Roof Closure Building 8 Too Early!

William McLaughlin

The last two nights that the roof was open on building 8 I noticed that it was closing around 4:30 AM.

Given that astronomical twilight is at about 5:45 AM, this is wasting an hour and 15 minutes of imaging time. Worse, during this phase of the moon, most or all of that is moonless time. In fact, even when the moon IS up during morning AT (the opposite side of the moon calendar), it is common to image a bit PAST astronomical twilight since one is typically using narrowband filters anyway and a small amount of early twilight is less than what the moon illumination contributes. In that case one should be closing as much as 30 minutes AFTER morning astronomical twilight. There is zero safety hazard to this since sunrise is still a half hour or more away in the most extreme case.

I have my own roll-off and have imaged at another remote site as well and have never heard of early closure for anything but weather.

I have talked to my imaging partner and he is in 100% agreement - he has imaged at three other remote sites and says none of them did anything like this.

How do we get this changed?

My images can be found at:


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