10.12.4 Processing steps

The short-timescale processing starts with the variogram analysis, similarly to what is described in Roelens et al. (2018). In short, the flagging of short-timescale candidates is based on the comparison of the variogram values of the considered source with a magnitude-dependent detection threshold ${\gamma }_{\det }(\overline{m})$, completed by an upper limit of $0.5$ day on the detection timescale ${\tau }_{\det }$ (which is the shortest lag for which the variogram value is above the detection threshold). However, a different formulation of the variogram is used here, based on the interquartile range (IQR) and not on the standard deviation. For more details about the variogram approach in the Gaia context, see Roelens et al. (2018). For Gaia DR3, we employed the same detection threshold ${\gamma }_{\det }(\overline{m})$ that was applied to short-timescale candidates in Gaia DR2.

For the candidates passing the variogram short-timescale selection, a Least-Square period search algorithm is run on the per-CCD time series, searching in the frequency range from 20 min to 1 day.

The short-timescale analysis applied a limit to the range of the $G$-band per-FoV Abbe value (abbe_mag_g_fov) to be between 0.7 and 2, in order to exclude long-period variables.

Further constraints were applied to the number of observations in the $G_{\mathrm{BP}}$ and $G_{\mathrm{RP}}$ bands, and an upper limit of 1.8 was set for the ratio of the sum of $G_{\mathrm{BP}}$ and $G_{\mathrm{RP}}$ mean fluxes to the one in the $G$ band. Additional limitations were set for astrometric parameters: ruwe , visibility_periods_used $>15$, and astrometric_excess_noise .

The Gaia DR3 vari_short_timescale table includes 471 679 candidates with the following fields:

• •

  amplitude_estimate, from the 5th to the 95th percentiles of per-CCD photometry,

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  number_of_fov_transits, with at least 8 CCD measurements,

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  mean_of_fov_abbe_values, from the per-CCD Abbe values of each FoV transit,

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  variogram_num_points, denoting that only one timescale was selected in Gaia DR3,

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  variogram_char_timescales, of the selected timescale values,

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  variogram_values, associated with the selected timescales,

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  frequency, searched with the Least Squares method on the per-CCD $G$-band photometry.