Lunar reference systems represent a fundamental aspect of lunar exploration. This paper presents a review of the topic in the context of the ESA lunar programme, MoonLight. This paper describes the current state of the art in the definition of the lunar reference frame and introduces TCL, a lunar time scale based on IAU resolutions. It also proposes several possible implementations of this time scale for orbiting and ground-based clocks. Finally, it provides an assessment of the improvement of the lunar reference frame that would result from the addition of lunar retro-reflectors on the Moon surface and the use of orbiter altimetry. This document is an appendix dedicated to lunar reference system definition of a more global document dedicated to the presentation of new concepts in orbit determination and time synchronization of a lunar radio navigation system.
{"title":"Lunar References Systems, Frames and Time-scales in the context of the ESA Programme Moonlight","authors":"Agnes Fienga, Nicolas Rambaux, Krzysztof Sosnica","doi":"arxiv-2409.10043","DOIUrl":"https://doi.org/arxiv-2409.10043","url":null,"abstract":"Lunar reference systems represent a fundamental aspect of lunar exploration.\u0000This paper presents a review of the topic in the context of the ESA lunar\u0000programme, MoonLight. This paper describes the current state of the art in the\u0000definition of the lunar reference frame and introduces TCL, a lunar time scale\u0000based on IAU resolutions. It also proposes several possible implementations of\u0000this time scale for orbiting and ground-based clocks. Finally, it provides an\u0000assessment of the improvement of the lunar reference frame that would result\u0000from the addition of lunar retro-reflectors on the Moon surface and the use of\u0000orbiter altimetry. This document is an appendix dedicated to lunar reference\u0000system definition of a more global document dedicated to the presentation of\u0000new concepts in orbit determination and time synchronization of a lunar radio\u0000navigation system.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aneta Siemiginowska, Douglas Burke, Hans Moritz Günther, Nicholas P. Lee, Warren McLaughlin, David A. Principe, Harlan Cheer, Antonella Fruscione, Omar Laurino, Jonathan McDowell, Marie Terrell
We present an overview of Sherpa, an open source Python project, and discuss its development history, broad design concepts and capabilities. Sherpa contains powerful tools for combining parametric models into complex expressions that can be fit to data using a variety of statistics and optimization methods. It is easily extensible to include user-defined models, statistics, and optimization methods. It provides a high-level User Interface for interactive data-analysis, such as within a Jupyter notebook, and it can also be used as a library component, providing fitting and modeling capabilities to an application. We include a few examples of Sherpa applications to multiwavelength astronomical data. The code is available GitHub: https://github.com/sherpa/sherpa
{"title":"Sherpa: An Open Source Python Fitting Package","authors":"Aneta Siemiginowska, Douglas Burke, Hans Moritz Günther, Nicholas P. Lee, Warren McLaughlin, David A. Principe, Harlan Cheer, Antonella Fruscione, Omar Laurino, Jonathan McDowell, Marie Terrell","doi":"arxiv-2409.10400","DOIUrl":"https://doi.org/arxiv-2409.10400","url":null,"abstract":"We present an overview of Sherpa, an open source Python project, and discuss\u0000its development history, broad design concepts and capabilities. Sherpa\u0000contains powerful tools for combining parametric models into complex\u0000expressions that can be fit to data using a variety of statistics and\u0000optimization methods. It is easily extensible to include user-defined models,\u0000statistics, and optimization methods. It provides a high-level User Interface\u0000for interactive data-analysis, such as within a Jupyter notebook, and it can\u0000also be used as a library component, providing fitting and modeling\u0000capabilities to an application. We include a few examples of Sherpa\u0000applications to multiwavelength astronomical data. The code is available\u0000GitHub: https://github.com/sherpa/sherpa","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hyukmo Kang, Kyle Van Gorkom, Meghdoot Biswas, Daewook Kim, Ewan S. Douglas
Continuous wavefront sensing benefits space observatories in on-orbit optical performance maintenance. To measure the phase of a wavefront, phase retrieval is an attractive technique as it uses multiple point spread function (PSF) images that are acquired by the telescope itself without extra metrology systems nor complicated calibration. The focus diverse phase retrieval utilizes PSFs from predetermined defocused positions to enhance the dynamic range of the algorithm. We describe an updated visible light active optics testbed with the addition of a linear motorized focus stage. The performance of the phase retrieval algorithm in broadband is tested under various cases. While broadband pass filters have advantages in higher signal-to-noise ratio (SNR), the performance of phase retrieval can be restricted due to blurred image caused by diffraction and increased computing cost. We used multiple bandpass filters (10 nm, 88 nm, and 150 nm) and investigated effects of bandwidth on the accuracy and required image acquisition conditions such as SNR, reaching accuracies below 20 nm RMS wavefront error at the widest bandwidth. We also investigated the dynamic range of the phase retrieval algorithm depending on the bandwidth and required amount of defocus to expand dynamic range. Finally, we simulated the continuous wavefront sensing and correction loop with a range of statistically generated representative telescope disturbance time series to test for edge cases.
