star.phases: Calculate the seasons and phases of a star

Description Usage Arguments References See Also Examples

View source: R/stars.R

Description

This function calculates the seasons (Rising, Setting, etc.) and phases (Arising and Lying Hidden, Curtailed Passage) of a star for a given location and epoch. This functions uses the arcus visionis approximation of Purrington (1988). For the nomenclature used, and description of star phases, see Brady (2015).

Usage

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star.phases(star, year, loc, alt.hor = 0, alt.rs = 10, res = 24/3600,
  ncores)

Arguments

star

Either the star name or a skyscapeR.star object.

year

The year of interest.

loc

Location, either a skyscapeR.object or a vector containing the latitude and longitude of location, in this order.

alt.hor

(Optional) The altitude of the horizon to consider. Defaults to zero degrees.

alt.rs

(Optional) The maximum altitude of a star's first or last visibility for it to still be considered to be as rising or setting. Defaults to ten degrees.

res

(Optional) Resolution of calculation. The smaller this figure the slower the computation. Defaults to 24/3600 = 1 sec.

ncores

(Optional) Number of processing cores to use for parallelisation. Defaults to the number of available cores minus 1.

References

Purrington, Robert D. (1988) Heliacal Rising and Setting: Quantitative Aspects, Journal for the History of Astronomy (Archaeoastronomy Supplement 12) 19, S72-S84. Available online at [SAO/NASA ADS Astronomy Abstract Service](http://adsabs.harvard.edu/abs/1988JHAS...19...72P)

Brady, Bernadette (2015) Star Phases: the Naked-eye Astronomy of the Old Kingdom Pyramid Texts. In F Silva and N Campion (eds) Skyscapes: The Role and Importance of the Sky in Archaeology. Oxford: Oxbow Books, pp. 76-86.

See Also

plotPhases

Examples

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## Not run: 
ss1 <- star.phases('Aldebaran',-4000, c(35,-8))

# One can then look at the star's phase:
ss1$phase

# Date range of seasons:
ss1$seasons

# Date range of events/phases:
ss1$events

# And plot them:
plotPhases(ss1)

# You can play with the parameters and see how predictions change:
ss1 <- star.phases('Aldebaran',-4000, c(35,-8), alt.hor=2, alt.rs=5)
plotPhases(ss1)

## End(Not run)

f-silva-archaeo/skyscapeR documentation built on Jan. 22, 2019, 8:11 a.m.