S. Hale, W. Chaplin, G. Davies, Y. Elsworth, R. Howe
The Birmingham Solar Oscillations Network (BiSON) observes acoustic oscillations of the Sun. The dominant noise source is caused by fluctuations of Earth’s atmosphere, and BiSON seeks to mitigate this effect by combining multiple rapid observations in alternating polarisation states. Current instrumentation uses bespoke Pockels-effect cells to select the polarisation state. Here, we investigate an alternative off-the-shelf solution, a liquid crystal retarder, and discuss the potential impact of differences in performance. We show through electrical simulation of the photodiode-based detectors, and assessment of both types of polarisation device, that although the switching rate is slower the off-the-shelf LCD retarder is a viable replacement for a bespoke Pockels-effect cell. The simplifications arising from the use of off-the-shelf components allows easier and quicker instrumentation deployment.
{"title":"Detector bandwidth and polarisation switching rates: Spectrophotometric observations of the Sun by the Birmingham Solar Oscillations Network (BiSON)","authors":"S. Hale, W. Chaplin, G. Davies, Y. Elsworth, R. Howe","doi":"10.1093/rasti/rzad008","DOIUrl":"https://doi.org/10.1093/rasti/rzad008","url":null,"abstract":"\u0000 The Birmingham Solar Oscillations Network (BiSON) observes acoustic oscillations of the Sun. The dominant noise source is caused by fluctuations of Earth’s atmosphere, and BiSON seeks to mitigate this effect by combining multiple rapid observations in alternating polarisation states. Current instrumentation uses bespoke Pockels-effect cells to select the polarisation state. Here, we investigate an alternative off-the-shelf solution, a liquid crystal retarder, and discuss the potential impact of differences in performance. We show through electrical simulation of the photodiode-based detectors, and assessment of both types of polarisation device, that although the switching rate is slower the off-the-shelf LCD retarder is a viable replacement for a bespoke Pockels-effect cell. The simplifications arising from the use of off-the-shelf components allows easier and quicker instrumentation deployment.","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114482387","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}
K. Wiersema, R. Starling, J. C. N. Campagnolo, D. Thanki, R. McErlean
We describe the development, construction, data analysis, initial calibration and first results of LE2Pol, an inexpensive dual-beam optical imaging polarimeter. LE2Pol is designed for a 20 inch telescope at the observatory of the University of Leicester, but can also be used as a visiting instrument on a wide range of small telescopes (≲ 1 m). We show how simple imaging polarimeters on small telescopes can be used to provide useful scientific and educational data at low cost.
{"title":"LE2Pol: The Leicester dual-beam imaging polarimeter","authors":"K. Wiersema, R. Starling, J. C. N. Campagnolo, D. Thanki, R. McErlean","doi":"10.1093/rasti/rzad005","DOIUrl":"https://doi.org/10.1093/rasti/rzad005","url":null,"abstract":"\u0000 We describe the development, construction, data analysis, initial calibration and first results of LE2Pol, an inexpensive dual-beam optical imaging polarimeter. LE2Pol is designed for a 20 inch telescope at the observatory of the University of Leicester, but can also be used as a visiting instrument on a wide range of small telescopes (≲ 1 m). We show how simple imaging polarimeters on small telescopes can be used to provide useful scientific and educational data at low cost.","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"2017 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122371357","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}
In this study we introduce a novel moving-average model for analyzing stationary time series observed irregularly in time. The process is strictly stationary and ergodic under normality and weakly stationary when normality is not assumed. Maximum likelihood estimation can be efficiently carried out through a Kalman algorithm obtained from the state-space representation of the model. The Kalman algorithm has order O(n) (where n is the number of observations in the sequence), from which it is possible to efficiently generate parameter estimators, linear predictors and their mean squared errors. Two procedures were developed for assessing parameter estimation errors: one based on the Hessian of the likelihood function and another one based on the bootstrap method. The behavior of these estimators was assessed through Monte Carlo experiments. Both methods give accurate estimation performance, even with relatively small number of observations. Moreover, it is shown that for non-Gaussian data, specifically for the Student’s-t and Generalized error distributions, the parameters of the model can be estimated precisely by maximum likelihood. The proposed model is compared to the continuous autoregressive moving average models (CARMA), showing better performance when the moving average parameter is negative or close to one. We illustrate the implementation of the proposed model with light curves of variable stars from the OGLE and HIPPARCOS surveys and stochastic objects from ZTF. The results suggest that the iMA model is a suitable alternative for modeling astronomical light curves, particularly when they have negative autocorrelation.
