Aperture photometry is a fundamental technique widely used to obtain high-precision light curves in optical survey projects like Tianyu.However,its effectiveness is limited in crowded fields,and the choice of aperture...Aperture photometry is a fundamental technique widely used to obtain high-precision light curves in optical survey projects like Tianyu.However,its effectiveness is limited in crowded fields,and the choice of aperture size critically impacts photometric precision.To address these challenges,we propose DeepAP,an efficient and accurate two-stage deep learning framework for aperture photometry.Specifically,for a given source,we first train a Vision Transformer(ViT)model to assess its feasibility of aperture photometry.We then train the Residual Neural Network(ResNet)to predict its optimal aperture size.For aperture photometry feasibility assessment,the ViT model yields an ROC AUC value of 0.96,and achieves a precision of 0.974,a recall of 0.930,and an F1 score of 0.952 on the test set.For aperture size prediction,the ResNet model effectively mitigates biases inherent in classical growth curve methods by adaptively selecting apertures appropriate for sources of varying brightness,thereby enhancing the signal-to-noise ratio(SNR)across a wide range of targets.Meanwhile,some samples in the test set have a higher SNR than those obtained by exhaustive aperture size enumeration because of the finer granularity of aperture size estimation.By integrating ResNet with the ViT network,the DeepAP framework achieves a median total processing time of 18 ms for a batch of 10 images,representing a speed-up of approximately 5.9×10^(4) times compared to exhaustive aperture size enumeration.This work paves the way for the automatic application of aperture photometry in future high-precision surveys such as Tianyu and Legacy Survey of Space and Time.The source code and model are available at https://github.com/ruiyicheng/DeepAP.展开更多
The lensing effect of a cosmic string is studied, and some new methods are proposed to detect the cosmic string. The technique for using jets as extended gravitational lensing probes was first explored by Kronberg. We...The lensing effect of a cosmic string is studied, and some new methods are proposed to detect the cosmic string. The technique for using jets as extended gravitational lensing probes was first explored by Kronberg. We use the ＂alignment-breaking parameter＂ nc as a sensitive indicator of gravitational distortion by a wiggly cosmic string. Then, we applied the non-constant deflection angle to jets, and na of a specific jet is just related to the projected slope of the jet. At least three jets in the sample of Square Kilometer Array （SKA） would have significant signals （na 〉 10°） if the wiggly infinite cosmic string existed. The distortion of elliptical object is also studied and used to do a statistical research on the directions of axes and ellipticities of galaxies. In the direction of the string, we find that galaxies appear to be more elliptical for an observer and the distribution of apparent ellipticity changes correspondingly. The ellipticity distribution of current SDSS spiral sample has the signal- to-noise ratio up to 8.48 which is large enough for astronomical observations. The future survey, such as Large Synoptic Survey Telescope （LSST） and Dark Energy Survey （DES） would weaken the requirement of special geometry in the data processing. As a result, all kinds of distributions, including ellipticity axis distribution, would serve as probes to detect wiggly strings in the near future. In brief, if a wiggly cosmic string existed, these signals would be convenient to be observed with the future weak lensing survey or other surveys in the deep space. If there was no lensing signal in these distributions, it would give the upper limit of the abundance of infinite strings.展开更多
基金supported by the Youth Program of the Natural Science Foundation of Qinghai Province(2023-ZJ-951Q)Qinghai University Research Ability Enhancement Project(2025KTSQ26).
文摘Aperture photometry is a fundamental technique widely used to obtain high-precision light curves in optical survey projects like Tianyu.However,its effectiveness is limited in crowded fields,and the choice of aperture size critically impacts photometric precision.To address these challenges,we propose DeepAP,an efficient and accurate two-stage deep learning framework for aperture photometry.Specifically,for a given source,we first train a Vision Transformer(ViT)model to assess its feasibility of aperture photometry.We then train the Residual Neural Network(ResNet)to predict its optimal aperture size.For aperture photometry feasibility assessment,the ViT model yields an ROC AUC value of 0.96,and achieves a precision of 0.974,a recall of 0.930,and an F1 score of 0.952 on the test set.For aperture size prediction,the ResNet model effectively mitigates biases inherent in classical growth curve methods by adaptively selecting apertures appropriate for sources of varying brightness,thereby enhancing the signal-to-noise ratio(SNR)across a wide range of targets.Meanwhile,some samples in the test set have a higher SNR than those obtained by exhaustive aperture size enumeration because of the finer granularity of aperture size estimation.By integrating ResNet with the ViT network,the DeepAP framework achieves a median total processing time of 18 ms for a batch of 10 images,representing a speed-up of approximately 5.9×10^(4) times compared to exhaustive aperture size enumeration.This work paves the way for the automatic application of aperture photometry in future high-precision surveys such as Tianyu and Legacy Survey of Space and Time.The source code and model are available at https://github.com/ruiyicheng/DeepAP.
文摘The lensing effect of a cosmic string is studied, and some new methods are proposed to detect the cosmic string. The technique for using jets as extended gravitational lensing probes was first explored by Kronberg. We use the ＂alignment-breaking parameter＂ nc as a sensitive indicator of gravitational distortion by a wiggly cosmic string. Then, we applied the non-constant deflection angle to jets, and na of a specific jet is just related to the projected slope of the jet. At least three jets in the sample of Square Kilometer Array （SKA） would have significant signals （na 〉 10°） if the wiggly infinite cosmic string existed. The distortion of elliptical object is also studied and used to do a statistical research on the directions of axes and ellipticities of galaxies. In the direction of the string, we find that galaxies appear to be more elliptical for an observer and the distribution of apparent ellipticity changes correspondingly. The ellipticity distribution of current SDSS spiral sample has the signal- to-noise ratio up to 8.48 which is large enough for astronomical observations. The future survey, such as Large Synoptic Survey Telescope （LSST） and Dark Energy Survey （DES） would weaken the requirement of special geometry in the data processing. As a result, all kinds of distributions, including ellipticity axis distribution, would serve as probes to detect wiggly strings in the near future. In brief, if a wiggly cosmic string existed, these signals would be convenient to be observed with the future weak lensing survey or other surveys in the deep space. If there was no lensing signal in these distributions, it would give the upper limit of the abundance of infinite strings.
