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  SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES)
                    Final images                   

Version 20230206
-- Chen-Fatt Lim & Zhen-Kai Gao
---- README written by Zhen-Kai Gao
---- Calibrated with Mairs et al. (2021)

Updates
  2023/08/29
    Correcting the description of `_residual`
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Description of the files
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SCS: STUDIES, Casey et al. (2013), and S2CLS

_450/_850: 450um or 850um

_even/_odd: two interlacing halves for making true noise map

_rm: spikes (>4 sigma in 5x5 box) are replaced with median values (5x5 box).

_mf: matched filtered

_psf: point spread function (PSF) modeled from synthetic PSF

_true_noise: true noise (source-free) map made with jackknife method

_snr: signal-to-noise map calculated by HDU0 / sqrt(HDU1)

_residual: residual map after iteratively subtracting 5% peak-scaled PSFs of
           sources until no peaks remain above 3.5 sigma. Note that the sources
           were not fully subtracted. There are still ~3.5 sigma remaining in
           the residual maps.


Note 1: If a file has both `_rm` and `_mf` suffixes, it indicates that
        the `_rm` process was completed first, followed by the `_mf` step.
Note 2: It is recommended to use files with the `_rm_mf` suffix for
        source extraction and simulations.


Header structure
(excluding `*_psf.fits`, `*_true_noise.fits`,  `*_snr.fits`)

-- HDU 0: Image
-- HDU 1: Variance
---- Note: Instrumental noise = sqrt(HDU 1)
-- HDU 2: Unknown
-- HDU 3: Integration time
-- HDU 4: Weights
-- HDU 5: Unknown

(`*_residual.fits`)
-- HDU 0: Image
-- HDU 1: Instrumental noise (450um) or
          combined noise (instrumental and confusion noise, 850um)


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Contacts: 
Wei-Hao Wang: whwang@asiaa.sinica.edu.tw