{"title":"Extending time series models for irregular observational gaps with a moving average structure for astronomical sequences","authors":"C. Ojeda, W. Palma, S. Eyheramendy, F. Elorrieta","doi":"10.1093/rasti/rzac011","DOIUrl":"https://doi.org/10.1093/rasti/rzac011","url":null,"abstract":"\u0000 In this study we introduce a novel moving-average model for analyzing stationary time series observed irregularly in time. The process is strictly stationary and ergodic under normality and weakly stationary when normality is not assumed. Maximum likelihood estimation can be efficiently carried out through a Kalman algorithm obtained from the state-space representation of the model. The Kalman algorithm has order O(n) (where n is the number of observations in the sequence), from which it is possible to efficiently generate parameter estimators, linear predictors and their mean squared errors. Two procedures were developed for assessing parameter estimation errors: one based on the Hessian of the likelihood function and another one based on the bootstrap method. The behavior of these estimators was assessed through Monte Carlo experiments. Both methods give accurate estimation performance, even with relatively small number of observations. Moreover, it is shown that for non-Gaussian data, specifically for the Student’s-t and Generalized error distributions, the parameters of the model can be estimated precisely by maximum likelihood. The proposed model is compared to the continuous autoregressive moving average models (CARMA), showing better performance when the moving average parameter is negative or close to one. We illustrate the implementation of the proposed model with light curves of variable stars from the OGLE and HIPPARCOS surveys and stochastic objects from ZTF. The results suggest that the iMA model is a suitable alternative for modeling astronomical light curves, particularly when they have negative autocorrelation.","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127778684","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}
Solar occultation is a satellite-based technique for high-resolution vertical profiling of planetary atmospheres. Owing to the distinctive observational geometry, the deduction of the spatiotemporal coverage of solar occultation measurements as a function of the spacecraft orbit is non-trivial. In this work, we have implemented python-based 3D simulations of the occultation-viewing geometry for a hypothetical Solar Occultation Experiment (SOE) to study the atmosphere of Venus. The simulations incorporate planetary motions and orbital propagation using the astropy and poliastro packages, and compute the instantaneous line-of-sight (LoS) tangent point using 3D vector algebra. SPICAV/SOIR data from Venus Express was used to validate the simulations, showing excellent agreement. Using the simulations, we conducted a first-of-its-kind theoretical study on the effect of varying different spacecraft orbital elements on the spatiotemporal distribution of solar occultation measurements in the Venusian atmosphere, confirming a highly sensitive dependence. The semimajor axis (a) and inclination (i) of the spacecraft orbit are found to influence the latitudinal extent of observations and the nature/duration of occultation seasons, while the eccentricity (e) and argument of periapsis (ω) determine the distinct regions of sparse observations. The spatiotemporal spread of individual SOE profiles is found to depend on the orbital parameters as well as the solar beta angle. Our results show that spacecraft orbits can be designed with appropriate parameters to optimize the coverage of SOE measurements in view of achieving specific science goals, providing valuable inputs for future missions to Venus that aim to implement the solar occultation technique.
