II/358 SkyMapper Southern Sky Survey. DR1.1 (Wolf+, 2018)
SkyMapper Southern Sky Survey: First Data Release (DR1)
Wolf C., Onken C.A., Luvaul L.C., Schmidt B.P., Bessell M.S., Chang S.-W.,
Da Costa G.S., Mackey D., Martin-Jones T., Murphy S.J., Preston T.,
Scalzo R.A., Shao L., S. Jon, Tisserand P., White M.C., Yuan F.
<Publ. Astron. Soc. Australia, 35, 10 (2018)>
=2018PASA...35...10W 2018PASA...35...10W
=2019yCat.2358....0W 2019yCat.2358....0W
ADC_Keywords: Surveys ; Photometry
Keywords: surveys - catalogs - methods: observational - telescopes
Abstract:
We present the first data release of the SkyMapper Southern Survey, a
hemispheric survey carried out with the SkyMapper Telescope at Siding
Spring Observatory in Australia. Here, we present the survey strategy,
data processing, catalogue construction, and database schema. The
first data release dataset includes over 66000 images from the
Shallow Survey component, covering an area of 17200 deg2 in all six
SkyMapper passbands uvgriz, while the full area covered by any
passband exceeds 20000 deg2. The catalogues contain over 285 million
unique astrophysical objects, complete to roughly 18mag in all bands.
We compare our griz point-source photometry with Pan-STARRS1 first
data release and note an RMS scatter of 2%. The internal
reproducibility of SkyMapper photometry is on the order of 1%.
Astrometric precision is better than 0.2arcsec based on comparison
with Gaia first data release. We describe the end-user database,
through which data are presented to the world community, and provide
some illustrative science queries.
Description:
SkyMapper is a purpose-built, optical wide-field survey facility
located at Siding Spring Observatory near Coonabarabran in New South
Wales, Australia, at the edge of the Warrumbungle National Park, which
is Australia's first declared Dark Sky Park. It has a 1.35m primary
mirror and uses a mosaic of 32 CCDs, each having 2048x4096-pixels
with a scale of ∼0.5". The 268 million pixels cover a nearly-square
field-of view measuring 2.4x2.3deg2. After the commissioning phase
ended in March 2014, observations for the Southern Survey started. The
telescope is fully robotic and nightly survey operations are planned
by autonomous scheduler software that can execute the entire survey
without needing human intervention.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 48 6 Properties of SkyMapper DR1 imaging data
smss.sam 746 1000 SkyMapper DR1.1
ccd.dat 401 2124198 Table of CCD-specific exposure information
images.dat 171 66840 Table of exposures and telescope information
mosaic.dat 15 32 CCD positions within the SkyMapper mosaic
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See also:
I/322 : UCAC4 Catalogue (Zacharias+, 2012)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/328 : AllWISE Data Release (Cutri+ 2013)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/335 : Revised catalog of GALEX UV sources, GUVcat_AIS GR6+7 (Bianchi+ 2017)
II/336 : AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016)
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 A1 --- Filter [uvgriz] Filter
3- 5 I3 nm lambdac Central wavelength
6 A1 --- --- [/]
7- 9 I3 nm Dlambda Wavelenght length
11- 15 F5.3 --- Rband Reddening coefficient from a Fitzpatrick
(1999PASP..111...63F 1999PASP..111...63F) law with RV=3.1
17- 18 I2 s Texp Exposure time
20- 24 I5 --- Nimage Number of images (1)
26- 29 F4.1 mag 10slimit 10σ limit (in AB mag)
31- 33 F3.1 arcsec FWHM PSF FWHM (median values among the 66840
individual exposures)
35- 39 F5.2 mag zeropoint Image zeropoint (median values among the 66840
individual exposures) (in AB mag)
41- 43 I3 ct bkgd Background level (median values among the
66840 individual exposures)
45- 48 I4 ct bkgdlimit Upper limit of the background level
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Note (1): Most uvgri images are read-noise limited in the Shallow Survey.
