Browsing by Author "Pereyra, Antonio"
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Item Open Access A new optical polarization catalog for the small magellanic cloud: the magnetic field structure(IOP Publishing, 2015-06-10) Lobo Gomes, Aiara; Magalhães, Antônio Mário; Pereyra, Antonio; Vilega Rodrigues, CláudiaWe present a new optical polarimetric catalog for the Small Magellanic Cloud (SMC). It contains a total of 7207 stars, located in the northeast (NE) and Wing sections of the SMC and part of the Magellanic Bridge. This new catalog is a significant improvement compared to previous polarimetric catalogs for the SMC. We used it to study the sky-projected interstellar magnetic field structure of the SMC. Three trends were observed for the ordered magnetic field direction at position angles (PAs) of (65◦ ± 10◦), (115◦ ± 10◦), and (150◦ ± 10◦). Our results suggest the existence of an ordered magnetic field aligned with the Magellanic Bridge direction and SMC’s Bar in the NE region, which have PAs roughly at 115◦.4 and 45◦, respectively. However, the overall magnetic field structure is fairly complex. The trends at 115◦ and 150◦ may be correlated with the SMC’s bimodal structure, observed in Cepheids’ distances and HI velocities. We derived a value of Bsky = (0.947 ± 0.079) µG for the ordered sky-projected magnetic field, and δB = (1.465±0.069) µG for the turbulent magnetic field. This estimate of Bsky is significantly larger (by a factor of ∼ 10) than the line of sight field derived from Faraday rotation observations, suggesting that most of the ordered field component is on the plane of the sky. A turbulent magnetic field stronger than the ordered field agrees with observed estimates for other irregular and spiral galaxies. For the SMC the Bsky/δB ratio is closer to what is observed for our Galaxy than other irregular dwarf galaxies.Item Open Access Characterizing a CCD detector for astronomical purposes: OAUNI Project(Universidad Nacional de Ingeniería, 2016-08) Pereyra, Antonio; Zevallos, María I.; Ricra, José; Tello, Julio C.El presente trabajo verificó las capacidades del detector CCD que forma parte del instrumental asociado al proyecto del Observatorio Astronómico de la UNI. Fueron medidos la respuesta lineal del detector CCD de la cámara SBIG STXL6303E, así como su ganancia y el ruido de lectura asociados. La respuesta lineal a la luz incidente del detector es extremadamente lineal (R2=99.99%), su ganancia efectiva es 1.65 ± 0.1 e-/ADU y su ruido de lectura 12.2 e-. Estos valores están de acuerdo con los proporcionados por el fabricante. Se confirma que el detector analizado es extremadamente preciso para realizar medidas con fines astronómicos.Item Open Access Detección y caracterización de planetas extrasolares desde el Perú(Universidad Nacional de Ingeniería, 2019) Ricra Mayorca, Jose Luis; Pereyra, AntonioSe presentan observaciones en la banda Rc de los tránsitos de los exoplanetas WASP-80 b, COROT-2 b y WASP-46 b obtenidos con el telescopio de 0.5m del Observatorio Astronómico de la Universidad Nacional de Ingeniería (OAUNI). Se aplicaron diversas técnicas para optimizar el proceso de fotometría y así obtener la curva de luz con la menor dispersión posible para cada exoplaneta. El modelamiento de los tránsitos se realizó empleando los códigos JKTEBOP y TAP. En el caso de los exoplanetas WASP-80 b y WASP-46 b se pudieron determinar sus radios, semiejes mayores, periodos orbitales, tiempos centrales de transito e inclinación de los planos orbitales respectivos. En el caso de COROT-2 b, la intensa actividad de la estrella y la presencia de una compañera visual dificultaron el cálculo de sus parámetros físicos y orbitales; a pesar de eso, los tiempos centrales de transito calculados en esta tesis junto con los obtenidos en estudios anteriores, permitieron mejorar la precisión del periodo orbital de este exoplaneta. En todos los casos, los parámetros obtenidos se encuentran acordes entre sí y con la literatura, estando a menos de 2σ de los valores obtenidos por otros autores.Item Restricted Exoplanet transits observed at OAUNI(Universidad Nacional de Ingeniería, 2019-06-07) Pereyra, Antonio; Ricra, JoséThis