With the upgrade of both the grating and detector for the OSIRIS spectrometer, there was a substantial increase in overall throughput for the instrument. In the table below, we have calculated the new spectroscopic zero points by applying the measured throughput values and scaling the limiting magnitudes appropriately.

Zero points are defined in the standard way:

N = counts or electrons, depending upon calculation

t = time

N/t = counts or electrons per second

	Spectroscopic Zero Points
Band	Delivered (H2)	Upgraded 2016 (H2RG)
J-Band	23.5	24.7
H-Band	24.3	25.3
K-Band	23.7	25.1

These sensitivity improvements are a result of a better grating reflectivity, increased detector sensitivity, and decreases in the detector noise both in dark current and read noise. In addition, the new focus stage improved the focus across the array so the PSF is tighter.

Imager Zero Points

Method: