diff --git a/Appendix.tex b/Appendix.tex index c593235..1d1fc20 100644 --- a/Appendix.tex +++ b/Appendix.tex @@ -2,21 +2,21 @@ \section{Science use cases and translation to ADQL queries based on ObsCore Rad \label{ADQLusecases} -\textit{ The queries in subsections \ref{sec:s_resolution_max} and \ref{sec:s_fov_min} +The queries in subsections \ref{sec:s_resolution_max} and \ref{sec:s_fov_min} can be run with s\_resolution\_min and s\_fov\_max instead of s\_resolution\_max and s\_fov\_min respectively, to obtain results in which at least part of the dataset satisfy the condition.\\ For instance, consider datasets with a large observed bandwidth, like those taken with wide/ultrawide band receivers. -The condition s\_resolution\_max 0.017 deg \\ II Target Virgo A or position inside 15 arcmin from 187.7059308,+12.3911232 \\ @@ -34,11 +34,11 @@ \subsection{Use case - s\_resolution\_min} \subsection{Use case - s\_resolution\_max} \label{sec:s_resolution_max} -\textit{Morphological study of SNR IC443. Select any dataset obtained in map scanning mode (raster or on-the-fly) with s\_resolution\_max less than the desired spatial resolution of 1 arcmin.} - +\textit{Morphological study of SNR IC443. \\ +Select any dataset obtained in map scanning mode (raster or on-the-fly) with s\_resolution\_max less than the desired spatial resolution of 1 arcmin.}\\ Show me all datasets satisfying: \\ I. Maximum spatial resolution < 0.017 deg \\ -II Target IC443 or position inside 15 arcmin from 94.2500000,+22.5699997 \\ +II. Target IC443 or position inside 15 arcmin from 94.2500000,+22.5699997 \begin{verbatim} SELECT * FROM ivoa.obscore @@ -56,7 +56,7 @@ \subsection{Use case - s\_fov\_min - large field of views} Show me all datasets satisfying:\\ I. Minimum FOV > 0.8 deg \\ -II Target name = Abell 194 or position inside 15 arcmin from 21.5054167, -1.3672221 \\ +II. Target name = Abell 194 or position inside 15 arcmin from 21.5054167, -1.3672221 \begin{verbatim} SELECT * FROM ivoa.obscore NATURAL JOIN ivoa.obscore_radio @@ -68,10 +68,10 @@ \subsection{Use case - s\_fov\_min - large field of views} \subsection{Use case - s\_fov\_min - extended target completly included} \label{sec:s_fov_max} -\textit{Pictor A has a typical angular extension of 8 arcminutes , select any image/cube completely containing the target} +\textit{Pictor A has a typical angular extension of 8 arcminutes, select any image/cube completely containing the target}.\\ Show me all datasets satisfying: \\ I. Target name = Pictor A \\ -II. The circle defined by the minimum FOV of the dataset fully contains the circle delimiting Pictor A. \\ +II. The circle defined by the minimum FOV of the dataset fully contains the circle delimiting Pictor A. \begin{verbatim} SELECT * FROM ivoa.obscore NATURAL JOIN ivoa.obscore_radio @@ -81,15 +81,13 @@ \subsection{Use case - s\_fov\_min - extended target completly included} \end{verbatim} \subsection{Use case - dataproduct\_type} -\textit{Select all observations of calibrator source 3C48 with the Medicina Grueff radio telescope at frequencies in the range 20-21 GHz, to investigate its flux variability (light curve) in the years 2000-2023} +\textit{Select all observations of calibrator source 3C48 with the Medicina Grueff radio telescope at frequencies in the range 20-21 GHz, to investigate its flux variability (light curve) in the years 2000-2023}.\\ Show me all datasets satisfying: \\ -I. Target name = 3C 48 \\ -II. obs\_collection = ?INAF-Medicina, single dish?\\ +I. Target name = 3C48 \\ +II. obs\_collection = "INAF-Medicina, single dish"\\ III. Observed frequency in the range 20-21 GHz \\ IV. dataproduct\_type = spatial\_profile or scan\_mode contains map\\ -V. 51544 < observation time (MJD) < 60309 \\ - - +V. 51544 < observation time (MJD) < 60309 \begin{verbatim} SELECT * FROM ivoa.obscore NATURAL JOIN ivoa.obscore_radio @@ -120,19 +118,17 @@ \subsection{Use case - f\_resolution, frequency ranges} \end{verbatim} \subsection{Use case - frequency selection for images } -\textit{Any image or cube observed at frequencies below 1 GHz.}\\ \\ +\textit{Any image or cube observed at frequencies below 1 GHz.}\\ Show me all datasets satisfying:\\ I. Product type is image or cube \\ -II. higher spectral limit < 1Ghz +II. Higher spectral limit < 1 GHz \begin{verbatim} SELECT * FROM ivoa.obscore WHERE (dataproduct_type = 'image' OR dataproduct_type = 'cube') AND 299792458 / em_min < 1e9 \end{verbatim} -% Mireille Louys: shall we also look for spectra with these frequency constrains ? - - +% Mireille Louys: shall we also look for spectra with these frequency constrains ? % end section Alexandra's science case @@ -142,8 +138,10 @@ \subsection{Use case - frequency selection for images } % Should these restrict the dataproduct_type? \subsection{Use case - high resolution data around FRB targets } -\textit{Give me high-resolution data on possible persistent radio sources within an arc second of FRB 121102:} - +\textit{Give me high-resolution data on possible persistent radio sources within an arc second of FRB 121102.} \\ Show me all datasets satisfying: +% add constraints +I. Source close to FRB 121102 \\ +II. Spatial resolution < 1 arcsec \begin{verbatim} SELECT * FROM ivoa.obscore NATURAL JOIN ivoa.obscore_radio WHERE CONTAINS(POINT(s_ra,s_dec),CIRCLE(82.99458,33.14794,0.0003)) = 1 @@ -153,13 +151,17 @@ \subsection{Use case - high resolution data around FRB targets } \subsection{Use case - reasonable fidelity} \textit{Give me data on extended HI emission around the source 3C84 that can -be imaged with reasonable fidelity:} - +be imaged with reasonable fidelity.}\\ Show me all datasets satisfying: +%add constraints +I. Region contains source 3C84 \\ +II. Maximum angular scale > 1arcsec +III. uv plane is filled at more than 0.2 +IV. Estimated uv eccentricity < 0.75 \begin{verbatim} SELECT * FROM ivoa.obscore NATURAL JOIN ivoa.obscore_radio WHERE CONTAINS(POINT(s_ra,s_dec),CIRCLE(24.4212500,33.1588889,0.003)) = 1 -AND s_largest_angular_scale > 0.018 +AND s_largest_angular_scale > 0.017 AND uv_distribution_fill > 0.2 AND uv_distribution_ecc < 0.75 AND em_min < 0.21 @@ -168,12 +170,12 @@ \subsection{Use case - reasonable fidelity} % end of Mark's (VLBI) science cases -\subsection{ use case - visibility data product and target object selection } +\subsection{ Use case - visibility data product and target object selection } \textit{Any raw interferometry observation containing target Fornax cluster.}\\ \\ Show me all observation identifiers satisfying:\\ I. DataType = visibility \\ -II. Target Name = Fornax Cluster \\ +II. Target Name = Fornax Cluster \begin{verbatim} SELECT obs_id FROM ivoa.obscore WHERE dataproduct_type = 'visibility' @@ -181,33 +183,33 @@ \subsection{ use case - visibility data product and target object selection } \end{verbatim} \subsection{Use case - maximum angular scale selection} -\textit{Any visibility dataset Within an arcec around FRB 121102 where maximum angular scale is larger than 1 minute .}\\ \\ +\textit{Any visibility dataset within an arsec around FRB 121102 where maximum angular scale is larger than 1 minute.}\\ \\ Show me all datasets satisfying:\\ I. Product type is visibility \\ -II. Maximum angular scale > 0.018 deg \\ +II. Maximum angular scale > 0.017 deg \\ III. Position within 1 arcsec of 82.99458 + 33.14794 \begin{verbatim} SELECT * FROM ivoa.obscore NATURAL JOIN ivoa.obscore_radio WHERE dataproduct_type = 'visibility' - AND s_largest_angular_scale_max > 0.018 + AND s_largest_angular_scale_max > 0.017 AND CONTAINS(POINT(s_ra,s_dec),CIRCLE(82.99458, 33.14794,0.0003)) = 1)) \end{verbatim} \subsection{Use case - maximum angular scale selection with reasonable fidelity} -\textit{Any visibility data within an arcsec around FRB 121102 where maximum angular scale is larger than 1 minute and -of good quality from the uv distribution point of view.}\\ \\ +\textit{Any visibility data within an arcsec around FRB 121102 where maximum angular scale is larger than 1 minute and of good quality from the uv distribution point of view.}\\ \\ Show me all datasets satisfying:\\ I. Product type = visibility \\ -II. Maximum angular scale > 0.018 deg \\ +II. Maximum angular scale > 0.017 deg \\ III. uv distribution filling factor > 0.7 \\ -IV. uv distribtion factor eccentricity < 0.1 \\ +IV. uv distribution factor eccentricity < 0.1 \\ V. Position within 1 arcsec of 82.99458 + 33.14794 + \begin{verbatim} SELECT * FROM ivoa.obscore NATURAL JOIN ivoa.obscore_radio WHERE dataproduct_type = 'visibilty' - AND s_largest_angular_scale_max > 0.018 + AND s_largest_angular_scale_max > 0.017 AND uv_distribution_fill > 0.7 AND uv_distribution_ecc < 0.1 AND CONTAINS(POINT(s_ra,s_dec),CIRCLE(82.99458, 33.14794,0.0003)) =1)) @@ -219,10 +221,10 @@ \subsection{Use case - time selection } I. Instrument type = beam forming\\ II. Product type = time series \\ III. time resolution < 0.1 s\\ -IIV. maximal duration per sample < 0.05 s \\ +IIV. maximal duration per sample < 0.05 s \begin{verbatim} - SELECT * FROM ivoa.obscore + SELECT * FROM ivoa.obscore NATURAL JOIN ivoa.obscore_radio WHERE instr_type = 'beamForming' AND dataproduct_type = 'timeseries' @@ -237,24 +239,24 @@ \subsection{Use case - instrument type and mode selection } I. Instrument type is Single dish \\ II. Scan mode is raster \\ III. Target name = 3C 273 or \\ -IV. position inside 3 arcmin around 187.2779159404900 +02.0523882305500 +IV. position inside 3 arcmin around 187.2779159404900 +02.0523882305500 + \begin{verbatim} SELECT * FROM ivoa.obscore NATURAL JOIN ivoa.obscore_radio WHERE instr_type = 'SD' AND scan_mode = 'raster' AND (target_name = '3C 273' OR - CONTAINS(POINT(s_ra,s_dec), CIRCLE(187.2779159404900, +02.0523882305500,0.05)) = 1) + CONTAINS(POINT(s_ra,s_dec), CIRCLE(187.2779159404900, +02.0523882305500,0.05)) = 1) \end{verbatim} - \subsection{Use case - instrument type and frequency selection } \textit{Any single dish or beam forming dataset with spectral range inside the 500 Mhz - 1Ghz band and in the Coma Cluster.}\\ \\ Show me all datasets satisfying:\\ I. Instrument type is Single dish or beam forming \\ -II. lower spectral limit > 500 Mhz \\ -III. higher spectral limit < 1Ghz \\ +II. lower spectral limit > 500 MHz \\ +III. higher spectral limit < 1GHz \\ IV. position inside 18 arcmin around 194.93502 +27.91246 \begin{verbatim} @@ -270,12 +272,11 @@ \subsection{Use case - instrument type and frequency selection } \subsection{Use case - instrument parameters selection } -\textit{Any interferometry data of good quality and significant spatial resolution from the instrumental point of view. }\\ \\ +\textit{Any interferometry data of good quality and significant spatial resolution from the instrumental point of view. }\\ Show me all datasets satisfying:\\ I. Instrument type = visibility \\ II. number of antennae > 40 \\ -III. antenna maximum distance in meters > 5000 \\ - +III. antenna maximum distance in meters > 5000 \begin{verbatim} SELECT * FROM ivoa.obscore_radio WHERE instr_type = 'interferometry' diff --git a/Makefile b/Makefile index d1e0579..d238f11 100644 --- a/Makefile +++ b/Makefile @@ -7,7 +7,7 @@ DOCNAME = ObsCoreExtensionForRadioData DOCVERSION = 1.0 # Publication date, ISO format; update manually for "releases" -DOCDATE = 2025-09-15 +DOCDATE = 2026-04-29 # What is it you're writing: NOTE, WD, PR, or REC DOCTYPE = PEN diff --git a/ObsCoreExtensionForRadioData.tex b/ObsCoreExtensionForRadioData.tex index 8f1beae..920ceb3 100644 --- a/ObsCoreExtensionForRadioData.tex +++ b/ObsCoreExtensionForRadioData.tex @@ -70,7 +70,7 @@ \section{Introduction} ObsCore specification \citep{2017ivoa.spec.0509L} defines both a minimal datamodel to describe datasets and a table consistent with the model which can be served by TAP services. It has been successful -to define a lot of data discovery services in astronomy. +to define several of data discovery services in astronomy. The emergence of the Radio Astronomy Interest Group in the IVOA in April 2020 confirmed the strong interest of the radio astronomy community to distribute their data in the VO. Many teams now @@ -85,10 +85,10 @@ \section{Introduction} Various discovery use cases have been collected in the radio community and gathered in the \ref{ADQLusecases} appendix. The