Ancillary targets are defined by the ancillary science teams. Depending on the tiling chunk, the appropriate description files referenced below can be found in $BOSSTILELIST_DIR/inputs/ancillary/bossN.
maskbits ANCILLARY_TARGET1 0 AMC # defined in blake_boss_v2.descr maskbits ANCILLARY_TARGET1 1 FLARE1 # defined in blake_boss_v2.descr maskbits ANCILLARY_TARGET1 2 FLARE2 # defined in blake_boss_v2.descr maskbits ANCILLARY_TARGET1 3 HPM # defined in blake_boss_v2.descr maskbits ANCILLARY_TARGET1 4 LOW_MET # defined in blake_boss_v2.descr maskbits ANCILLARY_TARGET1 5 VARS # defined in blake_boss_v2.descr maskbits ANCILLARY_TARGET1 6 BLAZGVAR # defined in brandtxmm-andersonblazar-merged.descr maskbits ANCILLARY_TARGET1 7 BLAZR # defined in brandtxmm-andersonblazar-merged.descr maskbits ANCILLARY_TARGET1 8 BLAZXR # defined in brandtxmm-andersonblazar-merged.descr maskbits ANCILLARY_TARGET1 9 BLAZXRSAM # defined in brandtxmm-andersonblazar-merged.descr maskbits ANCILLARY_TARGET1 10 BLAZXRVAR # defined in brandtxmm-andersonblazar-merged.descr maskbits ANCILLARY_TARGET1 11 XMMBRIGHT # defined in brandtxmm-andersonblazar-merged.descr maskbits ANCILLARY_TARGET1 12 XMMGRIZ # defined in brandtxmm-andersonblazar-merged.descr maskbits ANCILLARY_TARGET1 13 XMMHR # defined in brandtxmm-andersonblazar-merged.descr maskbits ANCILLARY_TARGET1 14 XMMRED # defined in brandtxmm-andersonblazar-merged.descr maskbits ANCILLARY_TARGET1 15 FBQSBAL # defined in master-BAL-targets.descr maskbits ANCILLARY_TARGET1 16 LBQSBAL # defined in master-BAL-targets.descr maskbits ANCILLARY_TARGET1 17 ODDBAL # defined in master-BAL-targets.descr maskbits ANCILLARY_TARGET1 18 OTBAL # defined in master-BAL-targets.descr maskbits ANCILLARY_TARGET1 19 PREVBAL # defined in master-BAL-targets.descr maskbits ANCILLARY_TARGET1 20 VARBAL # defined in master-BAL-targets.descr maskbits ANCILLARY_TARGET1 21 BRIGHTGAL # defined in bright_gal_v3.descr maskbits ANCILLARY_TARGET1 22 QSO_AAL # defined in qsoals_v2.descr maskbits ANCILLARY_TARGET1 23 QSO_AALS # defined in qsoals_v2.descr maskbits ANCILLARY_TARGET1 24 QSO_IAL # defined in qsoals_v2.descr maskbits ANCILLARY_TARGET1 25 QSO_RADIO # defined in qsoals_v2.descr maskbits ANCILLARY_TARGET1 26 QSO_RADIO_AAL # defined in qsoals_v2.descr maskbits ANCILLARY_TARGET1 27 QSO_RADIO_IAL # defined in qsoals_v2.descr maskbits ANCILLARY_TARGET1 28 QSO_NOAALS # defined in qsoals_v2.descr maskbits ANCILLARY_TARGET1 29 QSO_GRI # defined in sdss3_fan.descr maskbits ANCILLARY_TARGET1 30 QSO_HIZ # defined in sdss3_fan.descr maskbits ANCILLARY_TARGET1 31 QSO_RIZ # defined in sdss3_fan.descr maskbits ANCILLARY_TARGET1 32 RQSS_SF # defined in rqss090630.descr maskbits ANCILLARY_TARGET1 33 RQSS_SFC # defined in rqss090630.descr maskbits ANCILLARY_TARGET1 34 RQSS_STM # defined in rqss090630.descr maskbits ANCILLARY_TARGET1 35 RQSS_STMC # defined in rqss090630.descr maskbits ANCILLARY_TARGET1 36 SN_GAL1 # defined in ancillary_supernova_hosts_v5.descr maskbits ANCILLARY_TARGET1 37 SN_GAL2 # defined in ancillary_supernova_hosts_v5.descr maskbits ANCILLARY_TARGET1 38 SN_GAL3 # defined in ancillary_supernova_hosts_v5.descr maskbits ANCILLARY_TARGET1 39 SN_LOC # defined in ancillary_supernova_hosts_v5.descr maskbits ANCILLARY_TARGET1 40 SPEC_SN # defined in ancillary_supernova_hosts_v5.descr maskbits ANCILLARY_TARGET1 41 SPOKE # defined in BOSS_slowpokes_v2.descr maskbits ANCILLARY_TARGET1 42 WHITEDWARF_NEW # defined in WDv5_eisenste_fixed.descr maskbits ANCILLARY_TARGET1 43 WHITEDWARF_SDSS # defined in WDv5_eisenste_fixed.descr maskbits ANCILLARY_TARGET1 44 BRIGHTERL # defined in sd3targets_final.descr maskbits ANCILLARY_TARGET1 45 BRIGHTERM # defined in sd3targets_final.descr maskbits ANCILLARY_TARGET1 46 FAINTERL # defined in sd3targets_final.descr maskbits ANCILLARY_TARGET1 47 FAINTERM # defined in sd3targets_final.descr maskbits ANCILLARY_TARGET1 48 RED_KG # defined in redkg.descr maskbits ANCILLARY_TARGET1 49 RVTEST # defined in redkg.descr
No target flags defined yet.
