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The Cirebon Coastal Area (CCA) has the potential for the growth of mangrove forests and their rehabilitation efforts. Therefore, to support the rehabilitation efforts, an inventory of the existing mangrove forest is needed. It is to facilitate the management and monitoring of mangrove areas. One of the methods is by investigating and mapping the existing mangrove forest area. Remote sensing data Sentinel-2A imagery (10 m) and UAV imagery were used in this study. The purpose of this study is to map the spatial distribution of mangrove forests in the CCA. The method used is the supervised classification for Sentinel-2A with the Mahalanobis Distance, Maximum Likelihood, Minimum Distance, and Parallelepiped algorithms. We compared the four algorithms. Visual interpretation method for UAV images that will be used as reference data. So that the results of the visual interpretation of the UAV image are used as reference data to test the accuracy of the classification results from the sentinel-2A image. The accuracy test method used is area-based accuracy assessment. The results showed that the use of the supervised classification algorithm on sentinel-2A images was the most effective as the highest accuracy value, namely maximum likelihood, was 85.68%. Based on the classification results, the existing area of mangrove forest in CCA is 317.81 Ha. This research contributes to assessing the most effective supervised classification algorithm for mapping the spatial distribution of mangrove forests in the Cirebon coastal area which is integrated with UAV imagery as a data reference for accuracy assessment. [ABSTRACT FROM AUTHOR]

We present the design of laser-driven materials experiments conducted at the OMEGA-EP laser facility. These experiments measure ripple growth via the Rayleigh-Taylor (RT) instability in solid copper to understand its dynamic strength under high pressure and high temperature conditions. Historically, these ramp-compression experiments have been carried out by releasing a reservoir of layered materials across a gap and onto a second stack of materials that encase the target sample. In the experimental designs considered in this manuscript the target stack containing the copper sample is directly irradiated by the laser; ramp-compression is achieved through laser pulse shaping. The sample is designed to follow two different loading paths to megabar pressures: first, using a smooth ramp, yielding a low-temperature adiabatic path; second by shocking to a given pressure and then accelerating the sample along a high-temperature adiabat path. Strength is inferred from experimentally obtained measurements using face-on radiography of ripple growth that is compared to simulated growth using different strength models. [ABSTRACT FROM AUTHOR]

Monocrystalline tantalum with orientations [100] and [111] was subjected to laser driven compression at laser energies of 350 to 685 J, generating shock amplitudes varying from 15 to 100 GPa. The laser beam, with a beam spot diameter of ~1 mm, created a crater of significant depth (~ 80 to ~ 200 |im). Twins were observed just below the crater surface (~ 42 |im) by back-scattered SEM. Transmission electron microscopy (TEM) revealed profuse mechanical twinning within a distance from the energy deposition surface of ~ 1.5 mm at 684 J compression power, corresponding to an approximate pressure of 35 GPa. The decay of the pulse through the specimens was accompanied by an attendant decrease in the density of shock-generated dislocations. Microhardness measurements were conducted on the recovered samples. The experimentally measured dislocation densities and threshold stress for twinning are compared with predictions using analyses based on the constitutive response and the similarities and differences are discussed in terms of the mechanisms of defect generation. [ABSTRACT FROM AUTHOR]

Nanocrystalline tantalum was prepared by high pressure torsion from monocrystalline [100] stock, yielding a grain size of 70nm. It was subjected to laser driven compression at energy levels of ~ 350 J to ~ 850 J in the Omega facility (LLE, U. of Rochester) with corresponding pressures as high as ~ 170 GPa. The laser beam created a crater of significant depth (~ 100 μm). Transmission electron microscopy (TEM) revealed dislocations in the grains but no twins in contrast with monocrystalline tantalum. Hardness measurements were conducted and show the same trend as single crystalline tantalum. The grain size was found to increase close to the energy deposition surface due to the thermomechanical excursion. [ABSTRACT FROM AUTHOR]

We present the application of short-pulse laser-driven hard x-rays (>40 keV) for the direct density measurement of iron compressed by a laser-driven shock. By using an on-shot calibration of the line density, we are able to obtain line densities even though the x-ray source is not monochromatic. The consequences for the line density measurement using a polychromatic source are discussed in detail, as well as the calibration method we propose to solve this problem. [ABSTRACT FROM AUTHOR]

