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Last modified: 14 September 2017

URL: http://cxc.harvard.edu/csc/pd1/index.html

CSC 2.0 pd1 Preliminary Detections List (21 March 2017)

[WARNING]
This version has been superseded by the September 2017 release

Please see the September 2017 preliminary detections list (CSC 2.0 pd2).

Contents


Data Access

The March 2017 preliminary detections list is available at:

It contains the results of Maximum Likelihood Estimator (MLE) fits to the candidate source detections. The column definitions and Caveats for this file can be found below. The file contains 362182 detections, with 279549 labelled as SRC_QUALITY = ‘TRUE’ and 82633 (23%) with SRC_QUALITY = ‘MARGINAL’. When split by EXTSRC_CLASS, there are 358382 detections with a value of ‘POINT’, 3183 (0.9%) with ‘EXTENDED’, and 617 (0.2%) with ‘POSSIBLE’. The breakdown by EBAND—the energy band correponding to the measured values—there are 271687 broad band ('b'), 395 ultra-soft ('u'), 26995 soft ('s'), 26524 medium ('m'), 31297 hard ('h'), and 5284 wide (HRC) band ('w') rows; the band definitions are the same as in release 1. There are 354 detections with STREAK_SRC_FLAG = True.

Column Definitions

unix% dmlist preliminary_detlist.fits blocks
 
--------------------------------------------------------------------------------
Dataset: preliminary_detlist.fits
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     Block Name                          Type         Dimensions
--------------------------------------------------------------------------------
Block    1:                                Null        
Block    2: DETLIST                        Table        48 cols x 362182   rows

