Calcareous nannofossils from the Eocene North Atlantic Ocean (IODP Expedition 342 Sites U1403-1411)

Integrated Ocean Drilling Program Expedition 342 (June-July 2012) cored nine sites and 18 holes (Sites U1403-U1411) on the J-Anomaly and the Southeast Newfoundland ridges in the NW Atlantic Ocean. These sites recovered sections ranging from Pleistocene to upper Albian, but the expedition particularly focussed on the recovery of expanded Paleogene successions with high quality microfossil preservation. This was achieved by choosing sites with thick packages of drift-type sediments on topographic highs that would maximise the preservation of carbonate. The expedition suceeded in recovering middle Eocene to lower Oligocene and upper Oligocene to lower Miocene high sedimentation rate sediment sequences with very well preserved microfossils. Highlights of the expedition include the recovery of continuous Eocene/Oligocene and Oligocene/Miocene boundaries, a Cretaceous-Paleogene boundary section with intact spherule layer, and Cenomanian/Turonian section with a 44 cm black shale. Here, we describe notable aspects of the Eocene nannofossil record, including the exceptional preservation and the evolution of several important Eocene groups: Nannotetrina, the Sphenolithus furcatolithoides group, the Reticulofenestra bisecta group and the Coccolithus gigas group. We also present a taxonomic overview of the Eocene nannofossil assemblages from Sites U1403-1411, illustrating 164 taxa and describing 25 new species (Blackites friedrichii, Blackites sextonii, Blackites subtilis, Calcidiscus scullyae, Clausicoccus norrisii, Coccolithus hulliae, Coccolithus opdykei, Cruciplacolithus nishii, Helicosphaera prolixa, Holodiscolithus agniniae, Holodiscolithus lippertii, Holodiscolithus liuii, Holodiscolithus whitesideae, Nannotetrina plana, Nannotetrina ruda, Neococcolithes purus, Neococcolithes radiatus, Pontosphaera brinkhuisii, Pontosphaera hollisii, Pontosphaera romansii, Pontosphaera wilsonii, Reticulofenestra magniscutum, Scyphosphaera interstincta, Semihololithus pseudobiskayae, Syracosphaera octiforma) and five new combinations (Blackites inversus, Pontosphaera zigzag, Reticulofenestra erbae, Reticulofenestra isabellae, Umbilicosphaera elliptica)

Muted calcareous nannoplankton response at the Middle/Late Eocene Turnover event in the western North Atlantic

Key extinctions in two major planktonic foraminiferal groups and high taxic turnover in radiolarians have led to the identification of the Middle/Late Eocene Turnover (MLET) and point towards significant palaeoclimatic and/or palaeoceanographic changes at around 38 million years ago. Here we present quantitative calcareous nannofossil data from Ocean Drilling Program Site 1052 (Blake Nose, western North Atlantic) in order to investigate the response of phytoplankton during the MLET. Our data show only minor shifts in taxon abundance, with no strong trends identified through the interval and no nannofossil origination or extinction events associated with the MLET. The assemblages are characterised by the dominance of neritic braarudosphaerids and eurytopic reticulofenestrids. The increased abundance of warm to temperate and mesotrophic nannofossils (Reticulofenestra reticulata, Reticulofenestra bisecta and Coccolithus pelagicus) in and around the MLET occur against a backdrop of cooling, as indicated by oxygen isotopes, suggesting that changing nutrient conditions was the principle driver of these shifts in the nannoplankton assemblage. This is further supported by an increase in radiolarian accumulation rates at this time. The lack of response in the calcareous nannoplankton relative to the zooplanktonic planktonic foraminifera and radiolaria demonstrates the contrasting sensitivity to environmental change in these different plankton groups, with radiolarians showing the highest degree of change at the MLET and the nannoplankton showing little or none

