On March 1^st, via an earlier Observer News Item, we informed the community of our efforts to improve guiding success in the very crowded, highly-reddened region surrounding the galaxy’s supermassive black hole, Sagittarius A* (SgrA*). The special work for this region included incorporating the Galactic Nucleus Catalogue (GNC¹) into our Guide Star Catalog 3.0 and determining appropriate photometric corrections. The goal has been to better predict the sources, their brightness, and their locations, as seen by the Fine Guidance Sensor (FGS).

Those enhancements were put through a critical test during the Galactic Center most recent visibility window which ran from mid-March through the first week of May. Over this time, 50 visits with targets in this region were scheduled. These executed with a success rate of 74%, representing a factor ~5 improvement over earlier rounds of Galactic Center science, the latest of which closed this past October. 

The detailed guiding data and FGS images from each of these recent visits are being analyzed using additional tools we have developed, and the results are providing valuable insight into guiding performance in bright crowded fields. Some of these results may enable improvements to observations in this very challenging region, while some may give more broadly applicable guiding knowledge.

Now that guiding on SgrA* and its surrounding regions has seen its first round of improvements, we will be turning some attention to challenges presented by other types of fields. These range from extremely sparse fields, to regions of high backgrounds and nebulosity, to dense globular clusters. Our approaches to these various scenes will likely span a variety of mitigations.

Observers with questions about guiding, in the Galactic Center or other regions, are encouraged to reach out to the JWST Help Desk.

Reference:

¹ Nogueras-Lara, F. et al. 2019, A&A, vol. 631, A20.