Find twilight stars sans almanac

Rude Starfinder

Greg Rudzinski has a great blog post on his S/V Nightcap blog about how to set the Rude  (or 2102-D) star finder without the need for an almanac (click on the image below for a larger version):

Set the 2102-D star finder without using a Nautical Almanac by scaling a radar plotting sheet as depicted by the above image.

1. Set Aries zero to month and day (clockwise)
2. Set blue latitude template to zone time of twilight (counter clockwise)
3. Select stars for twilight viewing.

The image example is for 12 October 2010 zone time civil twilight 1800 at 35°N 120°W

Try penciling in the Sun onto the 2102-D base disc using the slotted red template.

1. Set Aries to month and day.
2. Set red template to time of meridional passage.
3. Mark Sun’s declination through the slot onto the base disc.

The twilight sky can now be set by rotating the blue latitude template so the Sun is 5° to 10° below zero altitude.

By Ocean Navigator