Magnitudes within the SDSS are expressed as inverse hyperbolic sine (or "asinh") magnitudes, described in detail by Lupton, Gunn, & Szalay (1999). They are sometimes referred to informally as luptitudes.
The transformation from linear nanomaggie measurements to asinh magnitudes is designed to be virtually identical to the standard astronomical magnitude at high signal-to-noise ratio, but to behave reasonably at low signal-to-noise ratio and even at negative values of flux, where the logarithm in the Pogson magnitude fails.
The relation between detected flux f in maggies and asinh magnitude m is:
m = -(2.5/ln(10))*[asinh(f/2b)+ln(b)].
The parameter b is a softening parameter measured in maggies, and for the [u, g, r, i, z] bands has the values
[1.4, 0.9, 1.2, 1.8, 7.4] × 10-10
(Table 21 in Stoughton et al. 2002, the EDR paper). These choices reflect the typical 1-sigma noise of the sky in a point spread function sized aperture in 1 arcsec seeing.
Of some use may be the resulting asinh magnitudes of zero flux objects, which in each band are:
[24.6347, 25.1144, 24.8020, 24.3618, 22.8269]
and the asinh magnitude at which the difference between these magnitudes and Pogson magnitudes exceeds 1 percent:
[22.12, 22.60, 22.29, 21.85, 20.32]
For IDL users, the photoop product contains the routine "sdss_flux2lups", which converts fluxes in nanomaggies into asinh magnigtudes.
For main survey quasars, fibers are assigned to objects with any of these
BOSS_TARGET1 flags set:
QSO_BONUS_MAIN QSO_KNOWN_MIDZ QSO_FIRST_BOSS
For main survey galaxies, fibers are assigned to objects with any of these
BOSS_TARGET1 flags set:
GAL_LOZ GAL_CMASS GAL_CMASS_SPARSE
masktype BOSS_TARGET1 64 # galaxies maskbits BOSS_TARGET1 0 GAL_LOZ # low-z lrgs maskbits BOSS_TARGET1 1 GAL_CMASS # dperp > 0.55, color-mag cut maskbits BOSS_TARGET1 2 GAL_CMASS_COMM # dperp > 0.55, commissioning color-mag cut maskbits BOSS_TARGET1 3 GAL_CMASS_SPARSE # GAL_CMASS_COMM & (!GAL_CMASS) & (i < 19.9) sparsely sampled maskbits BOSS_TARGET1 7 GAL_CMASS_ALL # GAL_CMASS and the entire sparsely sampled region #maskbits BOSS_TARGET1 3 GAL_GRRED # red in g-r #maskbits BOSS_TARGET1 4 GAL_TRIANGLE # GAL_HIZ and !GAL_CMASS #maskbits BOSS_TARGET1 5 GAL_LODPERP # Same as hiz but between dperp00 and dperp0 maskbits BOSS_TARGET1 6 SDSS_GAL_KNOWN # Matches to existing ZWARNING=0 SDSS galaxy spectra # qsos maskbits BOSS_TARGET1 10 QSO_CORE # restrictive qso selection: commissioning only maskbits BOSS_TARGET1 11 QSO_BONUS # permissive qso selection: commissioning only maskbits BOSS_TARGET1 12 QSO_KNOWN_MIDZ # known qso between [2.2,9.99] maskbits BOSS_TARGET1 13 QSO_KNOWN_LOHIZ # known qso outside of miz range. never target maskbits BOSS_TARGET1 14 QSO_NN # Neural Net that match to sweeps/pass cuts maskbits BOSS_TARGET1 15 QSO_UKIDSS # UKIDSS stars that match sweeps/pass flag cuts maskbits BOSS_TARGET1 16 QSO_KDE_COADD # kde targets from the stripe82 coadd maskbits BOSS_TARGET1 17 QSO_LIKE # likelihood method maskbits BOSS_TARGET1 18 QSO_FIRST_BOSS # FIRST radio match maskbits BOSS_TARGET1 19 QSO_KDE # selected by kde+chi2 maskbits BOSS_TARGET1 40 QSO_CORE_MAIN # Main survey core sample maskbits BOSS_TARGET1 41 QSO_BONUS_MAIN # Main survey bonus sample # standards maskbits BOSS_TARGET1 20 STD_FSTAR # standard f-stars maskbits BOSS_TARGET1 21 STD_WD # white dwarfs maskbits BOSS_TARGET1 22 STD_QSO # qso # template stars maskbits BOSS_TARGET1 32 TEMPLATE_GAL_PHOTO # galaxy templates maskbits BOSS_TARGET1 33 TEMPLATE_QSO_SDSS1 # QSO templates maskbits BOSS_TARGET1 34 TEMPLATE_STAR_PHOTO # stellar templates maskbits BOSS_TARGET1 35 TEMPLATE_STAR_SPECTRO # stellar templates (spectroscopically known)
BOSSTILE_STATUS is set for each target in the final-bossN.fits files by the bosstile product. It records the fate of each input target during the tiling process.
