# elev: Source elevation In astroFns: Astronomy: time and position functions, misc. utilities

## Description

Calculates source elevation and azimuth in degrees given declination, hour angle, and observatory latitude.

## Usage

 ```1 2 3``` ```elev(dec.sou = "33d 09m 35.0s", ha = 0, lat.obs = "38d 25m 59.2s") azimuth(dec.sou = "33d 09m 35.0s", ha = 0, lat.obs = "38d 25m 59.2s") ```

## Arguments

 `dec.sou` Source declination (string) `ha` Hour angle (decimal hours) `lat.obs` Observatory latitude (string)

## Details

Enter latitude as s text string with fields separated by characters d, h, m, s, a colon, or a comma, e.g. '38d25m59.2s' or '38, 25, 59.2' or '38:25:59.2' or '38:25.987' for the Green Bank Telescope. Spaces are removed in input conversion. Decimal values for degrees or minutes are allowed. Trailing missing values are taken as zero.

## Value

Source elevation or azimuth (E from N) in degrees.

## Note

Geometrical calculation only, no corrections for refraction, aberration, precession, etc.

Andrew Harris

## References

"Astrophysical Formulae," K.R. Lang, Springer c. 1986, 5-45

`dms2rad`, `hms2rad` for input formats, `ut2ha` to convert UT to hour angle.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19``` ```# Maximum elevation at Green Bank elev(dms2rad('-28, 20')) # Maximum elevation at Mauna Kea elev(dms2rad('-28, 20'), 0, '19:49') # Plot elevation and azimugh vs. hour angle ha <- seq(0, 24, 0.25) el <- elev('30d 33m 22s', ha) plot(ha, el, t='l', col=4) az <- azimuth('30d 33m 22s', ha) plot(ha, az, t='l', col=4) # Plot elevation and azimuth vs. UT (using many defaults) h.ut <- seq(0, 24, 0.25) el <- elev(dec.sou='30d 33m 22s', ha=ut2ha(hr=h.ut)) plot(h.ut, el, t='l', col=4) az <- azimuth(dec.sou='30d 33m 22s', ha=ut2ha(hr=h.ut)) plot(h.ut, az, t='l', col=4) ```

astroFns documentation built on May 29, 2017, 3:02 p.m.