{"title":"Focus diverse phase retrieval test results on broadband continuous wavefront sensing in space telescope applications","authors":"Hyukmo Kang, Kyle Van Gorkom, Meghdoot Biswas, Daewook Kim, Ewan S. Douglas","doi":"arxiv-2409.10500","DOIUrl":"https://doi.org/arxiv-2409.10500","url":null,"abstract":"Continuous wavefront sensing benefits space observatories in on-orbit optical\u0000performance maintenance. To measure the phase of a wavefront, phase retrieval\u0000is an attractive technique as it uses multiple point spread function (PSF)\u0000images that are acquired by the telescope itself without extra metrology\u0000systems nor complicated calibration. The focus diverse phase retrieval utilizes\u0000PSFs from predetermined defocused positions to enhance the dynamic range of the\u0000algorithm. We describe an updated visible light active optics testbed with the\u0000addition of a linear motorized focus stage. The performance of the phase\u0000retrieval algorithm in broadband is tested under various cases. While broadband\u0000pass filters have advantages in higher signal-to-noise ratio (SNR), the\u0000performance of phase retrieval can be restricted due to blurred image caused by\u0000diffraction and increased computing cost. We used multiple bandpass filters (10\u0000nm, 88 nm, and 150 nm) and investigated effects of bandwidth on the accuracy\u0000and required image acquisition conditions such as SNR, reaching accuracies\u0000below 20 nm RMS wavefront error at the widest bandwidth. We also investigated\u0000the dynamic range of the phase retrieval algorithm depending on the bandwidth\u0000and required amount of defocus to expand dynamic range. Finally, we simulated\u0000the continuous wavefront sensing and correction loop with a range of\u0000statistically generated representative telescope disturbance time series to\u0000test for edge cases.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"85 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Z. Wang, K. W. Bannister, V. Gupta, X. Deng, M. Pilawa, J. Tuthill, J. D. Bunton, C. Flynn, M. Glowacki, A. Jaini, Y. W. J. Lee, E. Lenc, J. Lucero, A. Paek, R. Radhakrishnan, N. Thyagarajan, P. Uttarkar, Y. Wang, N. D. R. Bhat, C. W. James, V. A. Moss, Tara Murphy, J. E. Reynolds, R. M. Shannon, L. G. Spitler, A. Tzioumis, M. Caleb, A. T. Deller, A. C. Gordon, L. Marnoch, S. D. Ryder, S. Simha, C. S. Anderson, L. Ball, D. Brodrick, F. R. Cooray, N. Gupta, D. B. Hayman, A. Ng, S. E. Pearce, C. Phillips, M. A. Voronkov, T. Westmeier
We present the first results from a new backend on the Australian Square Kilometre Array Pathfinder, the Commensal Realtime ASKAP Fast Transient COherent (CRACO) upgrade. CRACO records millisecond time resolution visibility data, and searches for dispersed fast transient signals including fast radio bursts (FRB), pulsars, and ultra-long period objects (ULPO). With the visibility data, CRACO can localise the transient events to arcsecond-level precision after the detection. Here, we describe the CRACO system and report the result from a sky survey carried out by CRACO at 110ms resolution during its commissioning phase. During the survey, CRACO detected two FRBs (including one discovered solely with CRACO, FRB 20231027A), reported more precise localisations for four pulsars, discovered two new RRATs, and detected one known ULPO, GPM J1839-10, through its sub-pulse structure. We present a sensitivity calibration of CRACO, finding that it achieves the expected sensitivity of 11.6 Jy ms to bursts of 110 ms duration or less. CRACO is currently running at a 13.8 ms time resolution and aims at a 1.7 ms time resolution before the end of 2024. The planned CRACO has an expected sensitivity of 1.5 Jy ms to bursts of 1.7 ms duration or less, and can detect 10x more FRBs than the current CRAFT incoherent sum system (i.e., 0.5-2 localised FRBs per day), enabling us to better constrain the FRB emission mechanism model and use them as cosmological probes.
