search

dstndstn / astrometry.net

Astrometry.net -- automatic recognition of astronomical images
http://astrometry.net
Other
661 stars 185 forks source link

UCAC5 Support #213

Closed vkoupr closed 3 years ago

vkoupr commented 3 years ago

Add support for UCAC5 catalog + shell script for automatically building the full set of indexes from z??? files.

Features:

Prerequisites:

Building UCAC5 indexes:

  1. Optionally edit catalogs/build_ucac5_indexes.sh. The following options located at the top of the file can be set:

    • EPOCH = epoch of coordinates in years. Set to 0 to use the original UCAC epochs (not recommended since the mean UCAC epoch is 2001; not accounting for proper motion will lead to errors of e.g. 0.2 arcsec in 2021 for a 10 mas/yr proper motion star, while the accuracy of UCAC5 positions is 60 mas or better).

    • MARGIN = index overlap in degrees. Set to half-width of the field of view. Fractional numbers allowed. MARGIN = 0 disables index overlap. The default is 2 degrees, which is perhaps an overkill for most applications.

    • FULL = include tag-along data. Set FULL = 1 to include the following columns in the resulting indexes, in addition to RA, DEC, and MAG:

      • ID: 64-bit Gaia source ID
      • RA_GAIA: Gaia RA at epoch 2015.0 [degrees]
      • DEC_GAIA: Gaia Dec at epoch 2015.0 [degrees]
      • RA_GAIA_ERR: error of Gaia DR1 RA at epoch 2015.0 [degrees]
      • DEC_GAIA_ERR: error of Gaia DR1 Dec at epoch 2015.0 [degrees]
      • FLAGS: 1 = TGAS, 2 = other UCAC-Gaia star, 3 = other NOMAD
      • NUM_POS: number of images used for UCAC mean position
      • UCAC_EPOCH: mean UCAC epoch [yr]
      • RA_UCAC: mean UCAC RA at 'UCAC_EPOCH' on Gaia reference frame [degrees]; equal to RA if EPOCH = 0
      • DEC_UCAC: mean UCAC Dec at 'UCAC_EPOCH' on Gaia reference frame [degrees]; equal to DEC if EPOCH = 0
      • PM_RA: proper motion RA*cosDec (UCAC-Gaia) [degrees/yr]
      • PM_DEC: proper motion Dec (UCAC-Gaia) [degrees/yr]
      • PM_RA_ERR: formal error of UCAC-Gaia proper motion RA*cosDec [degrees/yr]
      • PM_DEC_ERR: formal error of UCAC-Gaia proper motion Dec [degrees/yr]
      • GMAG: Gaia DR1 G magnitude
      • RMAG: NOMAD photographic R magnitude
      • JMAG: 2MASS J magnitude
      • HMAG: 2MASS H magnitude
      • KMAG: 2MASS K magnitude

      Note that enabling tag-along data increases the size of the resulting indexes by ~2x to 3x.

    • JOBS = number of parallel jobs. Speed up the build process by setting this to the maximum number of concurrently running build-astrometry-index jobs provided there is enough RAM. JOBS = 1 disables parallelization.

    • PREFIX = common index file prefix. Default is "ucac5-index-".

  2. cd to directory containing the original UCAC5 files.

  3. Make sure that at least ~55 Gbytes (if including tag-along data) or ~25 Gbytes otherwise are available and run catalogs/build_ucac5_indexes.sh.

Indexes are output to the same dir. To maintain approximately the same size of the resulting indexes for all scales, 48-healpix subdivision (Nside=2) is used for scale presets 0 to 2; 12 healpixes (Nside=1) are used for scales 3 to 6; no healpixelization for scales 7 to 19.

The build process may take hours or days, depending on the CPU and disk performance.

Pre-built indexes for EPOCH=2022, MARGIN=2 are available for download at

https://users.castle.unc.edu/~vkoupr/ucac5_anet.zip (14G, w/o tag-along data)

or

https://users.castle.unc.edu/~vkoupr/ucac5_anet_full.zip (30G, w/tag-along data)

dstndstn commented 3 years ago

Thank you very much for this!

And thank you for your patience, I know this has been waiting a long time.

Can I ask you to add a license statement to catalogs/build_ucac5_indexes.sh ? If you are happy with 3-clause BSD, that would be ideal.

vkoupr commented 3 years ago

Thanks Dustin, and apologies from my end this time. 3-clause BSD works just fine, feel free to add a statement to the script.

vkoupr commented 3 years ago

Reopened as #219, license statement added.