Photometric calibration of the Swift ultraviolet/optical telescope

Poole, T.; Breeveld, A. A.; Page, M. J.; Landsman, W. B.; Holland, S. T.; Roming, P. W. A.; Kuin, N. P. M.; Brown, P. J.; Grönwall, C.; Hunsberger, S.; Koch, S.; Mason, K. O.; Schady, P.; Berk, Daniel Vanden; Blustin, A. J.; Boyd, Patricia T.; Broos, P. S.; Carter, M.; Chester, M.; Cucchiara, Antonino; Hancock, B.; Huckle, H.; Immler, S.; Ivanushkina, M.; Kennedy, Thomas E.; Marshall, F. E.; Morgan, A. N.; Pandey, S. B.; Pasquale, M. De; Smith, Phil; Still, M.

doi:10.1111/j.1365-2966.2007.12563.x

Cited by 842 publications

(638 citation statements)

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“…Swift-UVOT Swift data were processed through the standard UVOT pipeline procedure (Poole et al 2007) in order to remove the bad pixels, to flat-field and to correct for the system response. The magnitude extraction per filter was performed with the UVOT task, UVOTMAGHIST.…”

Section: Discussionmentioning

confidence: 99%

NEW HIGH-z FERMI BL LACS WITH THE PHOTOMETRIC DROPOUT TECHNIQUE

Kaur

Rau

Ajello

et al. 2016

ApJ

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Determining redshifts for BL Lacertae (BL Lac) objects using the traditional spectroscopic method is challenging due to the absence of strong emission lines in their optical spectra. We employ the photometric dropout technique to determine redshifts for this class of blazars using the combined 13 broadband filters from Swift-UVOT and the multi-channel imager GROND at the MPG 2.2 m telescope at ESOʼs La Silla Observatory. The wavelength range covered by these 13 filters extends from far-ultraviolet to the near-infrared. We report results on 40 new Fermidetected BL Lacs with the photometric redshiftdeterminations for fivesources, with 3FGL J1918.2-4110 being the most distant in our sample at z=2.16. Reliable upper limits are provided for 20 sources in this sample. Using the highest energy photons for these Fermi-LAT sources, we evaluate the consistency with the gamma-ray horizon due to the extragalactic background light.

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Section: Discussionmentioning

confidence: 99%

NEW HIGH-z FERMI BL LACS WITH THE PHOTOMETRIC DROPOUT TECHNIQUE

Kaur

Rau

Ajello

et al. 2016

ApJ

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“…The normalization factor C j in Equation (3) is also determined Cardelli et al (1989), while the others are deduced from those at the adjacent reference wavelengths. b References for the wavelengths: (1) Morrissey et al (2005), (2) Poole et al (2008), (3) Dressel (2016), (4) 2.5 m reference in Doi et al (2010), (5) 2MASS bands in Skrutskie et al (2006). c For the GALEX NUV band, the effective wavelength is 0.2271 µm.…”

Section: Model Of Interstellar Dustmentioning

confidence: 99%

Properties of interstellar dust responsible for extinction laws with unusually low total-to-selective extinction ratios of R=1−2

Nozawa

2016

Planetary and Space Science

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It is well known that the extinction properties along lines of sight to Type Ia supernovae (SNe Ia) are described by steep extinction curves with unusually low total-to-selective extinction ratios of R V = 1.0-2.0. In order to reveal the properties of interstellar dust that causes such peculiar extinction laws, we perform the fitting calculations to the measured extinction curves by applying a two-component dust model composed of graphite and silicate. As for the size distribution of grains, we consider two function forms of the power-law and lognormal distributions. We find that the steep extinction curves derived from the one-parameter formula by Cardelli et al. (1989) with R V = 2.0, 1.5, and 1.0 can be reasonably explained even by the simple power-law dust model that has a fixed power index of −3.5 with the maximum cut-off radii of a max ≃ 0.13 µm, 0.094 µm, and 0.057 µm, respectively. These maximum cut-off radii are smaller than a max ≃ 0.24 µm considered to be valid in the Milky Way, clearly demonstrating that the interstellar dust responsible for steep extinction curves is highly biased to smaller sizes. We show that the lognomal size distribution can also lead to good fits to the extinction curves with R V = 1.0-3.1 by taking the appropriate combinations of the relevant parameters. We discuss that the extinction data at ultraviolet wavelengths are essential for constraining the composition and size distribution of interstellar dust.