{"title":"The CRAFT Coherent (CRACO) upgrade I: System Description and Results of the 110-ms Radio Transient Pilot Survey","authors":"Z. Wang, K. W. Bannister, V. Gupta, X. Deng, M. Pilawa, J. Tuthill, J. D. Bunton, C. Flynn, M. Glowacki, A. Jaini, Y. W. J. Lee, E. Lenc, J. Lucero, A. Paek, R. Radhakrishnan, N. Thyagarajan, P. Uttarkar, Y. Wang, N. D. R. Bhat, C. W. James, V. A. Moss, Tara Murphy, J. E. Reynolds, R. M. Shannon, L. G. Spitler, A. Tzioumis, M. Caleb, A. T. Deller, A. C. Gordon, L. Marnoch, S. D. Ryder, S. Simha, C. S. Anderson, L. Ball, D. Brodrick, F. R. Cooray, N. Gupta, D. B. Hayman, A. Ng, S. E. Pearce, C. Phillips, M. A. Voronkov, T. Westmeier","doi":"arxiv-2409.10316","DOIUrl":"https://doi.org/arxiv-2409.10316","url":null,"abstract":"We present the first results from a new backend on the Australian Square\u0000Kilometre Array Pathfinder, the Commensal Realtime ASKAP Fast Transient\u0000COherent (CRACO) upgrade. CRACO records millisecond time resolution visibility\u0000data, and searches for dispersed fast transient signals including fast radio\u0000bursts (FRB), pulsars, and ultra-long period objects (ULPO). With the\u0000visibility data, CRACO can localise the transient events to arcsecond-level\u0000precision after the detection. Here, we describe the CRACO system and report\u0000the result from a sky survey carried out by CRACO at 110ms resolution during\u0000its commissioning phase. During the survey, CRACO detected two FRBs (including\u0000one discovered solely with CRACO, FRB 20231027A), reported more precise\u0000localisations for four pulsars, discovered two new RRATs, and detected one\u0000known ULPO, GPM J1839-10, through its sub-pulse structure. We present a\u0000sensitivity calibration of CRACO, finding that it achieves the expected\u0000sensitivity of 11.6 Jy ms to bursts of 110 ms duration or less. CRACO is\u0000currently running at a 13.8 ms time resolution and aims at a 1.7 ms time\u0000resolution before the end of 2024. The planned CRACO has an expected\u0000sensitivity of 1.5 Jy ms to bursts of 1.7 ms duration or less, and can detect\u000010x more FRBs than the current CRAFT incoherent sum system (i.e., 0.5-2\u0000localised FRBs per day), enabling us to better constrain the FRB emission\u0000mechanism model and use them as cosmological probes.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Imdad Mahmud Pathi, John Y. H. Soo, Mao Jie Wee, Sazatul Nadhilah Zakaria, Nur Azwin Ismail, Carlton M. Baugh, Giorgio Manzoni, Enrique Gaztanaga, Francisco J. Castander, Martin Eriksen, Jorge Carretero, Enrique Fernandez, Juan Garcia-Bellido, Ramon Miquel, Cristobal Padilla, Pablo Renard, Eusebio Sanchez, Ignacio Sevilla-Noarbe, Pau Tallada-Crespí
ANNZ is a fast and simple algorithm which utilises artificial neural networks (ANNs), it was known as one of the pioneers of machine learning approaches to photometric redshift estimation decades ago. We enhanced the algorithm by introducing new activation functions like tanh, softplus, SiLU, Mish and ReLU variants; its new performance is then vigorously tested on legacy samples like the Luminous Red Galaxy (LRG) and Stripe-82 samples from SDSS, as well as modern galaxy samples like the Physics of the Accelerating Universe Survey (PAUS). This work focuses on testing the robustness of activation functions with respect to the choice of ANN architectures, particularly on its depth and width, in the context of galaxy photometric redshift estimation. Our upgraded algorithm, which we named ANNZ+, shows that the tanh and Leaky ReLU activation functions provide more consistent and stable results across deeper and wider architectures with > 1 per cent improvement in root-mean-square error ($sigma_{textrm{RMS}}$) and 68th percentile error ($sigma_{68}$) when tested on SDSS data sets. While assessing its capabilities in handling high dimensional inputs, we achieved an improvement of 11 per cent in $sigma_{textrm{RMS}}$ and 6 per cent in $sigma_{68}$ with the tanh activation function when tested on the 40-narrowband PAUS dataset; it even outperformed ANNZ2, its supposed successor, by 44 per cent in $sigma_{textrm{RMS}}$. This justifies the effort to upgrade the 20-year-old ANNZ, allowing it to remain viable and competitive within the photo-z community today. The updated algorithm ANNZ+ is publicly available at https://github.com/imdadmpt/ANNzPlus.
{"title":"ANNZ+: an enhanced photometric redshift estimation algorithm with applications on the PAU Survey","authors":"Imdad Mahmud Pathi, John Y. H. Soo, Mao Jie Wee, Sazatul Nadhilah Zakaria, Nur Azwin Ismail, Carlton M. Baugh, Giorgio Manzoni, Enrique Gaztanaga, Francisco J. Castander, Martin Eriksen, Jorge Carretero, Enrique Fernandez, Juan Garcia-Bellido, Ramon Miquel, Cristobal Padilla, Pablo Renard, Eusebio Sanchez, Ignacio Sevilla-Noarbe, Pau Tallada-Crespí","doi":"arxiv-2409.09981","DOIUrl":"https://doi.org/arxiv-2409.09981","url":null,"abstract":"ANNZ is a fast and simple algorithm which utilises artificial neural networks\u0000(ANNs), it was known as one of the pioneers of machine learning approaches to\u0000photometric redshift estimation decades ago. We enhanced the algorithm by\u0000introducing new activation functions like tanh, softplus, SiLU, Mish and ReLU\u0000variants; its new performance is then vigorously tested on legacy samples like\u0000the Luminous Red Galaxy (LRG) and Stripe-82 samples from SDSS, as well as\u0000modern galaxy samples like the Physics of the Accelerating Universe Survey\u0000(PAUS). This work focuses on testing the robustness of activation functions\u0000with respect to the choice of ANN architectures, particularly on its depth and\u0000width, in the context of galaxy photometric redshift estimation. Our upgraded\u0000algorithm, which we named ANNZ+, shows that the tanh and Leaky ReLU activation\u0000functions provide more consistent and stable results across deeper and wider\u0000architectures with > 1 per cent improvement in root-mean-square error\u0000($sigma_{textrm{RMS}}$) and 68th percentile error ($sigma_{68}$) when tested\u0000on SDSS data sets. While assessing its capabilities in handling high\u0000dimensional inputs, we achieved an improvement of 11 per cent in\u0000$sigma_{textrm{RMS}}$ and 6 per cent in $sigma_{68}$ with the tanh\u0000activation function when tested on the 40-narrowband PAUS dataset; it even\u0000outperformed ANNZ2, its supposed successor, by 44 per cent in\u0000$sigma_{textrm{RMS}}$. This justifies the effort to upgrade the 20-year-old\u0000ANNZ, allowing it to remain viable and competitive within the photo-z community\u0000today. The updated algorithm ANNZ+ is publicly available at\u0000https://github.com/imdadmpt/ANNzPlus.