{"title":"Solar Occultation Experiments (SOE) in the Venusian Atmosphere: effect of orbital parameters on the spatiotemporal distribution of measurements","authors":"Jayadev Pradeep, S. Sunilkumar","doi":"10.1093/rasti/rzad019","DOIUrl":"https://doi.org/10.1093/rasti/rzad019","url":null,"abstract":"\u0000 Solar occultation is a satellite-based technique for high-resolution vertical profiling of planetary atmospheres. Owing to the distinctive observational geometry, the deduction of the spatiotemporal coverage of solar occultation measurements as a function of the spacecraft orbit is non-trivial. In this work, we have implemented python-based 3D simulations of the occultation-viewing geometry for a hypothetical Solar Occultation Experiment (SOE) to study the atmosphere of Venus. The simulations incorporate planetary motions and orbital propagation using the astropy and poliastro packages, and compute the instantaneous line-of-sight (LoS) tangent point using 3D vector algebra. SPICAV/SOIR data from Venus Express was used to validate the simulations, showing excellent agreement. Using the simulations, we conducted a first-of-its-kind theoretical study on the effect of varying different spacecraft orbital elements on the spatiotemporal distribution of solar occultation measurements in the Venusian atmosphere, confirming a highly sensitive dependence. The semimajor axis (a) and inclination (i) of the spacecraft orbit are found to influence the latitudinal extent of observations and the nature/duration of occultation seasons, while the eccentricity (e) and argument of periapsis (ω) determine the distinct regions of sparse observations. The spatiotemporal spread of individual SOE profiles is found to depend on the orbital parameters as well as the solar beta angle. Our results show that spacecraft orbits can be designed with appropriate parameters to optimize the coverage of SOE measurements in view of achieving specific science goals, providing valuable inputs for future missions to Venus that aim to implement the solar occultation technique.","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115219688","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}
{"title":"FAIR publication and RASTI","authors":"Jonathan Tennyson","doi":"10.1093/rasti/rzad012","DOIUrl":"https://doi.org/10.1093/rasti/rzad012","url":null,"abstract":"","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"215 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133113966","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}
K. Alielden, D. MacTaggart, Q. Ming, C. Prior, B. Raphaldini
The importance of measuring topological quantities, such as magnetic helicity, in solar observations has long been recognized. In particular, topological quantities play an important role in both understanding and predicting solar eruptions. In this paper, we present ARTop (Active Region Topology), an open-source and end-to-end software tool that allows researchers to calculate the fluxes of topological quantities based on solar magnetograms. In addition to this, ARTop also allows for the efficient analysis of these quantities in both 2D maps and time series. ARTop calculates the fluxes of magnetic helicity and magnetic winding, together with particular decompositions of these quantities. To perform these calculations, SHARP magnetograms are downloaded and velocity maps are created using the DAVE4VM method. Visualization tools, written in Python, are provided to aid in the selection of appropriate output variables and for the straightforward creation of maps and time series. Additionally, other analysis functions are included to facilitate and aid solar flare investigations. This software offers researchers a powerful tool for investigating the behaviour of active regions and the origins of space weather.
{"title":"ARTop: an open-source tool for measuring active region topology at the solar photosphere","authors":"K. Alielden, D. MacTaggart, Q. Ming, C. Prior, B. Raphaldini","doi":"10.1093/rasti/rzad029","DOIUrl":"https://doi.org/10.1093/rasti/rzad029","url":null,"abstract":"\u0000 The importance of measuring topological quantities, such as magnetic helicity, in solar observations has long been recognized. In particular, topological quantities play an important role in both understanding and predicting solar eruptions. In this paper, we present ARTop (Active Region Topology), an open-source and end-to-end software tool that allows researchers to calculate the fluxes of topological quantities based on solar magnetograms. In addition to this, ARTop also allows for the efficient analysis of these quantities in both 2D maps and time series. ARTop calculates the fluxes of magnetic helicity and magnetic winding, together with particular decompositions of these quantities. To perform these calculations, SHARP magnetograms are downloaded and velocity maps are created using the DAVE4VM method. Visualization tools, written in Python, are provided to aid in the selection of appropriate output variables and for the straightforward creation of maps and time series. Additionally, other analysis functions are included to facilitate and aid solar flare investigations. This software offers researchers a powerful tool for investigating the behaviour of active regions and the origins of space weather.","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115855762","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}
C. Rhea, L. Rousseau-Nepton, I. Moumen, S. Prunet, J. Hlavacek-Larrondo, K. Grasha, C. Robert, C. Morisset, G. Stasińska, N. Vale-Asari, Justine Giroux, A. McLeod, M. Gendron-Marsolais, Junfeng Wang, J. Lyman, L. Chemin
Diagnostic diagrams of emission-line ratios have been used extensively to categorize extragalactic emission regions; however, these diagnostics are occasionally at odds with each other due to differing definitions. In this work, we study the applicability of supervised machine-learning techniques to systematically classify emission-line regions from the ratios of certain emission lines. Using the Million Mexican Model database, which contains information from grids of photoionization models using cloudy, and from shock models, we develop training and test sets of emission line fluxes for three key diagnostic ratios. The sets are created for three classifications: classic H ii regions, planetary nebulae, and supernova remnants. We train a neural network to classify a region as one of the three classes defined above given three key line ratios that are present both in the SITELLE and MUSE instruments’ band-passes: [O iii]λ5007/H β, [N ii]λ6583/H α, ([S ii]λ6717+[S ii]λ6731)/H α. We also tested the impact of the addition of the [O ii]λ3726, 3729/[O iii]λ5007 line ratio when available for the classification. A maximum luminosity limit is introduced to improve the classification of the planetary nebulae. Furthermore, the network is applied to SITELLE observations of a prominent field of M33. We discuss where the network succeeds and why it fails in certain cases. Our results provide a framework for the use of machine learning as a tool for the classification of extragalactic emission regions. Further work is needed to build more comprehensive training sets and adapt the method to additional observational constraints.
