We have two files from the Gemini (North) Observatory.

They are:

- gemini_sky_rad_ir.dat : 
	Model spectra of the infrared emission for Mauna Kea provided as `mk_skybg_zm_10_10_ph.dat`

	Gemini notes:
The files were manufactured starting from the sky transmission files generated by ATRAN 
(Lord, S. D., 1992, NASA Technical Memorandum 103957). These files were subtracted from unity to 
give an emissivity and then multiplied by a blackbody function of temperature 273 for Mauna Kea 
and 280 for Cerro Pachon. To these were added the OH emission spectrum (available from the European 
Southern Observatory's ISAAC web pages) a set of O2 lines near 1.3 microns with estimated strengths 
based on observations at Mauna Kea, and the dark sky continuum (in part zodiacal light), approximated 
as a 5800K gray body times the atmospheric transmission and scaled to produce 18.2 mag/arcsec^2 in the 
H band, as observed on Mauna Kea by Maihara et al. (1993 PASP, 105, 940).

Any use of the data in these tables should reference Lord (1992) and acknowledge Gemini Observatory. 
The 1-5 micron models are in ASCII two-column format: (a) wavelength with a sampling of 0.00002µm and 
a resolution of 0.00004µm (0.04nm) and (b) emission in ph/sec/arcsec^2/nm/m^2 . The 7-26 micron models 
have a sampling of 0.0001µm and a resolution of 0.0002µm (0.2nm) for Mauna Kea and 0.002µm and 0.004µm 
(4nm) for Cerro Pachon.

Note the crudity of the approximation of the thermal background, which assumes that all sources of 
sky opacity are at T=273K on Mauna Kea and T=280 on Cerro Pachon. In reality the sources occur at 
various altitudes above each site. Thus, these files should overestimate the thermal background. 
Note also that the OH lines can vary in intensity from night to night and vary greatly during the 
night as well. Finally note that background from moonlight is not included, but it can be very 
significant in the J, H, and K bands, especially if the target is located close to the bright moon.

- gemini_sky_rad_opt.dat :
	Model spectra of the optical sky emission for Mauna Kea provided as `skybg_50_10.dat`

	Gemini notes:
# sky background 0.3-1.0um
# DARK optical sky - 50%ile conditions (day 7)
# AM=1.0
#
# derived from (reverse engineered ESO model) sky spectrum plus 
# constant slope to match assumed photometric background (from
# von Hippel model.
#
# increasingly poor model at very bright sky (day14)
# patched to near-IR background at 920nm
#
# 1 March 2001 : Phil Puxley
# These spectra are used in the Integration Time Calculators. The sky spectrum is patched to the 
# near-IR sky spectrum at a wavelength of 920nm. 