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"210 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When a star is described as a spectral class G2V, we know its approximate mass, temperature, age, and size. At more than 5,700 exoplanets discovered, it is a natural developmental step to establish a classification for them, such as for example, the Harvard classification for stars. This exoplanet classification has to be easily interpreted and present the most relevant information about them and divides them into groups based on certain characteristics. We propose an exoplanet classification, which using an easily readable code, may inform you about a exoplanet's main characteristics. The suggested classification code contains four parameters by which we can quickly determine the range of temperature, mass, density and their eccentricity. The first parameter concerns the mass of an exoplanet in the form of the units of the mass of other known planets, where e.g. M represents the mass of Mercury, E that of Earth, N Neptune, or J Jupiter. The second parameter is the mean Dyson temperature of the extoplanet's orbit, for which we established four main classes: F represents the Frozen class, W the Water class, G the Gaseous class, and R the Roaster class. The third parameter is eccentricity and the fourth parameter is surface attribute which is defined as the bulk density of the exoplanet, where g represents a gaseous planet, w - water planet, t - terrestrial planet, i - iron planet and s - super dense planet. The classification code for Venus, could be EG0t (E - mass in the range of the mass of the Earth, G - Gaseous class, temperature in the range from 450 to 1000 K, 0 - circular or nearly circular orbit, t - terrestrial surface), for Earth it could be EW0t (W - Water class - a possible Habitable zone). This classification is very helpful in, for example, quickly delimiting if a planet can be found in the Habitable zone; if it is terrestrial or not.
当一颗恒星被描述为光谱等级 G2V 时，我们就知道了它的大致质量、温度、年龄和大小。随着系外行星的发现数量超过 5700 颗，为它们建立一个分类是一个自然的发展步骤，例如哈佛恒星分类法。这种系外行星分类法必须易于解释，并能提供与系外行星最相关的信息，还能根据某些特征将系外行星分为不同的组别。我们提出了一种系外行星分类法，通过一个易读的代码，可以让你了解系外行星的主要特征。建议的分类代码包含四个参数，我们可以通过它们快速确定温度、质量、密度及其偏心率的范围。第一个参数涉及系外行星的质量，其形式为其他已知行星的质量单位，例如 M 代表水星的质量，E 代表地球的质量，N 代表海王星的质量，J 代表木星的质量。第二个参数是系外行星轨道的平均失温度，我们将其分为四大类：F 代表冰冻类，W 代表水类，G 代表气态类，R 代表烤炉类。第三个参数是偏心率，第四个参数是表面属性，定义为系外行星的体积密度，其中 g 代表气态行星，w 代表水态行星，t 代表陆态行星，i 代表铁态行星，s 代表超致密行星。金星的分类代码可以是 EG0t（E-质量在地球质量范围内，G-气态行星，温度在 450 至 1000 K 之间，0-圆形或近似圆形轨道，t-陆地表面），地球的分类代码可以是 EW0t（W-水行星--可能的宜居带）。这种分类方法非常有用，例如，可以快速划定行星是否位于宜居带，是否为陆地行星。
{"title":"Classifications for Exoplanet and Exoplanetary Systems -- Could it be developed? I. Exoplanet classification","authors":"E. Plávalová, A. Rosaev","doi":"arxiv-2409.09666","DOIUrl":"https://doi.org/arxiv-2409.09666","url":null,"abstract":"When a star is described as a spectral class G2V, we know its approximate\u0000mass, temperature, age, and size. At more than 5,700 exoplanets discovered, it\u0000is a natural developmental step to establish a classification for them, such as\u0000for example, the Harvard classification for stars. This exoplanet\u0000classification has to be easily interpreted and present the most relevant\u0000information about them and divides them into groups based on certain\u0000characteristics. We propose an exoplanet classification, which using an easily\u0000readable code, may inform you about a exoplanet's main characteristics. The\u0000suggested classification code contains