You have encountered one of the crazy lies currently circulating on the Internet. To answer your question directly about G1.9+03, it is a supernova remnant (that is, an expanding gas cloud from a supernova explosion) about 25,000 light years away that was discovered in 1984. It has recently been determined using data from the Chandra x-ray telescope to be the youngest-known supernova in our Milky Way Galaxy. For details see Wikipedia
http://en.wikipedia.org/wiki/Supernova_remnant_G1.9%2B0.3. However, if you don't search Wikipedia but instead just google "G1.9+03" you immediately encounter an extraordinary collection of claims about this object. For example, "Disclose.tv, truth revealed" states that it is a "confirmed binary red dwarf star" in our own solar system with "planets or large satellites encircling it". They then show an absurd picture that has been bouncing around the Internet for several years as a photo of "Nibiru". This picture of a blue ball surrounded by orange flames is obviously not of any astronomical object. It is not even a clever fake.