COSMOS-Web DR1 NIRCam mosaics
COSMOS-Web: Comprehensive Data Reduction for Wide-Area JWST NIRCam Imaging
Authors: M. Franco, C. M. Casey, A. Koekemoer, D. Liu, M. Bagley, H. J. McCracken, H. B. Akins, O. Ilbert, M. Shuntov, S. Harish, B. Robertson et al.
The COSMOS-Web DR1 NIRCam mosaics can be downloaded using the following links. This page provides a description of the data products; for more details on data reduction methodology, please refer to the NIRCam imaging paper: Franco et al. (2025).
Description
NIRCam data reduction was conducted using version 1.14.0 of the STScI JWST pipeline and Calibration References Data System (CRDS) pmap 1223.
The field has been divided into 20 tiles pictured below
Table of tile corners (click to expand)
| Tile | Corner 1 (RA, Dec) | Corner 2 (RA, Dec) | Corner 3 (RA, Dec) | Corner 4 (RA, Dec) |
|---|---|---|---|---|
| A1 | 149.8703317 2.0856512 | 149.7198796 2.1403395 | 149.7908786 2.3354095 | 149.9413496 2.2807163 |
| A2 | 150.0058959 2.0363591 | 149.8554506 2.0910612 | 149.9264667 2.2861269 | 150.0769300 2.2314186 |
| A3 | 150.1414523 1.9870553 | 149.9910155 2.0417704 | 150.0620479 2.2368306 | 150.2125019 2.1821081 |
| A4 | 150.2769995 1.9377408 | 150.1265729 1.9924679 | 150.1976208 2.1875215 | 150.3480637 2.1327859 |
| A5 | 150.4125359 1.8884166 | 150.2621212 1.9431545 | 150.3331838 2.1382005 | 150.4836139 2.0834528 |
| A6 | 149.8045087 1.9048087 | 149.6540746 1.9594923 | 149.7250552 2.1545612 | 149.8755087 2.0998725 |
| A7 | 149.9400575 1.8555218 | 149.7896293 1.9102182 | 149.8606274 2.1052826 | 150.0110740 2.0505800 |
| A8 | 150.0755992 1.8062243 | 149.9251788 1.8609325 | 149.9961935 2.0559913 | 150.1466316 2.0012757 |
| A9 | 150.2111325 1.7569171 | 150.0607214 1.8116361 | 150.1317520 2.0066883 | 150.2821799 1.9519607 |
| A10 | 150.3466557 1.7076011 | 150.1962556 1.7623299 | 150.2673014 1.9573744 | 150.4177173 1.9026358 |
| B1 | 150.0020274 2.4473359 | 149.8515406 2.5020333 | 149.9225757 2.6970916 | 150.0730806 2.6423895 |
| B2 | 150.1376214 2.3980335 | 149.9871430 2.4527469 | 150.0581944 2.6478011 | 150.2086900 2.5930817 |
| B3 | 150.2732061 2.3487174 | 150.1227378 2.4034461 | 150.1938048 2.5984949 | 150.3442894 2.5437590 |
| B4 | 150.4087801 2.2993886 | 150.2583236 2.3541315 | 150.3294054 2.5491739 | 150.4798772 2.4944226 |
| B5 | 150.5443418 2.2500480 | 150.3938989 2.3048040 | 150.4649946 2.4998389 | 150.6154520 2.4450733 |
| B6 | 149.9361713 2.2664951 | 149.7857017 2.3211879 | 149.8567188 2.5162544 | 150.0072070 2.4615567 |
| B7 | 150.0717506 2.2171978 | 149.9212885 2.2719056 | 149.9923224 2.4669678 | 150.1428020 2.4122539 |
| B8 | 150.2073213 2.1678878 | 150.0568686 2.2226097 | 150.1279183 2.4176665 | 150.2783878 2.3629373 |
| B9 | 150.3428821 2.1185662 | 150.1924404 2.1733011 | 150.2635052 2.3683514 | 150.4139629 2.3136080 |
| B10 | 150.4784314 2.0692337 | 150.3280023 2.1239807 | 150.3990815 2.3190234 | 150.5495255 2.2642668 |
All tiles are drizzled with the same tangent point:
CRVAL1 = 150.1163213
CRVAL2 = 2.200973097Names of the files are:
mosaic_nircam_{filter}_COSMOS-Web_{pixel_scale}_{tile}_v1.0_i2d.fitswhere filter is one of the four NIRCam filters available in COSMOS-Web: f115w, f150w, f277w, or f444w. Mosaics are provided at two different pixel_scales, given by the pixel_scale keyword, either 30mas or 60mas.
The full mosaics are provided as *_i2d.fits files, as described in the JWST pipeline documentation. The structure of the *i2d.fits files is as following:
HDU EXTNAME HDU Type DataType Dimensions
0 N/A primary N/A N/A
1 SCI IMAGE float32 ncols x nrows
2 ERR IMAGE float32 ncols x nrows
3 CON IMAGE int32 ncols x nrows x nplanes
4 WHT IMAGE float32 ncols x nrows
5 VAR_POISSON IMAGE float32 ncols x nrows
6 VAR_RNOISE IMAGE float32 ncols x nrows
7 VAR_FLAT IMAGE float32 ncols x nrowsThe i2d files are quite large, typically ~10Gb compressed for 30mas pixel scale. To facilitate the handling of these data, the sci, err, and wht extensions have been extracted and are provided separately.
The pipeline used for the data reduction integrated codes from Anton M. Koekemoer, Micaela Bagley, and Daizhong Liu. Astrometry is anchored to Gaia-EDR3 and bootstrapped from HST/F814W imaging (Koekemoer et al. 2007) and the COSMOS2020 catalogs (Weaver et al. 2022).
Downloads
Tarballs of all tiles
30mas pixel scale
| Extension | F115W | F150W | F277W | F444W |
|---|---|---|---|---|
i2d |
F115W (174 Gb) | F150W (174 Gb) | F277W (172 Gb) | F444W (169) Gb) |
sci |
F115W (31 Gb) | F150W (31 Gb) | F277W (31 Gb) | F444W (31 Gb) |
err |
F115W (28 Gb) | F150W (28 Gb) | F277W (28 Gb) | F444W (27 Gb) |
wht |
F115W (28 Gb) | F150W (28 Gb) | F277W (28 Gb) | F444W (28 Gb) |
60mas pixel scale
| Extension | F115W | F150W | F277W | F444W |
|---|---|---|---|---|
i2d |
F115W (43 Gb) | F150W (43 Gb) | F277W (43 Gb) | F444W (42 Gb) |
sci |
F115W (7.7 Gb) | F150W (7.7 Gb) | F277W (7.7) Gb) | F444W (7.7 Gb) |
err |
F115W (6.9 Gb) | F150W (7.0 Gb) | F277W (6.9 Gb) | F444W (6.7 Gb) |
wht |
F115W (7.1 Gb) | F150W (7.1 Gb) | F277W (7.0 Gb) | F444W (7.0 Gb) |
Individual tiles
30mas pixel scale
i2d files are typically 7-10 Gb each (compressed). Individual sci extensions are typically 1.2-1.7 Gb each (compressed).
60mas pixel scale
i2d flies are typically 1.5-2.5 Gb each (compressed). Individual sci extensions are typically only ~500 Mb each (compressed).