hips2fits

Fast generation of FITS cutouts from HiPS datasets


The hips2fits service enables generation of FITS images cutouts of arbitrary size and resolution from a given HiPS.

Try it now!

Use the form above to test the service

x pixels
degrees
degrees


API Endpoints

The service has 2 independent endpoints:

http://alasky.u-strasbg.fr/hips-image-services/hips2fits

http://alaskybis.u-strasbg.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 galactic
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.

Access from Python

We will develop an access to hips2fits from astroquery.cds. In the meantime, this notebook should get you started to query hips2fits from Python scripts.

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.u-strasbg.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.



© Université de Strasbourg/CNRS

    • Contact