Rapid GRB Follow-up with the 2-m Robotic Liverpool Telescope

We present the capabilities of the 2-m robotic Liverpool Telescope (LT), owned and operated by Liverpool John Moores University and situated at ORM, La Palma. Robotic control and scheduling of the LT make it especially powerful for observations in time domain astrophysics including: (i) rapid response to Targets of Opportunity: Gamma Ray Bursts, novae, supernovae, comets; (ii) monitoring of variable objects on timescales from seconds to years, and (iii) observations simultaneous or coordinated with other facilities, both ground-based and from space. Following a GRB alert from the Gamma Ray Observatories HETE-2, INTEGRAL and Swift we implement a special over-ride mode which enables observations to commence in about a minute after the alert, including optical and near infrared imaging and spectroscopy. In particular, the combination of aperture, site, instrumentation and rapid response (aided by its rapid slew and fully-opening enclosure) makes the LT excellently suited to help solving the mystery of the origin of optically dark GRBs, for the investigation of short bursts (which currently do not have any confirmed optical counterparts) and for early optical spectroscopy of the GRB phenomenon in general. We briefly describe the LT's key position in the RoboNet-1.0 network of robotic telescopes.Comment: 6 pages, 2 figures, to appear in the proceedings of Interacting Binaries: Accretion, Evolution and Outcomes, 4-10 July 2004, Cefalu, Sicily, Italy, eds. Antonelli et a

Coccolithophore calcification response to past ocean acidification and climate change

Anthropogenic carbon dioxide emissions are forcing rapid ocean chemistry changes and causing ocean acidification (OA), which is of particular significance for calcifying organisms, including planktonic coccolithophores. Detailed analysis of coccolithophore skeletons enables comparison of calcite production in modern and fossil cells in order to investigate biomineralization response of ancient coccolithophores to climate change. Here we show that the two dominant coccolithophore taxa across the Paleocene–Eocene Thermal Maximum (PETM) OA global warming event (~56 million years ago) exhibited morphological response to environmental change and both showed reduced calcification rates. However, only Coccolithus pelagicus exhibits a transient thinning of coccoliths, immediately before the PETM, that may have been OA-induced. Changing coccolith thickness may affect calcite production more significantly in the dominant modern species Emiliania huxleyi, but, overall, these PETM records indicate that the environmental factors that govern taxonomic composition and growth rate will most strongly influence coccolithophore calcification response to anthropogenic change

Difference image photometry with bright variable backgrounds

Over the last two decades the Andromeda Galaxy (M31) has been something of a test-bed for methods aimed at obtaining accurate time-domain relative photometry within highly crowded fields. Difference imaging methods, originally pioneered towards M31, have evolved into sophisticated methods, such as the Optimal Image Subtraction (OIS) method of Alard & Lupton (1998), that today are most widely used to survey variable stars, transients and microlensing events in our own Galaxy. We show that modern difference image (DIA) algorithms such as OIS, whilst spectacularly successful towards the Milky Way bulge, may perform badly towards high surface brightness targets such as the M31 bulge. Poor results can occur in the presence of common systematics which add spurious flux contributions to images, such as internal reflections, scattered light or fringing. Using data from the Angstrom Project microlensing survey of the M31 bulge, we show that very good results are usually obtainable by first performing careful photometric alignment prior to using OIS to perform point-spread function (PSF) matching. This separation of background matching and PSF matching, a common feature of earlier M31 photometry techniques, allows us to take full advantage of the powerful PSF matching flexibility offered by OIS towards high surface brightness targets. We find that difference images produced this way have noise distributions close to Gaussian, showing significant improvement upon results achieved using OIS alone. We show that with this correction light-curves of variable stars and transients can be recovered to within ~10 arcseconds of the M31 nucleus. Our method is simple to implement and is quick enough to be incorporated within real-time DIA pipelines. (Abridged)Comment: 12 pages. Accepted for publication in MNRAS. Includes an expanded discussion of DIA testing and results, including additional lightcurve example

The Automatic Real-Time GRB Pipeline of the 2-m Liverpool Telescope

The 2-m Liverpool Telescope (LT), owned by Liverpool John Moores University, is located in La Palma (Canary Islands) and operates in fully robotic mode. In 2005, the LT began conducting an automatic GRB follow-up program. On receiving an automatic GRB alert from a Gamma-Ray Observatory (Swift, INTEGRAL, HETE-II, IPN) the LT initiates a special override mode that conducts follow-up observations within 2-3 min of the GRB onset. This follow-up procedure begins with an initial sequence of short (10-s) exposures acquired through an r' band filter. These images are reduced, analyzed and interpreted automatically using pipeline software developed by our team called "LT-TRAP" (Liverpool Telescope Transient Rapid Analysis Pipeline); the automatic detection and successful identification of an unknown and potentially fading optical transient triggers a subsequent multi-color imaging sequence. In the case of a candidate brighter than r'=15, either a polarimetric (from 2006) or a spectroscopic observation (from 2007) will be triggered on the LT. If no candidate is identified, the telescope continues to obtain z', r' and i' band imaging with increasingly longer exposure times. Here we present a detailed description of the LT-TRAP and briefly discuss the illustrative case of the afterglow of GRB 050502a, whose automatic identification by the LT just 3 min after the GRB, led to the acquisition of the first early-time (< 1 hr) multi-color light curve of a GRB afterglow.Comment: PASP, accepted (8 pages, 3 figures