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Byte-by-byte Description of file: smss.sam
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- ObjectId Global unique object ID in the master table
(object_id)
11- 23 F13.9 deg RAdeg Mean ICRS Right Ascension of the object
(raj2000)
25- 37 F13.9 deg DEdeg Mean ICRS Declination of the object
(dej2000)
39- 42 I4 mas e_RAdeg RMS variation around the mean Right
Ascension, in milliarcseconds (e_raj2000)
44- 47 I4 mas e_DEdeg RMS variation around the mean Declination,
in milliarcseconds (e_dej2000)
49- 66 A18 --- SMSS SkyMapper Southern Survey designation of
the form SMSS Jhhmmss.ss±ddmmss.s,
derived from mean ICRS coordinates
(HHMMSS.s+DDMMSS.s) (smss_j)
68- 77 F10.4 d EpMean Mean MJD epoch of the observations
(mean_epoch)
79- 86 F8.4 d e_EpMean ? RMS variation around the mean epoch
(rms_epoch)
88- 97 F10.6 deg GLON Galactic longitude derived from ICRS
coordinates. Not to be used as primary
astrometric reference (glon)
99-108 F10.6 deg GLAT Galactic latitude derived from ICRS
coordinates. Not to be used as primary
astrometric reference (glat)
110-113 I4 --- flags [0/4096] Bitwise OR of Source Extractor
flags across all observations (flags) (1)
115-119 I5 --- Niflags Total number of flagged pixels from bad,
saturated, and crosstalk pixel masks
across all observations (nimaflags)
121-122 I2 --- Ngood [1/91] Number of observations used across
all filters (ngood)
124-125 I2 --- Ngoodmin [0/11] Minimum number of observations used
in any filter (excluding filters with 0
observations) (ngood_min)
127 I1 --- Nchmax [1/5] Maximum number of child sources
combined into this global object_id in any
filter (nch_max)
129-131 I3 --- flagsu [-1/100] Bitwise OR of Source Extractor
flags from u-band measurements in
photometry table (u_flags) (1)
133-137 I5 --- Niflagsu ? Number of flagged pixels from bad,
saturated, and crosstalk pixel masks from
u-band measurements in photometry table
(u_nimaflags)
139-140 I2 --- Ngoodu Number of u-band observations used
(u_ngood)
142-143 I2 --- Nchu [-1/4] Number of u-band child sources
combined into this object_id (u_nch)
145-146 I2 --- Nvisitu [0/35] Number of u-band observations for
which the mean RA/Dec position fell on a
CCD (u_nvisit)
148-149 I2 --- flagsv [-1/45] Bitwise OR of Source Extractor
flags from v-band measurements in
photometry table (v_flags) (1)
151-155 I5 --- Niflagsv ? Number of flagged pixels from bad,
saturated, and crosstalk pixel masks from
v-band measurements in photometry table
(v_nimaflags)
157-158 I2 --- Ngoodv [0/19] Number of v-band observations used
(v_ngood)
160-161 I2 --- Nchv [-1/4] Number of v-band child sources
combined into this object_id (v_nch)
163-164 I2 --- Nvisitv [0/16] Number of v-band observations for
which the mean RA/Dec position fell on a
CCD (v_nvisit)
166-167 I2 --- flagsg [-1/56] Bitwise OR of Source Extractor
flags from g-band measurements in
photometry table (g_flags) (1)
169-172 I4 --- Niflagsg ? Number of flagged pixels from bad,
saturated, and crosstalk pixel masks from
g-band measurements in photometry table
(g_nimaflags)
174-175 I2 --- Ngoodg Number of g-band observations used
(g_ngood)
177-178 I2 --- Nchg [-1/4] Number of g-band child sources
combined into this object_id (g_nch)
180-181 I2 --- Nvisitg [0/17] Number of g-band observations for
which the mean RA/Dec position fell on a
CCD (g_nvisit)
183-184 I2 --- flagsr [-1/60] Bitwise OR of Source Extractor
flags from r-band measurements in
photometry table (r_flags) (1)
186-189 I4 --- Niflagsr ? Number of flagged pixels from bad,
saturated, and crosstalk pixel masks from
r-band measurements in photometry table
(r_nimaflags)
