标题： BTC40类星体调查在4.8 < z < 6范围内的研究 显示英文标题

标题： The BTC40 Survey for Quasars at 4.8 < z < 6

摘要： BTC40巡天用于高红移类星体，是一项多色搜索，使用在CTIO 4米望远镜上用V、I和z滤镜获得的图像，以寻找红移在4.8 < z < 6之间的类星体。该巡天在B、V和I波段覆盖了40平方度，在z波段覆盖了36平方度。极限星等（3 sigma）达到V = 24.6，I = 22.9和z = 22.9。我们使用(V-I)对(I-z)两色图，从成像数据中被分类为点源的天体中选择高红移类星体候选体。对具有I < 21.5的候选体进行后续光谱观测，使用AAT和CTIO 4米望远镜，得到了两个红移为z = 4.6和z = 4.8的类星体以及四个红移为z = 0.6的发射线星系。更暗的候选体已识别到I = 22，以便在未来使用8米级望远镜进行光谱观测。 显示英文摘要

摘要： The BTC40 Survey for high-redshift quasars is a multicolor search using images obtained with the Big Throughput Camera (BTC) on the CTIO 4-m telescope in V, I, and z filters to search for quasars at redshifts of 4.8 < z < 6. The survey covers 40 sq. deg. in B, V, & I and 36 sq. deg. in z. Limiting magnitudes (3 sigma) reach to V = 24.6, I = 22.9 and z = 22.9. We used the (V-I) vs. (I-z) two-color diagram to select high-redshift quasar candidates from the objects classified as point sources in the imaging data. Follow-up spectroscopy with the AAT and CTIO 4-m telescopes of candidates having I < 21.5 has yielded two quasars with redshifts of z = 4.6 and z = 4.8 as well as four emission line galaxies with z = 0.6. Fainter candidates have been identified down to I = 22 for future spectroscopy on 8-m class telescopes.