Time Of Breakout Research Articles

Do Energy Prices Put the Tourism Sector at Risk?

This paper studies the effect of a shock in the hospitality sector, namely the energy price increase, with stated preference methods and performs the subsequent analysis with a mixture of quantitative and qualitative tools. The hospitality sector is very important and is the backbone of the tourism industry worldwide. We designed and administered two semi-structured anonymous questionnaires that were sent randomly to recipients for completion. One questionnaire investigated tourists’ behavior, visit and their stay and their spending intentions, whereas the second questionnaire investigated the hoteliers/managers estimations and beliefs on energy price increases and whether or how this price increase would have an effect on tourists’ behavior and their visit, stay and spending intentions in the destination. Through two surveys, we collected answers to questions for three consecutive years—2021: representing the past/before the energy crisis, 2022: the present/the time of the crisis breakout and 2023: the future/after the crisis outbreak. Overall, a lower tourist expenditure is found for the future due to the energy price shock, but there are no significant differences between the answers of the two groups. Our results are insightful for tourism policy makers, hoteliers and managers and particularly those economies that rely heavily on tourism, e.g., island economies.

Novel approach to TNSA enhancement using multi-layered targets—a numerical study

In the context of ion acceleration driven by ultra-high contrast lasers using thin foils, there is a clear trend towards increasing ion energy when the target thickness is reduced. However when the target is too thin and the prepulse strength is not negligible, this trend is reversed due to degradation of the target mainly caused by prepulse-induced shocks, among other effects (thermal plasma expansion, early onset of transparency, etc). In this paper, we propose and motivate the use of multi-layered targets for the purpose of enhancing the target normal sheath acceleration mechanism by means of attenuating the shock waves inside the target. It is demonstrated through hydrodynamic simulations that multi-layered targets, composed of alternating layers of plastic and gold, can significantly delay the time of shock wave breakout, reducing the shock energy that breaks out of the target and shortening the plasma scale-length. This approach paves the way for enhanced laser-driven ion acceleration using thinner targets even for relatively low contrast lasers.

Excellence VS Relevance in Engineering Education in the Era of the Fourth Industrial Revolution

Engineering is crucial for economic development in developed and developing countries. With various changes taking place globally over the years, it has had influence on all aspect of human endeavor and we are now at a time of pervasive breakout of technologies known as the fourth industrial revolution. This study therefore conceptualizes excellence VS relevance in engineering education in the era of the fourth industrial revolution by first demystifying what the fourth industrial revolution is and then conceptualizing excellence and relevance in engineering education. Findings from the study revealed that Findings from the study revealed that the world is at a stage of massive changes and this requires solutions to these numerous changes. It was also found out that excellence and relevance are not new as it is a common term used across various spheres of human life especially within the university where excellence in research and learning is emphasized. The study recommended that STEM education should be encouraged across board so as to develop the skills necessary in the fourth industrial age and also effort should be made at intensifying action on adopting some of the technologies that are emerging in the fourth industrial revolution especially in the developing countries.

S1143 High Frequency of Gastrointestinal, Hepatic, and Nutritional Disorders in Hospitalized Patients With COVID-19 Infection: An Early Institutional Experience