{"title":"A machine learning approach to galactic emission-line region classification","authors":"C. Rhea, L. Rousseau-Nepton, I. Moumen, S. Prunet, J. Hlavacek-Larrondo, K. Grasha, C. Robert, C. Morisset, G. Stasińska, N. Vale-Asari, Justine Giroux, A. McLeod, M. Gendron-Marsolais, Junfeng Wang, J. Lyman, L. Chemin","doi":"10.1093/rasti/rzad023","DOIUrl":"https://doi.org/10.1093/rasti/rzad023","url":null,"abstract":"\u0000 Diagnostic diagrams of emission-line ratios have been used extensively to categorize extragalactic emission regions; however, these diagnostics are occasionally at odds with each other due to differing definitions. In this work, we study the applicability of supervised machine-learning techniques to systematically classify emission-line regions from the ratios of certain emission lines. Using the Million Mexican Model database, which contains information from grids of photoionization models using cloudy, and from shock models, we develop training and test sets of emission line fluxes for three key diagnostic ratios. The sets are created for three classifications: classic H ii regions, planetary nebulae, and supernova remnants. We train a neural network to classify a region as one of the three classes defined above given three key line ratios that are present both in the SITELLE and MUSE instruments’ band-passes: [O iii]λ5007/H β, [N ii]λ6583/H α, ([S ii]λ6717+[S ii]λ6731)/H α. We also tested the impact of the addition of the [O ii]λ3726, 3729/[O iii]λ5007 line ratio when available for the classification. A maximum luminosity limit is introduced to improve the classification of the planetary nebulae. Furthermore, the network is applied to SITELLE observations of a prominent field of M33. We discuss where the network succeeds and why it fails in certain cases. Our results provide a framework for the use of machine learning as a tool for the classification of extragalactic emission regions. Further work is needed to build more comprehensive training sets and adapt the method to additional observational constraints.","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"11 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123664688","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}
The continuous wavelet transform (CWT) is very useful for processing signals with intricate and irregular structures in astrophysics and cosmology. It is crucial to propose precise and fast algorithms for the CWT. In this work, we review and compare four different fast CWT algorithms for the 1D signals, including the FFTCWT, the V97CWT, the M02CWT, and the A19CWT. The FFTCWT algorithm implements the CWT using the Fast Fourier Transform (FFT) with a computational complexity of $mathcal {O}(Nlog _2N)$ per scale. The rest algorithms achieve the complexity of $mathcal {O}(N)$ per scale by simplifying the CWT into some smaller convolutions. We illustrate explicitly how to set the parameters as well as the boundary conditions for them. To examine the actual performance of these algorithms, we use them to perform the CWT of signals with different wavelets. From the aspect of accuracy, we find that the FFTCWT is the most accurate algorithm, though its accuracy degrades a lot when processing the non-periodic signal with zero boundaries. The accuracy of $mathcal {O}(N)$ algorithms is robust to signals with different boundaries, and the M02CWT is more accurate than the V97CWT and A19CWT. From the aspect of speed, the $mathcal {O}(N)$ algorithms do not show an overall speed superiority over the FFTCWT at sampling numbers of N ≲ 106, which is due to their large leading constants. Only the speed of the V97CWT with real wavelets is comparable to that of the FFTCWT. However, both the FFTCWT and V97CWT are substantially less efficient in processing the non-periodic signal because of zero padding. Finally, we conduct wavelet analysis of the 1D density fields, which demonstrate the convenience and power of techniques based on the CWT. We publicly release our CWT codes as resources for the community.