current specification suggests addition of new features in the ObsCore metadata profile to fill the gap. % Mireille an attempt to widen the scope ?? -With the expansion of large radio astronomy projects such as LOFAR, NenuFAR, the future SKA, ngVLA, etc... +With the advent of new generation radio telescopes such as LOFAR, NenuFAR, the future SKA, ngVLA, etc... and the emergence of interesting research topics matching data in all electromagnetic regimes, the Virtual Observatory framework can facilitate a wider access to radio data for experts and -non-specialists radio astronomers in order to support collaborations in multi-wavelength, +non-specialists radio astronomers in order to support collaborations in multi-wavelength and multi-messenger astronomy. %mireille: @@ -105,8 +105,8 @@ \section{Introduction} %The role of this Visibility ObsCore extension in the IVOA is very close to ObsCore itself. It's only a fine grain improvement of this specification. % Mireille's suggestion -This Radio ObsCore extension in the IVOA, relies on ObsCore itself and expands it -to allow data providers to describe their radio data further the ObsTAP framework. +This Radio ObsCore extension in the IVOA relies on ObsCore itself and expands it +to allow data providers to improve the description of their radio data within the ObsTAP framework. Its goal is to clarify how ObsCore metadata can be used in the radio context and to add new specific features to the existing ObsCore metadata. @@ -119,10 +119,10 @@ \section{Radio data specifities from the Data Discovery point of view} ObsCore attributes \emph{em\_min, em\_max} are expressed in wavelength and are not really convenient. Enabling queries in units natural for the sub-disciplines is desirable, but should not be done by duplicating the same information in two different attributes. +User Defined Functions can be used to translate em\_* values in appropriate units. -Receivers with a (ultra)wide bandwidth, up to tens of GHz, are -nowadays commonly used for both interferometric and Single Dish (herefater SD) radio observations. -Given that the spatial field of view and resolution linearly depend on wavelength, these quantities may significantly vary across the observed bandwidth in a radio observation. +Receivers with a (ultra-)wide bandwidth, up to tens of GHz, are +nowadays commonly used for both interferometric and Single Dish (hereafter SD) radio observations. Given that the spatial field of view and resolution linearly depend on wavelength, these quantities may significantly vary across the observed bandwidth in a radio observation. Generally only a representative value (for instance the %median receiver nominal frequency) for these two parameters can be given on ObsCore. We @@ -134,15 +134,16 @@ \section{Radio data specifities from the Data Discovery point of view} Instead one could introduce a new ObsCore element for the absolute spectral resolution, in frequency unit, for which a representative value for each observation can be given. Modern radio instrumentation offers the possibility of several spectral windows within the same observation with significant separation or different resolutions. -Such observations may be represented at the highest granularity as a set of combined data sets represented by several entries in an ObsCore table. However, it is up to data provider to decide which level of granularity is best adapted in order to optimize data discoverability and ease data access, depending on the scientific content of the observation. -%(see Sect. \ref{subsec:sd} for an example). +Such observations may be represented at the highest granularity as a set of combined data sets represented by several entries in an ObsCore table. However it is up to the data provider to decide which level of granularity is best adapted in order to optimize data discoverability and thus ease data access, depending on the scientific content of the observation. +%(see Sect. \ref{sec:sd} for an example). -\subsection{Single dish data}\label{subsec:sd} +\subsection{Single dish data} +\label{sec:sd} -Single Dish (SD) observations can be done with different types of receiving systems. Typical frontends are mono-feed, multi-feed and phased array feed (PAF). The last two suitable to efficiently span wider parts of the sky. -Data can be acquired by various backend systems providing either the total intensity (integrated over the whole available bandwidth) or the spectroscopic/spectropolarimetric intensity (acquired in each spectral channel/sample). +Single Dish (SD) observations can be done with different types of receiving systems. Typical frontends are mono-feed, multi-feed and phased array feed (PAF), the last two suitable to efficiently span larger sky areas. +Data can be acquired by various backend systems providing either the total intensity (integrated over the whole available bandwidth) or the spectroscopic/spectro-polarimetric intensity (acquired in each spectral channel/sample). Data are saved as raw counts resulting from the digitization of the voltage signal measured by the receiving system. Commonly-used SD data formats are registered FITS standard conventions (FITS, SDFITS and MBFITS) or unregistered conventions like the standard FITS-based format delivered by the INAF radio telescopes. @@ -180,14 +181,14 @@ \subsection{Visibility data } Visibility data are sets of complex numbers corresponding to the amplitude and phase of correlation coefficients measured between pair of antennas (i.e., a baseline), at -a given time, a given wavelength or polarisation. The visibility data are a sparse -representation of the observed sky. The visibility data sets can be processed to obtain +a given time, a given wavelength or polarisation. Visibility data are a sparse +representation of the observed sky. They can be processed to obtain interferometric images through inverse Fourier algorithms. Each visibility measurement corresponds to an interferometric fringe system on the sky. -The imaging algorithms include a calibration step that requires fixing the center of the -reconstructed image as a phase reference. The