MetFns (version 2.1.0)

pop.index2: Calculation of population index based on average distance from the limiting magnitude

Description

Calculates and plots population index of a meteor shower for a given magnitude data, specified time period, minimum and maximum bin size, and number of meteors.

Usage

pop.index2(data,year,month.beg,month.end=month.beg,day.beg,day.end=day.beg,
time.beg=0,time.end=2359,shw,k1=0.01,k2=1,num,add.plot=FALSE,xlim1=NULL,
xlim2=NULL,xinc=NULL,ylim1=NULL,ylim2=NULL,yinc=NULL)

Arguments

data

data frame consisting of visual meteor magnitude data.

year

numeric vector of length 4 specifying year.

month.beg

numeric vector specifying the beginning month.

month.end

numeric vector specifying the ending month. By default, month.end is set to be equal to month.beg.

day.beg

numeric vector specifying the beginning day.

day.end

numeric vector specifying the ending day. By default, day.end is set to be equal to day.beg.

time.beg

numeric vector (0-2359) specifying lower boundary of time in hours and minutes, corresponding to day.beg. By default, time.beg is set to be equal to 0.

time.end

numeric vector (0-2359) specifying upper boundary of time in hours and minutes, corresponding to day.end. By default, time.end is set to be equal to 2359.

shw

character string consisting of three capital letters which represent meteor shower code.

k1

numeric vector specifying minimum bin size, in degrees of solar longitude. By default, it is equal to 0.01.

k2

numeric vector specifying maximum bin size, in degrees of solar longitude. By default, it is equal to 1.

num

numeric vector specifying total number of meteors per interval.

add.plot

logical vector. If TRUE, the population index is plotted.

xlim1

numeric vector specifying minimum value on x-axis.

xlim2

numeric vector specifying maximum value on x-axis.

xinc

numeric vector specifying increment between labels on x-axis.

ylim1

numeric vector specifying minimum value on y-axis.

ylim2

numeric vector specifying maximum value on y-axis.

yinc

numeric vector specifying increment between labels on y-axis.

Value

Data frame containing following vectors

start

factor Calendar date and time in UTC of left bound of time interval

stop

factor Calendar date and time in UTC of right bound of time interval

sollong

numeric Solar longitude corresponding to the middle of time interval

nINT

numeric Number of observing time intervals

nSHW

numeric Number of observed meteors belonging to the shower

pop.index

numeric Population index

r.error

numeric Error margins of population index

If add.plot is TRUE, additionally xy plot of population index is made. Solar longitude is on x-axis and population index on y-axis. Population index is represented with black filled circles and 68% confidence intervals. Values of limits (minimum and maximum values) on x and y axis (xlim1,xlim2,ylim1,ylim2), as well as increments between the axis labels (xinc,yinc) should be provided to function call.

Details

Adaptive-bin size algorithm is used. It tries to maintain a used-defined optimum meteor number per bin. For the case that not enough meteors are available, a maximum bin size is used.

Average distance from the limiting magnitude, as difference between the limiting magnitude and average meteor magnitude, is calculated for each observing time interval. Final average distance from the limiting magnitude is calculated as a weighted average of all individual average distances, where numbers of meteors in each observing interval represent weights. Conversion of average distance from limiting magnitude to population index is done using natural spline interpolation spline of table values popind. Error margins of population index are calculated using bivariate Krige interpolation krigeInterp of table values popind.err

References

Arlt, R. (2003). Bulletin 19 of the International Leonid Watch: Population index study of the 2002 Leonid meteors. WGN, Journal of the IMO,31:3, 77-87.

See Also

pop.index,zhr

Examples

## calculate population index for observations of 1997 Perseids, time period 
## 27th July to 16th August, radiant elevation higher than 20 degrees,
## total correction factor smaller than 5, bin sizes 1 degree
## First select magnitude data for Perseids activity - time period 15th July to 24th August, 
## radiant elevation higher than 20 degrees, total correction factor smaller than 5
## data(magn97)
## magn<-filter(magn97,year=1997,month.beg=7,month.end=8,day.beg=15,day.end=24,
## shw="PER",h.low=20)
## pop.index2(magn,year=1997,month.beg=7,month.end=8,day.beg=27,day.end=16,shw="PER",
## k1=1,num=300)

## make graphic of population index
## x-axis limits: min(sollong)=124.549, max(sollong)=144.111
## y-axis limits: min(pop.index-sigma.r)=1.91,max(pop.index+sigma.r)=3.07
## pop.index2(magn,year=1997,month.beg=7,month.end=8,day.beg=27,day.end=16,shw="PER",
## k1=1,num=300,add.plot=TRUE,xlim1=124,xlim2=145,xinc=1,ylim1=1.9,ylim2=3.1,yinc=0.1)




## calculate population index around maximum activity of 1997 Perseids, time period 
## 10th August 19h to 14th August 7h, radiant elevation higher than 20 degrees, 
## total correction factor smaller than 5
## pop.index2(magn,year=1997,month.beg=8,day.beg=10,day.end=14,time.beg=1900,
## time.end=700,shw="PER",num=300)


## make graphic of population index around max activity of 1997 Perseids
## x-axis limits: min(sollong)=138.272, max(sollong)=141.397
## y-axis limits: min(pop.index-sigma.r)=1.59,max(pop.index+sigma.r)=2.79
## pop.index2(magn,year=1997,month.beg=8,day.beg=10,day.end=14,time.beg=1900,
## time.end=700,shw="PER",num=300,add.plot=TRUE,xlim1=138.2,xlim2=141.4,xinc=0.1,
## ylim1=1.5,ylim2=2.8,yinc=0.1)