Comparing ESO sky model to current OpSim sky values

[yoachim (Peter Yoachim)]

I ran through ewok_1004 and compared the current sky brightness values to the ones calculated from the ESO model.
It looks like ESO is predicting significantly fainter sky values. I think the outliers in the lower rights are caused by OpSim using a simple twilight model, where it just sets the sky to a bright value if there is any twilight. There were 19 points that the model couldn’t compute values for because they were above an airmass of 2.5.

Results running on 1/100 of the opsim pointings:
filter, median OpSim, median ESO
u, 22.04, 22.69
g, 21.75, 22.09
r, 21.05, 20.99
i, 19.83, 20.02
z, 17.61, 18.67
y, 17.30, 17.68

[yoachim (Peter Yoachim)]

Exploring the z-band since it looks the strangest, it looks like the issue is a large difference in the moonlight models when one gets close to the moon (~40 degrees).

[yoachim (Peter Yoachim)]

But this does raise the question of why there are so many z-band observations near the moon.

It’s peaked at 40 degrees. So either the z-filter is only getting put in when the moon is already very high, or we’re doing a bad job avoiding the moon (or both).

[yoachim (Peter Yoachim)]

Both.