Prompt optical observations of GRB050319 with the Swift UVOT

The UVOT telescope on the Swift observatory has detected optical afterglow emission from GRB 050319. The flux declines with a power law slope of alpha = -0.57 between the start of observations some 230 seconds after the burst onset (90s after the burst trigger) until it faded below the sensitivity threshold of the instrument after ~5 x 10^4s. There is no evidence for the rapidly declining component in the early light curve that is seen at the same time in the X-ray band. The afterglow is not detected in UVOT shortward of the B-band, suggesting a redshift of about 3.5. The optical V-band emission lies on the extension of the X-ray spectrum, with an optical to X-ray slope of beta = -0.8. The relatively flat decay rate of the burst suggests that the central engine continues to inject energy into the fireball for as long as a few x 10^4s after the burst.Comment: 16 pages, 4 figures, accepted by Ap

Swift-UVOT detection of GRB 050318

We present observations of GRB 050318 by the Ultra-Violet and Optical Telescope (UVOT) on-board the Swift observatory. The data are the first detections of a Gamma Ray Burst (GRB) afterglow decay by the UVOT instrument, launched specifically to open a new window on these transient sources. We showcase UVOTs ability to provide multi-color photometry and the advantages of combining UVOT data with simultaneous and contemporaneous observations from the high-energy detectors on the Swift spacecraft. Multiple filters covering 1,800-6,000 Angstroms reveal a red source with spectral slope steeper than the simultaneous X-ray continuum. Spectral fits indicate that the UVOT colors are consistent with dust extinction by systems at z = 1.2037 and z = 1.4436, redshifts where absorption systems have been pre-identified. However, the data can be most-easily reproduced with models containing a foreground system of neutral gas redshifted by z = 2.8 +/- 0.3. For both of the above scenarios, spectral and decay slopes are, for the most part, consistent with fireball expansion into a uniform medium, provided a cooling break occurs between the energy ranges of the UVOT and Swifts X-ray instrumentation.Comment: 15 pages, 4 figures, ApJ Letters, in pres

Photometric Calibration of the Swift Ultraviolet/Optical Telescope

We present the photometric calibration of the Swift UltraViolet/Optical Telescope (UVOT) which includes: optimum photometric and background apertures, effective area curves, colour transformations, conversion factors for count rates to flux, and the photometric zero points (which are accurate to better than 4 per cent) for each of the seven UVOT broadband filters. The calibration was performed with observations of standard stars and standard star fields that represent a wide range of spectral star types. The calibration results include the position dependent uniformity, and instrument response over the 1600-8000A operational range. Because the UVOT is a photon counting instrument, we also discuss the effect of coincidence loss on the calibration results. We provide practical guidelines for using the calibration in UVOT data analysis. The results presented here supersede previous calibration results.Comment: Minor improvements after referees report. Accepted for publication in MNRA

Paper II: Calibration of the Swift ultraviolet/optical telescope

The Ultraviolet/Optical Telescope (UVOT) is one of three instruments onboard the Swift observatory. The photometric calibration has been published, and this paper follows up with details on other aspects of the calibration including a measurement of the point spread function with an assessment of the orbital variation and the effect on photometry. A correction for large scale variations in sensitivity over the field of view is described, as well as a model of the coincidence loss which is used to assess the coincidence correction in extended regions. We have provided a correction for the detector distortion and measured the resulting internal astrometric accuracy of the UVOT, also giving the absolute accuracy with respect to the International Celestial Reference System. We have compiled statistics on the background count rates, and discuss the sources of the background, including instrumental scattered light. In each case we describe any impact on UVOT measurements, whether any correction is applied in the standard pipeline data processing or whether further steps are recommended.Comment: Accepted for publication in MNRAS. 15 pages, 21 figures, 4 table

Ultraviolet, Optical, and X-Ray Observations of the Type Ia Supernova 2005am with Swift

We present ultraviolet and optical light curves in six broadband filters and grism spectra obtained by Swift's Ultraviolet/Optical Telescope for the Type Ia supernova SN2005am. The data were collected beginning about four days before the B-band maximum, with excellent coverage of the rapid decline phase and later observations extending out to 69 days after the peak. The optical and near UV light curve match well those of SN1992A. The other UV observations constitute the first set of light curves shorter than 2500 Angstroms and allow us to compare the light curve evolution in three UV bands. The UV behavior of this and other low redshift supernovae can be used to constrain theories of progenitor evolution or to interpret optical light curves of high redshift supernovae. Using Swift's X-Ray Telescope, we also report the upper limit to SN2005am's X-ray luminosity to be 1.77 x 10^40 erg s^-1 in the 0.3--10 keV range from 58,117 s of exposure time.Comment: 15 pages, including 3 figures and 2 tables, submitted to Astrophysical Journa

Swift panchromatic observations of the bright gamma-ray burst GRB050525a

The bright gamma-ray burst GRB050525a has been detected with the Swift observatory, providing unique multiwavelength coverage from the very earliest phases of the burst. The X-ray and optical/UV afterglow decay light curves both exhibit a steeper slope ~0.15 days after the burst, indicative of a jet break. This jet break time combined with the total gamma-ray energy of the burst constrains the opening angle of the jet to be 3.2 degrees. We derive an empirical `time-lag' redshift from the BAT data of z_hat = 0.69 +/- 0.02, in good agreement with the spectroscopic redshift of 0.61. Prior to the jet break, the X-ray data can be modelled by a simple power law with index alpha = -1.2. However after 300 s the X-ray flux brightens by about 30% compared to the power-law fit. The optical/UV data have a more complex decay, with evidence of a rapidly falling reverse shock component that dominates in the first minute or so, giving way to a flatter forward shock component at later times. The multiwavelength X-ray/UV/Optical spectrum of the afterglow shows evidence for migration of the electron cooling frequency through the optical range within 25000 s. The measured temporal decay and spectral indices in the X-ray and optical/UV regimes compare favourably with the standard fireball model for Gamma-ray bursts assuming expansion into a constant density interstellar medium.Comment: 31 pages, 7 figures, referee comments implemented, typo corrected in author list, accepted by Ap

Optical, Infrared, and Ultraviolet Observations of the X-Ray Flash GRB 050416A

We present ultraviolet, optical, and infrared photometry of the afterglow of the X-ray flash XRF 050416A taken between approximately 100 seconds and 36 days after the burst. We find an intrinsic spectral slope between 1930 and 22,200 Angstrom of beta = -1.14 +/- 0.20 and a decay rate of alpha = -0.86 +/- 0.15. There is no evidence for a change in the decay rate between approximately 0.7 and 4.7 days after the burst. Our data implies that there is no spectral break between the optical and X-ray bands between 0.7 and 4.7 days after the burst, and is consistent with the cooling break being redward of the K_s band (22,200 Angstrom) at 0.7 days. The combined ultraviolet/optical/infrared spectral energy distribution shows no evidence for a significant amount of extinction in the host galaxy along the line of sight to XRF 050416A. Our data suggest that the extragalactic extinction along the line of sight to the burst is only approximately A_V = 0.2 mag, which is significantly less than the extinction expected from the hydrogen column density inferred from $X$-ray observations of XRF 050416A assuming a dust-to-gas ratio similar to what is found for the Milky Way. The observed extinction, however, is consistent with the dust-to-gas ratio seen in the Small Magellanic Cloud. We suggest that XRF 050416A may have a two-component jet similar to what has been proposed for GRB 030329. If this is the case the lack of an observed jet break between 0.7 and 42 days is an illusion due to emission from the wide jet dominating the afterglow after approximately 1.5 days.Comment: 22 pages, 5 figures, LaTeX, AASTeX 5.2 Minor changes made in response to the referee's repor

Безопасность режимов лечения больных туберкулезом с множественной лекарственной устойчивостью возбудителя согласно новым рекомендациям ВОЗ 2019 г.

The objective: safety assessment of chemotherapy regimens compiled in accordance with the recommendations of World Health Organization (WHO), 2019, in patients with multiple drug resistant tuberculosis (MDR) in clinical practice settings.Subjects: Frequency, patterns, severity and risk factors of adverse events (AE) of chemotherapy regimens compiled in accordance with the WHO recommendations as of 2019 were analyzed in 122 patients with MDR and XDR respiratory tuberculosis within programmatic use of new anti-tuberculosis drugs.Results. The frequency of AE made 64.8% (95% CI 55.9-72.7%), gastrointestinal, cardiovascular and allergic events prevailed, the comorbidity was the risk factor of AE development (OR 6.44; 95% CI 1.91-21.76). AEs of with severity degrees 3-4 were observed in 24.6% (95% CI 17.8-33.0%), neurotoxic, ototoxic and hepatotoxic reactions prevailed; risk factors included female sex (OR 3.15, 95% CI 1.32-7.53) and complications of chemotherapy in the past (OR 3.50%, 95% CI 1.49-8.70). At least one anti-tuberculosis drug was canceled due to AE in 26.2% (95% CI 19.2-34.7%), and any of Group A drugs was canceled during the first 6 months of chemotherapy in 13.9% (95% CI 8.8-21.3%) of patients.Цель: оценка безопасности режимов химиотерапии, сформированных согласно принципам рекомендаций Всемирной организации здравоохранения (ВОЗ) 2019 г., у больных туберкулезом с множественной лекарственной устойчивостью (МЛУ) возбудителя в условиях клинической практики.Методы. Проведен ретроспективный анализ частоты, спектра, тяжести и факторов риска нежелательных реакций (НР) при реализации режимов химиотерапии согласно рекомендациям ВОЗ 2019 г. у 122 больных туберкулезом органов дыхания с МЛУ и широкой лекарственной устойчивостью в рамках программного применения новых противотуберкулезных препаратов.Результаты. Частота НР составила 64,8% (95%-ный ДИ 55,9-72,7%), преобладали гастроинтестинальные, сердечно-сосудистые и аллергические реакции, фактором риска являлось наличие сопутствующей патологии (ОШ = 6,44, 95%-ный ДИ 1,91-21,76). НР 3-4-й степени тяжести отмечены у 24,6% (95%-ный ДИ 17,8-33,0%), с преобладанием нейро-, ото- и гепатотоксических реакций, факторами риска являлись женский пол (ОШ = 3,15, 95%-ный ДИ 1,32-7,53) и осложнения химиотерапии в анамнезе (ОШ = 3,50, 95%-ный ДИ 1,49-8,70). Отмена минимум одного противотуберкулезного препарата в связи с НР потребовалась у 26,2% (95%-ный ДИ 19,2-34,7%), любого из препаратов группы А в течение первых 6 мес. химиотерапии ‒ у 13,9% (95%-ный ДИ 8,8-21,3%) пациентов