maskbits BOSSTILE_STATUS 0 TILED # assigned a fiber maskbits BOSSTILE_STATUS 1 NAKED # not in area covered by tiles maskbits BOSSTILE_STATUS 2 BOSSTARGET # in the high priority set of targets maskbits BOSSTILE_STATUS 3 DECOLLIDED # in the decollided set of high priority maskbits BOSSTILE_STATUS 4 ANCILLARY # in the lower priority, ancillary set maskbits BOSSTILE_STATUS 5 POSSIBLE_KNOCKOUT # knocked out of at least one tile by BOSSTARGET maskbits BOSSTILE_STATUS 6 IGNORE_PRIORITY # priority exceeds max (ANCILLARY only) maskbits BOSSTILE_STATUS 7 TOOBRIGHT # fibermag too bright maskbits BOSSTILE_STATUS 9 CENTERPOST # 92 arcsec collision with center post maskbits BOSSTILE_STATUS 10 REPEAT # included on more than one tile maskbits BOSSTILE_STATUS 11 FILLER # was a filler (not normal repeat) maskbits BOSSTILE_STATUS 12 NOT_TILED_TARGET # though in input file, not a tiled target maskbits BOSSTILE_STATUS 13 OUT_OF_BOUNDS # outside bounds for this sort of target (for restricted QSO geometry, e.g.) maskbits BOSSTILE_STATUS 14 BAD_CALIB_STATUS # bad CALIB_STATUS
The CALIB_STATUS bitmask describes the calibration status of a field and/or object.
The cloud camera status is built from an analysis of the 10 micron cloud cameras used at the APO site. The full history is stored in two files:
The software generating these files from the raw IRCAM data is in $PHOTOOP_DIR/pro/ircam.
In individual files in the reductions the CLOUDCAM flag gets set with the following possible values:
Corrected survey coordinates are usually referred to as "ceta" and "clambda". They are very similar to the regular SDSS survey coordinates (eta and lambda).
Corrected survey coordinates are an ordinary spherical coordinate system with ceta corresponding to a longitude (like phi) and clambda corresponding to a latitude (like 90-theta). ceta is usually taken to span the range [-180., 180.], and clambda to span the range [-90., 90]. (The only substantive difference from eta/lambda is in the choice of these ranges).
To fully specify the rotation of the coordinates use the rules:
(ceta,clambda)=(0,90.) corresponds to (ra,dec)=(275.,0.) (ceta,clambda)=(57.5,0.) corresponds to (ra,dec)=(0.,90.) (ceta,clambda)=(0.,0.) corresponds to (ra,dec)=(185.,32.5)
All values are in degrees, and here (ra,dec) is on the J2000 system.
Software to convert from ceta/clambda to ra/dec is provided in idlutils for IDL users (in the code "csurvey2eq" and "eq2csurvey"), as well as in the SDSSPix software package distributed by Ryan Scranton.
The fieldID parameter is an integer uniquely identifying a detection in the photo catalog. It needs to be cast as unsigned 64-bit, though in many files we waste a few bytes and write it as an string to avoid FITS compliance issues.
The bits are assigned exactly as for objid, but setting the object id within the field to 0.
For IDL users, the function "sdss_fieldid()" in photoop will convert RUN, CAMCOL, FIELD, RERUN into a properly formatted fieldID.
The RESOLVE_STATUS flag describes what happened to this field during frames. In the fpFieldStat files it is returned as the "status" variable.
It is an integer, which can take the following values, with the associated meanings:
This information was inferred from $PHOTO_DIR/include/phFramestat.h.
The IMAGE_STATUS bitmask describes the quality of the observations of the field.
No target flags defined yet.