INTRODUCTION: COVID-19 illness is caused by a coronavirus called SARS-CoV-2. Many reports on hospitalized patients with COVID-19 highlight the pulmonary, renal and cardiac involvement. However, there is limited information about GI, Hepatic and Nutritional disorders in the natural history of hospitalized patients with COVID-19. Furthermore, the impact of racial and ethnic differences on outcome and mortality has not been well examined. We undertook a retrospective study for all the adult patients (n = 146) who were hospitalized with suspected COVID-19 infection to evaluate these factors, at the time of early breakout of COVID-19. METHODS: A retrospective study was conducted for the patients (n = 146) who were hospitalized with COVID-19 infection, between 1st Feb to 1st Jun, 2020. RESULTS: Of the 146 patients, 52% were females, 68% were African Americans (AA), 24% Caucasians, 6% Hispanics. The mean age of presentation was 62 years (±17, SD). A large number of patients(41%) were obese(BMI >30). Gastrointestinal manifestations were observed in about 56% of patients, which included diarrhea (24%), nausea (19%), anorexia (14%) and emesis (13%). Other GI manifestations were GI Bleeding (10%) and dysgeusia (3%). Majority of patients (64%) had elevated one or more liver function test, AST was elevated in about 60% of the patients. The other abnormal labs were inflammatory markers (CRP, Ferritin and LDH), and coagulation parameters (D-Dimer, PT/INR). Significant number of patients were Hypertensive(65%) and Diabetics(30%). Acute kidney injury was noted in 30% of the cohort. Overall mortality rate in this group of patients was 24%. The underlying primary cause of death was Respiratory Failure (n = 19), Sepsis(n = 12), GI Bleeding(n = 2), Multi Organ Failure (n = 1) and in these patients. It is noteworthy that the the mortality in AA was 72%, Caucasian was 25%. CONCLUSION: These observations from a single institution demonstrate a higher proportion of AA population who were afflicted with COVID-19 infection. A large number of these patients were obese with associated comorbidities and developed a very high mortality (30%) secondary to COVID-19. Interestingly, a significant number of patients from this group showed higher frequency of GI, hepatic and nutritional derangements. Lastly, the biomarkers of coagulation such as D-Dimer, PT/INR as well as inflammatory markers like CRP, Ferritin, and LDH were elevated in large number of patients. This study highlights involvement of several additional organ systems in patients with COVID-19.

Two Predictions of Supernova: GRB 130427A/SN 2013cq and GRB 180728A/SN 2018fip

Abstract On 2018 July 28, GRB 180728A triggered Swift satellites and, soon after the determination of the redshift, we identified this source as a type II binary-driven hypernova (BdHN II) in our model. Consequently, we predicted the appearance time of its associated supernova (SN), which was later confirmed as SN 2018fip. A BdHN II originates in a binary composed of a carbon–oxygen core (COcore) undergoing SN, and the SN ejecta hypercritically accrete onto a companion neutron star (NS). From the time of the SN shock breakout to the time when the hypercritical accretion starts, we infer the binary separation ≃3 × 1010 cm. The accretion explains the prompt emission of isotropic energy ≃3 × 1051 erg, lasting ∼10 s, and the accompanying observed blackbody emission from a thermal convective instability bubble. The new neutron star (νNS) originating from the SN powers the late afterglow from which a νNS initial spin of 2.5 ms is inferred. We compare GRB 180728A with GRB 130427A, a type I binary-driven hypernova (BdHN I) with isotropic energy >1054 erg. For GRB 130427A we have inferred an initially closer binary separation of ≃1010 cm, implying a higher accretion rate leading to the collapse of the NS companion with consequent black hole formation, and a faster, 1 ms spinning νNS. In both cases, the optical spectra of the SNe are similar, and not correlated to the energy of the gamma-ray burst. We present three-dimensional smoothed-particle-hydrodynamic simulations and visualizations of the BdHNe I and II.

Aspherical Supernovae: Effects on Early Light Curves

Abstract Early light from core-collapse supernovae, now detectable in high-cadence surveys, holds clues to a star and its environment just before it explodes. However, effects that alter the early light have not been fully explored. We highlight the possibility of nonradial flows at the time of shock breakout. These develop in sufficiently nonspherical explosions if the progenitor is not too diffuse. When they do develop, nonradial flows limit ejecta speeds and cause ejecta–ejecta collisions. We explore these phenomena and their observational implications using global, axisymmetric, nonrelativistic FLASH simulations of simplified polytropic progenitors, which we scale to representative stars. We develop a method to track photon production within the ejecta, enabling us to estimate band-dependent light curves from adiabatic simulations. Immediate breakout emission becomes hidden as an oblique flow develops. Nonspherical effects lead the shock-heated ejecta to release a more constant luminosity at a higher, evolving color temperature at early times, effectively mixing breakout light with the early light curve. Collisions between nonradial ejecta thermalize a small fraction of the explosion energy; we will address emission from these collisions in a subsequent paper.