four parameters by which we can quickly\u0000determine the range of temperature, mass, density and their eccentricity. The\u0000first parameter concerns the mass of an exoplanet in the form of the units of\u0000the mass of other known planets, where e.g. M represents the mass of Mercury, E\u0000that of Earth, N Neptune, or J Jupiter. The second parameter is the mean Dyson\u0000temperature of the extoplanet's orbit, for which we established four main\u0000classes: F represents the Frozen class, W the Water class, G the Gaseous class,\u0000and R the Roaster class. The third parameter is eccentricity and the fourth\u0000parameter is surface attribute which is defined as the bulk density of the\u0000exoplanet, where g represents a gaseous planet, w - water planet, t -\u0000terrestrial planet, i - iron planet and s - super dense planet. The\u0000classification code for Venus, could be EG0t (E - mass in the range of the mass\u0000of the Earth, G - Gaseous class, temperature in the range from 450 to 1000 K, 0\u0000- circular or nearly circular orbit, t - terrestrial surface), for Earth it\u0000could be EW0t (W - Water class - a possible Habitable zone). This\u0000classification is very helpful in, for example, quickly delimiting if a planet\u0000can be found in the Habitable zone; if it is terrestrial or not.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"85 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Simon Schleich, Sudeshna Boro Saikia, Quentin Changeat, Manuel Güdel, Aiko Voigt, Ingo Waldmann
We investigate the impact of using multipoint p-T profiles of varying complexity on the retrieval of synthetically generated hot Jupiter transmission spectra modelled after state-of-the-art observations of the hot Jupiter WASP-39~b with JWST. We perform homogenised atmospheric retrievals with the TauREx retrieval framework on a sample of synthetically generated transmission spectra, accounting for varying cases of underlying p-T profiles, cloud-top pressures, and expected noise levels. These retrievals are performed using a fixed-pressure multipoint p-T prescription with increasing complexity, ranging from isothermal to an eleven-point profile. We evaluate the performance of the retrievals based on the Bayesian model evidence, and the accuracy of the retrievals compared to the known input parameters. We find that performing atmospheric retrievals using an isothermal prescription for the pressure-temperature profile consistently results in wrongly retrieved atmospheric parameters when compared to the known input parameters. For an underlying p-T profile with a fully positive lapse rate, we find that a two-point profile is sufficient to retrieve the known atmospheric parameters, while under the presence of an atmospheric temperature inversion, we find that a more complex profile is necessary. Our investigation shows that, for a data quality scenario mirroring state-of-the-art observations of a hot Jupiter with JWST, an isothermal p-T prescription is insufficient to correctly retrieve the known atmospheric parameters. We find a model complexity preference dependent on the underlying pressure-temperature structure, but argue that a p-T prescription on the complexity level of a four-point profile should be preferred. This represents the overlap between the lowest number of free parameters and highest model preference in the cases investigated in this work.
