Andrew J. Adamson

JHK observations of faint standard stars in the Mauna Kea Observatories near-infrared photometric system

JHK photometry in the Mauna Kea Observatories (MKO) near-infrared system is presented for 115 stars. Of these stars, 79 are United Kingdom Infrared Telescope (UKIRT) standards from Hawarden et al., and 42 are Las Campanas Observatory (LCO, or NICMOS) standards from Persson et al. The average brightness of the sample in all three bandpasses is 11.5 mag, with a range between 10 and 15. The average number of nights each star was observed is 4, and the average of the internal error of the final results is 0.011 mag. These JHK data agree with those reported by other groups to 0.02 mag, for stars in common, which is consistent with the uncertainties. The measurements are used to derive colour transformations between the MKO JHK photometric system and the UKIRT, LCO and Two Micron All-Sky Survey (2MASS) systems. The 2MASS–MKO data scatter by 0.05 mag for redder stars, which is consistent with a dependence on stellar luminosity: the 2MASS J bandpass includes H2O features in dwarfs and the MKO K bandpass includes CO features in giants. We stress that colour transformations derived for stars whose spectra contain only weak features cannot give accurate transformations for objects with strong absorption features within one, but not both, of the filter bandpasses. We find evidence of systematic effects at the 0.02 mag level in the photometry of stars with J < 11 and H,xa0K < 10.5 presented here and in Hawarden et al. This is due to an underestimate of the linearity correction for stars observed with the shortest exposure times; very accurate photometry of stars approaching the saturation limits of infrared detectors which are operated in double-read mode is difficult to obtain. There are indications that four stars in the sample, GSPC S705-D, FS 116 (B216-b7), FS 144 (Ser-EC84) and FS 32 (Feige 108), may be variable. There are 84 stars in the sample presented here that have 11 < J < 15 and 10.5 < H,xa0K < 15, are not suspected to be variable, and have magnitudes with an estimated error ≤0.027 mag; 79 of these have an error of ≤0.020 mag. These represent the first published high-accuracy JHK stellar photometry in the MKO near-infrared photometric system; we recommend these objects be employed as primary standards for that system.

L′ and M′ standard stars for the Mauna Kea Observatories Near-Infrared system

We present L′ and M′ photometry, obtained at the United Kingdom Infrared Telescope (UKIRT) using the Mauna Kea Observatories Near-Infrared (MKO-NIR) filter set, for 46 and 31 standard stars, respectively. The L′ standards include 25 from the in-house ‘UKIRT Bright Standards’ with magnitudes deriving from Elias et al. and observations at the Infrared Telescope Facility in the early 1980s, and 21 fainter stars. The M′ magnitudes derive from the results of Sinton and Tittemore. We estimate the average external error to be 0.015 mag for the bright L′ standards and 0.025 mag for the fainter L′ standards, and 0.026 mag for the M′ standards. The new results provide a network of homogeneously observed standards, and establish reference stars for the MKO system, in these bands. They also extend the available standards to magnitudes which should be faint enough to be accessible for observations with modern detectors on large and very large telescopes.

A shallow though extensive H2 2.122-μm imaging survey of Taurus–Auriga–Perseus – I. NGC 1333, L1455, L1448 and B1

We discuss wide-field near-infrared (near-IR) imaging of the NGC 1333, L1448, L1455 and B1 star-forming regions in Perseus. The observations have been extracted from a much larger narrow-band imaging survey of the Taurus-Auriga-Perseus complex. These H-2 2.122-mu m observations are complemented by broad-band K imaging, mid-IR imaging and photometry from the Spitzer Space Telescope, and published submillimetre CO J = 3-2 maps of high-velocity molecular outflows. We detect and label 85 H-2 features and associate these with 26 molecular outflows. Three are parsec-scale flows, with a mean flow lobe length exceeding 11.5 arcmin. 37 (44 per cent) of the detected H-2 features are associated with a known Herbig-Haro object, while 72 (46 per cent) of catalogued HH objects are detected in H-2 emission. Embedded Spitzer sources are identified for all but two of the 26 molecular outflows. These candidate outflow sources all have high near-to-mid-IR spectral indices (mean value of alpha similar to 1.4) as well as red IRAC 3.6-4.5 mu m and IRAC/MIPS 4.5-24.0 mu m colours: 80 per cent have [3.6]-[4.5] > 1.0 and [4.5]-[24] > 1.5. These criteria - high alpha and red [4.5]-[24] and [3.6]-[4.5] colours - are powerful discriminants when searching for molecular outflow sources. However, we find no correlation between alpha and flow length or opening angle, and the outflows appear randomly orientated in each region. The more massive clouds are associated with a greater number of outflows, which suggests that the star formation efficiency is roughly the same in each region.

