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#!/usr/bin/env python3
#
# Copyright (c) 2017 Aaron LI
# MIT license
"""
Get the SDSS image around a specified position using the
"Image Cutout" service.
* Image Cutout:
http://skyserver.sdss.org/dr13/en/help/docs/api.aspx#imgcutout
* Image List Tool help:
http://skyserver.sdss.org/dr13/en/tools/started/list.aspx
* Science Archive Server (SAS): coverage check:
https://dr12.sdss.org/coverageCheck
* Science Archive Server (SAS): single field search
https://dr12.sdss.org/fields
Can get images of u, g, r, i, z bands in FITS format
"""
import os
import sys
import argparse
import requests
def get_image(outfile, ra, dec, scale=0.4, width=1024, height=1024,
opt="", clobber=False):
"""
Get and save the requested SDSS image.
Credits:
[1] Requests - Raw Response Content
http://docs.python-requests.org/en/master/user/quickstart/
[2] How to download image using requests?
https://stackoverflow.com/a/13137873/4856091
"""
if os.path.exists(outfile) and clobber is False:
raise OSError("output file already exists: %s" % outfile)
params = {
"ra": ra,
"dec": dec,
"scale": scale,
"width": width,
"height": height,
"opt": opt
}
url = "http://skyserver.sdss.org/dr13/SkyServerWS/ImgCutout/getjpeg"
print("Get image from SDSS ...", file=sys.stderr)
r = requests.get(url, params=params, stream=True)
print("URL:", r.url, file=sys.stderr)
r.raise_for_status()
with open(outfile, "wb") as f:
for chunk in r.iter_content(chunk_size=1024):
f.write(chunk)
print("Saved image to file:", outfile, file=sys.stderr)
def main():
parser = argparse.ArgumentParser(description="Get SDSS image")
parser.add_argument("-o", "--outfile", dest="outfile",
help="output image filename [jpeg]")
parser.add_argument("-C", "--clobber", dest="clobber", action="store_true",
help="overwrite existing file")
parser.add_argument("-r", "--ra", dest="ra",
type=float, required=True,
help="right ascention [degree]")
parser.add_argument("-d", "--dec", dest="dec",
type=float, required=True,
help="declination [degree]")
parser.add_argument("-s", "--scale", dest="scale",
type=float, default=0.4,
help="scale of image [arcsec/pixel] (default: 0.4)")
parser.add_argument("-W", "--width", dest="width",
type=int, default=1024,
help="image width [pixel] (default: 1024)")
parser.add_argument("-H", "--height", dest="height",
type=int, default=1024,
help="image height [pixel] (default: 1024)")
parser.add_argument("-G", "--opt-G", dest="optG", action="store_true",
help="overlay coordinate grid and scale")
parser.add_argument("-L", "--opt-L", dest="optL", action="store_true",
help="overlay label of RA/Dec, scale and zoom factor")
parser.add_argument("-P", "--opt-P", dest="optP", action="store_true",
help="mark photometrically identified objects " +
"with blue circles")
parser.add_argument("-S", "--opt-S", dest="optS", action="store_true",
help="mark objects with measured spectra " +
"using red squares")
parser.add_argument("-O", "--opt-O", dest="optO", action="store_true",
help="mark outlines of photometrically " +
"identified objects")
parser.add_argument("-B", "--opt-B", dest="optB", action="store_true",
help="put a box around the outline for each object")
parser.add_argument("-F", "--opt-F", dest="optF", action="store_true",
help="mark boundaries of SDSS fields")
parser.add_argument("-M", "--opt-M", dest="optM", action="store_true",
help="mark regions masked out of the science data")
parser.add_argument("-Q", "--opt-Q", dest="optQ", action="store_true",
help="show boundaries of SDSS spectroscopic plates")
parser.add_argument("-I", "--opt-I", dest="optI", action="store_true",
help="invert the colors (i.e., white background)")
args = parser.parse_args()
options = ""
for optv, optc in [(args.optG, "G"),
(args.optL, "L"),
(args.optP, "P"),
(args.optS, "S"),
(args.optO, "O"),
(args.optB, "B"),
(args.optF, "F"),
(args.optM, "M"),
(args.optQ, "Q"),
(args.optI, "I")]:
if optv:
options += optc
if args.outfile:
outfile = args.outfile
else:
outfile = "sdss_ra{ra:.2f}_dec{dec:.2f}_s{scale:.1f}_{opt}.jpg".format(
ra=args.ra, dec=args.dec, scale=args.scale, opt=options)
print("RA:", args.ra, file=sys.stderr)
print("Dec:", args.dec, file=sys.stderr)
print("Scale:", args.scale, file=sys.stderr)
print("Size: %dx%d" % (args.width, args.height), file=sys.stderr)
print("Options:", options, file=sys.stderr)
print("Outfile:", outfile, file=sys.stderr)
get_image(outfile=outfile, ra=args.ra, dec=args.dec, scale=args.scale,
width=args.width, height=args.height, opt=options,
clobber=args.clobber)
if __name__ == "__main__":
main()
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