DETLIST HDU: PRELIMINARY DETECTIONS LIST

Column name Units Comment Data type Notes Example
DETECT_ID Stack_id.component string (29 characters) 'acisfJ0123456p012345_001.0001'
LIKELIHOOD Highest source log likelihood double Highest source likelihood 100.0
SRC_QUALITY Preliminary source quality string (8 characters) Values are 'TRUE' or 'MARGINAL' and are based on comparison of likelihood with draft catalog thresholds. 'TRUE'
EBAND Energy band of maximum likelihood value string (1 character) Energy band corresponding to likelihood value; Science energy band designation (i.e., lower case) not detect energy band: one of 'b', 'u', 's', 'm', 'h', or 'w'. 'b'
THETA arcmin Highest likelihood src model mean off-axis ang double Corresponds to fitted [x,y] 0.0
STREAK_SRC_FLAG Is source on a streak? logical 'F'
RA deg Highest likelihood source model position RA double 20.94000
DEC deg Highest likelihood source model position Dec double 1.39583
ERR_ELLIPSE_RA deg 95% confidence error ellipse position RA double 95% confidence error ellipse RA in deg; 0.0 <= ERR_ELLIPSE_RA < 360.0 20.94000
ERR_ELLIPSE_DEC deg 95% confidence error ellipse position Dec double 95% confidence error ellipse Dec in deg; -90.0 <= SRC_ERR_ELLIPSE_DEC_B <= +90.0 1.39583
ERR_ELLIPSE_R0 arcsec 95% confidence error ellipse semi-major axis double 95% confidence error ellipse semi-major axis radius in arcsec 0.35
ERR_ELLIPSE_R1 arcsec 95% confidence error ellipse semi-minor axis double 95% confidence error ellipse semi-minor axis radius in arcsec 0.30
ERR_ELLIPSE_ANG deg 95% confidence error ellipse smaj axis rotang double 95% confidence error ellipse rotation angle of semi-major axis; 0.0 <= ERR_ELLIPSE_ANG < 180.0; 0.0 along SKY +X, 90.0 along SKY +Y 60.0
SRC_RDATA_B count Raw data counts in ECF90 aperture ACIS b band long 100
SRC_AMPL_B photon/cm**2/s Best fit point src model amplitude ACIS b band double 1.00E-08
SRC_AMPL_LOLIM_B photon/cm**2/s 68% confidence lower limit on SRC_AMPL_B double 9.00E-09
SRC_AMPL_HILIM_B photon/cm**2/s 68% confidence upper limit on SRC_AMPL_B double 1.10E-08
SRC_RDATA_S count Raw data counts in ECF90 aperture ACIS s band long 30
SRC_AMPL_S photon/cm**2/s Best fit point src model amplitude ACIS s band double 3.00E-09
SRC_AMPL_LOLIM_S photon/cm**2/s 68% confidence lower limit on SRC_AMPL_S double 2.00E-09
SRC_AMPL_HILIM_S photon/cm**2/s 68% confidence upper limit on SRC_AMPL_S double 4.00E-09
SRC_RDATA_M count Raw data counts in ECF90 aperture ACIS m band long 50
SRC_AMPL_M photon/cm**2/s Best fit point src model amplitude ACIS m band double 5.00E-09
SRC_AMPL_LOLIM_M photon/cm**2/s 68% confidence lower limit on SRC_AMPL_M double 4.00E-10
SRC_AMPL_HILIM_M photon/cm**2/s 68% confidence upper limit on SRC_AMPL_M double 6.00E-09
SRC_RDATA_H count Raw data counts in ECF90 aperture ACIS h band long 20
SRC_AMPL_H photon/cm**2/s Best fit point src model amplitude ACIS h band double 2.00E-09
SRC_AMPL_LOLIM_H photon/cm**2/s 68% confidence lower limit on SRC_AMPL_H double 1.00E-09
SRC_AMPL_HILIM_H photon/cm**2/s 68% confidence upper limit on SRC_AMPL_H double 3.00E-09
SRC_RDATA_W count Raw data counts in ECF90 aperture HRC w band long TNULL
SRC_AMPL_W photon/cm**2/s Best fit point src model amplitude HRC w band double NaN
SRC_AMPL_LOLIM_W photon/cm**2/s 68% confidence lower limit on SRC_AMPL_W double NaN
SRC_AMPL_HILIM_W photon/cm**2/s 68% confidence upper limit on SRC_AMPL_W double NaN
EBAND_EXT Energy band of extended source model properties string (1 character) Energy band corresponding to reported extended source parameters: set to ' ' if not evaluated, otherwise one of 'b', 'u', 's', 'm', 'h', or 'w'. 's'
EXTSRC_CLASS Extended source classification string (8 characters) 'POINT', 'EXTENDED', or 'POSSIBLE' 'POSSIBLE'
EXT_RDATA count Raw data counts in source region aperture long 40
EXT_AMPL photon/cm**2/s Best fit ext src model amplitude double 2.50E-09
EXT_AMPL_LOLIM photon/cm**2/s 68% confidence lower limit on EXT_AMPL double 1.50E-09
EXT_AMPL_HILIM photon/cm**2/s 68% confidence upper limit on EXT_AMPL double 3.50E-09
EXT_SMAJ arcsec Best fit extended source model semi-major axis double 5.0
EXT_SMIN arcsec Best fit extended source model semi-minor axis double 3.5
EXT_ROTANG deg Best fit extended source model rotation angle double 30.0
EXT_SMAJ_LOLIM arcsec 68% confidence lower limit on EXT_SMAJ double 4.5
EXT_SMAJ_HILIM arcsec 68% confidence upper limit on EXT_SMAJ double 5.5
EXT_SMIN_LOLIM arcsec 68% confidence lower limit on EXT_SMIN double 3.0
EXT_SMIN_HILIM arcsec 68% confidence upper limit on EXT_SMIN double 4.0
EXT_ROTANG_LOLIM deg 68% confidence lower limit on EXT_ROTANG double 10.0
EXT_ROTANG_HILIM deg 68% confidence upper limit on EXT_ROTANG double 50.0

Caveats

  1. This version of the preliminary detections table is constructed from a partial run of Chandra observations that will be included in release 2.0 of the CSC, and includes 362,182 detections from 7,247 observation stacks.

  2. Roughly 0.5% of observation stacks have not yet completed processing or are awaiting manual quality assurance review. The list of observation stacks not included in this version of the preliminary detections table is reported in Table 1.

  3. The preliminary detections table includes detections and not sources. In particular:

    • Sources that are detected in multiple observation stacks are not combined in any way. Each detection is reported separately.

    • Off-axis detections from one observation stack may correspond to multiple detections in another observation stack where the detections are on-axis. These matches will be resolved in second major catalog processing phase.

    • As a consequence, source names have not yet been assigned. Instead, an identifier has been provided for each detection. Note that the identifiers included in this version of the preliminary detections table may not match the identifiers included in the August 2015 version of the table because a significant fraction of the observation stacks required complete reprocessing since then.

  4. Detections:

    • A small number of compact detections identified as definitely or possibly extended (extsrc_class = ‘EXTENDED’ or ‘POSSIBLE’) may consist of a close association (typically a pair or triple) of point detections. These will not be corrected in the CSC 2.0 release.

    • Detections that are extremely piled-up (cratered) have likelihood = +Inf. A very small number (of order 10) of these detections are incorrectly classified and will be corrected in the CSC 2.0 release.

