LRS Throughput Estimates

It is important for the PI to realize that due to the design of the HET the effective collecting area changes over a trajectory. Near the end of a trajectory the HET has half the collecting area that it has near the middle. As such two medium length visits centered on middle of a track could be more valuable than a single long visit. All throughput estimates are based upon center of track efficiency.

To see the effect of changing exposure times in a moving aperture try the HET Filling Factor Calculator.

The UV chip currently has some significant charge transfer issues and lower throughput than predicted. For the UV chips bias values seem to change over time thus fluxing (perhaps even relative fluxing) can not be done on the UV chips while it can be done on the orange, red and far red chips.

Below we give the estimated on-sky performance for LRS2-B and LRS2-R in 10E-16 ergs (A) and in AB-mag (B) under a dark sky with 2x30 minute exposures with 1.2" FWHM image quality, ie. best possible conditions. Note the caveat about the UV flux above!

As we gain more information we will update these plots or generate a throughput calculator.

Last updated: Wed, 01 Jun 2016 15:44:19 -0500 shetrone


The Telescope

Technical Overview

Object Observability




HRS-2 Summary

HRS-2 Details

HRS-2 configurations

HRS-2 exposure meter

HRS-2 Position Angle and Fiber layout

HRS-2 Throughput


LRS2 Summary

LRS2 Details

LRS2 Fiber Layout and Position Angle

LRS2 Throughput

LRS2 Observing details


VIRUS - Summary

VIRUS - Details

VIRUS - Throughput

VIRUS - Fiber Layout and Position Angle

Old Instruments

LRS - old

Wavelength Calibration

Program Preparation

Web Management System

Other HET Documentation