OHANA phase II: a prototype demonstrator of fiber-linked interferometry between very large telescopes

The OHANA (Optical Hawaiian Array for Nanoradian Astronomy, means family in Hawaiian) aims at making a large and sensitive optical/IR array with the Mauna Kea 3 to 10 meter telescopes. Telescopes will be linked with single-mode fibers to carry the coherence of the beams from the output of the telescopes adaptive optics systems to the beam combination units. The project has been divided into three phases. The first phase is dedicated to the injection of light into single-mode fibers and to the building of the injection module. The third phase is the realization of the complete array and its use by a wide community of astronomers. In the second phase, a prototype OHANA will be built and the shortest baselines will be explored. The baselines will be located in the South-East and West parts of the observatory. An extra baseline will possibly link the two groups of telescopes if infrastructure comply with it. This phase II OHANA will already be the longest and most sensitive optical/IR interferometer built. Scientific targets will span young stellar objects, extragalactic sources and other types of astronomical topics which require both high angular resolution and sensitivity. This paper reviews the main characteristics of the phase II interferometer.

Design status of WFCAM: a wide-field camera for the UK Infrared Telescope

An update on the design status of the UKIRT Wide Field Camera (WFCAM) is presented. WFCAM is a wide field infrared camera for the UK Infrared Telescope, designed to produce large scale infrared surveys. The complete system consists of a new IR camera with integral autoguider and a new tip/tilt secondary mirror unit. WFCAM is being designed and built by a team at the UK Astronomy Technology Centre in Edinburgh, supported by the Joint Astronomy Centre in Hawaii. The camera uses a novel quasi-Schmidt camera type design, with the camera mounted above the UKIRT primary mirror. The optical system operates over 0.7 - 2.4 μm and has a large corrected field of view of 0.9° diameter. The focal plane is sparsely populated with 4 2K x 2K Rockwell HAWAII-2 MCT array detectors, giving a pixel scale of 0.4 arcsec/pixel. A separate autoguider CCD is integrated into the focal plane unit. Parallel detector controllers are used, one for each of the four IR arrays and a fifth for the autoguider CCD.

ORAC: a modern observing system for UKIRT

The steady improvement in telescope performance at UKIRT and the increase in data acquisition rates led to a strong desired for an integrated observing framework that would meet the needs of future instrumentation, as well as providing some support for existing instrumentation. Thus the Observatory Reduction and Acquisition Control (ORAC) project was created in 1997 with the goals of improving the scientific productivity in the telescope, reducing the overall ongoing support requirements, and eventually supporting the use of more flexibly scheduled observing. The project was also expected to achieve this within a tight resource allocation. In October 1999 the ORAC system was commissioned at the United Kingdom Infrared Telescope.

