The Herschel-PACS photometer calibration

Balog, Z.; Müller, Thomas; Nielbock, M.; Altiéri, B.; Klaas, U.; Blommaert, J. A. D. L.; Linz, H.; Lutz, D.; Moór, A.; Billot, N.; Sauvage, M.; Okumura, K.

doi:10.1007/s10686-013-9352-3

Cited by 174 publications

(203 citation statements)

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“…2.6 of Men'shchikov et al 2012). Aperture corrections are applied by getsources using tables of the encircled energy fraction values for the actual point spread functions (PSFs) provided by the PACS and SPIRE ICCs (Balog et al 2014;Bendo et al 2013).…”

Section: Multiwavelength Core Extraction With Getsourcesmentioning

confidence: 99%

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A census of dense cores in the Aquila cloud complex: SPIRE/PACS observations from theHerschelGould Belt survey

Könyves

André

Men’shchikov

et al. 2015

A&A

412

471

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We present and discuss the results of the Herschel Gould Belt survey (HGBS) observations in an ∼11 deg 2 area of the Aquila molecular cloud complex at d ∼ 260 pc, imaged with the SPIRE and PACS photometric cameras in parallel mode from 70 μm to 500 μm. Using the multi-scale, multi-wavelength source extraction algorithm getsources, we identify a complete sample of starless dense cores and embedded (Class 0-I) protostars in this region, and analyze their global properties and spatial distributions. We find a total of 651 starless cores, ∼60% ± 10% of which are gravitationally bound prestellar cores, and they will likely form stars in the future. We also detect 58 protostellar cores. The core mass function (CMF) derived for the large population of prestellar cores is very similar in shape to the stellar initial mass function (IMF), confirming earlier findings on a much stronger statistical basis and supporting the view that there is a close physical link between the stellar IMF and the prestellar CMF. The global shift in mass scale observed between the CMF and the IMF is consistent with a typical star formation efficiency of ∼40% at the level of an individual core. By comparing the numbers of starless cores in various density bins to the number of young stellar objects (YSOs), we estimate that the lifetime of prestellar cores is ∼1 Myr, which is typically ∼4 times longer than the core free-fall time, and that it decreases with average core density. We find a strong correlation between the spatial distribution of prestellar cores and the densest filaments observed in the Aquila complex. About 90% of the Herschel-identified prestellar cores are located above a background column density corresponding to A V ∼ 7, and ∼75% of them lie within filamentary structures with supercritical masses per unit length > ∼ 16 M /pc. These findings support a picture wherein the cores making up the peak of the CMF (and probably responsible for the base of the IMF) result primarily from the gravitational fragmentation of marginally supercritical filaments. Given that filaments appear to dominate the mass budget of dense gas at A V > 7, our findings also suggest that the physics of prestellar core formation within filaments is responsible for a characteristic "efficiency" SFR/M dense ∼ 5 +2 −2 × 10 −8 yr −1 for the star formation process in dense gas.

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Section: Multiwavelength Core Extraction With Getsourcesmentioning

confidence: 99%

“…In the first run the 70 μm data point was included in the fit and the getsources 13 The photometric point-source calibration uncertainty is less than 7% for the PACS bands (Balog et al 2014) and ∼5% for the SPIRE bands (Bendo et al 2013). …”

Section: Derived Core Propertiesmentioning

confidence: 99%

A census of dense cores in the Aquila cloud complex: SPIRE/PACS observations from theHerschelGould Belt survey

Könyves

André

Men’shchikov

et al. 2015

A&A

412

471

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“…Its resulting flux of 52.8 mJy is 13% lower than the average 60.9 mJy from the two scan maps. Here we should note that the annulus used for background determination is closer to the source and narrower for chop/nod aperture photometry (radius 24 -28 , Nielbock et al (2013)) than for scan map photometry (radius 35 -45 , Balog et al (2014)). As we discuss in Sect.…”

Section: Appendix C: Comparison Scan Map With Chop/nod Photometrymentioning

confidence: 97%

“…The data reduction and calibration performed in HIPE 1 (Ott 2010) followed the description in Balog et al (2014), applying the high-pass filter (HPF) algorithm to remove the 1 f -noise Table 2. Relevant scan map parameters for photometry and noise determination.…”

Section: Data Analysis and Calibrationmentioning

confidence: 99%

Herschel-PACS photometry of faint stars for sensitivity performance assessment and establishment of faint FIR primary photometric standards

