Small and large telescopes are being installed all around the world. Astronomers have thus acquired better access to more modern equipment; not in the least to photometers, which are very important tools for the contemporary observer. This development of higher quality and more sensitive equipment makes it very necessary to improve the accuracy of the measurements. This guide helps the astronomer and astronomy student to improve the quality of their photometric measurements and to extract a maximum of information from their observations.
In 1941 in occupied Paris, brothers Maurice and Joseph play a last game of marbles before running home to their father's barbershop. This is the day that will change their lives forever. With the German occupation threatening their family's safety, the boys' parents decide Maurice and Joseph must disguise themselves and flee to their older brothers in the free zone. Surviving the long journey will take every scrap of ingenuity and courage they can muster. If they hope to elude the Nazis, they must never, under any circumstances, admit to being Jewish. The boys travel by train, ferry, and on foot, facing threats from strangers and receiving help from unexpected quarters. Along the way they must adapt to the unfamiliar world beyond their city and find a way to be true to themselves even as they conceal their identities. Based on an autobiographical novel by Joseph Joffo and adapted with the author's input, this true story offers a harrowing but inspiring glimpse of a childhood cut short.