Pub Date : 2024-05-30DOI: 10.1088/1538-3873/ad4b9e
Sanjib Sharma and Stefano Casertano
We investigate algorithms for detecting and correcting for jumps due to cosmic rays in infrared detectors, with emphasis on Roman telescope’s Wide Field Instrument. We use a statistic S based on the excess difference between adjacent resultants (average over a group of reads) normalized to the square root of the expected variance that accommodates the uneven resultants of Roman. We show that it is important to account for the covariance of excess difference with that of the estimated count rate. Due to averaging of reads, the ability to detect jumps is reduced, specially if the jump is in the first or the last resultant. Having the first and last resultants as a single-read resultants improves the ability to detect cosmic rays. The signal due to a jump is split across two resultant differences and this motivates small adjustments to the basic algorithm which improves the jump detection. Bias and false negative rate are investigated using Monte Carlo simulations for a few readout patterns. In order to investigate other scenarios approximate formulas for predicting the bias and the misclassification rate are presented. Using cosmic ray properties based on JWST darks, we show that for high count rates (1000 e−1 s−1) most of the cosmic rays remain undetected, with 65% missed identifications. When averaging over multiple exposures, due to low event rates of cosmic rays, the overall bias in estimated count rate due to undetected cosmic rays is negligible. However, for a single exposure with an undetected cosmic ray, one can have a bias of a few percent. This will manifest as abrupt changes in brightness of targets. Fortunately, the bias ranges between 1 and 5 the measurement uncertainty, and this fact can be used to screen out cosmic rays for scientific applications that seek to detect short duration time domain events.
我们以罗曼望远镜的宽视场仪器为重点，研究了在红外探测器中探测和校正宇宙射线引起的跳变的算法。我们使用的统计量 S 基于相邻结果之间的超差（一组读数的平均值），归一化为预期方差的平方根，以适应 Roman 不均匀的结果。我们发现，考虑超差与估计计数率的协方差非常重要。由于读数的平均化，检测跳跃的能力会降低，特别是当跳跃发生在第一个或最后一个结果中时。将第一个和最后一个结果作为单读数结果可以提高探测宇宙射线的能力。跃迁产生的信号被两个结果差分开，这促使对基本算法进行微小调整，从而提高了跃迁检测能力。针对一些读出模式，使用蒙特卡罗模拟对偏差和假阴性率进行了研究。为了研究其他情况，还提出了预测偏差和误判率的近似公式。利用基于 JWST 暗的宇宙射线特性，我们发现在高计数率（1000 e-1 s-1）条件下，大部分宇宙射线仍未被检测到，漏检率高达 65%。由于宇宙射线的事件发生率较低，在对多次曝光进行平均时，未检测到的宇宙射线导致的估计计数率总体偏差可以忽略不计。然而，对于未检测到宇宙射线的单次曝光，偏差可能会达到百分之几。这将表现为目标亮度的突然变化。幸运的是，偏差范围在测量不确定性的 1 到 5 之间，这一事实可用于筛选出宇宙射线，以用于探测短时域事件的科学应用。
{"title":"Cosmic Ray Jump Detection for the Roman Wide Field Instrument","authors":"Sanjib Sharma and Stefano Casertano","doi":"10.1088/1538-3873/ad4b9e","DOIUrl":"https://doi.org/10.1088/1538-3873/ad4b9e","url":null,"abstract":"We investigate algorithms for detecting and correcting for jumps due to cosmic rays in infrared detectors, with emphasis on Roman telescope’s Wide Field Instrument. We use a statistic S based on the excess difference between adjacent resultants (average over a group of reads) normalized to the square root of the expected variance that accommodates the uneven resultants of Roman. We show that it is important to account for the covariance of excess difference with that of the estimated count rate. Due to averaging of reads, the ability to detect jumps is reduced, specially if the jump is in the first or the last resultant. Having the first and last resultants as a single-read resultants improves the ability to detect cosmic rays. The signal due to a jump is split across two resultant differences and this motivates small adjustments to the basic algorithm which improves the jump detection. Bias and false negative rate are investigated using Monte Carlo simulations for a few readout patterns. In order to investigate other scenarios approximate formulas for predicting the bias and the misclassification rate are presented. Using cosmic ray properties based on JWST darks, we show that for high count rates (1000 e−1 s−1) most of the cosmic rays remain undetected, with 65% missed identifications. When averaging over multiple exposures, due to low event rates of cosmic rays, the overall bias in estimated count rate due to undetected cosmic rays is negligible. However, for a single exposure with an undetected cosmic ray, one can have a bias of a few percent. This will manifest as abrupt changes in brightness of targets. Fortunately, the bias ranges between 1 and 5 the measurement uncertainty, and this fact can be used to screen out cosmic rays for scientific applications that seek to detect short duration time domain events.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"45 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141190007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-28DOI: 10.1088/1538-3873/ad4b9f
