NavList:

Jim, I’m not entirely sure what you are asking. I’m not sure if you are questioning why LAN should be observed or why the Navy is doing celestial at all. The current instruction governing navigation in the Navy requires a full day’s work in (celestial) navigation every day weather permitting. A good navigator doesn’t place complete confidence in any single navigation system and checks all available systems against each other in order to determine if there are any discrepancies that aren’t apparent from one system alone. On most Navy ships Celnav is the only available check against GPS on the open sea. The following are excerpts from the current navigation instruction. The instruction is currently being revised and the new revision is expected to hit the fleet next month, if there are any changes in the requirements for celestial navigation I will post them here.

 

Stacy Hanna

 

 The Navigator is responsible, under the

Commanding Officer, for the safe navigation of the ship. The

Navigator will receive all orders relating to his/her

navigational duties directly from the Commanding Officer and

will make all reports in connection therewith directly to the

Commanding Officer. Additional duties of the Navigator include:

(1) Advising the Commanding Officer and Officer of the

Deck as to the ship's movements and, if the ship is running into

danger, a safe course to be steered. To this end, he/she will:

(a) Maintain or cause to be maintained an accurate

plot of the ship's position by all available means, including

celestial, visual, radar, and electronic and other appropriate

means. No single source of navigation information will be used

to the exclusion of others.

 

 

 

D-1

APPENDIX D

STANDARD DAY'S WORK IN NAVIGATION

OPEN OCEAN NAVIGATION. Weather permitting, minimum daily

celestial activity will include the following:

Morning Twilight: Usually 45 minutes before sunrise, shoot

available celestial bodies, to include selected stars,

planet(s), the moon, and Polaris. Reduce sightings to LOPs,

plot on plotting sheet, and determine ship's position. Advance

celestial fix to 0800 for 0800 Ship's Position Report. Transfer

fix to track chart. Inform CIC/CDC of position.

Early Morning: Determine gyro error by azimuth/amplitude of sun

or other celestial body. Include any gyro error noted in 0800

and 1200 Ship's Position Report. Verify Figure Of Merit (FOM)

on the WRN-6/GPS and include on position reports.

0800: Submit 0800 Ship's Position Report to Commanding Officer,

after being reviewed and signed by the Navigator.

8-12: QMOW compute watch time of LAN (Local Apparent Noon).

Morning: Shoot sun to determine LOP. Plot on plotting sheet.

Mid-morning: Shoot sun to determine LOP. Plot on plotting

sheet.

Noon: Observe LAN. Recommend observations be started at 10

minutes before computed time of LAN, and for a couple of minutes

after. Reduce sighting and determine ship's latitude. Advance

mid-morning sun LOP to LAN LOP on plotting sheet to obtain

running fix. Plot running fix on track chart and pass fix

information to CIC/CDC. Advance sun LOPs to 1200, for 1200

Ship's Position Report.

1200: Submit 1200 Ship's Position Report to Commanding Officer,

after being reviewed and signed by the Navigator.

Afternoon: Shoot sun to determine LOP. Plot LOP on plotting

sheet. Advance LAN LOP to afternoon LOP on plotting sheet to

obtain running fix (minimum three Sun Lines for R-Fix). Plot

running fix on track chart and pass fix information to CIC/CDC.

COMNAVAIRFORINST 3530.4/

COMNAVSURFORINST 3530.4

26 Feb 02

Mid-Afternoon: Shoot sun to determine LOP. Plot LOP on

plotting sheet. Advance afternoon LOPs to establish an R-Fix.

Plot on track chart and pass information to CIC/CDC.

12-16: QMOW determine time of sunset and star time. Compute

celestial bodies available, including planets.

Late Afternoon: Include any gyro error computed in 1200 Ship's

Position Report.

Evening Twilight: Usually 30 minutes after sunset, shoot

celestial bodies, to include selected stars, planet(s), moon,

and Polaris. Reduce sightings to LOPs, plot on plotting sheet,

and determine ship's position. Advance celestial fix to 2000

for 2000 Ship's Position Report. Transfer fix to track chart.

Inform CIC/CDC of position.

1600-2000: QMOW determine time of sunrise and moonrise/set for

Commanding Officer's Night Orders. Also compute star time for

morning star shoot. Determine celestial bodies available,

including planet(s).

2000: Submit 2000 Ship's Position Report to Commanding Officer,

after being reviewed and signed by the Navigator.

0000-0400: Compute Latitude by Polaris, lines of position of

the moon and planet(s), as available, and gyro error by Polaris.

All celestial work must be documented in the ship's Navigation

Workbook with the Navigator's signature at the end of each

celestial day. When using computer software (i.e., STELLA),

documentation of all observations must be maintained in a looseleaf

binder.

 

 

 

-----Original Message-----
From: Navigation Mailing List [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM] On Behalf Of Jim Thompson
Sent: Saturday, January 24, 2004 15:58
To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM
Subject: Re: Latitude AND Longitude by Noon Sun

 

Jim Thompson
jim2@jimthompson.net
www.jimthompson.net
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