Cutouts

The images are downloaded from different sources depending on what was the easiest at the moment of adding the survey.

PS1

These images are downloaded from the PS1 server directly. The code found at the end of the PS1 Image Cutout Service was adapted for HostPhot. The pixel scaling of the images is 0.25 arcsec/pixel, as described in the PS1 website. The available filters are: \(grizy\).

../_images/ps1_footprint.png

PS1 survey footprint. Image from https://arxiv.org/pdf/1507.07694.pdf.

DES

DES images are downloaded from the NOAO DataLab using the Simple Image Access (SIA) service. Here is an example notebook. The pixel scaling of the images is 0.263 arcsec/pixel, as described in the DES website. The available filters are: \(grizY\).

../_images/des_footprint.png

DES survey footprint. Image from https://www.darkenergysurvey.org/es/el-cartografiado/.

SDSS

These images are downloaded using astroquery.skyview. The astroquery.sdss module is not used as it downloads much larger images (taking longer to download) and thus need to be trimmed. The pixel scaling of the images is 0.396 arcsec/pixel, as described in the SDSS website. Note: it is recommended to use PS1 instead of SDSS as PS1 covers the same patch of the sky as SDSS and more (unless \(u\)-band is needed). Also, PS1 is better calibrated and goes deeper. The available filters are: \(ugriz\).

../_images/sdss_footprint.png

SDSS survey footprint. Image from https://www.sdss.org/wp-content/uploads/2016/08/DR13.pdf.

GALEX

These are downloaded with astroquery.skyview. Some header information missing in these images is retrieved from the images obtained with astroquery.mast.Observations (e.g. exposure time). The pixel scaling of the images is 1.5 arcsec/pixel, as described in the GALEX website. The available filters are: \(FUV\) (far-UV) and \(NUV\) (near-UV).

../_images/galex_footprint.jpg

GALEX survey footprint in galactic coordinates. Image from https://archive.stsci.edu/missions-and-data/galex.

2MASS

These images are downloaded from the 2MASS database following https://irsa.ipac.caltech.edu/ibe/docs/twomass/allsky/allsky/#main. Information such as the ordate is first obtained from the last rows of the header of the images downloaded with PyVo. However, the latter are not used as they are much larger and the 2MASS zero-points are missing in their headers. The pixel scaling of the images is 1.0 arcsec/pixel, as described in the 2MASS website. The available filters are: \(J\), \(H\) and \(K_{s}\).

../_images/2mass_footprint.png

2MASS survey footprint (\(K_s\) band) in galactic coordinates. Image from https://iopscience.iop.org/article/10.1088/0067-0049/199/2/26/pdf.

WISE

These images are downloaded from the WISE database following https://irsa.ipac.caltech.edu/ibe/docs/wise/allwise/p3am_cdd/#sample_code. Information such as the coadd_id is first obtained from the last rows of the header of the images downloaded with astroquery.skyview. However, the latter are not used as the 2MASS zero-points are missing in their headers. The pixel scaling of the images is 1.375 arcsec/pixel, as described in the WISE website. The available filters are: \(W1\) (\(3.4 \mu \text{m}\)), \(W2\) (\(4.6 \mu \text{m}\)), \(W3\) (\(12 \mu \text{m}\)) and \(W4\) (\(22 \mu \text{m}\)).

../_images/wise_footprint.jpg

WISE survey footprint in galactic coordinates. Image from https://wise2.ipac.caltech.edu/docs/release/allwise/expsup/sec4_2.html#figure1.

unWISE

unWISE is an unblurred coadd of the WISE imaging (i.e. better resolution). These images are directly obtained from the unWISE image service. The pixel scaling of the images is 2.75 arcsec/pixel, as described in the website. The available filters are \(W1\), \(W2\), \(W3\) and \(W4\) for the AllWISE version, and only \(W1\) and \(W2\) for the NeoWISE-R1 and NeoWISE-R2 versions.

Legacy Survey

Legacy Survey images are downloaded following the under the “Obtaining Images and Raw Data” section in the Legacy Survey website. The pixel scaling of the images is 0.262 arcsec/pixel, as described in the website. The available filters are: \(grz\).

../_images/legacysurvey_footprint.png

Legacy Survey survey footprint. Image from https://www.legacysurvey.org/status/.

Spitzer

Spitzer images are taken only from the SEIP survey (other surveys might be included in the future), using the IRSA IPAC cutouts service. The available filters are: IRAC.1 (\(3.6 \mu \text{m}\)), IRAC.2 (\(4.5 \mu \text{m}\)), IRAC.3 (\(5.8 \mu \text{m}\)), IRAC.4 (\(8.0 \mu \text{m}\)) and MIPS.1 (\(24 \mu \text{m}\)), with pixel scalings of 0.6 and 2.45 arcsec/pixel, as described in the IRAC manual (Section 4.10, for the mosaic images used) and MIPS manual (Table 4.9), respectively. This information is also found in the header of the images.

../_images/spitzer_seip_footprint.jpeg

Spitzer SEIP footprint. Image from the SEIP website.

VISTA

VISTA images are downloaded from the VISTA science archive. Three surveys are used: VHS (data release 6), VIDEO (data release 5) and VIKING (data release 4). The pixel scaling of the images is 0.339 arcsec/pixel, as described in the VISTA website. The available filters are: \(ZYJHK_{s}\) (survey dependent).

../_images/vista1_footprint.jpg
../_images/vista2_footprint.png

VISTA surveys footprints. Images from https://www.eso.org/public/images/allsky-vista/ and https://www.eso.org/rm/api/v1/public/releaseDescriptions/144.