Valeri V. Makarov, Sébastien Lambert, Phil Cigan, Christopher DiLullo and David Gordon
Astronomical time series often have non-uniform sampling in time, or irregular cadences, with long gaps separating clusters of observations. Some of these data sets are also explicitly non-Gaussian with respect to the expected model fit, or the simple mean. The standard Lomb–Scargle periodogram is based on the least squares solution for a set of test periods and, therefore, is easily corrupted by a subset of statistical outliers or an intrinsically non-Gaussian population. It can produce completely misleading results for heavy-tailed distribution of residuals. We propose a robust 1-norm periodogram technique, which is based on the principles of robust statistical estimation. This technique can be implemented in weighted or unweighted options. The method is described in detail and compared with the classical least squares periodogram on a set of astrometric VLBI measurements of the ICRF quasar IERS B0642+449. It is uniformly applied to a collection of 259 ICRF3 quasars each with more than 200 epoch VLBI measurements, resulting in a list of 49 objects with quasi-periodic position changes above the 3σ level, which warrant further investigation.
{"title":"Robust 1-norm Periodograms for Analysis of Noisy Non-Gaussian Time Series with Irregular Cadences: Application to VLBI Astrometry of Quasars","authors":"Valeri V. Makarov, Sébastien Lambert, Phil Cigan, Christopher DiLullo and David Gordon","doi":"10.1088/1538-3873/ad4b9f","DOIUrl":"https://doi.org/10.1088/1538-3873/ad4b9f","url":null,"abstract":"Astronomical time series often have non-uniform sampling in time, or irregular cadences, with long gaps separating clusters of observations. Some of these data sets are also explicitly non-Gaussian with respect to the expected model fit, or the simple mean. The standard Lomb–Scargle periodogram is based on the least squares solution for a set of test periods and, therefore, is easily corrupted by a subset of statistical outliers or an intrinsically non-Gaussian population. It can produce completely misleading results for heavy-tailed distribution of residuals. We propose a robust 1-norm periodogram technique, which is based on the principles of robust statistical estimation. This technique can be implemented in weighted or unweighted options. The method is described in detail and compared with the classical least squares periodogram on a set of astrometric VLBI measurements of the ICRF quasar IERS B0642+449. It is uniformly applied to a collection of 259 ICRF3 quasars each with more than 200 epoch VLBI measurements, resulting in a list of 49 objects with quasi-periodic position changes above the 3σ level, which warrant further investigation.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"16 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141190238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-27DOI: 10.1088/1538-3873/ad48b8
Aislyn Bell, Jiyuan Zhang, Weicheng Zang, Youn Kil Jung, Jennifer C. Yee, Hongjing Yang, Takahiro Sumi, Andrzej Udalski, Leading Authors, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Cheongho Han, Kyu-Ha Hwang, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Sang-Mok Cha, Dong-Jin Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, The KMTNet Collaboration, Yunyi Tang, Jennie McCormick, Subo Dong, Zhuokai Liu, Leandro de Almeida, Shude Mao, Dan Maoz, Wei Zhu, The MAP & FUN Follow-up Team, Fumio Abe, Richard Barry, David P. Bennett, Aparna Bhattacharya, Ian A. Bond, Hirosane Fujii, Akihiko Fukui, Ryusei Hamada, Yuki Hirao, Stela Ishitani Silva, Yoshitaka Itow, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Yutaka Matsubara, Sho Matsumoto, Shota Miyazaki, Yasushi Muraki, Arisa Okamura, Greg Lmschenk, Clément Ranc, Nicholas J. Rattenbury, Yuki Satoh, Daisuke Suzuki, Taiga Toda, Mio Tomoyoshi, Paul J. Tristram, Aikaterini Vandorou, Hib..