THE OBSERVABLE SIGNATURES OF GRB COCOONS

ABSTRACT As a long gamma-ray burst (GRB) jet propagates within the stellar atmosphere it creates a cocoon composed of an outer Newtonian shocked stellar material and an inner (possibly relativistic) shocked jet. The jet deposits erg into this cocoon. This is comparable to the energies of the GRB and of the accompanying supernova, yet the cocoon’s signature has been largely ignored. The cocoon radiates a fraction of this energy as it expands, following the breakout from the star, and later as it interacts with the surrounding matter. We explore the possible signatures of this emission and outline a framework to calculate them from the conditions of the cocoon at the time of the jet breakout. The cocoon signature depends strongly on the, currently unknown, mixing between the shocked jet and shocked stellar material. With no mixing the γ-ray emission from the cocoon is so bright that it should have been already detected. The lack of such detections indicates that some mixing must take place. For partial and full mixing the expected signals are weaker than regular GRB afterglows. However, the latter are highly beamed while the former are wider. Future optical, UV, and X-ray transient searches, like LSST, ZTF, ULTRASAT, ISS-Lobster, and others, will most likely detect such signals, providing a wealth of information on the progenitors and jets of GRBs. While we focus on long GRBs, analogous (but weaker) cocoons may arise in short GRBs. Their signatures might be the most promising electromagnetic counterparts for gravitational wave signals from compact binary mergers.

MAGNETAR-DRIVEN SHOCK BREAKOUT AND DOUBLE-PEAKED SUPERNOVA LIGHT CURVES

ABSTRACT The light curves of some luminous supernovae are suspected to be powered by the spindown energy of a rapidly rotating magnetar. Here we describe a possible signature of the central engine: a burst of shock breakout emission occurring several days after the supernova explosion. The energy input from the magnetar inflates a high-pressure bubble that drives a shock through the pre-exploded supernova ejecta. If the magnetar is powerful enough, that shock will near the ejecta surface and become radiative. At the time of shock breakout, the ejecta will have expanded to a large radius ( ∼ 10 14 cm) so that the radiation released is at optical/ultraviolet wavelengths ( T eff ≈ 20,000 K) and lasts for several days. The luminosity and timescale of this magnetar-driven shock breakout are similar to the first peak observed recently in the double-peaked light curve of SN-LSQ14BDQ. However, for a large region of model parameter space, the breakout emission is predicted to be dimmer than the diffusive luminosity from direct magnetar heating. A distinct double-peaked light curve may therefore only be conspicuous if thermal heating from the magnetar is suppressed at early times. We describe how such a delay in heating may naturally result from inefficient dissipation and thermalization of the pulsar wind magnetic energy. Without such suppression, the breakout may only be noticeable as a small bump or kink in the early luminosity or color evolution, or as a small but abrupt rise in the photospheric velocity. A similar breakout signature may accompany other central engines in supernovae, such as a black hole accreting fallback material.

Concurrent Velocimetry and Flash X-ray Characterization of Impact and Penetration in an Armor Ceramic

We present a methodology for concurrent Photon Doppler Velocimetry (PDV) and in-situ flash X-ray imaging during ballistic impact of metallic penetrators into monolithic armor grade ceramic targets. Tungsten heavy alloy long rod penetrators were launched from a smooth bore cannon into silicon carbide targets at velocities of 0.753 and 1.403mm/μs. Penetrator lengths and penetration depths were measured as a function of time using an array of four 450kV flash X-ray sources and digital film. A four channel PDV system coupled to a 16GHz oscilloscope was used to measure the velocity history of the penetrator and at three positions on the back surface of the target. This experimental technique shows great promise for measurements of the dwell time, penetration velocity, and the time of final break-out from the back of the target.

GENERALIZED SEMI-ANALYTICAL MODELS OF SUPERNOVA LIGHT CURVES

We present generalized supernova (SN) light curve (LC) models for a variety of power inputs. We provide an expression for the power input that is produced by self-similar forward and reverse shocks in SN ejecta - circumstellar matter (CSM) interaction. We find that this ejecta-CSM interaction luminosity is in agreement with results from multi-dimensional radiation hydrodynamics simulations in the optically-thin case. We develop a model for the case of an optically-thick CSM by invoking an approximation for the effects of radiative diffusion. In the context of this model, we provide predictions for the time of forward shock break-out from the optically-thick part of the CSM envelope. We also introduce a hybrid LC model that incorporates ejecta-CSM interaction plus Ni-56 and Co-56 radioactive decay input. We fit this hybrid model to the LC of the Super-Luminous Supernova (SLSN) 2006gy. We find that this model provides a better fit to the LC of this event than previously presented models. We also address the relation between Type IIL and Type IIn SN with ejecta-CSM interaction models. Forward and reverse shock power input due to CSM interaction can produce the LCs of Type IIn SNe in terms of duration, shape and decline rate. This model can also produce LCs that are symmetric in shape around peak luminosity. We conclude that the observed LC variety of SNe Type IIn and of the SLSNe is likely to be a byproduct of the large range of conditions relevant to significant ejecta-CSM interaction as a power source.

