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Single Object TOOL

As part of Gaia’s third data release (Gaia DR3), millions of stars have their spectra and/or light curves revealed by Gaia. In addition to the interactive visualisation service that is meant to explore the data in bulk, the Archive also offers a single-object visualisation tool to explore the Gaia DR3 data of single objects. The tool, which is meant for exploration and not for deep scientific analyses, offers a name resolver to find the object of interest, a data table listing selected fundamental measured and inferred quantities, and six interactive panels with graphical information (as summarised here and with full details provided below):

  • Name resolver: the name resolver works using Gaia DR3 designations but it also accepts other object names and coordinates as resolved by SIMBAD/Sesame. A showcase object is pre-loaded when opening the tool, namely the bright classical Cepheid “V* BF Oph” (Gaia DR3 4111834567779557376). Another interesting source worth trying is the RR Lyrae variable “V* RR Cet” (Gaia DR3 2558296724402139392).
  • Basic data: this box shows, in up to four tabs, selected basic data of the source extracted from the gaiadr3.gaia_source and gaiadr3.astrophysical_parameters tables.
  • ESASky: this widget shows a zoomed region of the sky centred on the object. All functionality of ESASky is available inside the widget using the customary controls.
  • Epoch Photometry: this panel displays the time-resolved, integrated photometry in the G, GBP and GRP bands. The individual bands can be toggled on and off in the legend; the display of (proxies for) magnitude errors can also be toggled on and off. This data is available for more than 11 million sources (those with gaiadr3.gaia_source.has_epoch_photometry = ‘TRUE’).
  • BP/RP (XP) Spectrum: this panel displays the externally calibrated sampled mean spectrum. This data is available for more than 34 million sources (those with gaiadr3.gaia_source.has_xp_sampled = ‘TRUE’).
  • RVS Spectrum: this panel displays the normalised RVS mean spectrum. This data is available for nearly 1 million sources (those with gaiadr3.gaia_source.has_rvs = ‘TRUE’).
  • Markov Chain Monte Carlo (MCMC) samples: General Stellar Parametrizer from Photometry (GSP-Phot): this panel displays, in corner-plot configuration, the posterior probability density functions of the Bayesian parameter estimates from the GSP-Phot module. This data is available for nearly 450 million sources (those with gaiadr3.gaia_source.has_mcmc_gspphot = ‘TRUE’).
  • Markov Chain Monte Carlo (MCMC) samples: Multiple Star Classifier (MSC): this panel displays, in corner-plot configuration, the posterior probability density functions of the Bayesian parameter estimates from the Multiple Star Classifier module. This data is available for nearly 350 million sources (those with gaiadr3.gaia_source.has_mcmc_msc = ‘TRUE’).

Any of the interactive boxes/panels can be expanded by clicking the “Expand”/“Collapse” button in the top-right corner. Inside the plotting panels, which use the Python Plotly framework, various icons allow the user to zoom, re-scale, output .png files, etc. 

Name resolver

The single object tool is tailored to Gaia’s third data release (Gaia DR3). The name resolver accepts three different types of inputs:

  1. Gaia DR3 designations, for instance “Gaia DR3 4111834567779557376”;
  2. Coordinates, for instance “256.5229102004341 -26.580565130784702”;
  3. Object names as resolved by the SIMBAD/Sesame name resolver, for instance “V* BF Oph”.

In the latter two cases, the tool executes a cone search (that takes into account epoch propagation) and selects the closest match in angular distance.

BASIC DATA

The data panel provides selected basic data of the source extracted from the gaiadr3.gaia_source and gaiadr3.astrophysical_parameters tables. The following fields are displayed in (up to) four separate tabs:

In all cases, the data that are displayed only show a limited number of decimal places. For high-precision scientific work, users are advised to query the Gaia ESA Archive and work with full-precision data.

Epoch Photometry

The epoch photometry panel displays the integrated epoch photometry in the G (green symbols), GBP (blue symbols), and GRP (red symbols) bands. These data are available, through the DataLink interface, for 11,754,237 sources, namely those with gaiadr3.gaia_source.has_epoch_photometry = ‘TRUE’. The individual bands can be toggled on and off in the legend. The horizontal axis shows time in barycentric coordinate time (TCB), converted to calendar date. The 34-month time range corresponds to the data segments that underlie Gaia DR3. The photometric data themselves are described in detail in the on-line documentation.