  5. Positions and position errors:

    • Position errors are typically reported in the form of an error ellipse that records the statistical confidence limits derived from a Markov chain Monte Carlo (MCMC) analysis of the fitted source model. The ellipse angle in the preliminary detections table defines 0° along the +X axis (i.e., the same definition as used by the DS9 imager); however, true astronomical position angles (measured from North through East) will be used in the CSC 2.0 release.

    • If the MCMC analysis did not converge (typically due to low S/N) then a circularly symmetric estimate of the position errors is provided. For a small number (~240) detections, this estimate is missing and the reported errors are blank. This will be corrected in the CSC 2.0 release of the catalog.

    • Reported position errors do not include the absolute uncertainty in the astrometry relative to the reference frame. The systematic error derived from release 1 of the catalog (0.16″ radial) should be a reasonable estimate of this value, and this number should be added in quadrature to the reported position errors to get the best estimate of the absolute position uncertainty on the sky.

  6. Aperture photometry:

    • Fit amplitudes are provided as a proxy for the detection flux: while these are expected to be reasonably reliable for relative photometry on a statistical basis, systematic uncertainties for a single detection basis may be large. As a guide to possible biases, Figure 1 compares - for a subset of the pd1 release - the fit amplitudes to aperture photometry calculated using the Bayesian X-ray photometry scheme that will be used in the CSC 2.0 release.

    • Reported fit amplitudes are incorrect (significantly too large) for one or more energy bands for ~3,500 detections. The broad band flux is equal to the sum of the soft, medium, and hard band fluxes. These cases can be identified by comparing the sum of the reported soft, medium, and hard band fit amplitudes with the reported broad band fit amplitude.

  7. Miscellaneous notes:

    • The detections have undergone all standard quality assurance reviews, and except for the caveats noted herein should match those that will be included in the CSC 2.0 release.

    • Detections are categorized as ‘MARGINAL’ or ‘TRUE’ (recorded in the SRC_QUALITY column) depending on their likelihood. These categorizations are those that will appear in the CSC 2.0 release.

    • Only point and compact detections are included. Extended (“convex hull”) detections are not included in the preliminary detections table, but will appear in the CSC 2.0 release.

    • Detections near the edges of the field of each observation, or near the gap between adjacent back-illuminated and front-illuminated ACIS-S CCDs, or on bright ACIS readout streaks, are masked out. This is intentional because these detector areas had an excessively high false source rate in release 1 of the catalog. In the CSC 2.0 release, the detection sensitivity will be set to zero in these areas. However, detection sensitivity information will not be available until completion of the second major catalog processing phase. There may be a higher-than-nominal false detection rate either near these masked-out regions or close to areas of extended emission. If this is a concern, we recommend that users review images of the individual observations from the Chandra Data Archive.

