Mauna Kea Limiting Visual Magnitude

[Quark]

Yep I'm back,

Before I went to the Keck's I had a few inquiries from IIS people about verifying the limiting visual mag on Mauna Kea.

All of my observing was done from the Keck HQ remote control rooms at Waimea at 3,000 ft, however thanks to Professor Chuck Steidel from Caltech, I was given the opportunity to join him on Keck I, the final night I spent on the Big Island.

The significance of this, relating to what the limiting visual mag at the summit might be, was that Chuck had considerable experience observing at the summit prior to the remote control rooms being built within the Keck HQ complex at Waimea.

Chuck tell me that due to the physiological effects of the lack of oxygen on our eyes (there is 40% less oxygen at 14,000 ft), that the limiting visual mag at the summit would be no better and more likely worse than from a dark site at sea level.

Obviously the detectors on the Keck's don't' suffer from the lack of oxygen and the average seeing is 0.6 arc seconds. The best seeing that Chuck had experienced was 0.3 arc seconds.

Trevor

[gary]

Hi Trevor,

Thanks for the report and I had heard before of this law of diminishing returns
for altitudes over 10,000 feet as far as the effect of the lack of oxygen has
on visual acuity.

Even if there are real physiological reasons for the visual acuity dropping,
all it takes is for those other common woes at altitude, like a splitting headache,
shortness of breath, dehydration, etc, to kick in and put a real damper on what
otherwise would have been a great night's observing in ideal seeing conditions.

Ironically and apparently for reasons not completely understood, altitude sickness
tends to affect fit, young males more than other demographics. Though it may
not be wise to therefore take on a regimen of a meat pie and two beers for
lunch everyday for a year before going to the top of Mauna Kea in the hope one
might better escape the effects of altitude, it is nice to know that you don't
have to be a twenty year old bandana wearing mountain climbing champion either. :)

Really looking forward to your stories. How did the observation runs go
and how was the weather and seeing on the nights in question?

Best regards

Gary

[Quark]

Hi Gary,
I have posted a detailed report on the whole trip as a word document within one of my posts on the Terrestrial Images forum.

Bill Henley, the Keck guy that showed us around, sat us down and went through the symptoms we may experience that might require administering oxygen or immediate evacuation. Apparently if you arrived at the summit without a cough and start to develop one, that is an early sign of a cerebral oedema and possible death if no action is taken.

Bill told a great story about showing a Lieutenant that looked like he could run through a brick outhouse around, Bill thought this guy was struggling but every time Bill asked how he was the Lieutenant would reply fine sir, right up to the point where he collapsed.

Trevor

[astroron]

I spent over two hours on the top of the mountain in 1990,except for having a snooze in the car for half an hour and a bit out of breath climbing the steps to viewing platforms of some of the observatories felt no ill effects.
I then spent quite a few hours observing from the 9000ft mark where the visitors center was situated.
I have also climbed a mountain over 14000ft, Mt Kinabalu in Sabah Malaysia.
Except for the exsertion of the climb felt fine.

[Kevnool]

Great to hear your back Trev will catch up with you to hear all about it......cheers Kev.