sdssDR9findingChart is a script that allows you to automatically download finding charts from Data Release 9 (DR9) of the Sloan Digital Sky Survey (SDSS).
It has been written without using the requests module so that it can be run without having the users install additional dependencies.
You invoke the tool with
sdssDR9findingChart [-options] fileWithAstroObjects
where fileWithAstroObjects is a text file containing an astronomical source name per line. Non-valid names are ignored.
The result is a finding chart from SDSS DR9 as a JPEG file which is downloaded in the directory from which the sdssDR9findingChart script is called.
See available options in the Configuration section.
wget https://github.com/juandesant/DownloadSDSSFindingCharts/archive/master.zipunzip master.zipcd DownloadSDSSFindingCharts-master/python setup.py install
The source code includes the object.txt file, with which you can test the script by typing
sdssDR9findingChart objects.txt
The expected output will look like:
Processing Sesame query for M31
Processing Sesame query for HCG7d
Processing Sesame query for m82
Processing Sesame query for HCG89a
Querying SDSS for coordinates 10.68470833 +41.26875000 (M31)
Querying SDSS for coordinates 9.82830417 +0.89190833 (HCG7d)
Querying SDSS for coordinates 320.00427083 -3.92211667 (HCG89a)
Querying SDSS for coordinates 148.96745833 +69.68022222 (m82)
Download of M31.jpg completed
Processing Sesame query for HCG1
Download of HCG89a.jpg completed
Processing Sesame query for HCG2
Querying SDSS for coordinates 6.50000000 +25.71666667 (HCG1)
Download of m82.jpg completed
Processing Sesame query for HCG92c
Querying SDSS for coordinates 7.85000000 +8.44666667 (HCG2)
Querying SDSS for coordinates 339.01483333 +33.97575000 (HCG92c)
Download of HCG1.jpg completed
Processing Sesame query for tontoElQueLoLea
Error. Coordinates for tontoElQueLoLea not found in Sesame
list index out of range
Processing Sesame query for CIG 96
Error. Coordinates for CIG 96 not found in Sesame
list index out of range
Processing Sesame query for CIG 3
Error. Coordinates for CIG 3 not found in Sesame
list index out of range
Processing Sesame query for ngc4321
Download of HCG2.jpg completed
Querying SDSS for coordinates 185.72874583 +15.82238056 (ngc4321)
Download of HCG92c.jpg completed
Download of ngc4321.jpg completed
Download of HCG7d.jpg completed
and the directory will contain the following files:
$ ls -ln \*.jpg
-rw-r--r-- 1 501 20 103406 21 feb 22:40 CIG 3.jpg
-rw-r--r-- 1 501 20 122245 21 feb 22:40 CIG 96.jpg
-rw-r--r-- 1 501 20 102133 21 feb 22:39 HCG1.jpg
-rw-r--r-- 1 501 20 101813 21 feb 22:40 HCG2.jpg
-rw-r--r-- 1 501 20 118322 21 feb 22:39 HCG7d.jpg
-rw-r--r-- 1 501 20 113634 21 feb 22:39 HCG89a.jpg
-rw-r--r-- 1 501 20 120794 21 feb 22:40 HCG92c.jpg
-rw-r--r-- 1 501 20 22884 21 feb 22:39 M31.jpg
-rw-r--r-- 1 501 20 106942 21 feb 22:39 m82.jpg
-rw-r--r-- 1 501 20 109373 21 feb 22:40 ngc4321.jpg
The tool allows the same configuration available in the web tool:
- Setting horizontal and vertical sizes (
-x,-y) - Setting image resolution by pixel scale (
-s), or zoom-ratio (-z) - Automatically adjusting size based on recession velocity (
-r) - Grid and cross-hairs (
-G) - Overlay label of image properties (
-L) - Colormap inversion (
-I) - Marking of photometric and spectroscopic objects (
-P,-S) - Outlines of objects, bounding boxes, fields, masks, and plates (
-O,-B,-F,-M,-Q)
The tool also sports two modes (selectable with the --mode option): OBJECT_LIST, where the file provided does not contain coordinates, but names that can be resolved with Sesame; and SDSS_COORDINATES, in which the file provides coordinates for the objects (a column named name, source, target or objid is looked up to use —if available— for naming the resulting images, but is not used to query Sesame), and optionally a column named size can be used to automatically size the image so that it fills the field (-c/--size-column).
