# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Pre Calculating (Hp) For Fixed Angle Reflectors
From: Fran Herranz
Date: 2018 Jun 4, 20:37 +0200
Greg,
Yes I was thinking make the taylored table. The biggest work to do with a Bris is the calibration. The rest is only a script like the ones made for Pub249. Do it once repeat for several Bris optimized angles depending the departure and arrival latitudes.
But it's a lot more work.
Fran Herranz

El lun., 4 jun. 2018 20:02, Greg Rudzinski <NoReply_Rudzinski@fer3.com> escribió:

Fran,

I was thinking just of the idea of precalculating a local hour angle for each reflected Bris image for a days work by pocket calculator using the time sight formula or by Martelli table if going nonelectronic. The precalculations would be done anytime before the observation so as to offer immediate results upon observation (aviation style).

I think what you are talking about is a compact custom table taylored to the specific Bris sextant angles. One problem doing this is that every Bris has a unique set of angles so each Bris sextant would need it's own custom table. Lots of work :(

Greg Rudzinski

From: Fran Herranz
Date: 2018 Jun 4, 18:19 +0200

Hello,
I had readed this list for years and Bris "sextant" is the reason. I have been thinking a lot about use it easily with simplified tables. Probably the ideas I explain afterwards are only a summary of all I read here.
I assume that is related to the improved number of angles Bris like sextant discussed now in other topic.
Are you proposing a Pub 229 or 249 like tables for every Bris angle? Maybe a lookout table organized in a page for every Bris sextant's angle with assumed latitude in columns, declination in rows that gives LHA and two azimuth (East and West of the meridian)like result. It could be generated after calibrate Bris sextant's angles and would be printed in a tiny booklet.
You only wait for time when object hits horizon. With the difference between tabulated time and actual time you could move the tabulated LoP.
Maybe for standard Bris or a non shaded Bris microscope slide for Moon needs the full range of declinations but for mirror star Bris (two fixed angle mirrors) you need to calculate only for several declinations as many as nautical stars.
P.S.: Sorry for my English and for so large boring speech.
Fran Herranz

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