National Astronomical Observatory of Japan / Astronomy Data Center
Digitized Sky Survey Data Archive

This interface is developed for the purpose to serve astronomical image data to those who are involved in astronomical researches and education.

1. Brief overview of the image sources

1.1. Digitized Sky Survey ( DSS ) 1st & 2nd

DSS1 includes images for the entire sky digitized with a spatial resolution of 1.7"/pixel from the "POSS-I E" survey plates (approxiamtely R) for the northern hemisphere taken with the Palomar Schmidt telescope and from the "SERC J" survey plates (Bj) for the southern hemisphere taken with the UK Schmidt telescope. DSS2, on the other hand, is an on-going project aiming the entire sky images digitized with a spatial resolution of 1.0"/pixel from the "POSS-II" survey plates (Bj,R,I) for the northern hemisphere taken with the Palomar Schmidt telescope and from the "SERC" and "AAO" survey plates (R) for the southern hemisphere taken with the UK Schmidt telescope. See STScI Digitized Sky Survey for details.

1.2. IRAS Sky Survey Atlas ( ISSA )

The Infrared Astronomical Satellite (IRAS) conducted a survey of 98% of the sky in four bands with effective wavelengths of 12, 25, 60 and 100 um. The ISSA covers the sky with 430 fields. Each field is a 12.5^o x 12.5^o region centered every 10^o along declination bands which are spaced 10^o apart. The ISSA covers ecliptic latitudes of |b| > 20^o. The remaining field between ecliptic latitudes -20^o to 20^o are released as a separate product, the ISSA Reject Set, so named because of their reduced quality compared to the rest of the ISSA. The ISSA Reject Set is also available in this interface. See IRAS Sky Survey Atlas for details.

1.3. Green Bank Sky Map ( GBSM )

The Green Bank 300-foot (91 m) transit telescope were used to make a 1400 MHz continuum survey of the -5^o to +82^o declination band (Condon and Broderick 1985, 1986) and a 4.85 GHz continuum survey of the 0^o to +75^o declination band (Condon et al. 1994). The former survey area was divided into 144 square total-intensity images, each 512 pixels times 2'/pixel = 17^o on a side, centered on all combinations of RA = 0h, 1h, ..., 23h, and Dec = 0^o, +15^o,..., +75^o (equinox B1950), while the latter into 288 square total-intensity images, each 1024 pixels times 40"/pixel = 11.4^o on a side, centered on all combinations of RA = 0h20m, 1h00m, 1h40m,..., 23h40m, and Dec = 0^o, +10^o,..., +70^o (equinox B1950). The point-source responses are nearly Gaussian with FWHM major axis = 12.7', minor axis = 11.1', major-axis position angle = 0^o for 1400 MHz and FWHM major axis = 3.7', minor axis = 3.3' for 4.85 GHz. The maps are confusion limited with rms confusion plus noise 25-30mJy except near the galactic plane, so that individual point sources stronger than about 150 mJy should be reliable.

2. How to use the interface

2.1. Image Sources and Band Selection

You can choose one or more image source(s) among DSS1, DSS2, ISSA, and GBSM. The field size can be specified for DSS1 and DSS2. Note, for ISSA and GBSM, that it is fixed to 12.5^o x 12.5^o and 1h x 15^o,respectively.

For DSS1 and DSS2, you can also choose a set of band selection.

Note also that DSS2 cannot always serve for your query. You can check the sky areas currently available with DSS2 by clicking DSS2 available maps (R, Bj, I) & list (R, Bj, I)

See section 1 for brief overview of the resources.

2.2. Field Specification

(a) Coordinate system

You can choose J2000 (Equatorial), Galactic, or Ecliptic for the coordinate system.

(b) Coordinates and Field size

The position of a sky field can be specified by its central coordinates. The position can be set with sexagesimal expression (space- or colon-separated) or numeric in degree. Following all expressions indicate a position of M105 galaxy.

The field size is specified by the width and the height, both in arcmin, which cannot exceed 90'. If not given, they are assumed to 5' for DSS1 and DSS2. For ISSA and GBSM, the field size is always fixed to 12.5^o x 12.5^o and 1h x 15^o, respectively, so specifing the size is useless. If you want to obtain images of larger area of the sky, Wide-Field mode is available that allows 360' in maximum.

(c) Wide-Field mode

This mode is used to obtain images of large area of the sky. You can set pixel size to rescale images.

Wide-Field mode offers four options: "Mixed-band Transgress plate" and "Single band Transgress plate" will use some plates to fill requested FOV, however, the resolution is not fine (5x5 binning for DSS1, 8x8 binning for DSS2). "North upward" will rotate original images to output images where north is up. "Align to plate edge" will not rotate original images.

Note that you have to wait for some minutes to obtain fine and large images.

Old version (2001-2012) had some problems that a number of plates cannot be found. The bugs have been fixed in the current version.

2.3. Name Resolver

The object name is converted to its corresponding coordinate by the SIMBAD name resolver. Beware that the SIMBAD resolver may not always be called because of a networking problem.

2.4. Hints for wget script

A link to download wget script is provided in each result page.

If you want to select images with band name or C/F flags, you can use grep command to downloaded wget script. We show some examples:

% cat script0.sh | grep 'Bj[+].[+].'"'"'$' > script1.sh

This selects only images of Bj band.

% cat script0.sh | grep 'Bj[+].[+]C'"'"'$' > script1.sh

This selects only images of Bj band with C flag.

C flag indicates the image closest to the plate center, and F flag indicates the image furthest from the plate edge, respectively.

3. Acknowledging DSS, ISSA, GBSM, and SIMBAD

People who used DSS are requested to include acknowledgments in any publications as appropriate. See "DSS Acknowledgments" page for details.

People who used ISSA are requested to include the following credit in any publication as appropriate: Infrared Processing and Analysis Center, Caltech/JPL. IPAC is NASA's Infrared Astrophysics Data Center.

See Reference below for GBSM original papers.

This service is provided in collaboration with the SIMBAD project, Centre de Donnees astronomiques de Strasbourg, France. ( For questions about SIMBAD content and for access to the full on-line interactive database, please contact: question@simbad.u-strasbg.fr )

We would be vary happy if our on-line interface will be acknowledged as well. Thank you.

Reference

Condon, J. J., Broderick, J. J., 1985, AJ, 90, 2540
Condon, J. J., Broderick, J. J., 1986, AJ, 91, 1051
Condon, J. J., Broderick, J. J., Seielstad, G. A., Douglas, K., Gregory, P. C., 1994, AJ, 107, 1829
Paturel, G., Fouqué, P., Bottinelli, L., Gouguenheim, L., 1989, Catalogue of Principal Galaxies (Lyon: Obs.de Lyon)
Nilson, P., 1973, Uppsala General Catalogue of Galaxies (Uppsala Astron. Obs. Ann. 6)
Abell, G.O., Corwin Jr., H.G., Olowin, R.P., 1973, ApJS, 70, 1

Questions and comments are welcome to