The Angstrom Project Alert System: real-time detection of extragalactic microlensing

The Angstrom Project is undertaking an optical survey of stellar microlensing events across the bulge region of the Andromeda Galaxy (M31) using a distributed network of two-meter class telescopes. The Angstrom Project Alert System (APAS) has been developed to identify in real time candidate microlensing and transient events using data from the Liverpool and Faulkes North robotic telescopes. This is the first time that real-time microlensing discovery has been attempted outside of the Milky Way and its satellite galaxies. The APAS is designed to enable follow-up studies of M31 microlensing systems, including searches for gas giant planets in M31. Here we describe the APAS and we present a few example light curves obtained during its commissioning phase which clearly demonstrate its real-time capability to identify microlensing candidates as well as other transient sources.Comment: 4 pages, submitted to ApJ Letter

Early GRB Optical and Infrared Afterglow Observations with the 2-m Robotic Liverpool Telescope

We present the first optical observations of a Gamma Ray Burst (GRB) afterglow using the 2-m robotic Liverpool Telescope (LT), which is owned and operated by Liverpool John Moores University and situated on La Palma. We briefly discuss the capabilities of LT and its suitability for rapid follow-up observations of early optical and infrared GRB light curves. In particular, the combination of aperture, site, instrumentation and rapid response (robotic over-ride mode aided by telescope's rapid slew and fully-opening enclosure) makes the LT ideal for investigating the nature of short bursts, optically-dark bursts, and GRB blast-wave physics in general. We briefly describe the LT's key position in the RoboNet-1.0 network of robotic telescopes. We present the LT observations of GRB041006 and use its gamma-ray properties to predict the time of the break in optical light curve, a prediction consistent with the observations.Comment: 4 pages, 1 figure, accepted for publication in Il nuovo cimento (4th Workshop Gamma-Ray Bursts in the Afterglow Era, Rome, 18-22 October 2004

Optical and X-ray characteristics of a newly discovered narrow-line QSO : RX J1334.2+3759

We report the discovery of a narrow-line QSO (NLQSO) RX J1334.2+3759 with a steep soft X-ray spectrum. Soft X-ray emission from the NLQSO is highly variable. Changes in the intensity by a factor of about 2 have been detected in the ROSAT PSPC observations of RX J1334.2+3759 on time scales of 20000-40000s. Rapid variability events have also been observed from RX J1334.2+3759. The most extreme variable event has Delta L/Delta t = (1.95+/-1.02)E42 erg/s/s corresponding to a change in intensity by a factor of about 4 within 400s. The PSPC spectra of the NLQSO can be well represented by a power-law of photon index 3.8, modified by an absorbing column local to the source over and above that due to our own Galaxy. The intrinsic soft X-ray luminosity of RX J1334.2+3759 is estimated to be 2.2E44 erg/s in the energy band of 0.1-2.0 keV. The optical spectrum of RX J1334.2+3759 is typical of the NLS1 galaxies showing strong Balmer Hbeta, Halpha, and forbidden line [O III]5007. Fe II multiplets, usually present in the optical spectra of NLS1 galaxies, are also detected from RX J1334.2+3759. Decomposition of the Hbeta and Halpha line profiles shows the presence of narrow (FWHM = 880 km/s) and broad (FWHM = 2850 km/s) components in the spectrum of RX J1334.2+3759. The narrow-line region of RX J1334.2+3759 appears to be significantly different from those of normal Seyfert galaxies. A possible explanation for the observed properties of the narrow line region and the broad line region is suggested in terms of density enhancements.Comment: 13 pages with 9 figures, LaTex. To appear in MNRA