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“…All UVOT magnitudes are in the Standard UVOT Photometric System [2]. Magnitudes obtained by ground based telescopes were taken from GCNs (in detail see at references [7]).…”

Section: Photometric Data Reductionmentioning

confidence: 99%

“…Then we chose those aperture sizes, which provided the most accurate results. For a given filter band we used the best aperture size, meaning that in some cases when obtaining photometry for a given GRB we used various apertures depending on the filter band.All UVOT magnitudes are in the Standard UVOT Photometric System [2]. Magnitudes obtained by ground based telescopes were taken from GCNs (in detail see at references [7]).…”

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Photometry of some recent Gamma-ray bursts

Kóbori

Kelemen

Vereš

et al. 2011

AIP Conference Proceedings

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Abstract. We present the results of the optical, X-ray and gamma-ray analysis of some recent GRBs. The data were obtained by the automated P60 telescope and the Swift telescope (UVOT, XRT and BAT). We present some example fits for the lightcurves. The data reduction and the investigations were made by the Konkoly Observatory HEART group (http://www.konkoly.hu/HEART/index.html).Keywords: gamma-ray bursts, astronomical observations, x-ray PACS: 98.70.Rz, 95.85.Pw, 98.70.Qy PHOTOMETRIC DATA REDUCTIONThe UVOT photometry was done using NASA's HEASOFT software package. This package provides a complete assistance for doing photometry for measurements done by various telescopes (e.g. Swift, CGRO, INTEGRAL).For photometry, contrary to the suggestions of the software manual, we explored various aperture sizes between 1" and 10" (instead of keeping 5" at all times) to get the most usable data. Then we chose those aperture sizes, which provided the most accurate results. For a given filter band we used the best aperture size, meaning that in some cases when obtaining photometry for a given GRB we used various apertures depending on the filter band.All UVOT magnitudes are in the Standard UVOT Photometric System [2]. Magnitudes obtained by ground based telescopes were taken from GCNs (in detail see at references [7]). When converting magnitudes to fluxes, we used the methods described in [3,4,5]. Magnitudes are not corrected for galactic extinction. X-ray data is taken from the XRT observations available from [6]. According to our results we suggest 19 magnitude as acceptable faintest limit in the UVOT photometry system.We used the mpfit package [1] for fitting broken power-law functions to the lightcurves with the F ν ∝ t α convention. INDIVIDUAL AFTERGLOWS GRB 080721:The afterglow was detected by several telescopes, but due to the lack of ground based observations we could not fit the data at the late times. However, the UVOT magnitudes show a lightcurve flattening about 6 ks. After this time the UVOT slope in "WHITE" filter is −0.70 ± 0.18, which is inconsistent with the one inferred from filter R, α R ∼ −0.95 (from 10.6 to 26.19 hours after the trigger), unless there was an additional steepening in the lightcurve. The redshift was inferred from the Lyman-α absorption line and it is z = 2.602, while other lines (O I, Si II, C II, Si IV, C IV, Fe II and Al II) suggest z = 2.591. GRB 081203A:The α index in the R band disagrees with those in the GCNs (α R,I = −0.66 between 6 and 12 ks), but after this time the results were similar. The redshift based on the Lyman-α line is about 2.1.GRB 090102: This is a well studied GRB [see GCN Circular: 8761, 8763, 8764, 8771, 8772, 8773, 8778, 8780]. Its redshift is 1.547. The observations have already begun 43 seconds after the BAT trigger and the TAROT magnitudes even show the brightening interval of the lightcurve. Furthermore, in the UVOT's V and UVW1 band there is an additional rebrightening around 800 s, which can be also seen in the X-ray band, but unfortunately, this part is lacki...

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Photometric calibration of the Swift ultraviolet/optical telescope

Cited by 842 publications

References 26 publications

NEW HIGH-z FERMI BL LACS WITH THE PHOTOMETRIC DROPOUT TECHNIQUE

NEW HIGH-z FERMI BL LACS WITH THE PHOTOMETRIC DROPOUT TECHNIQUE

Properties of interstellar dust responsible for extinction laws with unusually low total-to-selective extinction ratios of R=1−2

Photometry of some recent Gamma-ray bursts

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