The current studies of microlensing planets are limited by small number statistics. Follow-up observations of high-magnification microlensing events can efficiently form a statistical planetary sample. Since 2020, the Korea Microlensing Telescope Network (KMTNet) and the Las Cumbres Observatory (LCO) global network have been conducting a follow-up program for high-magnification KMTNet events. Here, we report the detection and analysis of a microlensing planetary event, KMT-2023-BLG-1431, for which the subtle (0.05 mag) and short-lived (5 hr) planetary signature was characterized by the follow-up from KMTNet and LCO. A binary-lens single-source (2L1S) analysis reveals a planet/host mass ratio of q = (0.72 ± 0.07) × 10−4, and the single-lens binary-source (1L2S) model is excluded by Δχ2 = 80. A Bayesian analysis using a Galactic model yields estimates of the host star mass of , the planetary mass of , and the lens distance of kpc. The projected planet-host separation of au or au, subject to the close/wide degeneracy. We also find that without the follow-up data, the survey-only data cannot break the degeneracy of central/resonant caustics and the degeneracy of 2L1S/1L2S models, showing the importance of follow-up observations for current microlensing surveys.
{"title":"KMT-2023-BLG-1431Lb: A New q < 10−4 Microlensing Planet from a Subtle Signature","authors":"Aislyn Bell, Jiyuan Zhang, Weicheng Zang, Youn Kil Jung, Jennifer C. Yee, Hongjing Yang, Takahiro Sumi, Andrzej Udalski, Leading Authors, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Cheongho Han, Kyu-Ha Hwang, Yoon-Hyun Ryu, In-Gu Shin, Yossi Shvartzvald, Sang-Mok Cha, Dong-Jin Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, The KMTNet Collaboration, Yunyi Tang, Jennie McCormick, Subo Dong, Zhuokai Liu, Leandro de Almeida, Shude Mao, Dan Maoz, Wei Zhu, The MAP & FUN Follow-up Team, Fumio Abe, Richard Barry, David P. Bennett, Aparna Bhattacharya, Ian A. Bond, Hirosane Fujii, Akihiko Fukui, Ryusei Hamada, Yuki Hirao, Stela Ishitani Silva, Yoshitaka Itow, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Yutaka Matsubara, Sho Matsumoto, Shota Miyazaki, Yasushi Muraki, Arisa Okamura, Greg Lmschenk, Clément Ranc, Nicholas J. Rattenbury, Yuki Satoh, Daisuke Suzuki, Taiga Toda, Mio Tomoyoshi, Paul J. Tristram, Aikaterini Vandorou, Hib..","doi":"10.1088/1538-3873/ad48b8","DOIUrl":"https://doi.org/10.1088/1538-3873/ad48b8","url":null,"abstract":"The current studies of microlensing planets are limited by small number statistics. Follow-up observations of high-magnification microlensing events can efficiently form a statistical planetary sample. Since 2020, the Korea Microlensing Telescope Network (KMTNet) and the Las Cumbres Observatory (LCO) global network have been conducting a follow-up program for high-magnification KMTNet events. Here, we report the detection and analysis of a microlensing planetary event, KMT-2023-BLG-1431, for which the subtle (0.05 mag) and short-lived (5 hr) planetary signature was characterized by the follow-up from KMTNet and LCO. A binary-lens single-source (2L1S) analysis reveals a planet/host mass ratio of q = (0.72 ± 0.07) × 10−4, and the single-lens binary-source (1L2S) model is excluded by Δχ2 = 80. A Bayesian analysis using a Galactic model yields estimates of the host star mass of , the planetary mass of , and the lens distance of kpc. The projected planet-host separation of au or au, subject to the close/wide degeneracy. We also find that without the follow-up data, the survey-only data cannot break the degeneracy of central/resonant caustics and the degeneracy of 2L1S/1L2S models, showing the importance of follow-up observations for current microlensing surveys.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"22 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141169777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-27DOI: 10.1088/1538-3873/ad481f
Bo Zhang, ShaoMing Hu, Junju Du, Xu Yang, Xu Chen, Hai Jiang, Hai Cao and Shuai Feng
In response to the exponential growth of space debris, an increasing number of observation devices are being used for the observation of moving objects, such as space debris and asteroids, which require further improvements in data-processing capabilities for the detection of moving objects. In this study, we propose a rapid detection algorithm designed for detecting moving objects, leveraging the power of the 3D Hough transform. By the simulated image experiments, our results show that the detection rate increases with the number of continuous images when fully extracting objects. Based on this foundation, the object detection rate is at least 87% regardless of the object number in the image sequence when detecting objects from at least six continuous images. In the observed image experiments, we used source-extractor to extract sources. The results show the method can successfully detect objects with signal-to-noise ratio higher than three from sidereal tracking images and can identify asteroids from asteroid tracking images while maintaining a detection speed that meets the requirements for real-time processing.
