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The Hubble Helix

ACS Data - NICMOS Data - File Download Instructions

ACS data

In the tables below are lists of available files:

  • Cosmetically Cleaned Mosaics
    Only cosmetically clean versions of the scale 2 mosaics were produced to make the color composite images. The scale 4 cosmetically cleaned mosaics are just binned-down versions of the scale 2 mosaics.
  • Residual Masks
    The residual masks (rm) show which pixels were cosmetically cleaned (flag=1), and which were protected from this cleaning (flag=2). Mostly cosmic rays were cleaned, but some faint stars and knots were too.
  • MultiDrizzle Output Mosaics
    The MultiDrizzle (dz) output mosaics before the cosmetic cleanup. Cosmic rays were rejected wherever there were at least two overlapping frames, but a significant amount of residual cosmic ray contamination remains. Get these if you want to try to improve upon the teams admittedly imperfect cosmetic cleanup of the residual cosmic rays.
  • Weight maps produced by MultiDrizzle
  • Scale 1 "Quadrant Mosaics"
    The following scale 1 images are provided as a possible convenience: they are easier to download and handle than the full scale 1 mosaics above. These are quadrants of the full mosaics. Quadrant 1 (q1) is "lower left". Quadrant 2 (q2) is "upper left". Quadrant 3 (q3) is "upper right". Quadrant 4 (q4) is "lower right".
  • Drizzled Scale 1 Tiles
    Just the combination of the two exposures at each pointing, with no cosmetic cleaning (residual cosmic rays are present). The two exposures in each tile are well registered (to within 0.1 WFC pixels or 5 mas), because they were both obtained using the same guide stars. The shift refinement that was needed for the full mosaics was primarily to improve the registration bewteen these tiles, which could be off by 5-10 WFC pixels (250-500 mas) because different guide stars had to be used for each.

Cosmetically Cleaned Mosaics
h_helix_502_s2cc_img.fits F502N 2
h_helix_658_s2cc_img.fits F658N 2
h_helix_502_s4cc_img.fits F502N 4
h_helix_658_s4cc_img.fits F658N 4
Residual Cosmic Ray Mask
h_helix_502_s1rm_img.fits F502N 1
h_helix_658_s1rm_img.fits F658N 1
h_helix_502_s2rm_img.fits F502N 2
h_helix_658_s2rm_img.fits F658N 2
Drizzled Mosaic Before Cosmetic Cleanup
h_helix_502_s1dz_img.fits F502N 1
h_helix_658_s1dz_img.fits F658N 1
h_helix_502_s2dz_img.fits F502N 2
h_helix_658_s2dz_img.fits F658N 2
Mosaic Weight Map
h_helix_502_s1wt_img.fits F502N 1
h_helix_658_s1wt_img.fits F658N 1
h_helix_502_s2wt_img.fits F502N 2
h_helix_658_s2wt_img.fits F658N 2

Scale 1 "Quadrant Mosaics"
File Filter Scale
h_helix_502_s1q1_img.fits F502N 1 1
h_helix_502_s1q2_img.fits F502N 1 2
h_helix_502_s1q3_img.fits F502N 1 3
h_helix_502_s1q4_img.fits F502N 1 4
Scale 1 "Quadrant Mosaics"
File Filter Scale
h_helix_658_s1q1_img.fits F658N 1 1
h_helix_658_s1q2_img.fits F658N 1 2
h_helix_658_s1q3_img.fits F658N 1 3
h_helix_658_s1q4_img.fits F658N 1 4

Drizzled Scale 1 Tiles
h_helix_502_s1t1_img.fitsF502N 1 1
h_helix_502_s1t2_img.fitsF502N 1 2
h_helix_502_s1t3_img.fitsF502N 1 3
h_helix_502_s1t4_img.fitsF502N 1 4
h_helix_502_s1t5_img.fitsF502N 1 5
h_helix_502_s1t6_img.fitsF502N 1 6
h_helix_502_s1t7_img.fitsF502N 1 7
h_helix_502_s1t8_img.fitsF502N 1 8
h_helix_502_s1t9_img.fitsF502N 1 9
Drizzled Scale 1 Tiles
h_helix_658_s1t1_img.fitsF658N 1 1
h_helix_658_s1t2_img.fitsF658N 1 2
h_helix_658_s1t3_img.fitsF658N 1 3
h_helix_658_s1t4_img.fitsF658N 1 4
h_helix_658_s1t5_img.fitsF658N 1 5
h_helix_658_s1t6_img.fitsF658N 1 6
h_helix_658_s1t7_img.fitsF658N 1 7
h_helix_658_s1t8_img.fitsF658N 1 8
h_helix_658_s1t9_img.fitsF658N 1 9
  • The "scale 1" data (*s1*) is "full-scale", i.e. the pixels are the same size as the input ACS/WFC pixels, or 0.05 arcsec. The scale 1 mosaics are 12400x13700 pixels and 678 MB uncompressed!

  • The "scale 2" data (*s2*) has 0.10 arcsec pixels (twice as big as the detector pixels). The scale 2 mosaics were used to produce the color composite images for the press release. The scale 2 mosaics are 6300x6900 pixels and 174 MB uncompressed.

  • The "scale 4" data (*s4*) has 0.20 arcsec pixels (four times bigger than the detector pixels). These are "quick-look" versions that download fast, and are convenient for reference and display, but they are not ideal for scientific analysis. The scale 4 mosaics are 3300x3500 pixels and 46 MB uncompressed.


h_helix_2120_dz_comb.fits F212N drizzled data, combination of all 5 pointings)

NICMOS Drizzled Data
File FilterPointing
h_helix_2120_p1dz_img.fits F212N1
h_helix_2120_p2dz_img.fits F212N 2
h_helix_2120_p3dz_img.fits F212N 3
h_helix_2120_p4dz_img.fits F212N 4
h_helix_2120_p5dz_img.fits F212N 5

Download Instructions

  • Download a single file by right-clicking on filename in the tables above.

  • You can use wget to download a single file or an entire directory:

    wget -r -A -l1 wget -r -np -nd

  • You may download the data via anonymous ftp:
    Name: anonymous
    Password: (provide your e-mail address)
    ftp> cd /pub/hlsp/helix/acs/f658n
    ftp> prompt
    ftp> binary
    ftp> mget *img.fits
    ftp> bye

There are subdirectories for each instrument and filter combination, and a subdirectory (named "jref" for ACS) with the reference files used by the calibration pipeline (CALACS). The following standard calibration pipeline products are included for ACS, with their standard archival filenames. See the Observations page for the individual rootnames for a specific filter or pointing:

*_flt.fits (flat-fielded images, input for MultiDrizzle)
*_drz.fits (individual pipeline-drizzled exposures; no cosmic ray rejection)