Terzan 1 is an globular star cluster located in the middle of Scorpio about 22,000 light years from Earth. It is one of 11 globular clusters discovered by Turkish- Armenian astronomer Agop Terzan between 1966 and 1971. This was his time in France, mainly at the Lyon Observatory.
Terzan 1, a globular cluster located in Scorpio, about 22,000 light-years from Earth. Source: ESA/Hubble and NASA, R. Cohen
A little confusingly, these 11 Terzan globular clusters are numbered from Terzan 1 to Terzan 12. This is due to a mistake Terzan made in 1971, when he rediscovered Terzan 5 - an cluster he had discovered and reported in 1968 - and named it Terzan 11. He published it along with the discoveries of Terzan 9, 10 and 12.
Then, he quickly realized his mistake and tried to rename No. 12 to No. 11. Unfortunately, he did not clearly state that 5 and 11 are the same, although another astronomer Ivan Robert King published a note in an attempt to clarify the confusion. These days, most papers acknowledge the original Terzan 5 and Terzan 12 and accept the weirdness of Terzan 11 without. There have been some confusing examples in the scientific literature over the past few decades.
Image of Terzan 1 taken by the Hubble Space Telescope by Wide Area Planetary Camera 2. Source: NASA ESA
In fact, Terzan 1 is not the new target of Hubble , the telescope released images of the cluster back in 2015 (see above), taken by Hubble's Wide Area Planetary Camera 2 (WFPC2). During the 2009 Hubble repair mission, the instrument was replaced by the wide field camera 3 (WFC3). Compared to WFPC2, WFC3 has higher resolution and a wider field of view, and the improvement is obvious in this very detailed image.
