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https://github.com/juandesant/downloadsdssfindingcharts

Python tool to download Sloan Digital Sky Survey (SDSS) finding charts from their Data Release 9 web service around a list of objects, which is resolved to coordinates by the Sesame web service.
https://github.com/juandesant/downloadsdssfindingcharts

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Python tool to download Sloan Digital Sky Survey (SDSS) finding charts from their Data Release 9 web service around a list of objects, which is resolved to coordinates by the Sesame web service.

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README 

        
Introduction

============



`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`](http://docs.python-requests.org/ "Requests: HTTP for Humans — Requests 1.1.0 documentation") module so that it can be run without having the users install additional dependencies.



Usage

=====



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](Configuration) section.



Installation

============



1. `wget https://github.com/juandesant/DownloadSDSSFindingCharts/archive/master.zip`

2. `unzip master.zip`

3. `cd DownloadSDSSFindingCharts-master/`

4. `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



Configuration

=============



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



Aknowledgements

===============



This tool has been written withing the framework of the [AMIGA project](http://amiga.iaa.es/ "AMIGA : Analysis of the interstellar Medium of Isolated GAlaxies"), 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.