191-192 I2 --- Ngoodr Number of r-band observations used
(r_ngood)
194-195 I2 --- Nchr [-1/5] Number of r-band child sources
combined into this object_id (r_nch)
197-198 I2 --- Nvisitr [0/17] Number of r-band observations for
which the mean RA/Dec position fell on a
CCD (r_nvisit)
200-201 I2 --- flagsi [-1/49] Bitwise OR of Source Extractor
flags from i-band measurements in
photometry table (i_flags) (1)
203-207 I5 --- Niflagsi ? Number of flagged pixels from bad,
saturated, and crosstalk pixel masks from
i-band measurements in photometry table
(i_nimaflags)
209-210 I2 --- Ngoodi [0/16] Number of i-band observations used
(i_ngood)
212-213 I2 --- Nchi [-1/5] Number of i-band child sources
combined into this object_id (i_nch)
215-216 I2 --- Nvisiti [0/12] Number of i-band observations for
which the mean RA/Dec position fell on a
CCD (i_nvisit)
218-219 I2 --- flagsz [-1/50] Bitwise OR of Source Extractor
flags from z-band measurements in
photometry table (z_flags) (1)
221-225 I5 --- Niflagsz ? Number of flagged pixels from bad,
saturated, and crosstalk pixel masks from
z-band measurements in photometry table
(z_nimaflags)
227-228 I2 --- Ngoodz [0/16] Number of z-band observations used
(z_ngood)
230-231 I2 --- Nchz [-1/5] Number of z-band child sources
combined into this object_id (z_nch)
233-234 I2 --- Nvisitz [0/11] Number of z-band observations for
which the mean RA/Dec position fell on a
CCD (z_nvisit)
236-240 F5.3 --- ClassStar Maximum stellarity index from photometry
table (between 0=no star and 1=star)
(class_star)
242-246 F5.2 pix RadrPetro Mean r-band Petrosian radius (radius_petro)
248-253 F6.2 pix a Mean r-band semi-major axis length (a)
255-259 F5.2 pix e_a Error in mean r-band semi-major axis length
(e_a)
261-265 F5.2 pix b Mean r-band semi-minor axis length (b)
267-271 F5.2 pix e_b Error in mean r-band semi-minor axis length
(e_b)
273-278 F6.2 deg PA [-90/90] Mean r-band position angle
(E of N, -90..+90 deg) (pa)
280-285 F6.2 deg e_PA Error in mean r-band position angle (e_pa)
287-292 F6.3 mag uPSF ? Mean u-band PSF magnitude (u_psf)
294-298 F5.3 mag e_uPSF ? Error in u-band PSF magnitude (eupsf)
300-305 F6.3 mag uPetro ? Mean u-band Petrosian magnitude (u_petro)
307-311 F5.3 mag e_uPetro ? Error in u-band Petrosian magnitude
(eupetro)
313-318 F6.3 mag vPSF ? Mean v-band PSF magnitude (v_psf)
320-324 F5.3 mag e_vPSF ? Error in v-band PSF magnitude (evpsf)
326-331 F6.3 mag vPetro ? Mean v-band Petrosian magnitude (v_petro)
333-338 F6.3 mag e_vPetro ? Error in v-band Petrosian magnitude
(evpetro)
340-345 F6.3 mag gPSF ? Mean g-band PSF magnitude (g_psf)
347-351 F5.3 mag e_gPSF ? Error in g-band PSF magnitude (egpsf)
353-358 F6.3 mag gPetro ? Mean g-band Petrosian magnitude (g_petro)
360-364 F5.3 mag e_gPetro ? Error in g-band Petrosian magnitude
(egpetro)
366-371 F6.3 mag rPSF ? Mean r-band PSF magnitude (r_psf)
373-377 F5.3 mag e_rPSF ? Error in r-band PSF magnitude (erpsf)
379-384 F6.3 mag rPetro ? Mean r-band Petrosian magnitude (r_petro)
386-390 F5.3 mag e_rPetro ? Error in r-band Petrosian magnitude
(erpetro)
392-397 F6.3 mag iPSF ? Mean i-band PSF magnitude (i_psf)
399-403 F5.3 mag e_iPSF ? Error in i-band PSF magnitude (eipsf)
405-410 F6.3 mag iPetro ? Mean i-band Petrosian magnitude (i_petro)
412-416 F5.3 mag e_iPetro ? Error in i-band Petrosian magnitude
(eipetro)
418-423 F6.3 mag zPSF ? Mean z-band PSF magnitude (z_psf)
425-429 F5.3 mag e_zPSF ? Error in z-band PSF magnitude (ezpsf)
431-436 F6.3 mag zPetro ? Mean z-band Petrosian magnitude (z_petro)
438-442 F5.3 mag e_zPetro ? Error in z-band Petrosian magnitude
(ezpetro)
444-451 F8.4 mag E(B-V) E(B-V) from Schlegel et al.