visibilities -are then usually represented in a spatial frequency plane, called the \emph{uv} plane, +The imaging algorithms include a possibility to set the center of the +reconstructed image, setting this direction as a phase reference. Visibilities +are usually represented in a spatial frequency plane, called the \emph{uv} plane, whose orientation is perpendicular to phase reference direction. The instantaneous PSF (Point Spread Function) of an interferometer is the Fourier transform of all baselines sampled in the \emph{uv} plane. Hence, the quality of the reconstructed images is @@ -213,7 +214,8 @@ \subsection{Visibility data } For large spectral ranges, the variations of the field of view and the spatial resolution along the axis may become so large that the typical value cannot be sufficient to characterize the dataset. Ranges of values for such parameters are required to accurately -describe such datasets. +describe such datasets, as already discussed in Sect. \ref{sec:specificities}. +%%% inserted comments from Alessandra till here. The quality of the data strongly depends from the distribution of the visibility measurements in the \emph{uv} plane: the more complete the \emph{uv} sampling plane, the better the reconstructed image. @@ -225,22 +227,21 @@ \subsection{Visibility data } Finally, the ellipticity of the distribution is a measure of the distortions that can affect the reconstruction. -Radio astronomers also check the quality of the visibility data by looking at some maps of -the data structure. The \emph{uv} coverage map can show how complete and regular is the sampling in -the \emph{uv} plane and gives an hint of the resolution and maximum angular scale. +Radio astronomers also check the quality of the visibility data by looking at some maps/plots derived from the observed quantities or of the observational parameters. +The \emph{uv} coverage map can show how complete and regular is the sampling in +the \emph{uv} plane and give an hint of resolution and maximum angular scale. The visualisation of the dirty beam, which is the Fourier transform of the \emph{uv} sampling -function gives an hint of the intrinsic quality of possible reconstruction. These maps side products cannot be represented by an ObsDataset class from ObsCore, with spatial axis on the sky, due to their specific axes. +function gives an hint of the intrinsic quality of possible reconstruction. +These maps side products cannot be represented by an ObsDataset class from ObsCore, with spatial axis on the sky, +due to their specific axes. They can be accessed from the visibility data product via a DataLink service. -%\todo{I don't understand what ``queriable'' is supposed to mean here} -%So links to these kind of maps will not be exposed in the extension -%table but only via a DataLink service . -If none of these \emph{uv} characterization features are available to be exposed in the service -we can still predict ranges of some of those by using parameters of the instrumental configuration. -Important features are the antenna diameter (or maximum antenna diameter), the number of -antennas and the minimum and maximum distance between antennas of the array. +Data providers may want to expose other useful instrumental parameters as well in order +to facilitate data discovery. For instance important features are the antenna diameter +(or maximum antenna diameter), the number of +antennas and the minimum and maximum distance between antennas in the array. -In addition to these specificities, most of the scan modes shown on figure~\ref{fig:SD} also +In addition to these specifities most of the scan modes shown in Fig. ~\ref{fig:SD} also apply to some interferometry observations and should be described. \section{ObsCore attributes definition valid for radio data} @@ -248,7 +249,7 @@ \section{ObsCore attributes definition valid for radio data} For radio data some of the definitions on ObsCore data model attributes need to be adjusted to fit the peculiarity of metadata for datasets partition, \emph{uv} space, etc. -Here is a list of common ObsCore parameters already available for the radio data discovery. +Here is a list of common ObsCore parameters already available for radio data discovery. \subsection{obs\_id} @@ -260,20 +261,22 @@ \subsection{obs\_publisher\_did} Radio data observations can be split in several subparts with homogeneous spatial, time, spectral coverage intervals, spectral resolution, etc. Each part can be described by -a single dataset and has its own \emph{obs\_publisher\_did}. It has to be unique in the -Virtual Observatory domain. -It identifies a dataset with homogeneous properties in terms of coverage on all physical axes: temporal, spectral, spatial. +a single dataset and has its own \emph{obs\_publisher\_did}. +It has to be unique in the Virtual Observatory domain and its value should be assigned +by the data provider. +It identifies a dataset with homogeneous properties in terms of coverage on all physical axes: +temporal, spectral, spatial. \subsection{s\_fov} \label{sec:fov} -This attribute measures the size of the field covered. -It usually depends on the spectral interval and of the telescope diameter. -A typical value for the size of the field of view is to be computed on the observation by taking into account the sky scan geometry and the receiver type in use. +This attribute measures the size of the observer field. +It usually depends on the spectral interval and the telescope diameter. +A typical value for the size of the field of view is to be computed on the observation by taking into account the sky scan geometry and the receiver type in use. (See Sect. \ref{sec:spatfreq} for a more detailed description of \emph{s\_fov} with respect to the receiver type). \emph{s\_fov } coincides with the instantaneous field of view $\lambda / D$ only for pointed observations (for instance, an ON in the SD case) obtained with a mono-feed receiver. In this case, $\lambda$ is the %mid value of the spectral range -receiver nominal wavelength and D coincides with the telescope diameter (SD case) or the largest diameter of the array antennae or