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.
Author(s)
Andrew Harris
References
"Astrophysical Formulae," K.R. Lang, Springer c. 1986, 5-45
See Also
dms2rad
, hms2rad
for input formats,
ut2ha
to convert UT to hour angle.
Examples
# 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)