work presents the exoplanet transit program developed at OAUNI on the 2016 and 2017 campaigns. Seventeen exoplanet transits were observed and in six of them more than one event was registered. In a couple of cases the same transit were gathered four times. Preliminary reductions are shown in three transits (WASP-80 b, WASP-52 b, and WASP-77 A b). The associated light curves show well-defined events and their modeling let to infer physical parameters of each system. These measurements are the first ones of their kind collected by a peruvian astronomical facility.Item Open Access Follow-up OAUNI photometry of SN 2024iss(R. E. Rutledge, 2024-07-16) Pereyra, Antonio; Zevallos, M.; Alvarado, D.; Delgado, J.; Torre, E.; Tello, J.; de Almeida, L.We report new photometry of Type II SN 2024iss gathered with the OAUNI 51cm telescope at Huancayo Observatory, Peru. CCD imaging in R filter was performed on four consecutive nights under non-photometric conditions with the target on higher airmasses. The integration time was 80x20s=1600s in each observation. Our measurements yielded: Date (UT) | filter | seeing (") | mag, 2024-07-03.124 | R | 14.70 +/- 0.02, 2024-07-04.129 | R | 14.72 +/- 0.02, 2024-07-05.112 | R | 14.76 +/- 0.01, 2024-07-06.097 | R | 14.77 +/- 0.01. UCAC4 field stars were used for the zero point calibration. Our observations are ~7.3 weeks after the GOTO detection. The OAUNI project is supported by UNI, TWAS, IGP and ProCiencia-Concytec (Convenio 133-2020 Fondecyt).Item Open Access Follow-up OAUNI photometry of SN2022hrs(R. E. Rutledge, 2022-08-03) Pereyra, Antonio; Tello, J.; Zevallos, M.; de Almeida, L.; Espinoza, M.; Alvarado, D.We report additional multiband photometry of Type Ia SN2022hrs (TNSTR-2022-994, TNSCR-2022-997, ATel #15378) on 2022-07-01 (UT) gathered with the OAUNI 51cm telescope (Pereyra et al. 2015; arXiv:1512.03104) at Huancayo Observatory, Peru. CCD imaging using BVRI filters was performed under non-photometric conditions (seeing ~2.1") and airmass lower than 1.9. Total integration times of (60x20s=1200s) for V, R and I filters, and (90x20s=1800s) for B filter yielded: Date (UT) filter mag 2022-07-01.111 B 15.94 +/- 0.05 2022-07-01.042 V 15.04 +/- 0.01 2022-07-01.062 R 15.00 +/- 0.01 2022-07-01.086 I 15.16 +/- 0.02. UCAC4 field stars (508-055361 and 508-055359) were used for the zero point calibration. Following the GELATO classification (TNSCR-2022-997), our measurements are approximately two months after the maximum brightness. The OAUNI project is supported by UNI, TWAS, IGP and ProCiencia-Concytec (Convenio 133-2020 Fondecyt).Item Restricted Measuring the continuum polarization with ESPaDOnS(European Southern Observatory, 2015) Pereyra, Antonio; Rodrigues, C. V.; Martioli, E.Aims. Our goal is to test the feasibility of obtaining accurate measurements of the continuum polarization from high-resolution spectra using the spectropolarimetric mode of ESPaDOnS. Methods. We used the new pipeline OPERA to reduce recent and archived ESPaDOnS data. Several polarization standard stars and science objects were tested for the linear mode. In addition, the circular mode was tested using several objects from the archive with expected null polarization. Synthetic broad-band polarization was computed from the ESPaDOnS continuum polarization spectra and compared with published values (when available) to quantify the accuracy of the instrument. Results. The continuum linear polarization measured by ESPaDOnS is consistent with broad-band polarimetry measurements available in the literature. The accuracy in the degree of linear polarization is around 0.2−0.3% considering the full sample. The accuracy in polarization position angle using the most polarized objects is better than 5◦. Consistent with this, the instrumental polarization computed for the circular continuum polarization is also between 0.2−0.3%. Our results suggest that measurements of the continuum polarization using ESPaDOnS are viable and can be used to study many astrophysical objects.Item Open Access Medidas de calidad de cielo (SEEING) usando la técnica DIMM en el Observatorio de Huancayo(Universidad Nacional