Downloading cutouts
This page gives a brief overview of how to download cutouts with EveryStamp and which surveys are supported.
Table of contents
The download subcommand allows you to download FITS or JPEG cutouts from various surveys. Available surveys include those offered by SkyView and a number of custom additions not (yet) present in SkyView.
Basic cutout download
A basic cutout download requires five arguments and can be obtained via
everystamp download --survey <survey> --ra <ra> --dec <dec> --size <size> --mode <mode>
This will download a square cutout centred on the given right ascension and declination of the given size. The mode can be fits, jpeg or both to download the respecitve formats. Note that not all surveys support JPEG cutouts. Various surveys may also have further arguments specific to them. See everystamp download -h for a complete summary of available parameters.
Local cutouts
EveryStamp also support making cutouts of local FITS files through everystamp cutout. A full list of options can be seen via everystamp cutout -h. An example is
everystamp cutout --image <image> --ra <ra> --dec <dec> --size <size> --mode <mode>
Catalogue download
For bulk cutouts at multiple positions, a user can specify a catalogue to use by passing --from_catalogue <catalogue> to either everystamp download or everystamp cutout. This catalogue must be readable by astropy.table.Table.read and must contain the columns RA and DEC.
SkyView surveys
Names of surveys covered by the SkyView service can be directly passed to the --survey argment. See e.g. astroquery’s documentation for an overview.
HiPS surveys
HiPS surveys offered by Aladin can also be queried for cutouts. The full list of available surveys is listed here. The name can be passed to the download option directly by prefixing it with hips: like --survey hips:<name>.
Optical surveys
DESI Legacy Imaging Surveys
Cutouts of the DESI Legacy Imaging Surveys are provided through a wrapper aroud their own cutout service. Examples of how to query that service can be found at https://www.legacysurvey.org/viewer/urls.
Pan-STARRS
Cutouts of the Pan-STARRS survey are provided through the panstamps package.
Radio surveys
The table below summarises available radio surveys.
| Survey | Argument name | Frequency/bandwidth | Angular resolution | Description |
|---|---|---|---|---|
| TGSS | tgss | 150 MHz | 25’’ | TFIR GMRT Sky Survey |
| LoLSS | lolls | 54 MHz | 45’’ (PDR), 15’’ (DR1) | LoFAR LBA Sky Survey |
| LoTSS | lotss | 120-168 MHz | 25’’ (PDR), 6’’ (DR1, DR2) | LoFAR Two-metre Sky Survey |
| VLASS | vlass | 2-4 GHz | 2.5’’ | VLA Sky Survey |
LoFAR LBA Sky Survey
Two versions of the LoFAR LBA Sky Survey are available:
- Preliminary data release (PDR): region around the HETDEX Spring Field with an angular resolution of 45’’ and a median noise level of 5 mJy/beam.
- Data Release 1 (DR1): great improvements over PDR with an angular resolution of 15’’ and a median noise level of 1.5 mJy/beam.
LoFAR Two-metre Sky Survey
Three versions of the LoFAR Two-metre Sky Survey (LoTSS) are available:
- Preliminary data release (PDR): a preliminary data release covering the HETDEX Spring Field at an angular resolution of 25’’ and a typical noise level of <0.5 mJy/beam.
- Data Release 1 (DR1): the first data release, covering the HETDEX Spring Field with a greatly improved angular resolution of 6’’ and a median noise level of ~71 uJy/beam.
- Data Release 2 (DR2): the second data release, covering 27% of the northern sky at an angular resolution of 6’’ and a median noise level of ~81 uJy/beam.
Cutous from the PDR or DR1 releases are made through the PDR image cutout and DR1 image cutout VO services hosted by ASTRON. For DR2 such a service is not yet available. Instead, CDS’ hips2fits service is used to generate FITS cutouts from the 6’’ DR2 HiPS.
For detailed information about LoTSS, see https://lofar-surveys.org/.
TIFR GMRT Sky Survey
TIFR GMRT Sky Survey (TGSS) Alternative Data Release 1 (ADR1) cutouts are provided through a wrapper around the VO image cutout service hosted at ASTRON.
VLA Sky Survey
Cutouts from the VLA Sky Survey (VLASS) are provided by code based on scripts written by annayqho and RedTimm. It queries the VLASS observation summary hosted at https://archive-new.nrao.edu/vlass/VLASS_dyn_summary.php to determine the epoch and tile to download a cutout from.