OHANA Phase III: scientific operation of an 800-meter Mauna Kea interferometer

Once the proof of concept of the OHANA Array has been demonstrated, the Phase II capabilities can be put into regular science operation, and the OHANA facility can be upgraded to extend interferometric operation to include all of the telescopes of the OHANA Consortium member observatories. This will constitute the Phase III of OHANA. The technical developments required will be relatively straight-forward. Longer fiber sets will be procured (fiber losses are not a limiting factor at the OHANA scale). An enhanced delay line capability will be needed in order to exploit longer baselines with good sky coverage and ample super-synthesis (several compact, multi-pass long optical delay concepts are under investigation). The scheduling and operation modes of an instrument such as OHANA present interesting opportunities and complications. We envision a place for both collaborative consortium science, based on mutual allocation of facility access, and PI-driven access, based on telescope access exchange between consortium members. The most potentially successful mode of operation would imply a community driven model, open to proposals from the different time allocation comittees. This poster looks at possible methods of allocation and operation, inspired by the UKIRT infrared survey (UKIDSS), the European VLBI, and the very interesting possibility of a Mauna Kea telescope time exchange scheme. The issue of data property is of course intimately tied with the proposal/operation system, and means of data availability and distribution are discussed, along with data interpretation tools, which may be modeled on existing systems such as the ISC at Caltech or the JMMC in France. when weighed against the UV coverage, the potential science and the uniqueness of this project, all these issues are worth an in depth study. Discussions are starting as to an OHANA Operation Committee, the goal of which would be to discuss, define and eventually carry out operational modes. The goal, of course, is for the Operation Committee to handle the details of multi-telescope scheduling in a way that will be transparent to the scientist who merely seeks the observational results.

Science returns of flexible scheduling on UKIRT and the JCMT

The Joint Astronomy Centre operates two telescopes at the Mauna Kea Observatory: the James Clerk Maxwell Telescope, operating in the submillimetre, and the United Kingdom Infrared Telescope, operating in the near and thermal infrared. Both wavelength regimes benefit from the ability to schedule observations flexibly according to observing conditions, albeit via somewhat different site quality criteria. Both UKIRT and JCMT now operate completely flexible schedules. These operations are based on telescope hardware which can quickly switch between observing modes, and on a comprehensive suite of software (ORAC/OMP) which handles observing preparation by remote PIs, observation submission into the summit database, conditions-based programme selection at the summit, pipeline data reduction for all observing modes, and instant data quality feedback to the PI who may or may not be remote from the telescope. This paper describes the flexible scheduling model and presents science statistics for the first complete year of UKIRT and JCMT observing under the combined system.

Seeing statistics at the upgraded 3.8m UK Infrared Telescope (UKIRT)

From 1991 until 1997, the 3.8m UK Infrared Telescope (UKIRT) underwent a programme of upgrades aimed at improving its intrinsic optical performance. This resulted in images with a FWHM of 0.17 at 2.2 μm in September 1998. To understand and maintain the improvements to the delivered image quality since the completion of the upgrades programme, we have regularly monitored the overall atmospheric seeing, as measured by radial displacements of supaperture images (i.e. seeing-generated focus fluctuations), and the delivered image diameters. The latter have been measured and recorded automatically since the beginning of 2001 whenever the facility imager UFTI (UKIRT Fast Track Imager) has been in use. In this paper we report the results of these measurements. We investigate the relation between the delivered image diameter and the RMS atmospheric seeing (as measured by focus fluctuations, mentioned above). We find that the best seeing occurs in the second half of the night, generally after 2am HST and that the best seeing occurs in the summer between the months of July and September. We also find tha the relationship between Zrms and delivered image diameter is uncertain. As a result Zrms frequently predicts a larger FWHM than that measured in the images. Finally, we show that there is no correlation between near-infrared seeing measured at UKIRT and sub-mm seeing measured at the Caltech Submillimetre Observatory (CSO).

Past and future evolution of Gemini operations

We review the multiple changes in Gemini Observatory operations over the past decade, and discuss their effect on scientific productivity. The initial mix of queue and classical programs, allocated by Partner-based Time Allocation Committees (TACs), has evolved to include “Large and Long” programs allocated from a pool by a dedicated TAC, a popular “Fast-turnaround” mode allocated by a novel “proposer review” system, and we are now receiving increasing numbers of visiting instruments, scheduled in blocks. Observations are carried out in queue (service), classical (visitor), and priority visitor (visitors execute both their own observations and the queue) modes. Gemini is already an important facility for following up time-domain discoveries. Looking ahead, Gemini South will be partnered by LSST on Cerro Pachón and both Gemini telescopes will put a significant fraction of observing time into responding to the LSST alert stream; we review Gemini’s positioning to fulfil this role and anticipate additional changes in our operational model, user software and data reduction to accommodate it.