{"title":"Knobs and dials of retrieving JWST transmission spectra. I. The importance of p-T profile complexity","authors":"Simon Schleich, Sudeshna Boro Saikia, Quentin Changeat, Manuel Güdel, Aiko Voigt, Ingo Waldmann","doi":"arxiv-2409.09127","DOIUrl":"https://doi.org/arxiv-2409.09127","url":null,"abstract":"We investigate the impact of using multipoint p-T profiles of varying\u0000complexity on the retrieval of synthetically generated hot Jupiter transmission\u0000spectra modelled after state-of-the-art observations of the hot Jupiter\u0000WASP-39~b with JWST. We perform homogenised atmospheric retrievals with the\u0000TauREx retrieval framework on a sample of synthetically generated transmission\u0000spectra, accounting for varying cases of underlying p-T profiles, cloud-top\u0000pressures, and expected noise levels. These retrievals are performed using a\u0000fixed-pressure multipoint p-T prescription with increasing complexity, ranging\u0000from isothermal to an eleven-point profile. We evaluate the performance of the\u0000retrievals based on the Bayesian model evidence, and the accuracy of the\u0000retrievals compared to the known input parameters. We find that performing\u0000atmospheric retrievals using an isothermal prescription for the\u0000pressure-temperature profile consistently results in wrongly retrieved\u0000atmospheric parameters when compared to the known input parameters. For an\u0000underlying p-T profile with a fully positive lapse rate, we find that a\u0000two-point profile is sufficient to retrieve the known atmospheric parameters,\u0000while under the presence of an atmospheric temperature inversion, we find that\u0000a more complex profile is necessary. Our investigation shows that, for a data\u0000quality scenario mirroring state-of-the-art observations of a hot Jupiter with\u0000JWST, an isothermal p-T prescription is insufficient to correctly retrieve the\u0000known atmospheric parameters. We find a model complexity preference dependent\u0000on the underlying pressure-temperature structure, but argue that a p-T\u0000prescription on the complexity level of a four-point profile should be\u0000preferred. This represents the overlap between the lowest number of free\u0000parameters and highest model preference in the cases investigated in this work.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many modern applications of Bayesian inference, such as in cosmology, are based on complicated forward models with high-dimensional parameter spaces. This considerably limits the sampling of posterior distributions conditioned on observed data. In turn, this reduces the interpretability of posteriors to their one- and two-dimensional marginal distributions, when more information is available in the full dimensional distributions. We show how to learn smooth and differentiable representations of posterior distributions from their samples using normalizing flows, which we train with an added evidence error loss term, to improve accuracy in multiple ways. Motivated by problems from cosmology, we implement a robust method to obtain one and two-dimensional posterior profiles. These are obtained by optimizing, instead of integrating, over other parameters, and are thus less prone than marginals to so-called projection effects. We also demonstrate how this representation provides an accurate estimator of the Bayesian evidence, with log error at the 0.2 level, allowing accurate model comparison. We test our method on multi-modal mixtures of Gaussians up to dimension 32 before applying it to simulated cosmology examples. Our code is publicly available at https://github.com/mraveri/tensiometer.
{"title":"Understanding posterior projection effects with normalizing flows","authors":"Marco Raveri, Cyrille Doux, Shivam Pandey","doi":"arxiv-2409.09101","DOIUrl":"https://doi.org/arxiv-2409.09101","url":null,"abstract":"Many modern applications of Bayesian inference, such as in cosmology, are\u0000based on complicated forward models with high-dimensional parameter spaces.\u0000This considerably limits the sampling of posterior distributions conditioned on\u0000observed data. In turn, this reduces the interpretability of posteriors to\u0000their one- and two-dimensional marginal distributions, when more information is\u0000available in the full dimensional distributions. We show how to learn smooth\u0000and differentiable representations of posterior distributions from their\u0000samples using normalizing flows, which we train with an added evidence error\u0000loss term, to improve accuracy in multiple ways. Motivated by problems from\u0000cosmology, we implement a robust method to obtain one and two-dimensional\u0000posterior profiles. These are obtained by optimizing, instead of integrating,\u0000over other parameters, and are thus less prone than marginals to so-called\u0000projection effects. We also demonstrate how this representation provides an\u0000accurate estimator of the Bayesian evidence, with log error at the 0.2 level,\u0000allowing accurate model comparison. We test our method on multi-modal mixtures\u0000of Gaussians up to dimension 32 before applying it to simulated cosmology\u0000examples. Our code is publicly available at\u0000https://github.com/mraveri/tensiometer.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. CodaW. M. Keck Observatory, T. OluyideCaltech/IPAC-NExScI, M. S. LynnCaltech/IPAC-NExScI, J. A. MaderW. M. Keck Observatory, G. Bruce BerrimanCaltech/IPAC-NExScI, M. BrodheimW. M. Keck Observatory, C. R. GelinoCaltech/IPAC-NExScI, J. GoodCaltech/IPAC-NExScI
The W. M. Keck Observatory Archive (KOA) has released the Observers Data Access Portal (ODAP), a web-application that delivers astronomical data from the W. M. Keck Observatory to the scheduled program's principal investigator and their collaborators anywhere in the world in near real-time. Data files and their associated metadata are streamed to a user's desktop machine moments after they are written to disk and archived in KOA. The ODAP User Interface is built in React and uses the WebSocket protocol to stream data between KOA and the user. This document describes the design of the tool, challenges encountered, shows how ODAP is integrated into the Keck observing model, and provides an analysis of usage metrics.