Klaas

Balog

Nielbock

et al. 2018

A&A

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Aims. Our aims are to determine flux densities and their photometric accuracy for a set of seventeen stars that range in flux from intermediately bright ( 2.5 Jy) to faint ( 5 mJy) in the far-infrared (FIR). We also aim to derive signal-to-noise dependence with flux and time, and compare the results with predictions from the Herschel exposure-time calculation tool. Methods. We obtain aperture photometry from Herschel-PACS high-pass-filtered scan maps and chop/nod observations of the faint stars. The issues of detection limits and sky confusion noise are addressed by comparison of the field-of-view at different wavelengths, by multi-aperture photometry, by special processing of the maps to preserve extended emission, and with the help of large-scale absolute sky brightness maps from AKARI. This photometry is compared with flux-density predictions based on photospheric models for these stars. We obtain a robust noise estimate by fitting the flux distribution per map pixel histogram for the area around the stars, scaling it for the applied aperture size and correcting for noise correlation.Results. For 15 stars we obtain reliable photometry in at least one PACS filter, and for 11 stars we achieve this in all three PACS filters (70, 100, 160 µm). Faintest fluxes, for which the photometry still has good quality, are about 10 -20 mJy with scan map photometry. The photometry of seven stars is consistent with models or flux predictions for pure photospheric emission, making them good primary standard candidates. Two stars exhibit source-intrinsic far-infrared excess: β Gem (Pollux), being the host star of a confirmed Jupiter-size exoplanet, due to emission of an associated dust disk, and η Dra due to dust emission in a binary system with a K1 dwarf. The investigation of the 160 µm sky background and environment of four sources reveals significant sky confusion prohibiting the determination of an accurate stellar flux at this wavelength. As a good model approximation, for nine stars we obtain scaling factors of the continuum flux models of four PACS fiducial standards with the same or quite similar spectral type. We can verify a linear dependence of signal-to-noise ratio (S/N) with flux and with square root of time over significant ranges. At 160 µm the latter relation is, however, affected by confusion noise. Conclusions. The PACS faint star sample has allowed a comprehensive sensitivity assessment of the PACS photometer. Accurate photometry allows us to establish a set of five FIR primary standard candidates, namely α Ari, ε Lep, ω Cap, HD 41047 and 42 Dra, which are 2 -20 times fainter than the faintest PACS fiducial standard (γ Dra) with absolute accuracy of <6%. For three of these primary standard candidates, essential stellar parameters are known, meaning that a dedicated flux model code may be run.

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“…Starting from the Level-1 stage, the observations were first corrected for the evaporator temperature effect (see Moór et al 2014) with correction factors of <0.3% to 3.2%. Then we followed the standard pipeline steps to eliminate the 1/f noise as described in Balog et al (2014) using iterative masked high-pass filtering of the observational timelines with the photProject(). For large scale, extended emission studies, the mapmaker algorithm JScanam is often more suitable, but in our case the structures were kept in the inner ∼30 of the source, so there was no need to use JScanam to deal with a broadened PSF.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Search for signatures of dust in the Pluto–Charon system usingHerschel/PACS observations

Márton

Kiss

Balog

et al. 2015

A&A

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In this letter we explore the environment of Pluto and Charon in the far infrared with the main aim of identifying the signs of any possible dust ring, should it exist in the system. Our study is based on observations performed at 70 μm with the PACS instrument onboard the Herschel Space Observatory at nine epochs between March 14 and 19, 2012. The far-infrared images of the Pluto-Charon system are compared to those of the point spread function (PSF) reference quasar 3C 454.3. The deviation between the observed PlutoCharon and reference PSFs are less then 1σ, indicating that clear evidence for an extended dust ring around the system was not found. Our method is capable of detecting a hypothetical ring with a total flux of ∼3.3 mJy at a distance of ∼153 000 km (∼8.2 Pluto-Charon distances) from the system's barycentre. We place upper limits on the total disk mass and on the column density in a reasonable disk configuration and analyse the hazard during the flyby of NASA's New Horizons in July 2015. This realistic model configuration predicts a column density of 8.7 × 10 −10 g cm −2 along the path of the probe and an impactor mass of 8.7 × 10 −5 g.

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The Herschel-PACS photometer calibration

Cited by 174 publications

References 11 publications

A census of dense cores in the Aquila cloud complex: SPIRE/PACS observations from theHerschelGould Belt survey

A census of dense cores in the Aquila cloud complex: SPIRE/PACS observations from theHerschelGould Belt survey

Herschel-PACS photometry of faint stars for sensitivity performance assessment and establishment of faint FIR primary photometric standards

Search for signatures of dust in the Pluto–Charon system usingHerschel/PACS observations

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