The 0.6-m Super-LOTIS (Livermore Optical Transient Imaging System) telescope is a fully robotic system dedicated to the search for prompt optical emission from gamma-ray bursts. The telescope began routine operations from its Steward Observatory site atop Kitt Peak in April 2000. We summarize the current capabilities of the system and present some recent scientific results. A progress report is given on the upgrade of the system to allow for simultaneous near-infrared (NIR) and optical imaging. This upgrade will be completed to coincide with the launch of the Swift GRB explorer mission in mid-2004. Swift will have the capability of localizing very high redshift GRBs but absorption by the Ly-α forest prohibits optical detection of z > 5 bursts. NIR observations can detect GRBs out to z ∼ 10. Although Swift is a multi-wavelength observatory capable of observing GRBs from the hard x-rays to the optical it has no NIR capability. The upgraded Super-LOTIS telescope will fill this NIR need. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

LOTIS (Livermore Optical Transient Imaging System) and Super-LOTIS are automatic telescope systems that measure very prompt optical emission occurring within seconds of the gamma-ray energy release during a Gamma Ray Burst (GRB). Unlike hour-todays delayed afterglow measurements, very early measurements will contain information about the GRB progenitor. To accomplish this, we developed and have been operating automated telescopes that rapidly image GRB coordinate error boxes in response to triggers distributed by the GRB Coordinate Distribution Network (GCN). LOTIS, located in California, consists of 4 cameras each with a different astronomical filter (B, V, R, open) that can respond to GRB triggers within 5 s. Super-LOTIS can point to any part of the sky within 30 s upon receipt of a GCN trigger and its sensitivity is as deep as V=17~19 depending on the integration times. Since the shutdown of the CGRO, there has been no real-time GRB triggers that enable the LOTIS systems to measure real-time GRB counterpart fluxes as of May 2001. This paper describes performance of these systems. We also present our plan to replace the current optical CCD camera on the Super-LOTIS to a near infrared camera to be able to probe dusty GRB environment. [ABSTRACT FROM AUTHOR]

Gamma Ray Bursts (GRBs) are brief, randomly located, releases of gamma-ray energy from unknown celestial sources that occur almost daily. The study of GRBs has undergone a revolution in the past three years due to an international effort of follow-up observations of coordinates provided by Beppo/SAX and IPN GRB. These follow-up observations have shown that GRBs are at cosmological distances and interact with surrounding material as described by the fireball model. However, prompt optical counterparts have only been seen in one case and are therefore very rare or much dimmer than the sensitivity of the current instruments. Unlike later time afterglows, prompt optical measurements would provide information on the GRB progenitor. LOTIS is the very first automated and dedicated telescope system that actively utilizes the GRB Coordinates Network (GCN) and it attempts to measure simultaneous optical light curve associated with GRBs. After 3 years of running, LOTIS has responded to 75 GRB triggers. The lack of any optical signal in any of the LOTIS images places numerical limits on the surrounding matter density, and other physical parameters in the environment of the GRB progenitor. This paper presents LOTIS results and describes other prompt GRB follow-up experiments including the Super-LOTIS at Kitt Peak in Arizona. [ABSTRACT FROM AUTHOR]

We present an update on our ongoing effort to establish a dedicated observation program with an automated 0.6 meter telescope system that can detect GRB optical signals from 30 s to many hours after the start of the burst. The Super-LOTIS telescope has a 0.8°×0.8° field-of-view, is sensitive to V 17∼19 objects, depending on the integration times, and will be placed at the Kitt Peak National Observatory. This paper presents technical aspects of this telescope and first results from initial operations at LLNL. Utilizing real-time coordinates from BATSE, BeppoSAX, XTE, IPN, HETE-2 and INTEGRAL, our LOTIS and SLOTIS systems will measure prompt GRB optical light curves that will enhance our understanding of GRBs. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

GRB 990123 established the existence of prompt optical emission from gamma-ray bursts (GRBs). The Livermore Optical Transient Imaging System (LOTIS) has been conducting a fully automated search for this kind of simultaneous low energy emission from GRBs since October 1996. Although LOTIS has obtained simultaneous, or near simultaneous, coverage of the error boxes obtained with BATSE, IPN, XTE, and BeppoSAX for several GRBs, image analysis resulted in only upper limits. The unique gamma-ray properties of GRB 990123, such as very large fluence (top 0.4%) and hard spectrum, complicate comparisons with more typical bursts. We scale and compare gamma-ray properties, and in some cases afterglow properties, from the best LOTIS events to those of GRB 990123 in an attempt to determine whether the prompt optical emission of this event is representative of all GRBs. Furthermore, using LOTIS upper limits in conjunction with the relativistic blast wave model, we weakly constrain the GRB and afterglow parameters such as density of the circumburster medium and bulk Lorentz factor of the ejecta. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]