{"title":"Comparisons between fast algorithms for the continuous wavelet transform and applications in cosmology: the 1D case","authors":"Yun Wang, P. He","doi":"10.1093/rasti/rzad020","DOIUrl":"https://doi.org/10.1093/rasti/rzad020","url":null,"abstract":"\u0000 The continuous wavelet transform (CWT) is very useful for processing signals with intricate and irregular structures in astrophysics and cosmology. It is crucial to propose precise and fast algorithms for the CWT. In this work, we review and compare four different fast CWT algorithms for the 1D signals, including the FFTCWT, the V97CWT, the M02CWT, and the A19CWT. The FFTCWT algorithm implements the CWT using the Fast Fourier Transform (FFT) with a computational complexity of $mathcal {O}(Nlog _2N)$ per scale. The rest algorithms achieve the complexity of $mathcal {O}(N)$ per scale by simplifying the CWT into some smaller convolutions. We illustrate explicitly how to set the parameters as well as the boundary conditions for them. To examine the actual performance of these algorithms, we use them to perform the CWT of signals with different wavelets. From the aspect of accuracy, we find that the FFTCWT is the most accurate algorithm, though its accuracy degrades a lot when processing the non-periodic signal with zero boundaries. The accuracy of $mathcal {O}(N)$ algorithms is robust to signals with different boundaries, and the M02CWT is more accurate than the V97CWT and A19CWT. From the aspect of speed, the $mathcal {O}(N)$ algorithms do not show an overall speed superiority over the FFTCWT at sampling numbers of N ≲ 106, which is due to their large leading constants. Only the speed of the V97CWT with real wavelets is comparable to that of the FFTCWT. However, both the FFTCWT and V97CWT are substantially less efficient in processing the non-periodic signal because of zero padding. Finally, we conduct wavelet analysis of the 1D density fields, which demonstrate the convenience and power of techniques based on the CWT. We publicly release our CWT codes as resources for the community.","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"131 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115150286","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}
KIDSpec, the Kinetic Inductance Detector Spectrometer, is a proposed optical to near-IR Microwave Kinetic Inductance Detector (MKID) spectrograph. MKIDs are superconducting photon counting detectors which are able to resolve the energy of incoming photons and their time of arrival. KIDSpec will use these detectors to separate incoming spectral orders from a grating, thereby not requiring a cross-disperser. In this paper, we present a simulation tool for KIDSpec’s potential performance upon construction to optimize a given design. This simulation tool is the KIDSpec Simulator (KSIM), a Python package designed to simulate a variety of KIDSpec and observation parameters. A range of astrophysical objects are simulated: stellar objects, an SDSS observed galaxy, a Seyfert galaxy, and a mock galaxy spectrum from the JAGUAR catalogue. Multiple medium spectral resolution designs for KIDSpec are simulated. The possible impact of MKID energy resolution variance and dead pixels was simulated, with impacts on KIDSpec performance observed using the Reduced Chi-Squared (RCS) value. Using dead pixel percentages from current instruments, the RCS result was found to only increase to 1.21 at worst for one of the designs simulated. SNR comparisons of object simulations between KSIM and X-Shooter’s ETC were also simulated. KIDSpec offers a particular improvement over X-Shooter for short and faint observations. For a Seyfert galaxy (mR = 21) simulation with a 180 s exposure, KIDSpec had an average SNR of 4.8, in contrast to 1.5 for X-Shooter. Using KSIM the design of KIDSpec can be optimized to improve the instrument further.
