PLATO input catalogs for technical calibration and fine guidance

Abstract

A few weeks after launch, the PLATO spacecraft is expected to start its payload commissioning, which will be completed within the first three months of the mission. This phase includes the in-orbit verification, calibration, and configuration of the instrument prior to nominal science operations. During this mission-critical period, and again later during regular spacecraft rotations and re-pointings, a set of reference stars is required to complete various calibration steps. This set, referred to as the calibration PLATO Input Catalog (cPIC), is part of the PIC. The cPIC comprises various stellar samples, each serving a dedicated technical calibration purpose, and it contains 71671 unique stellar targets across PLATO's entire field of view (FoV). Once the spacecraft commences science observations, the on-board Fine Guidance System (FGS) will rely on a small set of guide stars. These stars must be particularly bright and will be observed with the two fast cameras, which cover only a smaller central region of PLATO's FoV. This target list, referred to as the fine-guidance PLATO Input Catalog (fgPIC), contains 2640 unique targets, of which about 30 are used by the FGS at any given time. In this paper, we present the selection criteria for both the cPIC and the fgPIC, and asses their impact on the construction of these calibration catalogs for PLATO.

Figures (5)

• Figure 1: Histograms of the PLATO magnitude difference of the P1 Sample targets and the combined magnitude of the contaminants within a given radius of each P1 star. Legends summarize the number and the fraction of P1 stars that would have been selected into the LOPS2 cPIC if the respective ${\Delta}P$ had been chosen. Top left: Radius for contaminants: $40"$. Top right: Radius for contaminants: $60"$. Bottom left: Radius for contaminants: $80"$. Bottom right: Radius for contaminants: $120"$.
• Figure 2: Sky plot of the cPIC targets (red dots) that were selected before the waiver for photometric contaminants in crowded fields was introduced. The blue shaded regions are covered by targets from the LOPS2 PIC2.2.0.1. Light to dark blue regions correspond to a coverage by 6, 12, 18, and 24 N-CAMs, respectively. The apparent hole Galactic longitude of $280^\circ$ and Galactic latitude of $-33^\circ$ is caused by stellar crowding in the Large Magellanic Cloud and the resulting rejection of cPIC targets due to photometric contamination. Top left: R$i$ N-CAM sample. Top right: R2 N-CAM sample. Bottom left: R$i$ F-CAM sample. Bottom right: R2 F-CAM sample.
• Figure 3: Sky plot of the cPIC targets (red dots) that were selected due to the waiver for photometric contaminants in crowded fields. Top left: R$i$ N-CAM sample. Top right: R2 N-CAM sample. Bottom left: R$i$ F-CAM sample. Bottom right: R2 F-CAM sample.
• Figure 4: Sky plot of nine cPIC targets that are present in all stellar reference samples. Their PIC names are indicated with labels.
• Figure 5: Sky plot of the fgPIC targets that were rejected due to photometric contamination by nearby targets. Black crosses refer to 1325 targets rejected from the fgPIC (blue F-CAM), red dots indicate a total of 4271 targets rejected from the fgPIC (red F-CAM) due to photometric contamination from nearby Gaia DR3 sources. There are eight black crosses in total that do not fall exactly on a red dot (see Sect. \ref{['sec:PhotContfgPIC']}).