You can get the whole list of options using the -h or --help options:
Usage: sdssDR9findingChart [options] file
Options:
-h, --help show this help message and exit
-x PIXEL, --x-size=PIXEL
The finding chart will be PIXEL pixels wide. Default
value, 512.
-y PIXEL, --y-size=PIXEL
The finding chart will be PIXEL pixels high. Default
value, 512.
-s SCALE, --scale=SCALE
The finding chart pixel resolution will be SCALE arc-
seconds per pixel. Defaults to 0.396127 arc-seconds
per pixel (native SDSS pixel resolution).
-z ZOOM-RATIO, --zoom=ZOOM-RATIO
The finding chart pixel resolution will be zoomed by
ZOOM-RATIO from specified scale ratio (native scale
ratio if -s is not used). Values above 1 imply zooming
in, values below 1 zooming out. Used alone, is
equivalent to the -s option with a SCALE value of
0.396127/ZOOM-RATIO.
-r VELOCITY, --rescale=VELOCITY
When this option is set, the size of the image is
chosen so that most of the object can fit the image.
Works more reliably for objects with recessional
velocities >1500 km/s. If you want to know the actual
scale, use it with the -L option. The autosizing
mechanism will try to assume a scaling proportional to
the ration of the given VELOCITY and the object
velocity as reported by Sesame. It cannot work with
the SDSS_COORDINATES option. Use the --size-column
option instead.
-c, --size-column This option can only be used with the SDSS_COORDINATES
option. If present, the file must contain a column
named size, which shows the size of the object in
arcseconds. The script will use the size column to
compute the scale that will keep the galaxy centered
and zoomed in.
-G, --grid Corresponds with the G option in the SDSS web chart
tool; when used, the image sports a grid with and
crosshairs.
-L, --label Corresponds with the L option in the SDSS web chart
tool; when used, the image has a label overlay
indicating the chart parameters.
-I, --invert Corresponds with the I option in the SDSS web chart
tool; when set, the image color map is inverted.
-P, --photometric-objects
Corresponds with the P option in the SDSS web chart
tool; shows light-blue circles around SDSS photometric
objects.
-S, --spectroscopic-objects
Corresponds with the S option in the SDSS web chart
tool; shows red squares around SDSS spectroscopic
objects.
-O, --outlines Corresponds with the O option in the SDSS web chart
tool; shows green outlines around SDSS photometric
objects, showing where the area for which the
photometry is calculated.
-B, --bounding-boxes Corresponds with the B option in the SDSS web chart
tool; shows pink squares that bound SDSS photometric
objects.
-F, --fields Corresponds with the F option in the SDSS web chart
tool; shows gray outlines demarcating the SDSS fields.
-M, --masks Corresponds with the M option in the SDSS web chart
tool; shows pink footprints around masked objects,
such as bright objects and data artifacts.
-Q, --plates Corresponds with the Q option in the SDSS web chart
tool; shows circular plates (in lavender) used for
spectra collection.
-m MODE, --mode=MODE MODE can be either OBJECT_LIST or SDSS_COORDINATES. If
set to OBJECT_LIST, each line is expected to have an
object name, and Sesame will be used to obtain RA and
DEC. This is the default. If set to SDSS_COORDINATES,
the file is supposed to be either comma-, blank-, or
tab-separated, with at least columns for RA y Dec. If
a column with name size is present, the tool will try
to fit the size into the frame.
For more information on which options are valid, see http://skyserver.sdss3.org/dr9/en/tools/chart/chart.asp
This tool has been written withing the framework of the AMIGA project, and with support from Spanish grants AYA2008-06181 and AYA2011-30491-C02.
Juande Santander Vela has a contract with CSIC (National Council for Scientific Research) in the JAE-Doc modality of the "Junta de Ampliación de Estudios" program, with funding from the European Social Fund.