{"title":"KSIM: simulating KIDSpec, a Microwave Kinetic Inductance Detector spectrograph for the optical/NIR","authors":"V. B. Hofmann, K. O’Brien","doi":"10.1093/rasti/rzad018","DOIUrl":"https://doi.org/10.1093/rasti/rzad018","url":null,"abstract":"\u0000 KIDSpec, the Kinetic Inductance Detector Spectrometer, is a proposed optical to near-IR Microwave Kinetic Inductance Detector (MKID) spectrograph. MKIDs are superconducting photon counting detectors which are able to resolve the energy of incoming photons and their time of arrival. KIDSpec will use these detectors to separate incoming spectral orders from a grating, thereby not requiring a cross-disperser. In this paper, we present a simulation tool for KIDSpec’s potential performance upon construction to optimize a given design. This simulation tool is the KIDSpec Simulator (KSIM), a Python package designed to simulate a variety of KIDSpec and observation parameters. A range of astrophysical objects are simulated: stellar objects, an SDSS observed galaxy, a Seyfert galaxy, and a mock galaxy spectrum from the JAGUAR catalogue. Multiple medium spectral resolution designs for KIDSpec are simulated. The possible impact of MKID energy resolution variance and dead pixels was simulated, with impacts on KIDSpec performance observed using the Reduced Chi-Squared (RCS) value. Using dead pixel percentages from current instruments, the RCS result was found to only increase to 1.21 at worst for one of the designs simulated. SNR comparisons of object simulations between KSIM and X-Shooter’s ETC were also simulated. KIDSpec offers a particular improvement over X-Shooter for short and faint observations. For a Seyfert galaxy (mR = 21) simulation with a 180 s exposure, KIDSpec had an average SNR of 4.8, in contrast to 1.5 for X-Shooter. Using KSIM the design of KIDSpec can be optimized to improve the instrument further.","PeriodicalId":367327,"journal":{"name":"RAS Techniques and Instruments","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125913502","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}
To perform precise and accurate photometric catalogue cross-matches – assigning counterparts between two separate datasets – we need to describe all possible sources of uncertainty in object position. With ever-increasing time baselines between bservations, like 2MASS in 2001 and the next generation of surveys, such as the Vera C. Rubin Observatory’s LSST, Euclid, and the Nancy Grace Roman telescope, it is crucial that we can robustly describe and model the effects of stellar motions on source positions in photometric catalogues. While Gaia has revolutionised astronomy with its high precision astrometry, it will only provide motions for ≈10% of LSST sources; additionally, LSST itself will not be able to provide high-quality motion information for sources below its single-visit depth, and other surveys may measure no motions at all. This leaves large numbers of objects with potentially significant positional drifts that may incorrectly lead matching algorithms to deem two detections too far separated on the sky to be counterparts. To overcome this, in this paper we describe a model for the statistical distribution of on-sky motions of sources of given sky coordinates and brightness, allowing for the cross-match process to take into account this extra potential separation between Galactic sources. We further detail how to fold these probabilistic proper motions into Bayesian cross-matching frameworks, such as those of Wilson & Naylor. This will vastly improve the recovery of e.g. very red objects across optical-infrared matches, and decrease the false match rate of photometric catalogue counterpart assignment.
为了进行精确和准确的光度表交叉匹配——在两个独立的数据集之间分配对应物——我们需要描述物体位置中所有可能的不确定性来源。随着观测之间的时间间隔不断增加，如2001年的2MASS和下一代的调查，如Vera C. Rubin天文台的LSST，欧euclid和Nancy Grace Roman望远镜，我们能够在光度目录中可靠地描述和模拟恒星运动对源位置的影响是至关重要的。虽然盖亚以其高精度的天体测量技术彻底改变了天文学，但它只能提供约10%的LSST源的运动;此外，LSST本身将无法为低于其单次访问深度的源提供高质量的运动信息，而其他调查可能根本没有测量到运动。这就留下了大量具有潜在显著位置漂移的物体，这可能会错误地导致匹配算法认为两个在天空中相距太远的探测结果不可能是对应的。为了克服这一点，在本文中，我们描述了给定天空坐标和亮度的源在天空运动的统计分布模型，允许交叉匹配过程考虑到银河系源之间额外的潜在分离。我们进一步详细介绍了如何将这些概率固有运动折叠到贝叶斯交叉匹配框架中，例如Wilson & Naylor的框架。这将极大地提高例如非常红的物体在光学红外匹配中的恢复，并降低光度表对应物分配的错误匹配率。
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