{"title":"Detecting Moving Objects in Photometric Images Using 3D Hough Transform","authors":"Bo Zhang, ShaoMing Hu, Junju Du, Xu Yang, Xu Chen, Hai Jiang, Hai Cao and Shuai Feng","doi":"10.1088/1538-3873/ad481f","DOIUrl":"https://doi.org/10.1088/1538-3873/ad481f","url":null,"abstract":"In response to the exponential growth of space debris, an increasing number of observation devices are being used for the observation of moving objects, such as space debris and asteroids, which require further improvements in data-processing capabilities for the detection of moving objects. In this study, we propose a rapid detection algorithm designed for detecting moving objects, leveraging the power of the 3D Hough transform. By the simulated image experiments, our results show that the detection rate increases with the number of continuous images when fully extracting objects. Based on this foundation, the object detection rate is at least 87% regardless of the object number in the image sequence when detecting objects from at least six continuous images. In the observed image experiments, we used source-extractor to extract sources. The results show the method can successfully detect objects with signal-to-noise ratio higher than three from sidereal tracking images and can identify asteroids from asteroid tracking images while maintaining a detection speed that meets the requirements for real-time processing.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"49 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141169776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-15DOI: 10.1088/1538-3873/ad4177
Z. Dencs, A. Derekas, T. Mitnyan, M. F. Andersen, B. Cseh, F. Grundahl, V. Hegedűs, J. Kovács, L. Kriskovics, P. L. Palle, A. Pál, L. Szigeti and Sz. Mészáros
Understanding the atmospheric parameters of stars on the top of the RGB is essential to reveal the chemical composition of the Milky Way, as they can be used to probe the farthest parts of our Galaxy. Our goal is to determine the chemical composition of 21 RGB stars with Teff < 4200 K selected from the APOGEE-2 DR17 database using new observations carried out with the spectrograph mounted on the 1 m telescope of the Hungarian Piszkéstető Observatory and the SONG spectrograph (R = 77,000) on the Hertzsprung SONG telescope in the 4500–5800 Å wavelength range. This is the first time the spectrograph (R = 18,000) on the 1 m telescope at Piszkéstető Observatory was used to measure the abundances of stars. We created a new LTE spectral library using MARCS model atmospheres and SYNSPEC by including the line list of 23 molecules to determine atmospheric parameters (Teff, , [Fe/H], [α/Fe]) and abundances of Si, Ca, Ti, V, Cr, Mn, and Ni with FERRE. The resulting parameters were compared to that of APOGEE. We found a good agreement in general, the average difference is −11.2 K in Teff, 0.11 dex in , 0.10 dex in [Fe/H], and −0.01 dex in [α/Fe]. Our analysis successfully demonstrates the ability of the spectrograph at Piszkéstető Observatory to reliably measure the abundance of bright stars.