(1998ApJ...500..525S 1998ApJ...500..525S) extinction maps at
the ICRS coordinates (ebmv_sfd)
453-456 F4.1 arcsec Prox Distance to next-closest DR1 source
(=60 if no sources within 15 arcsec)
(prox)
458-466 I9 --- ProxId ? object_id of next-closest DR1 source
(prox_id)
468-477 I10 --- EDRId ? object_id of closest Early Data Release
source (edr_id)
479-483 F5.2 arcsec EDRDist ? Distance to closest Early Data Release
source (edr_dist)
485-494 I10 --- 2MASSKey1 ? Unique identifier (ptskey/extkey) of
closest 2MASS source (twomass_key1)
496-500 F5.2 arcsec 2MASSDist1 ? Distance on sky to closest 2MASS source
(twomass_dist1)
502-504 A3 --- 2MASSCat1 [cpsx -] 2MASS catalogue of closest match
(point source PSC, or extended XSC)
(twomass_cat1)
506-515 I10 --- 2MASSKey2 ? Unique identifier (ptskey/extkey) of
second closest 2MASS source (twomass_key2)
517-521 F5.2 arcsec 2MASSDist2 ? Distance on sky to second closest 2MASS
source (twomass_dist2)
523-525 A3 --- 2MASSCat2 [cpsx -] 2MASS catalogue of second closest
match (point source PSC, or extended XSC)
(twomass_cat2)
527-545 I19 --- ALLWISECntr ? Unique identifier (cntr) of closest
AllWISE source (allwise_cntr)
547-551 F5.2 arcsec ALLWISEDist ? Distance on sky to closest AllWISE source
(allwise_dist)
553-561 I9 --- UCAC4Mpos ? Unique identifier (mpos) of closest
UCAC4 source (ucac4_mpos)
563-567 F5.2 arcsec UCAC4Dist ? Distance on sky to closest UCAC4 source
(ucac4_dist)
569-576 I8 --- APASSRecno ? Unique identifier (recno) of closest
APASS DR9 source (only useful for this
copy of APASS) (apass_recno)
578-582 F5.2 arcsec APASSDist ? Distance on sky to closest APASS DR9
source (apass_dist)
584-602 I19 --- Gaiadr1Id ? Unique identifier (source_id) of closest
Gaia DR1 source (gaiadr1id)
604-608 F5.2 arcsec Gaiadr1Dist ? Distance on sky to closest Gaia DR1
source (gaiadr1dist)
610-627 I18 --- PS1dr1Id ? Unique identifier (objID) of closest
Pan-STARRS1 DR1 source (ps1dr1id)
629-633 F5.2 arcsec PS1dr1Dist ? Distance on sky to closest Pan-STARRS1
DR1 source (ps1dr1dist)
635-653 I19 --- GALEXbcsId ? Unique identifier (objid) of closest
GALEX AIS source (Bianchi et al., 2014,
Cat. II/335) (galexbcsid)
655-659 F5.2 arcsec GALEXbcsDist ? Distance on sky to closest GALEX AIS
source (galexbcsdist)
661-679 I19 --- Gaiadr2Id1 ? Unique identifier (source_id) of closest
Gaia DR2 source (gaiadr2id1)
681-685 F5.2 arcsec Gaiadr2Dist1 ? Distance on sky to closest Gaia DR2
source (gaiadr2dist1)
687-705 I19 --- Gaiadr2Id2 ? Unique identifier (source_id) of
second-closest Gaia DR2 source
(gaiadr2id2)
707-711 F5.2 arcsec Gaiadr2Dist2 ? Distance on sky to second-closest
Gaia DR2 source (gaiadr2dist2)
713-718 F6.3 mag (u-v)PSF ? (upsf-vpsf) color, computed by CDS
(uvpsfcolor)
720-725 F6.3 mag (u-g)PSF ? (upsf-gpsf) color, computed by CDS
(ugpsfcolor)
727-732 F6.3 mag (g-r)PSF ? (gpsf-rpsf) color, computed by CDS
(grpsfcolor)
734-739 F6.3 mag (g-i)PSF ? (gpsf-ipsf) color, computed by CDS
(gipsfcolor)
741-746 F6.3 mag (i-z)PSF ? (ipsf-zpsf) color, computed by CDS
(izpsfcolor)
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Note (1): All source detections in the photometry table include the Source
Extractor flags, complemented by additional flags from our data processing in
a higher bit range:
- From Source Extractor:
1 = The object has neighbors, bright and close enough to significantly
bias the photometry, or bad pixels (more than 10% of the integrated
area affected)
2 = The object was originally blended with another one
4 = At least one pixel of the object is saturated (or very close to)
8 = The object is truncated (too close to an image boundary)
16 = Object's aperture data are incomplete or corrupted
32 = Object's isophotal data are incomplete or corrupted
64 = A memory overflow occurred during deblending
128 = A memory overflow occurred during extraction
- From this survey:
512 = Source detections, whose magPSF or magPetro or magapr15 or magapc05
is either NULL or >19 have been flagged in the photometry table.
These may include real objects at very faint detection levels below
2sigma, but are mostly spurious combinations of noise peaks with
bright neighbours.
