An Efficient Low Resolution and Moderate Resolution Spectrograph for the Hale Telescope

TLDR

The spectrograph uses a dichroic to split light into blue (3200–5200 Å) and red (5200–10 000 Å) channels, each with dedicated detectors (320×512 RCA or Shectrograph for blue, 800×800 TI CCD for red). It achieves 5–13 % efficiency from 3600 to 8200 Å and operates across 3200 to 10 400 Å.

Abstract

A new low-to-moderate resolution spectrograph has been designed and built for the Cassegrain focus of the Hale 5.08- meter telescope. To maximize efficiency, resolution, and wavelength coverage the light is divided into two spectral regions by a dichroic filter behind the entrance slit, after which there are two completely separate spectrographs. The blue spectrograph operates from 3200 Å to 5200 Å while the red one goes from 5200 Å to 10,000 Å. The red detector is an 800 × 800 TI CCD while the blue detector is a 320 × 512 RCA CCD or a Shectrograph image pulse-counting system. A Boksenberg IPCS can also he mounted on the blue camera. The overall efficiency of the Cassegrain telescope, spectrographs, and CCD's combined, ranges from 5% to 13% between 3600 Å and 8200 Å. The spectrograph is usable from 3200 Å to 10,400 Å.