{"title":"Atmospheric Parameters and Abundances of Cool Red Giant Stars","authors":"Z. Dencs, A. Derekas, T. Mitnyan, M. F. Andersen, B. Cseh, F. Grundahl, V. Hegedűs, J. Kovács, L. Kriskovics, P. L. Palle, A. Pál, L. Szigeti and Sz. Mészáros","doi":"10.1088/1538-3873/ad4177","DOIUrl":"https://doi.org/10.1088/1538-3873/ad4177","url":null,"abstract":"Understanding the atmospheric parameters of stars on the top of the RGB is essential to reveal the chemical composition of the Milky Way, as they can be used to probe the farthest parts of our Galaxy. Our goal is to determine the chemical composition of 21 RGB stars with Teff < 4200 K selected from the APOGEE-2 DR17 database using new observations carried out with the spectrograph mounted on the 1 m telescope of the Hungarian Piszkéstető Observatory and the SONG spectrograph (R = 77,000) on the Hertzsprung SONG telescope in the 4500–5800 Å wavelength range. This is the first time the spectrograph (R = 18,000) on the 1 m telescope at Piszkéstető Observatory was used to measure the abundances of stars. We created a new LTE spectral library using MARCS model atmospheres and SYNSPEC by including the line list of 23 molecules to determine atmospheric parameters (Teff, , [Fe/H], [α/Fe]) and abundances of Si, Ca, Ti, V, Cr, Mn, and Ni with FERRE. The resulting parameters were compared to that of APOGEE. We found a good agreement in general, the average difference is −11.2 K in Teff, 0.11 dex in , 0.10 dex in [Fe/H], and −0.01 dex in [α/Fe]. Our analysis successfully demonstrates the ability of the spectrograph at Piszkéstető Observatory to reliably measure the abundance of bright stars.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"31 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141060490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-15DOI: 10.1088/1538-3873/ad3455
Thomas Henning, Inga Kamp, Matthias Samland, Aditya M. Arabhavi, Jayatee Kanwar, Ewine F. van Dishoeck, Manuel Güdel, Pierre-Olivier Lagage, Christoffel Waelkens, Alain Abergel, Olivier Absil, David Barrado, Anthony Boccaletti, Jeroen Bouwman, Alessio Caratti o Garatti, Vincent Geers, Adrian M. Glauser, Fred Lahuis, Michael Mueller, Cyrine Nehmé, Göran Olofsson, Eric Pantin, Tom P. Ray, Silvia Scheithauer, Bart Vandenbussche, L. B. F. M. Waters, Gillian Wright, Ioannis Argyriou, Valentin Christiaens, Riccardo Franceschi, Danny Gasman, Sierra L. Grant, Rodrigo Guadarrama, Hyerin Jang, Maria Morales-Calderón, Nicole Pawellek, Giulia Perotti, Donna Rodgers-Lee, Jürgen Schreiber, Kamber Schwarz, Benoît Tabone, Milou Temmink, Marissa Vlasblom, Luis Colina, Thomas R. Greve and Göran Östlin
The study of protoplanetary disks has become increasingly important with the Kepler satellite finding that exoplanets are ubiquitous around stars in our galaxy and the discovery of enormous diversity in planetary system architectures and planet properties. High-resolution near-IR and ALMA images show strong evidence for ongoing planet formation in young disks. The JWST MIRI mid-INfrared Disk Survey (MINDS) aims to (1) investigate the chemical inventory in the terrestrial planet-forming zone across stellar spectral type, (2) follow the gas evolution into the disk dispersal stage, and (3) study the structure of protoplanetary and debris disks in the thermal mid-IR. The MINDS survey will thus build a bridge between the chemical inventory of disks and the properties of exoplanets. The survey comprises 52 targets (Herbig Ae stars, T Tauri stars, very low-mass stars and young debris disks). We primarily obtain MIRI/MRS spectra with high signal-to-noise ratio (∼100–500) covering the complete wavelength range from 4.9 to 27.9 μm. For a handful of selected targets we also obtain NIRSpec IFU high resolution spectroscopy (2.87–5.27 μm). We will search for signposts of planet formation in thermal emission of micron-sized dust—information complementary to near-IR scattered light emission from small dust grains and emission from large dust in the submillimeter wavelength domain. We will also study the spatial structure of disks in three key systems that have shown signposts for planet formation, TW Hya and HD 169142 using the MIRI coronagraph at 15.5 μm and 10.65 μm respectively and PDS 70 using NIRCam imaging in the 1.87 μm narrow and the 4.8 μm medium band filter. We provide here an overview of the MINDS survey and showcase the power of the new JWST mid-IR molecular spectroscopy with the TW Hya disk spectrum where we report the detection of the molecular ion and the robust confirmation of HCO+ earlier detected with Spitzer.