telescopes (interferometric case). -In interferometry, the correlator can also restrict the fov depending on the trade-off set to build the signal. -Nominal wavelength SHOULD be taken as the mid value of the spectral range except if data providers have good reasons to choose another value. This should then be documented in this column's description metadata. +receiver nominal wavelength and D coincides with the telescope diameter (SD case) or with the largest diameter of the array antennae or telescopes (interferometric case). +In interferometry, the correlator can also restrict the field of view depending on the trade-off set to build the signal. +Nominal wavelength SHOULD be taken as the mid value of the spectral range except if data providers have good reasons to propose another value which should be documented in the FIELD DESCRIPTION tag in that case. \subsection{s\_resolution} \label{sec:res} @@ -301,35 +304,36 @@ \subsection{o\_ucd} \subsection{t\_exptime} Total duration of the observation for the given dataset or ObsCore entry. For instance in case of multiple targets, \emph{t\_exptime} -will be computed for each source and written in the appropriate ObsCore Table entry. The specific case of time series is addressed in another -specification\footnote{https://www.ivoa.net/documents/ObsCoreTimeExtension/20240717/index.html, IVOA working draft}. +will be computed for each source and written in the appropriate ObsCore Table entry. The specific case of time series is addressed in another IVOA document \footnote{https://www.ivoa.net/documents/ObsCoreTimeExtension/20240717/index.html, IVOA working draft}. \subsection{t\_resolution} -%Not applicable for single dish data (see Sect. \ref{subsec:sd}). -The ObsCore parameter \emph{t\_resolution} (see Sect. \ref{subsec:sd}) has limited applicability to SD data -except for \texttt{on-source} tracking observations like those for pulsar/FRB studies and could be set to the +%Not applicable for single dish data (see Sect. \ref{sec:sd}). +The ObsCore parameter \emph{t\_resolution} (see Sect~\ref{sec:sd}) has a limited application for SD data +except for \texttt{on-source} tracking observations like those for pulsar/FRB studies and could be set equal to the exposure time or could be NULL. For time-domain data, \emph{t\_resolution} can be set according to the Pulsar -and FRB Radio Data Discovery and Access IVOA Note\footnote{\url{https://wiki.ivoa.net/internal/IVOA/RadioastronomyInterestGroupFifthVirtualMeeting/PulsarRadioDataAccess.pdf}}. +and FRB Radio Data Discovery and Access IVOA Note \footnote{\url{https://wiki.ivoa.net/internal/IVOA/RadioastronomyInterestGroupFifthVirtualMeeting/PulsarRadioDataAccess.pdf}}. +%% add citation here when doc is available on ivoa.net/Documents For interferometric observations it is the integration time set at the correlation level. \subsection{dataproduct\_type and dataproduct\_subtype} Radio astronomy data cover a wide variety of data product types from visibility for raw interferometry data to cubes, images, spectra, time series -or even measurements (in the case of single dish on scan mode). Single dish observations in some modes show specificities which are not covered by -the current ObsCore \emph{dataproduct\_type} vocabulary. This is the case of spatial profiles obtained with on the fly cross scan or of the -tables of flux measurements obtained on a regular spatial grid but with specific time stamp for each spot as in the raster map mode. -A new external standard IVOA vocabulary\todo{What is this supposed to mean?} is currently defined for data product types\footnote{https://www.ivoa.net/rdf/product-type} -% don't have vocabulary links with dates in them. Don't discuss terms you -% want to add, just have them added them when you need them -and tackles some of these specificities. However some of them SHOULD be covered in the \emph{dataproduct\_subtype} attribute if no new term is introduced in the standard vocabulary. +or even measurements (in the case of \emph{scan\_mode=ON} for single dish ). +Some observing modes for single dish observations are not covered by +the current ObsCore \emph{dataproduct\_type} vocabulary. +This is the case of spatial profiles obtained with "on the fly" cross scan or of the +tables of flux measurements obtained on a regular spatial grid but with specific time stamp +for each spot as in the "raster-map" mode. +These terms can be added to the current product-type vocabulary \footnote{https://www.ivoa.net/rdf/product-type.html}. +%Mireille : need to re-examine what belongs to data product type and to scan mode. \section{ObsCore extension specific for radio data} Tables \ref{tab:ExtensionAtt}, \ref{tab:ExtensionAtt_interferometry} and \ref{tab:ExtensionAtt_instrumental} show the querying parameters we propose to include into the ObsCore radio extension table in order to better describe radio single dish and visibility data. -%Change Mir june 2025 . the 3 tables sort the various medata by category: general , interferometry and instrumental . The last column indicates if the attribute is useful for all radio datasets or only for visibilities, beam forming, or single dish data. +%Change Mir june 2025 . the 3 tables sort the various medata by category: general, interferometry and instrumental. The last column indicates if the attribute is useful for all radio datasets or only for visibilities, beam forming, or single dish data. \subsection{Spatial parameters} @@ -341,16 +345,18 @@ \subsection{Spatial parameters} \emph{s\_resolution\_min, s\_resolution\_max} are estimated like the typical value by the formula $\lambda / L$ (see subsection \ref{sec:res}) where $\lambda$ is replaced respectively by the minimum and maximum wavelength of the spectral range(s). The size L is the telescope diameter for SD observations and the largest distance in the \emph{uv} plane for interferometry. Beam forming may represent an exception to this rule, see sect.