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J/ApJ/676/1281        L and T dwarfs in 2MASS/SDSS     (Metchev+, 2008)

A cross-match of 2MASS and SDSS: newly found L and T dwarfs and an estimate of the space density of T dwarfs. Metchev S.A., Kirkpatrick J.D., Berriman G.B., Looper D. <Astrophys. J., 676, 1281-1306 (2008)> =2008ApJ...676.1281M
ADC_Keywords: Stars, dwarfs ; Photometry, infrared ; Photometry, SDSS Keywords: stars: individual (2MASS J00521232+0012172, 2MASS J01040750-0053283, 2MASS J01262109+1428057, 2MASS J09175418+6028065, 2MASS J12144089+6316434, 2MASS J13243553+6358281, 2MASS J15461461+4932114) - stars: low-mass, brown dwarfs - surveys Abstract: We report new L and T dwarfs found in a cross-match of the SDSS Data Release 1 and 2MASS. Our simultaneous search of the two databases effectively allows us to relax the criteria for object detection in either survey and to explore the combined databases to a greater completeness level. We find two new T dwarfs in addition to the 13 already known in the SDSS DR1 footprint. We also identify 22 new candidate and bona fide L dwarfs, including a new young L2 dwarf and a peculiar potentially metal-poor L2 dwarf with unusually blue near-IR colors. These discoveries underscore the utility of simultaneous database cross-correlation in searching for rare objects. Description: Our targets were selected from the 2099deg2 imaging footprint of SDSS DR1. We used the combined optical (from SDSS) and near-IR (from 2MASS) characteristics of cataloged objects to identify suitable targets. This section details our cross-correlation approach and the target selection process. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 86 43 Optical and near-IR photometry of candidate and known ultracool dwarfs table2.dat 55 7 Additional candidates near bright stars table3.dat 55 33 Discarded candidates table5.dat 84 3 Spitzer IRAC observations and photometry of ultracool dwarfs table6.dat 97 24 Spectral types and colors of confirmed and candidate ultracool dwarfs table7.dat 154 15 All Known T Dwarfs in SDSS DR1 and SDSS Flags (tables 7 and 14 of the paper) refs.dat 60 11 References
See also: II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003) J/AJ/123/3409 : SDSS M, L, and T dwarfs (Hawley+, 2002) J/AJ/126/2487 : T dwarfs in the southern hemisphere (Burgasser+, 2003) J/AJ/127/2856 : Brown dwarfs in the 2MASS Survey (Burgasser+, 2004) J/AJ/127/3553 : Land T dwarfs JHK phot. and spectroscopy (Knapp+, 2004) J/AJ/131/2722 : New L and T dwarfs from the SDSS (Chiu+, 2006) J/AJ/134/1162 : 11 new T dwarfs in 2MASS (Looper+, 2007) J/AJ/136/1290 : Ultracool dwarfs from the 2MASS (Reid+, 2008) J/MNRAS/384/1399 : Proper motions of field L and T dwarfs (Jameson+, 2008) J/other/ARA+A/43.195 : L and T dwarf stars (Kirkpatrick, 2005) : SDSS Home Page Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 16 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs, J2000.0) 18 A1 --- l_imag Limit flag in imag 19- 23 F5.2 mag imag SDSS i magnitude (1) 25- 28 F4.2 mag e_imag ? rms uncertainty on imag 29 A1 --- n_imag [d] Note on imag (2) 31- 35 F5.2 mag zmag SDSS z magnitude 37- 40 F4.2 mag e_zmag rms uncertainty on zmag 42 A1 --- l_Jmag Limit flag on Jmag 43- 47 F5.2 mag Jmag 2MASS J magnitude 49- 52 F4.2 mag e_Jmag ? rms uncertainty on Jmag 53 A1 --- n_Jmag [c] Note on Hmag (2) 55 A1 --- l_Hmag Limit flag on Hmag 56- 60 F5.2 mag Hmag 2MASS H magnitude 62- 65 F4.2 mag e_Hmag ? rms uncertainty on Hmag 67 A1 --- l_Ksmag Limit flag on Ksmag 68- 72 F5.2 mag Ksmag 2MASS Ks magnitude 74- 77 F4.2 mag e_Ksmag ? rms uncertainty on Ksmag 78 A1 --- n_Ksmag [c] Note on Ksmag (2) 80- 83 A4 --- SpType MK spectral type (3) 85- 86 I2 --- Ref ? Reference, in refs.dat file
Note (1): SDSS i-band magnitudes are listed if they are brighter than the i∼23.0mag 3σ detection limit. Otherwise, 23.00mag is listed as the lower magnitude limit. Note (2): Notes as follows: c = Below the S/N=5 limit in 2MASS. The photometry was obtained by fitting a PSF to the signal at the known location of the object from the other two 2MASS bands. d = The deblending of the source from a nearby star in SDSS was redone to obtain more reliable photometry. Note (3): The spectral types of all previously known T dwarfs have been updated to conform to the uniform near-IR T dwarf classification scheme of Burgasser et al. (2006, Cat. J/ApJ/637/1067) and are as listed at (Kirkpatrick 2003IAUS..211..189K; Gelino et al. 2004AAS...205.1113G).