The Type IIb SN 2008ax: spectral and light curve evolution

We present spectroscopy and photometry of the He-rich supernova (SN) 2008ax. The early-time spectra show prominent P-Cygni H lines, which decrease with time and disappear completely about 2 months after the explosion. In the same period He I lines become the most prominent spectral features. SN 2008ax displays the ordinary spectral evolution of a Type IIb supernova. A stringent pre-discovery limit constrains the time of the shock breakout of SN 2008ax to within only a few hours. Its light curve, which peaks in the B band about 20 d after the explosion, strongly resembles that of other He-rich core-collapse supernovae. The observed evolution of SN 2008ax is consistent with the explosion of a young Wolf-Rayet (of WNL type) star, which had retained a thin, low-mass shell of its original H envelope. The overall characteristics of SN 2008ax are reminiscent of those of SN 1993J, except for a likely smaller H mass. This may account for the findings that the progenitor of SN 2008ax was a WNL star and not a K supergiant as in the case of SN 1993J, that a prominent early-time peak is missing in the light curve of SN 2008ax, and that H alpha is observed at higher velocities in SN 2008ax than in SN 1993J.

Magnetar-energized supernova explosions and gamma-ray burst jets

In this paper, we report on the early evolution of a core-collapse supernova explosion following the birth of a magnetar with the dipolar magnetic field of B = 10 15 G and the rotational period of 2 ms, which was studied by means of axisymmetric general relativistic magnetohydrodynamic simulations. In this study, we use realistic equation of state and take into account the cooling and heating associated with emission, absorption, annihilation, and scattering of neutrinos; the neutrino transport is treated in the optically-thin regime. The supernova explosion is initiated via introducing into the initial solution the 'radiation bubble', whose total thermal energy is comparable with the typical energy of supernova ejecta. The numerical models exhibit highly collimated magnetically driven jets very early on. The jets are super-Alfvenic but remain subfast until the end of the simulations (t = 0.2 s). The power released in the jets is about 3 × 10 50 erg s -1 which implies the spin-down time of ≃37 s. The total rotational energy of the magnetar, E ≃ 10 52 erg, is sufficient to drive a hypernova but it is not clear as to how large a fraction of this energy can be transferred to the stellar ejecta. Given the observed propagation speed of the jets, ν p ≃ 0.17c, they are expected to traverse the progenitor in few seconds and after this most of the released rotational energy would be simply carried away by these jets into the surrounding space. Three-dimensional effects such as the kink mode instability may reduce the jet propagation speed and increase the amount of energy transferred by the jets to the supernova ejecta. Our results provide the first more or less self-consistent numerical model of a central engine capable of producing, in the supernova setting and on a long-term basis, collimated jets with sufficient power to explain long-duration gamma-ray bursts (GRBs) and their afterglows. Although the flow speed of our jets is relatively low, only ν j ≃ 0.5c, the cooling of protoneutron star will eventually result in much higher magnetization of its magnetosphere and ultrarelativistic asymptotic speeds of the jets. Given the relatively long cooling time-scale, we still expect the jets to be only weakly relativistic by the time of break-out. This leads to a model of GRB jets with a systematic longitudinal variation in the Lorentz factor which may have specific observational signatures both in the prompt and in the afterglow emission. The simulations also reveal quasi-periodic ejection of plasma clouds into the jet on a time-scale of 20 ms related to the large-scale global oscillation of magnetar's magnetosphere caused by the opening-closing of the dead zone field lines. These kinds of central engine variability may be partly responsible for the internal shocks of GRB jets and the short-time variability of their gamma-ray emission.

