Re: Table A4 + elevation?
Subject: Re: Table A4 + elevation?
From: Royer, Doug (doug.royer@XXX.XXX)
Date: Thu May 01 2003 - 20:13:06 EDT
Correction: 051113 gmt 05-01 Polaris Hs = 32*-23.3'
-----Original Message-----
From: Royer, Doug [mailto:doug.royer@XXX.XXX]
Sent: Thursday, May 01, 2003 12:59
To: NAVIGATION-L@XXX.XXX
Subject: Table A4 + elevation?
On 04-26 I completed 6 sets of reflected Sun altitudes during the day.I'm at
2100 ft. elevation.Temps. were 60-68*F while doing this.Sextant is 0.1' off
arc.After all corrections were made the standard error was about 0.1' of arc
for each set.I used Mr. Hebard's advice about elevation and Table A4.A4
corrections as he stated;between + 0.1- 0.3 for the temp. and elevation.Each
set of sightings had 3 shots and times to average against a calculated Hc
slope from Ho-229. All's well.Outstanding final position.Checked against the
software I was only off the above error. I didn't save the data.
04-30 I tried 3 sets of reflected star altitudes.Temp. was a steady 43*F
throughout.All averaged as above.After all corrections were made,the LOPs
drawn and checked against the software, the error turned out to be + 0.8' of
arc for each group.This was a constant for all this nights sights.
Here is the data from 04-30.Ic = + 0.1'. A4 cor. = 0.0' (column H. 970 mb
and 43*F). A2 cor. = -1.4' to -1.5'. zt = 2100 hrs. 04-30
050416 gmt 05-01 Spica Hs = 32*43.2'
051113 gmt 05-01 Polaris Hs = 32*42.7'
051822 gmt 05-01 Procyon Hs = 34*42.7'
The resulting error put the final LOP pos. less than 1/4 mi. from where I
was.All is real well!! However,usually I have errors around 0.1' of arc when
averageing.That would have placed the LOP pos. about a mile away.I can live
with either of these final positions but was wondering why this error
outside the usual error.
The reflections in the horizon and scope were clear and bright so I feal the
error isn' t in this area.Each seperate time was timed to the closest
secound.I don't think it was a time error.
I'm wondering about the temp. and the altitude as the cause.All the errors
are the same for each averaged sight.Do any of you guys have an idea on
this?