de Ingeniería, 2017-03-27) Meza, Erick; Pereyra, Antonio; Sicardy, Bruno; Comina, Germán; Ishitsuka, José K.Mostramos la implementación de un instrumento de medición de la calidad de cielo (seeing) basado en la técnica del Monitoreo del Movimiento Diferencial de Imagen (DIMM). Este instrumento permite la medición precisa y sistemática del seeing, así como su evolución temporal. Fue monitoreado el seeing en el Observatorio de Huancayo durante siete noches consecutivas de Agosto de 2012. El seeing promedio fue de 1.34” ± 0.33”.En 14% del tiempo observado el seeing estuvo por debajo de 1”, y en 71% del tiempo, por debajo de 1.5”. El dominio de la técnica y su aplicabilidad nos permitirá usar el instrumento en varios lugares donde campañas de medición de seeing sean programadas dentro del Perú. La selección de una facilidad astronómica óptica profesional (observatorio astronómico), será favorecida con medidas DIMM futuras.Item Open Access Multiband photometry of PSNJ14102342-4318437 with OAUNI(The Astronomer's Telegram, 2016-01-21) Pereyra, Antonio; Cori, W.; Ricra, J.; Tello, J.We report multiband photometry of Type Ib SN PSNJ14102342-4318437 (ATel #8415, ATel #8434, ATel #8437, ATel #8504) on 2016-01-10 (UT) gathered with the OAUNI 51cm telescope (Pereyra et al. 2015; arXiv:1512.03104) at Huancayo Observatory, Peru. CCD imaging using VRI filters was performed under non-photometric conditions (seeing ~1.9") and airmass = 1.4. Total integration times of (30x20s=600s) for V and R filters, and (24x20s=480s) for I filter yielded: Date (UT) | filter | mag 2016-01-10.385 | V | 16.79 +/- 0.06 2016-01-10.395 | R | 15.93 +/- 0.12 2016-01-10.409 | I | 15.68 +/- 0.10 USNO-B1 field stars were used for the zero point calibration. The measurements presented here are ~25d after the MASTER discovery (ATel #8415) and ~32d after the maximum (ATel #8434). Consistent with this, and considering the NED extinction toward the host galaxy (NGC5483, z=0.006), the color indices (V-R) and (R-I) are in reasonable agreement with the zero-redshift color-color diagrams for Type Ib SNe about 20-30d past the maximum (Poznanski et al., 2002, PASP, 114, 833). The OAUNI project is supported by UNI, TWAS and IGP.Item Restricted OAUNI astronomical photometry: stellar variability of FO Aqr on 2016 low state(IOP Publishing, 2020) Pereyra, AntonioThis work reports a photometric monitoring of the intermediate polar cataclysmic variable star FO Aqr. This is part of the ongoing OAUNI stellar variability program. Around 1200 individual measurements (or ∼ 9 hrs of observations) were gathered distributed in five nights. The observation epoch was coincident with the 2016 low state brightness of FO Aqr. Good quality light curves detect unambiguously the expected stellar variability of FO Aqr. The analysis using periodograms let to determine the main two known periods, P1 = 20.380 ± .003 min and P2 = 11.076 ± .001 min. Our full five-nights analysis shows that P1, the spin white dwarf period, is more prominent than P2, the one-half of the beat period between the spin and orbital periods. Nevertheless, individual light curves show than, at least in one case, a reverse pattern is found. It suggests a dependence of the beat period with the orbital phase of the system with important variations at the same phase interval.Item Open Access OAUNI confirmation of optical flickering from RS Oph(R. E. Rutledge, 2022-05-20) Pereyra, Antonio; Tello, J.; Zevallos, M.; de Almeida, L.; Espinoza, M.; Alvarado, D.We report photometry post 2021 outburst of the recurrent nova RS Oph on 2022-05-02 (UT) gathered with the OAUNI 51cm telescope (Pereyra et al. 2015; arXiv:1512.03104) at Huancayo Observatory, Peru. CCD imaging was performed in B filter under non-photometric conditions (seeing ~1.8") and airmass ~1.1. The observations span 1.7h with a total of 220 individual measurements of 20s each. UCAC4 field stars (417-071319 and 418-073342) were used for the zero point calibration. An average B magnitude of 12.43 +/- 0.04 (HJD middle = 2459701.772) is found with a clear detection of optical flickering on minute-to-hour time scale with peak-to-peak amplitude of 0.22 mag (see