1024 = Source detections that appear much more concentrated than PSFs and
with small minor axis extend have been flagged in the photometry table
as they may be affected by uncorrected cosmic rays or transient hot
pixels.
2048 = Source detections that are close to stars in the Yale Bright Star
Catalog or close to stars in the Gaia DR1 catalogue wih
photgmean_mag<8 are flagged in the photometry table, based on a
search radius in degrees of log10 (radius)←0.2*Vmag or
-0.2*photgmean_mag, respectively. These are usually affected by
scattered light from the bright star, and have either compromised
photometry or are spurious sources.
4096 = Sources that are known to be insifficiently merged as it happened
around the RA=0/360 border are flagged in the master table.
Only detections with flags<8 are used for the distill into the master
table. Hence, the averaged magnitudes exclude all measurements with
bad flags, and the master source list excludes all objects within the
exclusion zones around bright stars. However, detections with bad
flags or those close to bright stars can still be found in the
photometry table.
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Byte-by-byte Description of file: ccd.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- ImageId Unique image ID as used by the Science
Data Pipeline (image_id)
16- 17 I2 --- CCD [1/32] CCD on which the object was
detected (ccd)
19- 79 A61 --- FileName Filename of image (filename)
81-142 A62 --- MaskName Filename of mask (maskname)
144-160 A17 --- Image Unique image_id in text format (image)
162 A1 --- Filter Filter (filter)
164-179 F16.10 d MJDobs MJD of the exposure (mjd_obs)
181-189 F9.6 arcsec FWHM Median full width at half maximum on the
CCD (fwhm)
191-196 F6.4 --- elong Median elongation (A/B) on the CCD (elong)
198-203 I6 --- Nsatpix Number of saturated pixels on the CCD
(nsatpix)
205-211 F7.4 mag/arcsec+2 SuBr ? Surface brightness estimate on the
CCD (AB) (sb_mag)
213-217 I5 --- Nphot Number of objects found on the CCD
(phot_nstar)
222-242 E21.19 deg covRA1 CCD RA/Dec coverage array (coverage1)
243-263 E21.18 deg covDE1 CCD RA/Dec coverage array (coverage2)
267-286 E20.18 deg covRA2 CCD RA/Dec coverage array (coverage3)
288-308 E21.18 deg covDE2 CCD RA/Dec coverage array (coverage4)
312-331 E20.18 deg covRA3 CCD RA/Dec coverage array (coverage5)
333-353 E21.18 deg covDE3 CCD RA/Dec coverage array (coverage6)
357-377 E21.19 deg covRA4 CCD RA/Dec coverage array (coverage7)
378-401 E24.19 deg covDE4 CCD RA/Dec coverage array (coverage8)
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Byte-by-byte Description of file: images.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 I14 --- ImageId Unique image ID as used by the Science Data
Pipeline (image_id)
16- 20 I5 --- NightMJD Truncated Modified Julian Date at the start
of night (night_mjd)
22- 37 F16.10 d Date Modified Julian Date at the start of the
exposure (date)
39- 58 F20.16 deg RAdeg Right Ascension of the exposure centre
taken from the telescope (ra)
60- 80 F21.17 deg DEdeg Declination of the exposure centre taken
from the telescope (dcl)
82- 85 I4 --- FieldId SkyMapper field ID (field_id)
87- 88 I2 s ExpTime Exposure time (exp_time)
90- 96 F7.5 --- Airmass Airmass of the exposure centre taken from
the telescope (airmass)
98 A1 --- Filter [uvgriz] SkyMapper photometric filter
(u,v,g,r,i,z) (filter)
100-110 E11.9 deg Rotpos Angular position of the instrument rotator
(rotator_pos)
112-121 I10 --- Object Survey/field/image_type identifier
(not unique) (object)
123-124 A2 --- ImageType [fs] Type of image (fs=Fast Survey)
(image_type)
126-132 F7.5 arcsec FWHM Average full width at half maximum for the
exposure (cfwhm)
134-140 F7.5 --- elong Average elongation (A/B) for the exposure
(elong)
142-154 F13.8 ct Bckg Average background counts for the exposure
(background)
156-171 F16.13 mag zpapprox Approximate photometric zeropoint for the
exposure (zpapprox)
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Byte-by-byte Description of file: mosaic.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- CCD CCD number
5- 9 I5 pix x0 Mosaic x-position of CCD pixel
11- 15 I5 pix y0 Mosaic y-position of CCD pixel
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History:
Copied at http://www.mso.anu.edu.au/skymapper/DR1.1/
(End) Patricia Vannier [CDS] 30-Apr-2019