Tom,
I don't know if I can be of any help but will and address refraction, dip and body selection.
For your Westbound trip, since it's during the day the obvious choice is the Sun made to the starboard side of the aircraft or, if you can, "right on the nose" looking forward.
For your Eastbound trip, at night, depending upon the time of year, find the brightest stars you can and shoot them. Vega, Deneb and Altair would be a good choice- they're not too difficult to find, and so are the stars in Orion.
Take a look at this procedure and chart for star identification-
Navigational Star chart- how to use it.
If that seems confusing, just look at the bottom of that star chart and notice the months. Example, on your local meridian for January 21 (approximate, of course) Mirfak and the stars in it's vicinity...including all those in Orion are good ones. Capella is noticeably bright. Of course much of star selection depends upon your shooting position. This time of year you'll see the Planets Jupiter, Saturn an Venus quite well (But Jupiter is really high in the sky at night, presently).
Refraction: Since you'll be at high altitude you'll need to correct for refraction. The 2025 Air Almanac page 908 lists the correction for Refraction based on altitude. Page 909 list correction for the Dome (just provided that for curiosity for you)
As to Dip...that has me somewhat uncertain if a Dip correction is required considering you're using a bubble sextant.
Get it here- 2025 Air Almanac
For starters, you might make your life easy and just try shooting Polaris for latitude and see how close you get to what the GPS reads.
How to Determine Latitude using Polaris is found on this page (scroll down and you'll see it)
Determine Latitude using Polaris
I learned CN by "reverse engineering" so to speak- took shots that weren't well done and then reduced the sight. Plotted the LOP and then figured out why there were large errors. If...if you record the correct time in GMT and get a "close enough" altitude measurement of the celestial object, you'll then have enough information to slog through many of hours (God forbid) trying to figure it all out.
I hope that assists you in some way and isn't too terribly confusing.
Ed
I don't know if I can be of any help but will and address refraction, dip and body selection.
For your Westbound trip, since it's during the day the obvious choice is the Sun made to the starboard side of the aircraft or, if you can, "right on the nose" looking forward.
For your Eastbound trip, at night, depending upon the time of year, find the brightest stars you can and shoot them. Vega, Deneb and Altair would be a good choice- they're not too difficult to find, and so are the stars in Orion.
Take a look at this procedure and chart for star identification-
Navigational Star chart- how to use it.
If that seems confusing, just look at the bottom of that star chart and notice the months. Example, on your local meridian for January 21 (approximate, of course) Mirfak and the stars in it's vicinity...including all those in Orion are good ones. Capella is noticeably bright. Of course much of star selection depends upon your shooting position. This time of year you'll see the Planets Jupiter, Saturn an Venus quite well (But Jupiter is really high in the sky at night, presently).
Refraction: Since you'll be at high altitude you'll need to correct for refraction. The 2025 Air Almanac page 908 lists the correction for Refraction based on altitude. Page 909 list correction for the Dome (just provided that for curiosity for you)
As to Dip...that has me somewhat uncertain if a Dip correction is required considering you're using a bubble sextant.
Get it here- 2025 Air Almanac
For starters, you might make your life easy and just try shooting Polaris for latitude and see how close you get to what the GPS reads.
How to Determine Latitude using Polaris is found on this page (scroll down and you'll see it)
Determine Latitude using Polaris
I learned CN by "reverse engineering" so to speak- took shots that weren't well done and then reduced the sight. Plotted the LOP and then figured out why there were large errors. If...if you record the correct time in GMT and get a "close enough" altitude measurement of the celestial object, you'll then have enough information to slog through many of hours (God forbid) trying to figure it all out.
I hope that assists you in some way and isn't too terribly confusing.
Ed