Running the JAR locally enables you to control the processing. You need not share resources with other users and you have many more options for customization. Accessing the Web pages through our scripts or other software may be easier for occasional use and means that one gets the advantages of bug fixes and new surveys without needing to download software updates.
Since the SkyView web server is itself running the same software packaged in the SkyView-in-a-Jar you can use the User's Guide to get a detailed understanding of all of the arguments that are available for either approach. In this page we briefly describe how URLs are parsed into settings that are passed into the Web server's SkyView-in-a-Jar and then review some of the most commonly used settings.
When the SkyView-in-a-Jar is run from the command line, settings may be given in input files or on the command line using keyword=value strings. When we access SkyView over the Web, settings are extracted simply by taking the CGI keyword=value parameters and making them the settings for the run. The user is free to specify any settings with the exception of the the location of the output files (Output) and caches (Cache). Some settings do not make much sense in the Web environment but typically they are ignored if they cannot be used.
One easy way to build and retrieve SkyView URLs is using the skvbatch and webquery Perl scripts we provide (skvbatch calls webquery). These are old and very simple Perl scripts and may not work behind firewalls. In this case building the URL explicitly and using wget or curl may be your easiest option, or feel free to modify our scripts to your requirements. Note: The AF_INET and SOCK_STREAM values in webquery (lines 62 and 63) are operating system dependent. Please check your socket.h file (usually located in /usr/sys/include/sys or something similar) for the proper values and update webquery accordingly. You may also need to change the first lines of the scripts to point to your local version of perl. To use these just entre somthing like:
skvbatch file=FILE [key=Value key=Value etc.]
Example 1
skvbatch file=example1.fits position='+12 34, -10 23' \
Survey='Digitized Sky Survey'
Example 2
skvbatch file=example2.fits Position=hd184927 \
Survey='Digitized Sky Survey' LUT=Fire \
Coordinates='Galactic'
Example 3
skvbatch file=example3.fits Position='+12 34, -10 28' \
Catalog='SAO STAR CATALOG' Size=5 Pixels=500
Example 4
Perl script to do multiple queries
#!/usr/bin/perl
$i = 0;
@array = ("'3c273'","'0 41, +41 5'","'crab nebula'",
"'14 21 23.2, -12 24.3'");
foreach (@array) {
$i++;
$filename="example$i.gif";
system("skvbatch Position=$_ Survey='Digitized Sky Survey'
Catalog='HST guide stars (1.1)' Return=gif Grid
Pixels=400,200 file=$filename");
}
Once executed, a FITS file is returned into the file specified on the command line (or to standard output if no file is given).
Quotes are only necessary for values that contain blank spaces.
The following returns an GIF image with a grid and catalog overlay:
http://skyview.gsfc.nasa.gov/cgi-bin/images?Position=mkn421&Survey=HRI&Coordinates=Galactic&Grid=&Catalog=hipparcos&Return=GIF
Required:
Position=name/value - Coordinate position or name
Survey=survey[,survey,...] - Survey[s] to generate images from
Return=format - The format of the returned data.
This is not actually required, but if not specified
the output is an HTML page. Possible values include
FITS,GIF,JPEG,BMP,TIFF,PNG.
Optional:
Coordinates=value - Coordinate system (e.g., J2000, B1950, Galactic, ICRS)
Projection=proj - Map projection (Tan, Sin, Car, Ait, Zea, Csc)
Scaling=scl - Brightness scaling (Log, Linear, Sqrt, HistEq)
Size=size[,size] - The size[s] of the image in degrees. If only
one value is given the image is square.
Pixels=n[,m] - The number of pixels in the image. If only one
value is given the height and width are the same.
Catalog=catalogs[,catalog] - The name of the catalog[s] to be queried. Each name
can be a HEASARC short name, a Vizier catalog name,
or a VO Cone Search base URL.
Smooth=value[,value] - dimension[s] of smoothing box.
Sampler=samp - Sampling to use (NN, Lin, Clip, Lanczos, Spline)
Resolver=res - Resolver to translate names to coordinates
(SIMBAD-NED, NED-SIMBAD, NED, SIMBAD)
Grid[=Coords] - Overlay a grid on the image [in a given coordinate system]
LUT=name - Use the given lookup table to translate brightness to color.
Contour=survey[,scale[min,max[,nlevel]]]
- Overlay contours from the given survey using
the given scaling (Linear, Log, Sqrt). The
user can optionally specify the range and number
of contours.
RGB - If this is specified three values are
expected in the survey field and these
will be used to generate a three-color
image as Red/Green/Blue.
SkyView has been developed with generous support from the NASA AISR and ADP programs (P.I. Thomas A. McGlynn) under the auspices of the High Energy Astrophysics Science Archive Research Center (HEASARC) at the NASA/ GSFC Astrophysics Science Division.
We gratefully acknowledge the support of NASA and contributors of SkyView surveys.
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