In SDSS-III, we express all fluxes in terms of nanomaggies, which are a convenient linear unit. They are 109 times the ratio of the source to the AB standard source in each band (3631 Jy).
To relate these quantities to standard magnitudes, an object with flux f in nMgy has magnitude:
m = [22.5 mag] − 2.5 log 10 f .
Gives the type of object assignment made by the photo pipeline, with possible values:
For IDL users, the function "sdss_objid()" in photoop will convert RUN, CAMCOL, FIELD, ID, RERUN into a properly formatted objID.
The objID parameter is an integer uniquely identifying a detection in the photo catalog. It needs to be cast as unsigned 64-bit, though in many files we waste a few bytes and write it as an string to avoid FITS compliance issues.
The bits are assigned in objid as follows:
For IDL users, the function "sdss_objid()" in photoop will convert RUN, CAMCOL, FIELD, ID, RERUN into a properly formatted objID.
The RESOLVE_STATUS bitmask describes the resolve status of a field and/or object: whether it is a primary survey object, a secondary observation, or the "best" observation but in an area not considered primary at all.
To get a unique set of objects across the whole survey, search for objects with SURVEY_PRIMARY set.
The following bits are exclusive, and exactly one of these bits will be set for each object: RUN_PRIMARY, RUN_RAMP, RUN_OVERLAPONLY, RUN_IGNORE, RUN_DUPLICATE. In addition, RUN_EDGE can be set for any object. If analyzing only a single run, one typically wants all unique objects within a run that are not at the edge of field. To select such objects, the RUN_PRIMARY bit should be set, and the RUN_EDGE bit should not be set.
Only objects that pass RUN_PRIMARY (or have RUN_RAMP set and are near the edge) are considered for SURVEY_PRIMARY. That trims out the "bright", "parent" and "sky" objects.
The "score" is a numerical rating for the quality of an SDSS imaging field. It ranges from 0 to 1. Within this range, values have the following meaning:
"Binned" data typically refers to "Apache Wheel" rapid scans performed for the purposes of ubercalibration.
The formula for this score is:
sensitivity = (0.7 / (psf_fwhm[2] * sqrt(skyflux[2]))) < 0.4 score = QEXIST * (0.1 + 0.5 * QPHOT + sensitivity) * (xbin GT 1 : 0.1:1)
where "psf_fwhm" is in arcsec and "skyflux" is in nanomaggies/arcsec2. The sensitivity is bounded between [0, 0.4] and is proportional to the theoretical point-source sensitivity in the r-band.
"QEXIST" is 1 if the field "exists", which is to say:
PHOTO_STATUS = 0 BAD_ROTATOR not set in any band BAD_ASTROM not set in any band BAD_FOCUS not set in any band SHUTTERS not set in any band
and 0 otherwise.
"QPHOT" is 1 if the field is photometric, which is to say:
Darker than 12 deg twi in r-band
PSP_STATUS is <= 2 (in the lower 5 bits) in all bands
(i.e. PSP_FIELD_NOPSF,PSP_FIELD_ABORTED,PSP_FIELD_MISSING,
PSP_FIELD_OE_TRANSIENT are all not set)
CLOUDY not set in any band
UNKNOWN (possibly cloudy) not set in any band
FF_PETALS not set in any band
DEAD_CCD not set in any band
NOISY_CCD not set in any band
For binned scans, however, there is no cut on PSP_STATUS.
There are several SDSS PSF models that are calculated.
The composite PSF is estimated by the PSP pipeline and consists of
PSF = a1 exp(-r2/2s12) + a2 exp(-r2/2s22) + p (1+r2/sp2b)-b/2
segue2_target1 and segue2_target2 are 64-bit integers. They are bitmasks, and each bit describes the status of the object with respect to one of the target selection criteria. segue2_target1 is the science selection bitmask. segue2_target2 describes the standard, calibration and special target categories
For some examples of how to use these target selection bitmasks, see the SEGUE-2 wiki page attachment Segue2 Target Bits for the non-hexidecimally-minded.
For more details about the selection criteria, see the the SEGUE-2 wiki page attachment on target selection cuts.
No target flags defined yet.
The specObjID parameter is an integer uniquely identifying a spectrum in the spectroscopic catalog. It needs to be cast as unsigned 64-bit, though in many files we waste a few bytes and write it as an string to avoid FITS compliance issues.
The bits are assigned in specobjid as follows:
Note that this definition differs from that in DR7. For IDL users, the function "sdss_specobjid()" in sas will calculate this value. Note that implicitly MJD>=50000.
TAI is the time given in units of seconds, and is determined at APO using GPS-based NTP servers.
To get the TAI time in Modifed Julian Date format, use MJD = TAI/(24*3600).
In practice at APO, there are several definition of MJD that can differ by of order seconds; when TAI is available it is the more reliable time source.