link below). This is supported by the standard deviation ratio of magnitudes between RS Oph and the comparison stars that is 2.8. Our observations confirm previous RS Oph optical flickering detections post last outburst (ATel #15330, ATel #15339). Following the onset of the 2021 outburst (Munari & Valisa 2021; arXiv:2109.01101), our measurements are 266.8 days old with an ongoing re-establishment of accretion. The OAUNI project is supported by UNI, TWAS, IGP and ProCiencia-Concytec (Convenio 133-2020 Fondecyt).Item Open Access OAUNI multiband photometry of SN2022hrs(R. E. Rutledge, 2022-05-13) Pereyra, Antonio; Tello, J.; Zeballos, M.; de Almeida, L.; Espinoza, M.; Alvarado, D.We report multiband photometry of Type Ia SN2022hrs (TNSTR-2022-994, TNSCR-2022- 997) on 2022-05-02 (UT) gathered with the OAUNI 51cm telescope (Pereyra et al. 2015; arXiv:1512.03104) at Huancayo Observatory, Peru. CCD imaging using BVRI filters was performed under non-photometric conditions (seeing ~1.8") and airmass lower than 1.2. Total integration times of (45x20s=900s) for V, R and I filters, and (60x20s=1200s) for B filter yielded: Date (UT) filter mag 2022-05-02.208 B 12.54 +/- 0.22 2022-05-02.087 V 12.38 +/- 0.14 2022-05-02.104 R 12.52 +/- 0.10 2022-05-02.190 I 13.21 +/- 0.13. UCAC4 field stars were used for the zero point calibration. Following the GELATO classification (TNSCR-2022-997), our measurements are very close to the maximum brightness. The OAUNI project is supported by UNI, TWAS, IGP and ProCiencia-Concytec (Convenio 133-2020 Fondecyt).Item Open Access OAUNI non-detection of AT 2023pow in R band(R. E. Rutledge, 2023-08-23) Pereyra, Antonio; Tello, J.; Alvarado, D.; Torre, E.; Zevallos, M.; Espinoza, M.; de Almeida, L.CCD imaging was performed of the NGC 1640 field using the OAUNI 51cm telescope at Huancayo Observatory, Peru, on 2023-08-19.310 (UT). No source is detected at the position of AT 2023pow (TNSTR-2023-1982) with limiting magnitude R ~ 18.5. This is consistent with the AT 2023pow report by T. Noguchi few hours after the detection alert. The OAUNI project is supported by UNI, TWAS, IGP and ProCiencia-Concytec (Convenio133-2020 Fondecyt).Item Open Access OAUNI optical observation of the supernova ASASSN-15lp(The Astronomer's Telegram, 2015-08-26) Pereyra, Antonio; Cori, W.; Meza, E.; Ricra, J.; Zevallos, M.During the commissioning runs of the National University of Engineering's Astronomical Observatory (OAUNI) project, we report optical imaging of the Type Ia SN ASASSN-15lp (ATel #7691, ATel #7692) on 2015-07-17.352 (UT). The measurement was gathered using the OAUNI 51cm telescope at the Huancayo Observatory, Peru (3300 masl at the central peruvian Andes). The observation was made under non-photometric clear skies and through an airmass of 1.4. A 180-second exposure in V filter yielded V = (15.86 +/- 0.05) mag. The zero point calibration was obtained using comparison stars in the neighborhood of the field. Our measurement is 28 days after the discovery (ATel #7691) and caution must be taken for contamination with the host galaxy. The OAUNI project is supported by UNI, The World Academy of Sciences (TWAS) and IGP.Item Open Access OAUNI photometry of ASASSN-16gq/AT2016cym(The Astronomer's Telegram, 2017-04-21) Pereyra, Antonio; Ricra, J.; Zevallos, M.We report optical photometry of Type Ia SN ASASSN-16gq/AT2016cym (ATel #9199, ATel #9219) on 2016-07-11 (UT) gathered with the OAUNI 51cm telescope at Huancayo Observatory, Peru. CCD imaging was performed with seeing ~1.7" and airmass = 1.3. Our measurements yielded: Date (UT) | filter | IT | mag 2016-07-11.085 | V | 1200s (60x20s) | 17.94 +/- 0.06 2016-07-11.106 | R | 0760s (38x20s) | 17.84 +/- 0.04 Field stars were used for the zero point calibration. Caution must be taken for contamination of edge-on Sc host galaxy (ESO 446-G023). Following FLWO/FAST classification (ATel #9219), our measurements are ~17 days after maximum. The OAUNI project is supported by UNI, TWAS, IGP and Cienciactiva (Convenio 102-2015 Fondecyt)."Item Open Access OAUNI photometry of ASASSN-16hw(The Astronomer's Telegram, 2016-09-30) Pereyra, Antonio; Ricra, J.; Zevallos, M.We report