~\ref{sec:res}. -In the case of interferometry, we introduce a new column \emph{s\_largest\_angu\-lar\_scale} which is estimated as $\lambda/l$ where $\lambda$ is the typical -wavelength (and again typical value SHOULD be estimated as the mid value of the spectral range apart from documented exceptions) and $l$ is the typical smallest distance in the \emph{uv} plane. This parameter is not relevant for other observation modes. -The largest angular scale is also variable along the spectral range. This is why we describe %\todo{What does ``bound'' mean here? Why the past tense?} -it with \emph{s\_largest\_angular\_scale\_min} and \emph{s\_largest\_angular\_scale\_max} estimated as respectively $\lambda\_min/l$ and $\lambda\_max/l$. +In the case of interferometry, we introduce the new \emph{s\_largest\_angular\_scale} which is estimated as $\lambda/l$ where $\lambda$ is the typical +wavelength (and again typical value SHOULD be estimated as the mid value of the spectral range apart from documented exceptions) and l is the typical smallest distance in the \emph{uv} plane. +This parameter is not relevant for other observation modes. +The largest angular scale is also variable along the spectral range. +Thus it is best described using \emph{s\_largest\_angular\_scale\_min} and +\emph{s\_largest\_angular\_scale\_max} estimated as respectively $\lambda\_min/l$ and $\lambda\_max/l$. \subsection{Frequency characterization} -As was stated above (\ref{sec:specificities}) radio astronomers use frequency quantities to characterize their datasets. Therefore we introduce one additional parameter in the extension: -%\emph{f\_min} and \emph{f\_max} for spectral ranges and -\emph{f\_resolution} for absolute spectral resolution, which is a more stable parameter than the resolution power in the radio domain. +As was stated above (\ref{sec:specificities}) radio astronomers use frequency quantities to characterize their datasets. Therefore we introduce one additional parameter in the extension : +%\emph{f\_min} and \emph{f\_max} for spectral ranges and +\emph{f\_resolution} for the absolute spectral resolution which, in the radio domain is a more representative parameter. For users willing to access spectral ranges in frequencies we can imagine several scenarios: \begin{itemize} @@ -361,16 +367,21 @@ \subsection{Frequency characterization} Using the ADQL User Defined Functions \citep{2024ivoa.spec.1107C} in queries for unit conversion as well as \emph{ivo\_interval\_overlaps, ivo\_specconv} would simplify the interface for the user and avoid columns duplication for the spectral coverage . -%\textit{To avoid inconsistency between the core attributes \emph{em\_min, em\_max} and \emph{em\_respower} and these additional quantities we suggest to compute these new quantities when building a view on top of the basic ObsCore table. The frequency attributes MUST be expressed in Hz to allow interoperability.} +%%\textit{To avoid inconsistency between the core attributes \emph{em\_min, em\_max} and \emph{em\_respower} and these additional quantities we suggest to compute these new quantities when building a view on top of the basic ObsCore table. The frequency attributes MUST be expressed in Hz to allow interoperability.} -\subsection{Spatial frequency coverage for visibilities } +\subsection{Spatial frequency coverage for visibilities} +\label{sec:spatfreq} These parameters are valid for interferometry only. -The absolute \emph{uv}\_distance\_min and \emph{uv}\_distance\_max in the \emph{uv} plane give some outlier minimum and maximum scale in some direction. +The \emph{uv}\_distance\_min and \emph{uv}\_distance\_max in the \emph{uv} plane +express the minimum and maximum scale attainable in the observation. + +% suggestion by Alessandra & Vincenzo : add a figure illustrating a uv plane To compute the ellipse's eccentricity of the \emph{uv} distribution a principal component analysis (PCA) with 2 components is performed over the data points sampling the \emph{uv} plane to select the -main axis of data scattering. +main axis of data scattering. +% suggestion by Alessandra & Vincenzo : add a ref to the code ? The first component is used to rotate the distribution of uv in a way that the major variation of the distribution is leaning towards the $x$ axis of a bidimensional $xy$ Cartesian plane. The major axis length and the minor axis length of the ellipse are therefore defined as the @@ -398,7 +409,7 @@ \subsection{Spatial frequency coverage for visibilities } where $u_{max}$/$v_{max}$ are the respective maximum u/v of the \emph{uv} sample and $u_{min}$/$v_{min}$ is the minimum u/v of the \emph{uv} sample. -Given the above boundaries the number of samples within a cell (i,j) will be $n^{uv}_{i,j}$ +Given the above boundaries the number of samples within a cell(i,j) will be $n^{uv}_{i,j}$ and uv\_distribution\_fill will be then computed as \begin{equation} uv\_distribution\_fill = \frac{\sum^{N^{uv}_{samples}}_{i=1} \sum^{N^{uv}_{samples}}_{j=1} @@ -409,24 +420,26 @@ \subsection{Spatial frequency coverage for visibilities } % Mireille: moved time param below uv space because uv plane deals with spatial features - +% %\subsection{time parameters} %When the sampling along the time axis is not even, %\emph{t\_exp\_min, t\_exp\_max} and \emph{t\_exp\_mean} need to be added to cope with the variation in the individual time samples %duration. This is usually not the case for SD data and \emph{t\_exp\_min, t\_exp\_max} will be set to NULL in this case. \subsection{Observational configuration and instrumental parameters} -These parameters are intended to describe the main telescope(s) characteristics for both SD antennas and interferometers. +\label{sec:instrumental} +These parameters are intended to describe the main telescope(s) characteristics for both SD antennas and interferometers. Such instrumental characteristics give an approximate idea on the spanned angular scales, field of view, product types, etc. -The more global parameter to define is the instrument type allowing clients to discriminate single dish observations from interferometry or beam forming ones. +The more global parameter to be defined is the instrument type allowing to discriminate single dish observations from interferometry or beam forming ones. -Parameters \emph{instr\_tel\_number, instr\_tel\_min\_dist} and \emph{instr\_tel\_max\_dist} are related to interferometers only, while -\emph{instr\_tel\_diameter, instr\_feed } are valid also for SD. +Parameters \emph{instr\_tel\_number, instr\_tel\_min\_dist} and \emph{instr\_tel\_max\_dist} are related to interferometers only while +\emph{instr\_tel\_diameter, instr\_feed } are valid also for SD (See Table. \ref{tab:ExtensionAtt_instrumental} +for definitions). We note that \emph{instr\_feed} could also account for the number of beams in the case of a beam forming/PAF receiver. The scanning strategy adopted in an observation is described by the parameter \emph{scan\_mode}. This parameter covers both spatial -and frequency scanning modes (see Sect.