The hips2fits service enables generation of FITS images cutouts of arbitrary size and resolution from a given HiPS.
This means you can easily generate FITS cutouts (as well as JPEG) from popular image surveys (DSS2, SDSS, PanSTARRS, 2MASS, GALEX, AllWISE, etc) for your favorite set of objects or coordinates.
The form below will let you test the service. For intensive use, exhaustive description of the options and parameters, have a look at the hips2fits cutout API.Try it now!
Use the form above to test the service
API Endpoints
The service has 2 independent endpoints:
http://alasky.cds.unistra.fr/hips-image-services/hips2fits
http://alaskybis.cds.unistra.fr/hips-image-services/hips2fits
Input parameters
| Parameter name | Description | Comment |
|---|---|---|
hips |
ID or keyword identifying the HiPS to use | Compulsory If multiple HiPS surveys match, one is chosen randomly |
wcs |
The WCS definition of the cutout, defined as a key-value dictionary JSON string | Alternatively, you can define the astrometry you wish by passing lon, lat, fov, coordsys keywords (see below) |
width |
Width in pixels of the output image | Compulsory |
height |
Height in pixels of the output image | Compulsory |
projection |
Name of the requested projection, eg: SIN, TAN, MOL, AIT, CAR, CEA, STG | Compulsory if wcs is not provided.See this page for an exhaustive list. |
fov |
Size (FoV) of the cutout on the sky, in decimal degrees | Compulsory if wcs is not provided.This is the size of the largest dimension of the image. |
ra |
Right ascension in decimal degrees of the center of the output image | Compulsory if neither wcs or object are provided |
dec |
Declination in decimal degrees of the center of the output image | Compulsory if neither wcs or object are provided |
coordsys |
Coordinate frame system to be used for the projection | Possible values are icrs or galactic Default value is icrs |
rotation_angle |
Angle value (in decimal degrees) to be applied to the projection | Default value is 0 |
object |
Name of the object the output image will be centered on The name will be resolved to coordinated by the Sesame service. |
If wcs is missing, either object or (ra, dec) must be provided |
inverse_longitude |
Set to true if you want longitudes to be increasing from left to right. Mostly useful for planetary HiPS maps. | Defaults to true for planetary surfaces HiPS, false otherwise. |
format |
Format of the output image | Allowed values are fits (default), jpg and png In case of jpg or png format, scaling of the pixels value can be controlled with parameters min_cut, max_cut and stretch (see below) |
min_cut |
Minimal value considered for contrast adjustment normalization | Only applicable to jpg/png output formats Can be given as a percentile value, for example min_cut=1.5%Default value is 0.5% |
max_cut |
Maximal value considered for contrast adjustment normalization | Only applicable to jpg/png output formats Can be given as a percentile value, for example max_cut=97%Default value is 99.5% |
stretch |
Stretch function used for contrast adjustmnt | Only applicable to jpg/png output formats Possible values are: power, linear, sqrt, log, asinh Default value is linear |
cmap |
Name of the color map | Only applicable to jpg/png output formats Any colormap supported by Matplotlib can be specificed Default value is Greys_r (grayscale) |
Limitations
Dimension (width x height) of the cutout can not exceed 50 million pixels.
Examples
Here are a few examples showcasing the versatility of the cutouts the service can deliver. You can retrieve the actual FITS cutout generated by the service by clicking on the corresponding button.
-
Mollweide all-sky projection of HI4PI survey
Mars MOLA cutout centered on Valles Marineris
Galactic plane as seen by Spitzer MIPS1
-
Messier 31 center surveyed by XMM
DECaLS g-band cutout of galaxy UGC 10041
Access from Python
We have developed an easy access to hips2fits for the astroquery Python package. Exhaustive documentation is available on astroquery.hips2fits page.
Generating thumbnails for a list of targets and HiPS surveys
We offer an easy way to generate a matrix of thumbnails for a list of targets associated with a list of HiPS surveys.
The documentation will present you the available parameters
Here are some examples of thumbnails matrix URLs:
- This URL displays a list of thumbnails for galaxies in the different MATLAS HiPS. The thumbnails are grouped by target.
- This URL displays a list of thumbnails for various Messier objects in DSS, 2MASS, XMM, AllWISE,GALEX and PanSTARRS HiPS. The thumbnails are grouped by HiPS survey.
Acknowledging hips2fits
If you use hips2fits for your work or research, we kindly ask you to cite it with the following acknowledgment:
This research made use of hips2fits,\footnote{https://alasky.cds.unistra.fr/hips-image-services/hips2fits} a service provided by CDS.
Contact
If you have any question, comment or feedback regarding the hips2fits service, please send us a message.