{"title":"MINDS: The JWST MIRI Mid-INfrared Disk Survey","authors":"Thomas Henning, Inga Kamp, Matthias Samland, Aditya M. Arabhavi, Jayatee Kanwar, Ewine F. van Dishoeck, Manuel Güdel, Pierre-Olivier Lagage, Christoffel Waelkens, Alain Abergel, Olivier Absil, David Barrado, Anthony Boccaletti, Jeroen Bouwman, Alessio Caratti o Garatti, Vincent Geers, Adrian M. Glauser, Fred Lahuis, Michael Mueller, Cyrine Nehmé, Göran Olofsson, Eric Pantin, Tom P. Ray, Silvia Scheithauer, Bart Vandenbussche, L. B. F. M. Waters, Gillian Wright, Ioannis Argyriou, Valentin Christiaens, Riccardo Franceschi, Danny Gasman, Sierra L. Grant, Rodrigo Guadarrama, Hyerin Jang, Maria Morales-Calderón, Nicole Pawellek, Giulia Perotti, Donna Rodgers-Lee, Jürgen Schreiber, Kamber Schwarz, Benoît Tabone, Milou Temmink, Marissa Vlasblom, Luis Colina, Thomas R. Greve and Göran Östlin","doi":"10.1088/1538-3873/ad3455","DOIUrl":"https://doi.org/10.1088/1538-3873/ad3455","url":null,"abstract":"The study of protoplanetary disks has become increasingly important with the Kepler satellite finding that exoplanets are ubiquitous around stars in our galaxy and the discovery of enormous diversity in planetary system architectures and planet properties. High-resolution near-IR and ALMA images show strong evidence for ongoing planet formation in young disks. The JWST MIRI mid-INfrared Disk Survey (MINDS) aims to (1) investigate the chemical inventory in the terrestrial planet-forming zone across stellar spectral type, (2) follow the gas evolution into the disk dispersal stage, and (3) study the structure of protoplanetary and debris disks in the thermal mid-IR. The MINDS survey will thus build a bridge between the chemical inventory of disks and the properties of exoplanets. The survey comprises 52 targets (Herbig Ae stars, T Tauri stars, very low-mass stars and young debris disks). We primarily obtain MIRI/MRS spectra with high signal-to-noise ratio (∼100–500) covering the complete wavelength range from 4.9 to 27.9 μm. For a handful of selected targets we also obtain NIRSpec IFU high resolution spectroscopy (2.87–5.27 μm). We will search for signposts of planet formation in thermal emission of micron-sized dust—information complementary to near-IR scattered light emission from small dust grains and emission from large dust in the submillimeter wavelength domain. We will also study the spatial structure of disks in three key systems that have shown signposts for planet formation, TW Hya and HD 169142 using the MIRI coronagraph at 15.5 μm and 10.65 μm respectively and PDS 70 using NIRCam imaging in the 1.87 μm narrow and the 4.8 μm medium band filter. We provide here an overview of the MINDS survey and showcase the power of the new JWST mid-IR molecular spectroscopy with the TW Hya disk spectrum where we report the detection of the molecular ion and the robust confirmation of HCO+ earlier detected with Spitzer.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"23 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141060427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-14DOI: 10.1088/1538-3873/ad38da
Timothy D. Brandt
This paper implements likelihood-based jump detection for detectors read out up-the-ramp, using the entire set of reads to compute likelihoods. The approach compares the χ2 value of a fit with and without a jump for every possible jump location. I show that this approach can be substantially more sensitive than one that only uses the difference between sequential groups of reads, especially for long ramps and for jumps that occur in the middle of a group of reads. It can also be implemented for a computational cost that is linear in the number of resultants. I provide and describe a pure Python implementation that can process a 10-resultant ramp on a 4096 × 4096 detector in ≈20 s, including iterative cosmic ray detection and removal, on a single core of a 2020 Macbook Air. This Python implementation, together with tests and a tutorial notebook, are available at https://github.com/t-brandt/fitramp. I also provide tests and demonstrations of the full ramp fitting and cosmic ray rejection approach on data from the JWST.
