Professor Sinistra is the long-serving Professor of Astronomy at Hogwarts School of Witchcraft and Wizardry. She teaches her classes at midnight in the Astronomy Tower, the tallest tower of the castle. Throughout the series, she remains a background character, with her presence noted at school events and her subject being a core part of the Hogwarts curriculum, but she has no dialogue and very little direct interaction with the main characters in the novels.
Professor Sinistra's life before or after her tenure at Hogwarts is not detailed in the original novels. She was the Professor of Astronomy during Harry Potter's entire time at the school. In the 1992-1993 school year, Harry Potter and Ron Weasley, while flying the enchanted Ford Anglia to Hogwarts, spotted Professor Sinistra conducting a midnight Astronomy class in the Astronomy Tower. During the 1994-1995 school year, she attended the Yule Ball as part of the Triwizard Tournament celebrations. She was seen dancing with Professor Filius Flitwick, who was so short he could barely see over her arms. In the 1995-1996 school year, the practical portion of the Astronomy O.W.L. took place on the Astronomy Tower. During the exam, a major conflict erupted below as Dolores Umbridge and several Aurors attempted to sack Rubeus Hagrid. The ensuing battle resulted in Professor Minerva McGonagall being hit by four Stunning Spells simultaneously and hospitalized at St. Mungo's Hospital for Magical Maladies and Injuries, causing a great disturbance for the students taking their exam. Professor Sinistra's involvement in the Battle of Hogwarts during the Second Wizarding War is unknown.
The novels provide no description of Professor Sinistra's physical appearance. Her personality is largely unwritten. As a long-standing professor at Hogwarts, she is presumed to be a knowledgeable and competent witch. Her attendance at the Yule Ball and willingness to dance suggests a social side that is not reclusive. She maintains a professional, if distant, presence on the Hogwarts staff.
As a professor at Hogwarts, Sinistra is undoubtedly a highly skilled and magically proficient witch.
No specific spells, wand details, or Patronus form for Professor Sinistra are mentioned in the novels.
While no specific possessions are named, as the Astronomy professor, she would have owned and used various instruments for her work, such as telescopes, star charts, and armillary spheres. She would also have possessed a wand.
Professor Sinistra appears to have a standard professional relationship with her colleagues on the Hogwarts staff. Her most notable interaction is dancing with Professor Filius Flitwick at the Yule Ball, which indicates a friendly rapport between them. Her relationship with students is unknown, as she is never depicted speaking directly to them in the books.