Does Venus count? The top photo taken at longitude 66E, the bottom photo taken at 118W, and both taken at the same time.

A good iPhone app for annotating photos with notes is Phonto. Lines arrows text.

Be very critical on time apps. There are a lot that just repeat system time. Time.gov isn't too bad. But, Sequoia Emerald Time and Stamp are as true a...

Timing errors are so easily over these days, that there's no reason for timing errors beyond 0.05". And you can test hand-eye-coordination errors, and...

rfc, post: 369184, member: 8882 wrote: Accumulated results from several astro outings....10 April: 175-26-13.015 April: 175-26-08.324 April: 175-26-01...

Maybe related..,If the cal procedure is to repeatedly measure a hor angle with a BS that is level and a FS that is elevated, 15-25å¡, D/R, small angle...

First and foremost: the vial. (Just like putting crosshair on a target. A little to one side is a miss.)You get the bubble dead center, rotate 180, an...

RTK is a local solution, and not the more rigorous phase differential post process solution of precise work.

MarkO ...That's not radio linked RTK. That's phase differential with a base receiver, post processed. And integer fix determined while stationary at 6...

Max distance to the base receiver fixed integer: 550 nm. Which is just over 1,000,000 m.My experience has been that an accurate integer fix remains va...

And 20 lb is a comfortable tension, and not invalid, when the 20 lb values are used. At 50, 100, 150, and 200 ft. 20 lbs insures the tape is straight,...

That's the ticket. (You can see a mag nail at a mile?)When it's warmer, and you can take an Astro without much fuss, then you'll take enough to know h...

NIST description is calibrated at 50 newtons tension for all intervals of the tape. They also calibrate at 100 newtons for all intervals of the tape t...

Note how much his az change, or get better. There not some 20-30" erratic. But progressive. (And the first is probably an ignore. So a population of l...

Take tape in a parking lot and hook the zero on a spike, pk or concrete nail. Stretch out the full 200 ft. to a second nail. Pull a gentle 10-12 lbs, ...

He describes one chain, not two. And different tensions at 10 lbs at 100 ft v 20 lbs at 200 ft. And was asking if that means 8 lbs at 80 ft. I have ne...

Fully suspended or flat?You can pull too much. A chain has a correct tension, not 'can never pull too hard' tension. A 300' chain can be off 5/100 abo...

I use a fish scale and chaining clamp. A good sporting goods shop had them, not too much $. Makes a big difference, if 0.03' matters.

Here's an source of systematic error in Astro:If your obs on multiple days are at the same time of day. i.e. Setting sun v rising. If you only observe...

All azimuths are greater than expected. But not by the same amount. A systematic error would mean all azimuths are greater by the same amount. And if...