ChandraObservations of SN 2004et and the X‐Ray Emission of Type II‐P Supernovae

We report the X-ray detection of the Type II-P (plateau) supernova SN 2004et in the spiral galaxy NGC 6946, using the Chandra X-Ray Observatory. The position of the X-ray source was found to agree with the optical position within ~0.4. Chandra also surveyed the region before the 2004 event, finding no X-ray emission at the location of the progenitor. For the postexplosion observations, a total of 202, 151, and 158 photons were detected in three pointings, each 29 ks in length, on 2004 October 22, November 6, and December 3, respectively. The spectrum of the first observation is best fit by a thermal model with a temperature of kT = 1.3^(+∞)_(-0.8) keV and a line-of-sight absorption of N_H = (1.0 ± 1.0) × 10^(22) cm^(-2). The inferred unabsorbed luminosity (0.4-8 keV) is ~4 × 10^(38) erg s^(-1), adopting a distance of 5.5 Mpc. A comparison between hard and soft counts on the first and third epochs indicates a softening over this time, although there is an insufficient number of photons to constrain the variation of temperature and absorption by spectral fitting. We model the emission as arising from the reverse-shock region in the interaction between the supernova ejecta and the progenitor wind. For a Type II-P supernova with an extended progenitor, the cool shell formed at the time of shock wave breakout from the star can affect the initial evolution of the interaction shell and the absorption of radiation from the reverse shock. The observed spectral softening might be due to decreasing shell absorption. We find a presupernova mass-loss rate of (2-2.5) × 10^(-6) M_⊙ yr^(-1) for a wind velocity of 10 km s^(-1), which is in line with expectations for a Type II-P supernova.

Gamma-ray burst jet dynamics and their interaction with the progenitor star

The association of at least some long gamma-ray bursts with type Ic supernova explosions has been established beyond reasonable doubt. Theoretically, the challenge is to explain the presence of a light hyper-relativistic flow propagating through a massive stellar core without losing those properties. We discuss the role of the jet-star interaction in shaping the properties of the outflow emerging on the surface of the star. We show that the nature of the inner engine is hidden from the observer for most of the evolution, well beyond the time of the jet breakout on the stellar surface. The discussion is based on analytical considerations as well as high resolution numerical simulations. Finally, the observational consequences of the scenario are addressed in light of the present capabilities.

Real temperature calculation of shock wave driven by sub-nanosecond laser pulses

Time history of thermal band emission of a shock front, when breakout from aluminium target into vacuum, has been calculated numerically. It is assumed that the shock is produced by irradiation of high intensity sub-nanosecond pulsed laser on the surface of aluminium planar targets in vacuum. The opacity of dense plasma at the shock front and in the vacuum–aluminium interface, and its effects on thermal emissions was considered in these calculations. Using the results of an experiment that was recently reported and those of our model, the real temperature of the shock front was estimated. In that experiment simultaneous measurements of the colour temperature of dense plasma in a shock front, and the shock velocity at the time of shock breakout from the aluminium targets into the vacuum were reported for the study of the equation of state (EOS). The results of the model show a good agreement with the SESAME library EOS.

Trapped Protostellar Winds and Their Breakout

Observations show that high-velocity jets stem from deeply embedded young stars, which may still be experiencing infall from their parent cloud cores. Yet theory predicts that, early in this buildup, any outgoing wind is trapped by incoming material of low angular momentum. As collapse continues and brings in more rapidly rotating gas, the wind can eventually break out. Here we model this transition by following the motion of the shocked shell created by impact of the wind and a rotating, collapsing envelope. We first demonstrate, both analytically and numerically, that our previous, quasi-static solutions are dynamically unstable. Our present, fully time-dependent calculations include cases both where the wind is driven back by infall to the stellar surface and where it erupts as a true outflow. For the latter, we find that the time of breakout is 5 × 104 yr for wind speeds of 200 km s-1. The reason for the delay is that the shocked material, including the swept-up infall, must be able to climb out of the star's gravitational potential well. We explore the critical wind speed necessary for breakout as a function of the mass transport rates in the wind and infall, as well as the cloud rotation rate Ω0 and time since the start of infall. Breakout does occur for realistic parameter choices. The actual breakout times would change if we relaxed the assumption of perfect mixing between the wind and infall material. Our expanding shells do not exhibit the collimation of observed jets but continue to expand laterally. To halt this expansion, the density in the envelope must fall off less steeply than in our model.

