elev {astroFns} R Documentation

## Source elevation

### Description

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

### Usage

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

# Maximum elevation at Green Bank

# 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)



[Package astroFns version 4.2-1 Index]