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Pub Date : 2024-05-14DOI: 10.1088/1538-3873/ad37d8
Jingwen Zhang, 婧雯 张, Michael Bottom and Eugene Serabyn
Space-based direct imaging provides prospects for detection and spectral characterization of exoplanets at optical and near-infrared wavelengths. Integral field spectrographs (IFS) have been historically baselined for these mission concepts. However, multiple studies have revealed that detector noise is a serious obstacle for such instruments when observing extremely faint targets such as Earth-like planets. Imaging Fourier transform spectrographs (iFTS) are generally less sensitive to detector noise, and have several other compelling features such as simultaneous imaging and spectroscopy, smaller-format detector requirements, and variable spectral resolving power. To date, they have not been studied as options for such missions. Here, we compare the capabilities of IFS and iFTS for directly obtaining spectra from an Earth-like planet using both analytic and numerical models. Specifically, we compare the required exposure times to achieve the same signal-to-noise ratio with the two architectures over a range of detector and optical system parameters. We find that for a 6 m telescope, an IFS outperforms an iFTS at optical wavelengths due to the effects of distributed photon noise. In the near-IR, the relative efficiency of an IFS and iFTS depends critically on the instrument design and detector noise. An iFTS will be more efficient than an IFS if the readout noise of the near-IR detector is above ∼2–3 e− pix−1 frame−1 (tfrm = 1000 s), which correspond to half to one-third of the state-of-art detector noise. However, if the readout noise is reduced below this threshold, the performance of an IFS will experience a substantial improvement and become more efficient. These results motivate consideration of an iFTS as an alternative option for future direct imaging space missions in the near-IR.
{"title":"Direct Detection and Characterization of Exoplanets Using Imaging Fourier Transform Spectroscopy","authors":"Jingwen Zhang, 婧雯 张, Michael Bottom and Eugene Serabyn","doi":"10.1088/1538-3873/ad37d8","DOIUrl":"https://doi.org/10.1088/1538-3873/ad37d8","url":null,"abstract":"Space-based direct imaging provides prospects for detection and spectral characterization of exoplanets at optical and near-infrared wavelengths. Integral field spectrographs (IFS) have been historically baselined for these mission concepts. However, multiple studies have revealed that detector noise is a serious obstacle for such instruments when observing extremely faint targets such as Earth-like planets. Imaging Fourier transform spectrographs (iFTS) are generally less sensitive to detector noise, and have several other compelling features such as simultaneous imaging and spectroscopy, smaller-format detector requirements, and variable spectral resolving power. To date, they have not been studied as options for such missions. Here, we compare the capabilities of IFS and iFTS for directly obtaining spectra from an Earth-like planet using both analytic and numerical models. Specifically, we compare the required exposure times to achieve the same signal-to-noise ratio with the two architectures over a range of detector and optical system parameters. We find that for a 6 m telescope, an IFS outperforms an iFTS at optical wavelengths due to the effects of distributed photon noise. In the near-IR, the relative efficiency of an IFS and iFTS depends critically on the instrument design and detector noise. An iFTS will be more efficient than an IFS if the readout noise of the near-IR detector is above ∼2–3 e− pix−1 frame−1 (tfrm = 1000 s), which correspond to half to one-third of the state-of-art detector noise. However, if the readout noise is reduced below this threshold, the performance of an IFS will experience a substantial improvement and become more efficient. These results motivate consideration of an iFTS as an alternative option for future direct imaging space missions in the near-IR.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"41 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141060473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-14DOI: 10.1088/1538-3873/ad38d9
Timothy D. Brandt
This paper derives the optimal fit to a pixel’s count rate in the case of an ideal detector read out nondestructively in the presence of both read and photon noise. The approach is general for any readout scheme, provides closed-form expressions for all quantities, and has a computational cost that is linear in the number of resultants (groups of reads). I also derive the bias of the fit from estimating the covariance matrix and show how to remove it to first order. The ramp-fitting algorithm I describe provides the χ2 value of the fit of a line to the accumulated counts, which can be interpreted as a goodness-of-fit metric. I provide and describe a pure Python implementation of these algorithms that can process a 10-resultant ramp on a 4096 × 4096 detector in ≈8 s with bias removal on a single core of a 2020 Macbook Air. This Python implementation, together with tests and a tutorial notebook, are available at https://github.com/t-brandt/fitramp. A companion paper describes a jump detection algorithm based on hypothesis testing of ramp fits and demonstrates all algorithms on data from JWST.