~\ref{subsec:sd} for details and table~\ref{tab:scanmode} for possible values). +and frequency scanning modes (see Sect~\ref{sec:sd} for details and table~\ref{tab:scanmode} for possible values). It is applicable to SD as well as to interferometry cases. @@ -439,15 +452,15 @@ \subsection{Observational configuration and instrumental parameters} \hline \texttt{on-off}&switched measurements between two positions (source and background)\cr \hline - \texttt{raster-map}&successive measurement spots on a predefined mesh (generally regular and rectangular)\cr + \texttt{raster-map}&successive measurement on a predefined mesh (generally regular and rectangular)\cr \hline - \texttt{on-the-fly-cross-scan}&successive continuous measurements along a predefined spatial pattern\cr + \texttt{on-the-fly-cross-scan}&successive continuous measurements along a predefined spatial cross-shaped pattern\cr \hline \texttt{on-the-fly-map}&successive continuous measurements along parallel directions\cr \hline \texttt{skydip}&successive continuous measurements along a large span in elevation at a given azimuth (acquired for calibration purposes)\cr \hline - \texttt{frequency-switching}&subsequent measurements of the same target at two different central frequencies acquired with the same receiver \cr + \texttt{frequency-switching}&subsequent measurements of the same target at two different reference frequencies acquired with the same receiver \cr % \texttt{target}&\texttt{extrasolar target follow up}\cr \hline @@ -455,68 +468,65 @@ \subsection{Observational configuration and instrumental parameters} \label{tab:scanmode} \end{longtable} -Pointing mode distinguishes observations pointed on a fixed target from -observations fixed on a given elevation and azimuth. -%In addition the wobble mode observes both the source and the surrounding background. -The ObsLocTAP specification \citep{2021ivoa.spec.0724S} defines the term -\emph{tracking\_type} for describing this as well as a vocabulary for -these modes. We include the same terms here in the present extension. The +A celestial source or reference position in the sky may be tracked in different ways. + +%In addition the wobble mode observes both the source and the surrounding background. +The ObsLocTAP specification \citep{2021ivoa.spec.0724S} defines the term +\emph{tracking\_type} for describing this as well as a vocabulary for +these modes. We include the same terms here in the present extension. The possible values for radio astronomy data are the following: \begin{itemize} \item \texttt{sidereal}: observations pointed on a fixed target, as defined in ObsLocTAP \item \texttt{fixed-az-el-transit}: observations fixed on a given elevation and azimuth, as in ObsLocTAP - \item Solar-system-object-tracking: moving target, like moon or solar bodies -% \item Wobble: observations measuring both the source and the surroundings + \item \texttt{Solar-system-object-tracking} : moving target, like moon or solar bodies +% \item Wobble : observations measuring both the source and the surroundings \end{itemize} \subsection{Auxiliary datasets for data quality estimation} Auxiliary datasets such as \emph{uv} distribution map, dirty beam maps, frequency/amplitude plots, phase/amplitude plots are useful for astronomers to check data quality. -In that case, DataLink \citep{2023ivoa.spec.1215B} may provide a solution to attach these auxiliary data files to ObsCore records. The link between a data set and its associated data files, is described by a set of parameters in the specification as shown in the datalink table example below. -%\{link\} response will contain \#auxiliary in the \texttt{semantics} FIELD to bind maps or plots and a term identifying the nature of the data file in the \texttt{content\_qualifier} FIELD. Such a term would belong to a defined vocabulary following the IVOA vocabulary definition \citep{2021ivoa.spec.0525D} . See the example below. -% insert data link example table here +In that case, DataLink \citep{2023ivoa.spec.1215B} may provide a solution to attach these auxiliary data files to ObsCore records. The link between a data set and the data files associated with it is described by a set of parameters in the Datalink standard as shown in the datalink table example below. +%\{link\} response will contain \#auxiliary in the \texttt{semantics} FIELD to bind maps or plots and a term identifying the nature of the data file in the \texttt{content\_qualifier} FIELD. Such a term would belong to a defined vocabulary following the IVOA vocabulary definition \citep{2021ivoa.spec.0525D} . See the example below. +% insert data link example table here \begin{table}[h] \begin{flushleft} -\begin{tabular}{| l l l l l | |} +\begin{tabular}{|l|l|l|} \hline -{\bf parameter} & {\bf DL record } & {\bf DL record} \\ +{\bf parameter} & {\bf DL record } & {\bf DL record}\\ \hline ID & ivo://aaa/bb & ivo://aaa/bb \\ -(of ObsCore record ) & & \\ +of ObsCore entry & & \\ \hline -access\_url &http://atca/aaa & http://atca/bbb\\ +access\_url &http://atca/aaa & http://atca/bbb\\ \hline -description & \emph{uv} coverage map & dirty beam image \\ +description & \emph{uv} coverage map & dirty beam image \\ \hline -semantics & auxiliary& calibration\\ +semantics & auxiliary& auxiliary\\ \hline -content\_type & image/png& image/png \\ +content\_type & image/png& image/png \\ \hline content\_length & 25000 & 1000 000\\ \hline -content\_qualifier & \footnotesize{\url{www.ivoa.net/rdf/product-type#image}} & \footnotesize{\url{www.ivoa.net/rdf/product-type#image}}\\ +content\_qualifier & \footnotesize{\url{www.ivoa.net/rdf/...