Young Circumstellar Disks near Evolved Massive Stars and Supernovae

There is increasing evidence that low-mass stars with circumstellar disks can be born close to massive stars, in some cases within tenths of a parsec. If the disks have lifetimes greater than those of the more massive stars, they are exposed to radiation fields and gas flows from the late evolutionary phases and supernovae of the massive stars. The fast flows from supernovae are likely to give some stripping of mass from the disks but do not typically lead to complete disruption of the disks. In the slow wind from a red supergiant star, there is the possibility of gravitational accretion of wind matter onto the circumstellar disk. In the supernova explosion of a red supergiant, the radiative flux at the time of shock breakout can heat and ionize a nearby disk, leading to transient, narrow-line emission. There are consequences for the solar nebula if it was born ~0.2 pc from a massive star that became a red supergiant. Accretion from the wind could supply a substantial amount of 26Al to the disk. The high radiative luminosity of the eventual supernova could lead to the melting of dust grains and the formation of chondrules. The passage of the supernova ejecta could drive a shock wave in the disk, heating it.

High-energy Emission from Supernovae and Remnants

An early burst of energetic radiation is expected from a supernova at the time of shock breakout. This emission has not been directly observed but has been inferred from the photoionization around SN 1987A. X-ray emission has been detected from core-collapse supernovae in the days to years after the explosion as they interact with their circumstellar winds. Young Galactic supernova remnants provide the possibility of determining the composition structure of the ejecta through X-ray spectroscopy. An exciting finding for older remnants is that a number of remnants that appear to be interacting with molecular gas may be sources of high-energy γ-ray emission. The clumpy structure of molecular clouds has implications for the structure expected in high-energy emission. Finally, the field of γ-ray-line spectroscopy is beginning to yield results relevant to the explosive nucleosynthesis of radionuclides in supernovae.

Factors influencing the distribution of diatoms and other algae in the Ross Sea

Quantitative microscopic analyses of sediment trap samples collected in the Ross Sea between January 1990 and February 1992 reveal striking temporal and spatial differences in algal bloom composition and size. Trap samples from the southwestern Ross Sea (site A, 76°30′S, 167°30′E) were dominated by the diatom Fragilariopsis curia (maximum of 92%), a species associated with both sea ice and the retreating ice edge in the Ross Sea. This species was probably seeded by melting congelation ice. Highest flux of diatom valves to both upper and lower traps in the 1991–1992 season occurred as a distinct event in mid‐February 1991, after which flux decreased by 1 to 3 orders of magnitude. As overall flux decreased, an increase in relative abundance of Chaetoceros resting spores and the open water species Thalassiosira antarctica was observed in the lower trap, suggesting some localized lateral advection. In the south central Ross Sea (site B, 76°30′, S 175°W), algal diversity was much higher, with a greater contribution of nondiatom material. The prymnesiophyte Phaeocystis antarctica, dinoflagellates, and cysts of unknown affinity were much more common than at site A, as were the diatoms Fragilariopsis cylindrus, Fragilariopsis kerguelensis, and Thalassiosira gracilis. Highest diatom flux occurred later (February 20 to March 6,1991) at this site and was an order of magnitude lower as compared to maximum flux at site A. Distinct differences in bloom size and composition between sites A and B may be a function of upper water column structure, differences in the amount of sea ice melting, and the type of sea ice present at the time of ice breakout (congelation versus pack ice). Despite rich surface productivities, lower silica flux to the seafloor at site B results from the higher proportion of nonsiliceous algae. At site C (72°30′S, 172°30′E), in the northwestern Ross Sea, diatoms again dominated algal flux; however, assemblage composition differed from that observed at both sites A and B. Relative abundance of F. curta was lower, averaging 60–70%, while the remainder of the assemblage was made up of F. cylindrus, other more robust species of Fragilariopsis, and Chaetoceros resting spores. Algal flux at site C is intermediate in style between sites A and B. Significantly, spatial differences in diatom assemblages noted above appear to be reflected in seafloor surface sediments, suggesting that downcore diatom data provide an interpretable record of paleoproductivity in the Ross Sea.

SN 1987A in the UV: the Progenitor Star, the Reddening and the Possible Detection of a UV Light Echo

AbstractSome special issues to which IUE observations have provided crucial insight are presented. The arguments leading to the definitive identification of Sk−69°202 as the progenitor of the LMC supernova are reviewed, and a preliminary determination of the reddening toward SN 1987A, based on the IUE spectra of stars 2 and 3, is discussed. Recent observations at the predicted position of the SN ultraviolet light echo are reported, and evidence, albeit circumstantial, is provided that a UV echo has been detected. Some consequences of this result are explored. The relevance of this observation lies in the fact that a UV echo, if really detected, would give direct information of the spectrum of the SN at the time of the shock breakout.