Table 1: List of Observation Stacks not included in the current version of the Preliminary Detections Table.
Area of sky Stack ID Number of observations Approximate exposure time, in ks Observations
MACS0011.7-1523 acisfJ0011407m152147_001 1 40 6105
Perseus Cluster (Abell 426) acisfJ0319443p413138_001 11 800 4946, 4947, 4948, 4949, 4950, 4951, 4952, 4953, 6139, 6145, 6146
Crab Nebula acisfJ0534316p220052_001 45 769, 770, 771, 772, 773, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 13139, 13146, 13147, 13150, 13151, 13152, 13153, 13154, 13204, 13205, 13206, 13207, 13208, 13209, 13210, 13750_001, 13751, 13752, 13754, 13755, 13756, 13757, 14416, 14458, 14678, 14679, 14680, 14681, 14682, 14685, 16245, 16257
acisfJ0534322p215837_001 1 4607
acisfJ0534340p221143_001 1 20 2798
Orion Trapezium cluster acisfJ0535165m052323_001 11 990 1522, 3498, 3744, 4373, 4374, 4395, 4396, 13637, 14334, 14335, 15546
30 Doradus acisfJ0538411m690602_001 30 1520 5906, 7263, 7264, 16192, 16193, 16194, 16195, 16196, 16197, 16198, 16200, 16201, 16202, 16203, 16442, 16443, 16444, 16612, 16615, 16616, 16617, 16621, 16640, 17312, 17413, 17414, 17486, 17544, 17545, 17555, 17561, 17562
M82 (North West) acisfJ0955442p694142_001 1 120 10543
The Great Nebula in Carina acisfJ1047086m600555_001 1 60 9485
NGC 3377 acisfJ1047429p135930_001 1 40 2934
NGC 3384 acisfJ1048174p123757_001 3 140 4692, 11782, 13829
NGC 3603 acisfJ1115042m611530_001 5 520 633, 12328, 12329, 12330, 13162
G292.0+1.8 acisfJ1124354m591559_001 6 540 6677, 6678, 6679, 6680, 8221, 8447
G299.2-2.9 acisfJ1214458m652812_001 9 660 11098, 11099, 11100, 11101, 13157, 13158, 13159, 13160, 13187
M87 acisfJ1230487p122327_001 44 340 6186, 7348, 7349, 7350, 7351, 7352, 7353, 7354, 8510, 8511, 8512, 8513, 8514, 8515, 8516, 8517, 8575, 8576, 08577, 8578, 8579, 8580, 8581, 10282, 10283, 10284, 10285, 10286, 10287, 10288, 11512, 11513, 11514, 11515, 11516, 11517, 11518, 11519, 11520, 13964, 13965, 14973, 14974, 16042
Centaurus A acisfJ1325492m425819_001 4 120 7800, 10723, 10726, 12155
acisfJ1325538m425945_001 2 190 7798, 07799
M51 acisfJ1330038p471057_001 7 770 13812, 13813, 13814, 13815, 13816, 15496, 15553
Q1422+231 acisfJ1424365p225555_001 3 80 367, 1631, 12801
NGC 5813 acisfJ1501079p014443_001 7 510 12951, 12952, 12953, 13246, 13247, 13253, 13255
RCW89 acisfJ1513347m590144_001 2 90 5562, 9138
Abell 2063 acisfJ1523045p083741_001 4 60 4187, 5795, 6262, 6263
F16090-0139 acisfJ1611413m014634_001 1 10 4113
Ophiuchus cluster acisfJ1712268m232325_001 1 50 3200
NGC 6302 acisfJ1713442m370615_001 2 30 12370, 14364
G350.1-0.3 acisfJ1721036m372619_001 1 90 10102
Sagittarius A* acisfJ1745401m290028_001 70 2460 1561, 2943, 2951, 2952, 2953, 2954, 3392, 3393, 3549, 3663, 3665, 4683, 4684, 5360, 5950, 5951, 5952, 5953, 5954, 6113, 6363, 6639, 6640, 6641, 6642, 6643, 6644, 6645, 6646, 7554, 7555, 7556, 7557, 7558, 7559, 9169, 9170, 9171, 9172, 9173, 9174, 10556, 11843, 13016, 13017, 14702, 14703, 14704_001, 14941, 14942, 14943, 14944, 14945, 14946, 15041, 15042, 15043, 15044, 15045, 16210, 16211, 16212, 16213, 16214, 16215, 16216, 16217, 16218, 16508, 16597
G1.9+0.3 acisfJ1748454m271007_001 15 1310 6708, 8521, 10111, 10112, 10928, 10930, 12689, 12690, 12691, 12692, 12693, 12694, 12695, 13407, 13509
HESS J1800-240B (W28) acisfJ1800276m240230_001 1 10997
Kes 75 acisfJ1846224m025742_001 4 6686, 7337, 7338, 7339
3C397 acisfJ1907327p070619_001 1 1042
Ar Lac (calibration target) acisfJ2208400p454446_001 4 9686, 9687, 9688, 9689
Abell 2465 acisfJ2239250m054359_001 2 14010, 15547
Abell 2537 acisfJ2308192m020958_001 1 9372
Cassiopeia A acisfJ2323333p584655_001 3 1547, 9117, 9773
acisfJ2323335p585100_001 6 4634, 4635, 5320, 10643, 14229, 14480
acisfJ2323390p585033_001 6 4636, 4637, 4638, 4639, 5319, 6068
R Aquarii acisfJ2343503m151712_001 3 651, 4546, 5438
M31 (North) hrcfJ0044069p414315_001 15 30 279, 282, 283, 284, 285, 287, 288, 289, 290, 1571, 1572, 2907, 2908, 2909, 2910
[Thumbnail image: There is a strong linear correlation between the Bayesian photometry value (X axis) and the fitted source amplitude (Y axis), with the scatter being lower for the TRUE sources compared to the MARGINAL ones.]

[Version: full-size, PDF]

[Print media version: There is a strong linear correlation between the Bayesian photometry value (X axis) and the fitted source amplitude (Y axis), with the scatter being lower for the TRUE sources compared to the MARGINAL ones.]

Comparison of source photometry

Correlation between the fitted source amplitude and detailed Bayesian X-ray aperture photometry analysis for 14,360 detections, in the ACIS broad energy band. Note that the correlation is somewhat worse for faint detections categorized as ‘MARGINAL’. The correlation has not been demonstrated for energy bands other than the ACIS broad band; however, we expect that the correlations in the other bands should be similar.


Last modified: 14 September 2017
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