Copper Mountain Vna Calibration

[Dunstan Jomphe]

HiI just updated to iOS 10.3.2. When I went into the Maps app and tapped the pointer I got a compass calibrating circle. It's the one where one has to roll a ball round a circle perimeter. I tapped 'Cancel' just under the circle, thinking I could come back to it again (last time I do that dumb move with an Apple product!). When I went back in to Maps the calibration interface did not reappear! Grrrrrrr. P.S. Apple: If one cannot get a setting interface back...please don't add a cancel option! Just don't allow one to progress to next screen till complete!

Go into Settings/Privacy/Location Services. Scroll down and tap on System Services. There's a switch to toggle Compass Calibration on/off. Perhaps switching it off and then on again might force a calibration?

Thanks for all your feedback. Unfortunately there isn't an Apple 'compass' app on the iPad Pro like there is on the iPhone. I downloaded one or two compass apps from the app store and they had no way to calibrate the electronics.

As an aside: I used to be a rock climber and I always went into the mountains with a proper good old fashioned compass as part of my 'basic stuff one should never be without' gear! No need for batteries or any calibration!

A four inch hermetically sealed reflecting telescope has been attached to the prime-focus scanner to provide an observing system for absolute calibration work. Light sources, including a platinum and a copper furnace, are observed at a distance of approximately 1200 feet. Since the telescope focal length is only 13 inches these sources look like stars. Thus bright stars such as α Lyr are compared directly with the light sources under identical instrumental conditions.

It has been found that horizontal extinction can be abnormally large; therefore it is measured several times each night. The absolute calibration is being derived at present from 3500 to 11000 and will be extended to 3200 as soon as possible. The calibration lies approximately midway between that measured recently by Hayes and that adopted some years ago by Oke. A very preliminary value for the absolute flux from α Lyr at 5556 is 3.5 10-20 ergs sec-1 cm-2 Hz-1 or 3.4 10-9 ergs sec-1 cm-2 -1.

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