NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Round Two: with a bonus ex-meridian
From: Peter Hakel
Date: 2013 Mar 8, 14:09 -0800
From: Peter Hakel
Date: 2013 Mar 8, 14:09 -0800
The many-body fix at 19:00:00 local time comes out right on the money (see attached sights.xls and many_body_fix.xls):
Lat: N 20d 38.6'
Lon: E 120d 48.9'
For the Achernar ex-meridian, I first advance the above position by 4 minutes and 1 second ( = 0.0669 hours, using time.xls and dr.xls) to the instant when Achernar was observed:
Lat: N 20d 39.2'
Lon: E 120d 49.7'
This longitude has the "GHA equivalent" of 239d 10.3'. Achernar transited that meridian at UT = 09:50:53 (aries_stars.xls), whereas its observation was made 13 minutes and 8 seconds later (time.xls).
From ex_meridian.xls I get:
Lat: N 20d 39.3'
only 0.1' from the latitude of the DR-advanced many-body fix.
Peter Hakel
From: Antoine Couëtte <antoine.m.couette@club-internet.fr>
To: pmh099@yahoo.com
Sent: Friday, March 8, 2013 12:11 PM
Subject: [NavList] Re: Round Two: with a bonus ex-meridian
From your GPS Position used as DR, and updated for each observation time, I get:
Lat: N 20d 38.6'
Lon: E 120d 48.9'
For the Achernar ex-meridian, I first advance the above position by 4 minutes and 1 second ( = 0.0669 hours, using time.xls and dr.xls) to the instant when Achernar was observed:
Lat: N 20d 39.2'
Lon: E 120d 49.7'
This longitude has the "GHA equivalent" of 239d 10.3'. Achernar transited that meridian at UT = 09:50:53 (aries_stars.xls), whereas its observation was made 13 minutes and 8 seconds later (time.xls).
From ex_meridian.xls I get:
Lat: N 20d 39.3'
only 0.1' from the latitude of the DR-advanced many-body fix.
Peter Hakel
From: Antoine Couëtte <antoine.m.couette@club-internet.fr>
To: pmh099@yahoo.com
Sent: Friday, March 8, 2013 12:11 PM
Subject: [NavList] Re: Round Two: with a bonus ex-meridian
RE : NavList Post # 22641
Let us change things up a bit with this round of stars. 5 bodies, with one that can be reduced as an ex-meridian of an upper transit (hint it's Achernar).
We are going a bit faster now so you might want to advance the later sights for accuracy.
Ship data:
Date: 16 January 2013
ZD -9 (note change)
Crs: 049 Deg
Spd 14.6 knots
Height of eye: 83 ft
Index error: 0.9' on the arc
Temp 72 deg F
Pressure 1016 mB.
Date: 16 January 2013
ZD -9 (note change)
Crs: 049 Deg
Spd 14.6 knots
Height of eye: 83 ft
Index error: 0.9' on the arc
Temp 72 deg F
Pressure 1016 mB.
GPS fix at 1900-00 is Lat 20-38.6'N Long 120-48.9'E
Star Data:
Capella: 1900-27 Hs 40-40.2'
Aldebaran: 1901-12 Hs 50-13.3'
Rigel: 1902-27 Hs 32-03.8'
Achernar: 1904-01 Hs 12-21.2'
Fomalhaut: 1905-32 Hs 24-43.2'
Aldebaran: 1901-12 Hs 50-13.3'
Rigel: 1902-27 Hs 32-03.8'
Achernar: 1904-01 Hs 12-21.2'
Fomalhaut: 1905-32 Hs 24-43.2'
Fix a celestial fix at 1900 LT, "error" from the GPS fix, and standard deviation of the
intercepts.
*******************************************************************************
Hello Jeremy,
From your GPS Position used as DR, and updated for each observation time, I get:
CAPELLA -0.5NM/046°4
ALDEBARAN +0.4NM/088°6
RIGEL -0.4NM/114°4
ACHERNAR -0.1NM/181°8
FOMALHAUT _0.1NM/221°3
ALDEBARAN +0.4NM/088°6
RIGEL -0.4NM/114°4
ACHERNAR -0.1NM/181°8
FOMALHAUT _0.1NM/221°3
Sdev (i.e. LOP's dispersion) = 0.3 NM
Position in Bearing 298° from DR and at distance of 0.1 NM
Position in Bearing 298° from DR and at distance of 0.1 NM
Lesson learnt : What's the use of the GPS if you can get a Celnav position within 0.1 NM of true Position ?
Attaboy ! Well done, once again, Skipper !
Antoine M. "Kermit" Couëtte
----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------
: http://fer3.com/arc/m2.aspx?i=122730
File: 122735.sights.xlsx
File: 122735.many_body_fix.xls
File: 122735.time.xls
File: 122735.dr.xls
File: 122735.aries_stars.xls
File: 122735.ex_meridian.xls