Эффективность и безопасность основанных на использовании бедаквилина режимов химиотерапии у больных туберкулезом органов дыхания: непосредственные и окончательные результаты

The objective of the study: to determine the efficacy and safety of chemotherapy regimens with bedaquiline in patients with respiratory tuberculosis in the context of everyday clinical practice with minimal non-inclusion criteria. Subjects and methods. In a prospective, open-label, non-randomized, single-center trial which included 315 patients, the efficacy and safety of chemotherapy regimens were evaluated, when prescribing a regimen the priority was given to bedaquiline, linezolid, levofloxacin/moxifloxacin, and cycloserine/terizidone. Patients were followed up for at least 24 months, 52.4% suffered from extensive drug resistance of M. tuberculosis (MTB), the majority of patients (50.8%) had a failure of the previous course of treatment, and serious co-morbidities were found in 89.5% of patients. Results. In 104 patients, the duration of treatment with bedaquiline was limited to standard 24 weeks, in 42 patients, it lasted for 36 weeks, in 56 patients – 48 weeks, and 94 patients received bedaquiline for more than 48 weeks. The increased duration of treatment with bedaquiline for more than 24 weeks provided a significant increase of treatment efficacy (regardless of drug resistance profile) from 66.2% (95% CI 54.4-77.9%) to 84.3% (95% CI 80.0-89.7%). The used regimens were well tolerated: serious adverse events (AE) were observed only in 27.6% of patients, and bedaquiline contribution to their development was not significant (bedaquiline had to be discontinued due to AE in 2.2% of cases). The range of AE practically did not differ from that when using only traditional anti-tuberculosis drugs.Цель: определить эффективность и безопасность режимов химиотерапии, включающих бедаквилин, у больных туберкулезом органов дыхания в условиях повседневной клинической практики при минимальных критериях невключения пациентов. Материалы и методы. В проспективном открытом нерандомизированном одноцентровом исследовании у 315 больных изучены эффективность и безопасность режимов химиотерапии туберкулеза, основанных на первоочередном назначении бедаквилина, линезолида, левофлоксацина/моксифлоксацина и циклосерина/теризидона. Длительность наблюдения за пациентами составила не менее 24 мес., широкая лекарственная устойчивость микобактерий туберкулеза (МБТ) имела место у 52,4%, большинство пациентов (50,8%) имело неэффективный предыдущий курс лечения, серьезная сопутствующая патология выявлена у 89,5% пациентов. Результаты исследования. У 104 пациентов длительность приема бедаквилина была ограничена стандартными 24 нед., у 42 – продлена до 36 нед., у 56 – до 48 нед., а 94 пациента получали бедаквилин более 48 нед. Увеличение длительности приема бедаквилина свыше 24 нед. обеспечило достоверное повышение эффективности лечения (вне зависимости от спектра лекарственной устойчивости МБТ) с 66,2% (95%-ный ДИ 54,4-77,9%) до 84,3% (95%-ный ДИ 80,0-89,7%). Отмечена хорошая переносимость используемых режимов: серьезные нежелательные побочные реакции (НПР) отмечены только у 27,6% пациентов, причем вклад бедаквилина в их развитие не является существенным (отмена бедаквилина из-за НПР потребовалась в 2,2% случаев). Спектр НПР практически не отличается от такового при использовании только традиционных противотуберкулезных препаратов

Very Early Optical Afterglows of Gamma-Ray Bursts: Evidence for Relative Paucity of Detection

Very early observations with the Swift satellite of gamma-ray burst (GRB) afterglows reveal that the optical component is not detected in a large number of cases. This is in contrast to the bright optical flashes previously discovered in some GRBs (e.g. GRB 990123 and GRB 021211). Comparisons of the X-ray afterglow flux to the optical afterglow flux and prompt gamma-ray fluence is used to quantify the seemingly deficient optical, and in some cases X-ray, light at these early epochs. This comparison reveals that some of these bursts appear to have higher than normal gamma-ray efficiencies. We discuss possible mechanisms and their feasibility for explaining the apparent lack of early optical emission. The mechanisms considered include: foreground extinction, circumburst absorption, Ly-alpha blanketing and absorption due to high redshift, low density environments, rapid temporal decay, and intrinsic weakness of the reverse shock. Of these, foreground extinction, circumburst absorption, and high redshift provide the best explanations for most of the non-detections in our sample. There is tentative evidence of suppression of the strong reverse shock emission. This could be because of a Poynting-flux-dominated flow or a pure non-relativistic hydrodynamical reverse shock.Comment: 22 pages, 5 figures. Accepted for publication in Ap