ﻻ يوجد ملخص باللغة العربية
We combine deep, wide-field near-IR and optical imaging to demonstrate a reddening-independent quasar selection technique based on identifying outliers in the (g-z) / (z-H) colour diagram. In three fields covering a total of ~0.7 deg^2 to a depth of m_H~18, we identified 68 quasar candidates. Follow-up spectroscopy for 32 objects from this candidate list confirmed 22 quasars (0.86<z<2.66), five with significant IR excesses. 2 of 8 quasars from a subsample with U band observations do not exhibit UVX colours. From these preliminary results, we suggest that this combined optical and near-IR selection technique has a high selection efficiency (> 65% success rate), a high surface density of candidates, and is relatively independent of reddening. We discuss the implications for star/galaxy separation for IR based surveys for quasars. We provide the coordinate list and follow-up spectroscopy for the sample of 22 confirmed quasars.
We present preliminary results from a wide field near-IR imaging survey that uses the Cambridge InfraRed Survey Instrument (CIRSI) on the 2.5m Isaac Newton Telescope (INT). CIRSI is a JH-band mosaic imager that contains 4 Rockwell 1024$^{2}$ HgCdTe d
The ALHAMBRA survey aims to cover 4 square degrees using a system of 20 contiguous, equal width, medium-band filters spanning the range 3500 A to 9700 A plus the standard JHKs filters. Here we analyze deep near-IR number counts of one of our fields (
We present wide-field near-infrared J and Ks images of the Andromeda Galaxy taken with WIRCam on the Canada-France-Hawaii Telescope (CFHT) as part of the Andromeda Optical and Infrared Disk Survey (ANDROIDS). This data set allows simultaneous observa
The ongoing effort to implement compact and cheap optical systems is the main driving force for the recent flourishing research in the field of optical metalenses. Metalenses are a type of metasurface, used for focusing and imaging applications, and
We present a new technique for wide and shallow observations using the near-infrared channel of Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). Wide-field near-IR surveys with HST are generally inefficient, as guide star acquisitions