions and thoughts of elderly people on the use of current sensor network technology for assisted aged care. Focus groups of elderly people were presented with examples of current sensor nodes and example scenarios of their use, and then invited to provide input on a range of issues surrounding the design and use of the technology. The focus group findings were verified with a health care professional as a control measure. This study examines sensing based interaction, implementation methodologies and user acceptance issues specifically for the elderly, and from the elderly's perspective. A significant finding of the study is that the two most important factors for elderly acceptance of sensor technology are cost and contro

MOPTOP: A multi-colour optimised optical polarimeter

We present the design and science case for the Liverpool Telescope's fourth-generation polarimeter; MOPTOP: a Multicolour OPTimised Optical Polarimeter which is optimised for sensitivity and bi-colour observations. We introduce an optimised polarimeter which is as far as possible limited only by the photon counting efficiency of the detectors. Using a combination of CMOS cameras, a continuously rotating half-wave plate and a wire grid polarising beamsplitter, we predict we can accurately measure the polarisation of sources to ∼ 1% at ∼19th magnitude in 10 minutes on a 2 metre telescope. For brighter sources we anticipate much low systematics (0.1%) than our current polarimeter. The design also gives the ability to measure polarization and photometric variability on timescales as short as a few seconds. Overall the instrument will allow accurate measurements of the intra-nightly variability of the polarisation of sources such as gamma-ray bursts and blazars (AGN orientated with the jet pointing toward the observer), allowing the constraint of magnetic field models revealing more information about the formation, ejection and collimation of jets. © 2016 SPIE

The impact of population-based faecal occult blood test screening on colorectal cancer mortality:a matched cohort study

BACKGROUND: Randomised trials show reduced colorectal cancer (CRC) mortality with faecal occult blood testing (FOBT). This outcome is now examined in a routine, population-based, screening programme. METHODS: Three biennial rounds of the UK CRC screening pilot were completed in Scotland (2000–2007) before the roll out of a national programme. All residents (50–69 years) in the three pilot Health Boards were invited for screening. They received a FOBT test by post to complete at home and return for analysis. Positive tests were followed up with colonoscopy. Controls, selected from non-pilot Health Boards, were matched by age, gender, and deprivation and assigned the invitation date of matched invitee. Follow-up was from invitation date to 31 December 2009 or date of death if earlier. RESULTS: There were 379 655 people in each group (median age 55.6 years, 51.6% male). Participation was 60.6%. There were 961 (0.25%) CRC deaths in invitees, 1056 (0.28%) in controls, rate ratio (RR) 0.90 (95% confidence interval (CI) 0.83–0.99) overall and 0.73 (95% CI 0.65–0.82) for participants. Non-participants had increased CRC mortality compared with controls, RR 1.21 (95% CI 1.06–1.38). CONCLUSION: There was a 10% relative reduction in CRC mortality in a routine screening programme, rising to 27% in participants

Using dummy and pseudo-dummy amplifiers to correct for common mode CCD noise

Some modern CCD designs provide a dummy readout amplifier that is designed to be operated with the same clock and bias signals as the true amplifier in order to provide a measurement of clock induced and other common-mode noise signals in the true amplifier readout. In general the dummy output signal is subtracted electronically from the true output signal in a differential input preamplifier before digitization. Here we report on an alternative approach where both signals are digitized and the subtraction done in software. We present the results of testing this method of operation using the ARC SDSU generation III CCD controllers and an e2v CCD231 device and find it works well, allowing a noise figure of ~ 2:2 electrons to be reached in the presence of significantly higher (~ 6 electrons) pickup noise. In addition we test the effectiveness of using unused (but still genuine) readout amplifiers on the detector to provide a pseudo-dummy output, which we also find effective in cancelling common mode noise. This provides the option of implementing noise reduction on CCDs that are not equipped with dummy outputs at the expense of overall readout speed

Automated Spectral Reduction Pipelines

The Liverpool Telescope automated spectral data reduction pipelines perform both removal of instrumental signatures and provide wavelength calibrated data products promptly after observation. Unique science drivers for each of three instruments led to novel hardware solutions which required reassessment of some of the conventional CCD reduction recipes. For example, we describe the derivation of bias and dark corrections on detectors with neither overscan or shutter. In the context of spectroscopy we compare the quality of at fielding resulting from different algorithmic combinations of dispersed and non-dispersed sky and lamp flats in the case of spectra suffering from 2D spatial distortions. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only