{"title":"Observers' Data Access Portal: Realtime Streaming for Astronomical Data","authors":"T. CodaW. M. Keck Observatory, T. OluyideCaltech/IPAC-NExScI, M. S. LynnCaltech/IPAC-NExScI, J. A. MaderW. M. Keck Observatory, G. Bruce BerrimanCaltech/IPAC-NExScI, M. BrodheimW. M. Keck Observatory, C. R. GelinoCaltech/IPAC-NExScI, J. GoodCaltech/IPAC-NExScI","doi":"arxiv-2409.09231","DOIUrl":"https://doi.org/arxiv-2409.09231","url":null,"abstract":"The W. M. Keck Observatory Archive (KOA) has released the Observers Data\u0000Access Portal (ODAP), a web-application that delivers astronomical data from\u0000the W. M. Keck Observatory to the scheduled program's principal investigator\u0000and their collaborators anywhere in the world in near real-time. Data files and\u0000their associated metadata are streamed to a user's desktop machine moments\u0000after they are written to disk and archived in KOA. The ODAP User Interface is\u0000built in React and uses the WebSocket protocol to stream data between KOA and\u0000the user. This document describes the design of the tool, challenges\u0000encountered, shows how ODAP is integrated into the Keck observing model, and\u0000provides an analysis of usage metrics.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. S. Savchenko, D. A. Morozova, S. G. Jorstad, D. A. Blinov, G. A. Borman, A. A. Vasilyev, T. S. Grishina, A. V. Zhovtan, E. N. Kopatskaya, E. G. Larionova, I. S. Troitskiy, Yu. V. Troitskaya, E. V. Shishkina, E. A. Shkodkina
Observations of quasars show that the polarization position angle of the emission coming from them varies greatly over time, including periods called rotations during which the angle changes in an orderly manner. The study proposes a method for identifying such events and assessing their statistical significance. The operation of the method is demonstrated using the example of long-term polarimetric observations of the blazars CTA 102, 3C 454.3, and OT 081. During the analysis of light curves, 51 rotations of the polarization position angle were found and it was shown that for CTA 102 and 3C 454.3 the rotations are predominantly oriented in one direction.
{"title":"The Method of Searching for Rotations of the Polarization Position Angle of Quasars","authors":"S. S. Savchenko, D. A. Morozova, S. G. Jorstad, D. A. Blinov, G. A. Borman, A. A. Vasilyev, T. S. Grishina, A. V. Zhovtan, E. N. Kopatskaya, E. G. Larionova, I. S. Troitskiy, Yu. V. Troitskaya, E. V. Shishkina, E. A. Shkodkina","doi":"arxiv-2409.08674","DOIUrl":"https://doi.org/arxiv-2409.08674","url":null,"abstract":"Observations of quasars show that the polarization position angle of the\u0000emission coming from them varies greatly over time, including periods called\u0000rotations during which the angle changes in an orderly manner. The study\u0000proposes a method for identifying such events and assessing their statistical\u0000significance. The operation of the method is demonstrated using the example of\u0000long-term polarimetric observations of the blazars CTA 102, 3C 454.3, and OT\u0000081. During the analysis of light curves, 51 rotations of the polarization\u0000position angle were found and it was shown that for CTA 102 and 3C 454.3 the\u0000rotations are predominantly oriented in one direction.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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