{"title":"Optimal Fitting and Debiasing for Detectors Read Out Up-the-Ramp","authors":"Timothy D. Brandt","doi":"10.1088/1538-3873/ad38d9","DOIUrl":"https://doi.org/10.1088/1538-3873/ad38d9","url":null,"abstract":"This paper derives the optimal fit to a pixel’s count rate in the case of an ideal detector read out nondestructively in the presence of both read and photon noise. The approach is general for any readout scheme, provides closed-form expressions for all quantities, and has a computational cost that is linear in the number of resultants (groups of reads). I also derive the bias of the fit from estimating the covariance matrix and show how to remove it to first order. The ramp-fitting algorithm I describe provides the χ2 value of the fit of a line to the accumulated counts, which can be interpreted as a goodness-of-fit metric. I provide and describe a pure Python implementation of these algorithms that can process a 10-resultant ramp on a 4096 × 4096 detector in ≈8 s with bias removal on a single core of a 2020 Macbook Air. This Python implementation, together with tests and a tutorial notebook, are available at https://github.com/t-brandt/fitramp. A companion paper describes a jump detection algorithm based on hypothesis testing of ramp fits and demonstrates all algorithms on data from JWST.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"131 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141060628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-13DOI: 10.1088/1538-3873/ad430c
Dana I. Casetti-Dinescu, Roberto Baena-Gallé, Terrence M. Girard, Alejandro Cervantes-Rovira and Sebastian Todeasa
We present an expanded and improved deep-learning (DL) methodology for determining centers of star images on Hubble Space Telescope/Wide-Field Planetary Camera 2 (WFPC2) exposures. Previously, we demonstrated that our DL model can eliminate the pixel-phase bias otherwise present in these undersampled images; however that analysis was limited to the central portion of each detector. In the current work we introduce the inclusion of global positions to account for the point-spread function (PSF) variation across the entire chip and instrumental magnitudes to account for nonlinear effects such as charge transfer efficiency. The DL model is trained using a unique series of WFPC2 observations of globular cluster 47 Tuc, data sets comprising over 600 dithered exposures taken in each of two filters—F555W and F814W. It is found that the PSF variations across each chip correspond to corrections of the order of ∼100 mpix, while magnitude effects are at a level of ∼10 mpix. Importantly, pixel-phase bias is eliminated with the DL model; whereas, with a classic centering algorithm, the amplitude of this bias can be up to ∼40 mpix. Our improved DL model yields star-image centers with uncertainties of 8–10 mpix across the full field of view of WFPC2.
{"title":"Star Image Centering with Deep Learning. II. HST/WFPC2 Full Field of View","authors":"Dana I. Casetti-Dinescu, Roberto Baena-Gallé, Terrence M. Girard, Alejandro Cervantes-Rovira and Sebastian Todeasa","doi":"10.1088/1538-3873/ad430c","DOIUrl":"https://doi.org/10.1088/1538-3873/ad430c","url":null,"abstract":"We present an expanded and improved deep-learning (DL) methodology for determining centers of star images on Hubble Space Telescope/Wide-Field Planetary Camera 2 (WFPC2) exposures. Previously, we demonstrated that our DL model can eliminate the pixel-phase bias otherwise present in these undersampled images; however that analysis was limited to the central portion of each detector. In the current work we introduce the inclusion of global positions to account for the point-spread function (PSF) variation across the entire chip and instrumental magnitudes to account for nonlinear effects such as charge transfer efficiency. The DL model is trained using a unique series of WFPC2 observations of globular cluster 47 Tuc, data sets comprising over 600 dithered exposures taken in each of two filters—F555W and F814W. It is found that the PSF variations across each chip correspond to corrections of the order of ∼100 mpix, while magnitude effects are at a level of ∼10 mpix. Importantly, pixel-phase bias is eliminated with the DL model; whereas, with a classic centering algorithm, the amplitude of this bias can be up to ∼40 mpix. Our improved DL model yields star-image centers with uncertainties of 8–10 mpix across the full field of view of WFPC2.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"147 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140937571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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