}} & \footnotesize{\url{www.ivoa.net/rdf/...}}\\ +& \footnotesize{\url{...product-type#image}} & \footnotesize{\url{...product-type#image}}\\ \hline local\_semantics & uv\_distribution\_map& dirty\_beam \\ \hline \end{tabular} \end{flushleft} -\caption{Metadata of the Data Link (DL) response for an ObsCore \emph{visibility} data set associated to two auxiliary data file: \emph{uv} map and dirty beam image in their own column. } +\caption{Metadata of the Data Link (DL) response for an ObsCore \emph{visibility} data set associated to two auxiliary data file: \emph{uv} map and dirty beam image in their own column. } \label{fig:linkFields} \end{table} - - - -%end datalink table +%end datalink table \section{The ivoa.obscore\_radio table} \label{sec:implementation} The ObsCore Extension for Radio is accessed as a table within a TAP -\citep{2019ivoa.spec.0927D} service. At this -point, the name of this table is fixed to \verb|ivoa.obscore_radio|. +\citep{2019ivoa.spec.0927D} service. Its named is fixed to \verb|ivoa.obscore_radio|. Within the IVOA, it is forbidden to use this name for anything else than a table compliant with this specification. @@ -527,8 +537,8 @@ \section{The ivoa.obscore\_radio table} A TAP service that has \verb|ivoa.obscore_radio| must also have a table compliant to any version 1 of ObsCore, i.e., a table \verb|ivoa.obscore| containing only the basic ObsCore attributes. The two tables must share exactly the \emph{obs\_publisher\_did} column such -that a \verb|NATURAL JOIN| will yield per-dataset rows of obscore and -radio extension metadata. +that a \verb|NATURAL JOIN| will yield per-dataset rows of ObsCore and +radio extension metadata. To ensure that all compliant services can execute the same queries, all columns described in following tables ~\ref{tab:ExtensionAtt} , ~\ref{tab:ExtensionAtt_interferometry} and \ref{tab:ExtensionAtt_instrumental} must be gathered in the \verb|ivoa.obscore_radio| @@ -573,9 +583,10 @@ \section{The ivoa.obscore\_radio table} \sptablerule \textbf{column name}&\textbf{definition}&\textbf{utype}&\textbf{ucd}&\textbf{unit}\cr \sptablerule -\texttt{ s\_resolution\_min}&\texttt{ Angular resolution, longest baseline and max frequency dependent}&{ Char.SpatialAxis.\newline Resolution.Bounds.\newline Limits.LoLim}&{pos.angResolution;stat.min}&{arcsec}\cr +% to be checked again +\texttt{ s\_resolution\_min}&\texttt{ Angular resolution, min value, longest baseline and max frequency dependent}&{ Char.SpatialAxis.\newline Resolution.Bounds.\newline Limits.LoLim}&{pos.angResolution;stat.min}&{arcsec}\cr \sptablerule -\texttt{s\_resolution\_max}&\texttt{Angular resolution, longest baseline and min frequency dependent}&\texttt{Char.SpatialAxis.\newline Resolution.Bounds.\newline Limits.HiLim}&{pos.angResolution;stat.max}&arcsec\cr +\texttt{s\_resolution\_max}&\texttt{Angular resolution, max value, longest baseline and max frequency dependent}&\texttt{Char.SpatialAxis.\newline Resolution.Bounds.\newline Limits.HiLim}&{pos.angResolution;stat.max}&arcsec\cr \sptablerule \texttt{s\_fov\_min}&\texttt{field of view diameter, min value, max frequency dependent}&\texttt{Char.SpatialAxis.\newline Coverage.Bounds.\newline Extent.LowLim}&{phys.angSize;instr.fov;\newline stat.min}°\cr \sptablerule @@ -595,7 +606,7 @@ \section{The ivoa.obscore\_radio table} \ \textbf{column name}&\textbf{definition}&\textbf{utype}&\textbf{ucd}&\textbf{unit}\\ \hline -\texttt{s\_largest\_angular\_scale}&\texttt{maximum scale in dataset, shortest baseline and for typical frequency}&\texttt{Char.SpatialAxis.\newline Resolution.Scale.\newline Limits.HiLim}&{phys.angSize;stat.max}&arcsec \\ +\texttt{s\_largest\_angular\_scale}&\texttt{maximum scale in dataset, shortest baseline and for reference frequency}&\texttt{Char.SpatialAxis.\newline Resolution.Scale.\newline Limits.HiLim}&{phys.angSize;stat.max}&arcsec \\ \hline \texttt{s\_largest\_angular\_scale\_min}&\texttt{smallest maximum scale in dataset, shortest baseline and for highest frequency}&\texttt{Char.SpatialAxis.\newline Resolution.Scale.\newline Limits.HiLim.Low}&{phys.angSize;stat.max}&arcsec \\ \hline @@ -639,18 +650,18 @@ \section{The ivoa.obscore\_radio table} \hline \texttt{instr\_tel\_number}&\texttt{number of antennas in array}&\texttt{Provenance.ObsConfig.\newline Instrument.Array.\newline AntNumber}&meta.number;instr.param& \\ \hline -% same for all antenae features +% same for all antennae features \texttt{instr\_tel\_min\_dist}&\texttt{minimum distance between antennas in array}&\texttt{Provenance.ObsConfig.\newline Instrument.Array.\newline MinDist}&instr.baseline;stat.min&m \\ \hline \texttt{instr\_tel\_max\_dist}&\texttt{maximum distance between antennas in array}&\texttt{Provenance.ObsConfig.\newline Instrument.Array.\newline MaxDist}&instr.baseline;stat.max&m \\ \hline -\texttt{instr\_tel\_diameter}&\texttt{diameter of telecope or antennas in array}&\texttt{Provenance.ObsConfig.\newline Instrument.Array.\newline Diameter}&instr.param&m \\ +\texttt{instr\_tel\_diameter}&\texttt{diameter of the largest telecope or antenna in array}&\texttt{Provenance.ObsConfig.\newline Instrument.Array.\newline Diameter}&instr.param&m \\ \hline \texttt{instr\_feed}&\texttt{number of feeds}&\texttt{Provenance.ObsConfig.\newline Instrument.Feed}&instr.param& \\ \hline \texttt{scan\_mode}&\texttt{sky and spectral axis scan mode }&\texttt{Provenance.\newline Observation.\newline sky\_scan\_mode}&instr.param& \\ \hline -\texttt{tracking\_type}&\texttt{target tracking modes}&\texttt{Provenance.\newline Observation.\newline tracking\_mode}&instr.param& \\ +\texttt{tracking\_type}&\texttt{target tracking mode}&\texttt{Provenance.\newline Observation.\newline tracking\_mode}&instr.param& \\ \hline \caption{ObsCore radio extension columns for instrumental parameters.} diff --git a/role_diagram.pdf b/role_diagram.pdf index 92ba5fd..4c0175f 100644 Binary files a/role_diagram.pdf and b/role_diagram.pdf differ