The “Show errors” toggle allows to display magnitude errors. Since these are typically of order a milli-magnitude, the associated error bars are often so small that they appear as (two overlapping) horizontal bars that denote the end points of the “invisible” vertical error bar. The magnitude errors are computed as 1.086 / flux_over_error, which is an acceptable approximation for flux measurements with high signal-to-noise ratio. Horizontal error bars are not displayed. The G-band data points are averaged over typically 9 CCD observations that are collected in a time range of about 44 seconds; the BP and RP data points each reflect individual CCD observations, each with an integration time of 4.4 seconds.

ESASky

The ESASky widget features a zoomed region of the sky centred on the object. All functionality of ESASky is available inside the widget using the customary controls. Examples include loading the full Gaia DR3 catalogue as an overlay, changing the astronomical survey that is shown as background image, etc. Please refer to the ESASky documentation for more information. A special feature implemented here is “Set target”: use the Search functionality in the ESASky widget to look for your favourite object. Once the sky view has been readjusted and shows the object of interest in the centre, click “Set target” at the top of the widget. This will reload the single-object tool page with data for the object of interest.

BP/RP (XP) Spectrum

The BP/RP (or XP) panel shows the (externally-calibrated) sampled mean BP/RP spectrum, which covers the wavelength range 336 to 1020 nm with a step size of 2 nm. Such a spectrum is available for more than 34 million sources (those with gaiadr3.gaia_source.has_xp_sampled = ‘TRUE’) with details described here. Gaia DR3 contains mean BP/RP spectra based on a continuous representation in basis functions for more than 219 million sources (those with gaiadr3.gaia_source.has_xp_continuous = ‘TRUE’). These are not displayed in the single object tool but users can download these spectra and easily convert them to sampled mean spectra by means of the GaiaXPy tool. The 34 million sampled spectra are a subset of the 219 million continuous spectra.

RVS Spectrum

The RVS panel shows the flux-normalised RVS mean spectrum, which covers the wavelength range 846 to 870 nm with a step size of 0.01 nm. Such a spectrum is available for nearly 1 million sources (those with gaiadr3.gaia_source.has_rvs = ‘TRUE’) with details described here.

Markov Chain Monte Carlo (MCMC) samples: General Stellar Parametrizer from Photometry (GSP-Phot)

This panel shows, in canonical corner-plot configuration, the posterior probability density functions of the Bayesian parameter estimates from the GSP-Phot module. These data are available for nearly 450 million sources (those with gaiadr3.gaia_source.has_mcmc_gspphot = ‘TRUE’) with details described here. The corner plots show 100 MCMC samples except for sources brighter than G=12 mag and a random subset of 1% of fainter sources, for which 2000 samples are available and plotted. Contours are indicative and are only meant to guide the eye. The Bayesian posterior parameter estimates themselves, as well as associated upper (84%) and lower (16%) confidence levels for each parameter, are provided in the gaiadr3.astrophysical_parameters table. Individual panels can be zoomed by clicking (not pressing) the control-key once followed by a single, left mouse click. The resulting zoom can be removed by the same operation.

Markov Chain Monte Carlo (MCMC) samples: Multiple Star Classifier (MSC)

This panel shows, in canonical corner-plot configuration, the posterior probability density functions of the Bayesian parameter estimates from the Multiple Star Classifier module. These data are available for nearly 350 million sources (those with gaiadr3.gaia_source.has_mcmc_msc = ‘TRUE’) with details described here. The corner plots show 100 MCMC samples. Contours are indicative and are only meant to guide the eye. The Bayesian posterior parameter estimates themselves, as well as associated upper (84%) and lower (16%) confidence levels for each parameter, are provided in the gaiadr3.astrophysical_parameters table. Individual panels can be zoomed by clicking (not pressing) the control-key once followed by a single, left mouse click. The resulting zoom can be removed by the same operation.