7.3 Angular Resolution of GAIA BBP Flux Maps

The angular resolution achievable in flux maps obtained with different sample sizes is better illustrated in Figure 7.3, where two HII regions with a separation of about 0.5 arcsec near the center of the flux maps are shown.

Figure 7.3: Angular resolution of GAIA BBP flux maps of M100. A part near the center of GAIA BBP flux maps of M100 shown in Figure 7.2, showing two HII regions with a separation of about 0.5 arcsec. Upper row: $6\times8$ and $6\times4$ pixels/sample. Lower row: $6\times2$ and $1\times8$ pixels/sample. The side of each image is about 2 arcsec.

The increase of angular resolution with the decrease in the sample size can now be clearly seen, just as the increase in the noise in the fainter surroundings of the HII regions. It appears that an overall resolution of about 0.4 arcsec would be obtained with a sample size of $6\times4$ pixels. Such an angular resolution corresponds to that of an image obtained with an excellent large ground-based telescope during the short times of superb seeing. The best images obtained by the ESO Very Large Telescope have just about this small stellar image size.

Since the advantage of observing with such a sample size has been already variously demonstrated in Chapter 5, this is the only sample size considered in the following.