pairmass: Plot airmass vs time for a given coordinate

Package: obsutil

Usage

pairmass

Parameters

ra: The right ascension of the object in hours.

dec: The declination of the object in degrees.

epoch=INDEF: The epoch of the coordinates in years.

year: The year of the observation.

month: The month of the observation (a number from 1 to 12).

day: The day of the month of the observation.

observatory = "observatory": The observatory identifier in the observatory database. See the help for observatory task for more information.

timesys = "Standard" (Universal|Standard|Siderial): Time system for the plot or output list. The choices are "Universal" for universal time, "Standard" for standard time (where the time zone is determined from the observatory database), and "Siderial" for the siderial time.

resolution=4: The number of UT points per hour for which to calculate the airmass.

listout=no: List, rather than plot, the airmass versus time? Only airmasses below that given by the wy2 parameters are listed.

Plot parameters

wx1=-7., wx2=7., wy1=0., wy2=5.: The range of window (user) coordinates to be included in the plot. If the range of values in x or y = 0, the plot is automatically scaled from the minimum to maximum data values along that axis. The times are available from -24 hours to 48 hours so one can use negative numbers to plot hours from midnight or in actual hours.

pointmode = no: Plot individual points instead of a continuous line?

marker="box": If pointmode = yes, the marker drawn at each point is set with this parameter. The acceptable choices are "point", "box", "plus", "cross", "circle", "hebar", "vebar", "hline", "vline", and "diamond".

szmarker = 0.005: The size of the marker drawn when pointmode = yes. A value of 0 (zero) indicates that the task should read the size from the input list.

logx = no, logy = no: Draw the x or y axis in log units, versus linear?

xlabel="default": Label for the X-axis. The value "default" uses the specified time system.

ylabel="Airmass": Labels for the Y-axis.

title="default": Title for plot. If not changed from "default", a title string consisting of the date, observatory, and object position is used.

vx1=0., vx2=0., vy1=0., vy2=0.: NDC coordinates (0-1) of the plotting device viewport. If not set by the user, a suitable viewport which allows sufficient room for all labels is used.

majrx=5, minrx=5, majry=5, minry=5: The number of major and minor divisions along the x or y axis.

round = no: Round axes up to nice values?

fill = yes: Fill the plotting viewport regardless of the device aspect ratio?

append = no: Append to an existing plot?

device="stdgraph": Output device.

Description

The airmass is plotted over a specified set of hours for a given observatory. The observatory is specified by an identifier as given in the observatory database. See the help for "observatory" for more information about the database and identifiers.

The results can be shown in universal, standard, or siderial time. The standard time simply adds the time zone from the observatory database tothe universal time and so there is no explicit facility for daylight savings time. The times are computed in the range -24 hours to +48 hours. By setting the wx1 and wx2 parameters one can plot either in hours relative to 0 in the specified time system or as positive hours. This simple task does not support axis labeling which wraps around.

The list output prints date, observatory, object coordinates, and the time system. This is followed by the time sorted between 0 and 24 and the airmasses. The list only includes airmasses below the value specified by wy2.

Examples

To plot the airmass for M82 from Kitt Peak for Groundhog's Day in 1992:

pairmass ra=9:51:42 dec=69:56 epoch=1950 year=1992 month=2 day=2