optical photometry of Type Ia SN ASASSN-16hw (=SN 2016ekt, ATel #9278, ATel #9289, ATel #9300) on 2016-08-06 (UT) gathered with the OAUNI 51cm telescope (Pereyra et al. 2015;arXiv:1512.03104) at Huancayo Observatory, Peru. CCD imaging measurements using V and R broadband filters were acquired with seeing ~1.9" and airmass = 1.5. A total integration time of 42x20s=840s in each filter yielded: Date (UT) filter mag 2016-08-06.119 R 14.656 +/- 0.003 2016-08-06.120 V 14.497 +/- 0.004 Field stars were used for the zero point calibration. Following PESSTO and Du Pont classifications (ATel #9289, ATel #9300), our measurements are very close to maximum. The OAUNI project is supported by UNI, TWAS, IGP and Cienciactiva (Convenio 102-2015 Fondecyt).Item Open Access OAUNI photometry of ASASSN-16hz(The Astronomer's Telegram, 2016-12-07) Pereyra, Antonio; Ricra, J.; Zevallos, M.We report optical photometry of Type Ia SN ASASSN-16hz (=SN 2016eqb, ATel #9332, ATel #9333) on 2016-08-09 (UT) gathered with the OAUNI 51cm telescope at Huancayo Observatory, Peru. CCD imaging was performed with seeing ~1.8" and airmass = 1.3. A total integration time of 900s (45x20s) and 880s (44x20s) in R and V filter, respectively, yielded: Date (UT) | filter | mag 2016-08-09.397 | R | 15.84 +/- 0.04 2016-08-09.412 | V | 15.82 +/- 0.05 UCAC4 field stars were used for the zero point calibration. Following Mayall/KOSMOS classification (ATel #9333), our measurements are ~2 days after maximum. The OAUNI project is supported by UNI, TWAS, IGP and Cienciactiva (Convenio 102-2015 Fondecyt)."Item Open Access OAUNI photometry of SN 2023fyq(R. E. Rutledge, 2023-09-02) Pereyra, Antonio; Tello, J.; Alvarado, D.; Torre, E.; Zevallos, M.; Espinoza, M.; de Almeida, L.Photometry of Type Ib-pec SN 2023fyq was gathered with the OAUNI 51cm telescope at Huancayo Observatory, Peru. CCD imaging in R filter was performed on three consecutive nights under non-photometric conditions with the target at low altitude. Special care was taken to select the appropriate photometric aperture to minimize the contamination with the host galaxy. Our measurements are indicated below: Date (UT) | filter | IT | seeing (") | mag |, 2023-08-17.008 | R | 88x20s | 1.9 | 14.725 +/- 0.012, 2023-08-18.008 | R | 90x20s | 2.0 | 14.719 +/- 0.012, 2023-08-19.005 | R | 70x20s | 2.0 | 14.715 +/- 0.011. UCAC4 field stars were used for the zero point calibration. Our observations are ~3.8 weeks after K. Itagaki report showing the rapid brightening of the target. The OAUNI project is supported by UNI, TWAS, IGP and ProCiencia-Concytec (Convenio 133-2020 Fondecyt).Item Open Access OAUNI photometry of SN 2023gfo(R. E. Rutledge, 2023-06-10) Pereyra, Antonio; Espinoza, M.; Tello, J.; Zevallos, M.; Alvarado, D.; de Almeida, L.Multiband photometry of Type II SN 2023gfo on 2023-05-24 (UT) was gathered with the OAUNI 51cm telescope at Huancayo Observatory, Peru. CCD imaging using VRI filters was performed under non-photometric conditions (seeing ~1.8") and airmass lower than 1.6. Total integration times of (45x20s=900s) for V, R and I filters yielded: V = 15.60 +/- 0.01 on 2023-05-24.228 (UT); R = 15.33 +/- 0.03 on 2023-05-24.197; I = 15.12 +/- 0.05 on 2023-05-24-212.Item Open Access OAUNI photometry of SN 2023ijd(R. E. Rutledge, 2023-07-31) Pereyra, Antonio; Espinoza, M.; Tello, J.; Zevallos, M.; de Almeida, L.; Alvarado, D.Photometry of Type II SN 2023ijd (TNSTR-2023-1092, TNSCR-2023-1112) was gathered with the OAUNI 51cm telescope (arXiv:1512.03104) at Huancayo Observatory, Peru. CCD imaging in R filter was performed on three consecutive nights under non-photometric conditions with airmasses lower than 1.8. The integration time was 70x20s=1400s in each observation. Our measurements yielded: Date (UT) / filter / seeing (") / mag ; 2023-07-15.072 / R / 2.1 / 15.52 +/- 0.01 ; 2023-07-16.057 / R / 1.8 / 15.61 +/- 0.01 ; 2023-07-17.053 / R / 2.2 / 15.56 +/- 0.01. UCAC4 field stars were used for the zero point calibration. Our observations are ~two months after the ASAS-SN detection (TNSTR-2023-1092). The OAUNI project is supported by UNI, TWAS, IGP and ProCiencia-Concytec (Convenio 133-2020 Fondecyt).