A ROSAT-DETECTED, NEW GALACTIC SUPERNOVA REMNANT IN SAGITTARIUS, G13.3-1.3

Faint and diffuse soft X-ray emission, coincident with [S II] strong o ptical filaments, probably marks a previously unrecognized supernova r emnant (SNR) in Sagittarius (l = 13.3, b = -1.3). ROSAT PSPC data show soft X-rays from an area 40' x 70' with a flux of 1.3 x 10(-11) erg c m(-2) s(-1) between 0.1-2.4 keV. Optical interference-filter images ta ken of the region reveal a 20' long complex of relatively bright filam ents located along the south central boundary of the X-ray region whic h may be associated with a ridge of faint 11 cm continuum emission. Op tical spectra of these filaments show strong [S II] lambda lambda 6716 , 6731 emission ([S II]/H alpha = 0.85) and [O I] lambda lambda 6300, 6364 characteristic of shocked interstellar gas found in SNRs. Both X- rays and optical emissions along the source's NE extent show strong ab sorption by the dust regions Lynds 332, 336, and 342, indicating a loc ation behind these nebulae. CO emission from this region has been mapp ed and a kinematic distance derived for absorbing material. The remnan t is shown to lie between two absorbing regions located at distances o f 2 and 4 kpc.