Louis and I have finished the Doniol sight reduction form.  It only calculates Hc and we have not worked on determining Zn yet.

An unusual method of multiplying "1-q" and Haversine LHA" uses the butterfly method.  The answer isn't exact but it is close enough.

Here it is- Doniol form

Does anyone have a Davis Mark 15 sextant they want to sell?

Paul

We just uploaded a form for Planet sight reduction using Artificial Horizon.

Find it here under "Forms"-

Form- Planet sight reduction


CelNav57

We just uploaded a convenient form for determining Longitude using equal altitudes.


Form- Longitude- meridian by equal altitudes

Hi

I have a Mark 15 plastic sextant and I want to buy a better one.. 
I've heard about Astra IIIb and Astra Professional... differences? what is the best?

Other tips are welcome!!!

Thank you
Alberto

We were sent a spreadsheet that's both an electronic ephemeris (the "Daily Pages" from the Nautical Almanac) and a sight reduction tool. 

It covers all navigational bodies and is very easy to use.  It even has the nice ° symbol.

There are 2 spreadsheet based versions;

- Excel in xlsx format

- Ods format- typically used with LibreOffice Calc

If you can't use either of those formats the excel file can be converted using this website- File conversion service


Complete Celestial Sight Reduction Excel Spreadsheet

Complete Celestial Sight Reduction Spreadsheet in ODS format



Clear skies,

CelNav57

Anybody want to talk about their experience in doing a Doniol sight reduction?

Do you HAV your Haversine tables?

Louis

Much to my delight I noticed Venus this morning at UTC 07:00

Rather than freezing outside a dish of water was placed on the window sill and I got 3 good sights of Venus.

Now if I had referred to this-

PHENOMENA, 2016- VISIBILITY OF PLANETS

...then I wouldn't have forgotten Venus was out there!


Louis

Remember ebook readers?  I've found that my old Kindle Wifi is perfect for putting The Nautical Almanac on.  Since the file is a PDF zoom in is necessary.  The advantage of using the Kindle (old clunker I guess you could call it) is that cold boot up time is about 5 seconds.  Just to "wake it up" takes about 2 seconds.  Battery drain is extremely low.  Using it for a few minutes per day the Kindle has enough power for several months of use.  It'll do a good job- until the batteries are now longer available.  Then we'll have to go back to...what?....paper and pencil?  What's that?

Bruce Bauer's book, "The Sextant Handbook" mentions that you can use Jojoba oil as a lubricant for your sextant.  He says that it has similar characteristics as whale oil which was used in the past.

Jojoba oil can be found in health food stores or fancier super markets.
An eye dropper can be used to apply the oil.  It seems to be pretty good and doesn't make the index arm stiff in the cold (below freezing).

(I've used WD-40 on a micrometer years ago and regretted it- it seized up after many months of non-use so I'm not taking any chances with my Astra III-B).

The Sextant handbook is a good book and I got it at our local library.

Clendon