Byte-by-byte Description of file: table2.dat table3.dat
Bytes Format Units Label Explanations
1- 16 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs, J2000.0) 18- 55 A38 --- Com Comments
Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 16 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs, J2000.0) 18- 27 A10 "YYYY/MM/DD" Date Observation date 29- 36 I8 --- AOR AOR key 38- 40 I3 s Exp Exposure time 42- 46 F5.2 mag [3.6] Spitzer/IRAC 3.6um magnitude 48- 51 F4.2 mag e_[3.6] rms uncertainty on [3.6] 53- 57 F5.2 mag [4.5] Spitzer/IRAC 4.5um magnitude 59- 62 F4.2 mag e_[4.5] rms uncertainty on [4.5] 64- 68 F5.2 mag [5.8] Spitzer/IRAC 5.8um magnitude 70- 73 F4.2 mag e_[5.8] rms uncertainty on [5.8] 75- 79 F5.2 mag [8.0] Spitzer/IRAC 8.0um magnitude 81- 84 F4.2 mag e_[8.0] rms uncertainty on [8.0]
Byte-by-byte Description of file: table6.dat
Bytes Format Units Label Explanations
1- 16 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs, J2000.0) 18- 29 A12 --- SpType MK spectral type 31 A1 --- l_i-z Limit flag on i-z 32- 35 F4.2 mag i-z SDSS i-z colour index 37- 40 F4.2 mag e_i-z ? rms uncertainty on i-z 42 A1 --- l_z-J Limit flag on z-J 43- 46 F4.2 mag z-J SDSS-2MASS z-J colour index 48- 51 F4.2 mag e_z-J ? rms uncertainty on z-J 53 A1 --- l_J-H Limit flag on J-H 54- 57 F4.2 mag J-H 2MASS J-H colour index 59- 62 F4.2 mag e_J-H ? rms uncertainty on J-H 64 A1 --- l_H-Ks Limit flag on H-Ks 65- 68 F4.2 mag H-Ks ?=- 2MASS H-Ks colour index 70- 73 F4.2 mag e_H-Ks ? rms uncertainty on H-Ks 75 A1 --- l_J-Ks Limit flag on J-Ks 76- 79 F4.2 mag J-Ks ?=- 2MASS J-Ks colour index 81- 84 F4.2 mag e_J-Ks ? rms uncertainty on J-Ks 86 A1 --- l_Jmag Limit flag on Jmag 87- 91 F5.2 mag Jmag 2MASS J magnitude 93- 96 F4.2 mag e_Jmag ? rms uncertainty on Jmag 97 A1 --- n_Jmag [a] a: H-only detection in 2MASS
Byte-by-byte Description of file: table7.dat
Bytes Format Units Label Explanations
1 A1 --- Flag [PN] Previously known or New T dwarf 3- 20 A18 --- SDSS SDSS name (, J2000.0) 22- 37 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs, J2000.0) 39- 48 A10 --- SpType MK spectral type 50- 51 I2 --- Ref Reference, in refs.dat file 53 A1 --- Note [ab] Note on SDSS star (1) 55-154 A100 --- SDSSf SDSS Flags
Note (1): Notes as follows: a = Not recovered in the present cross-match (see Sect. 5.1). b = The field containing this object [run,rerun,camcol,field)=(2125, 40, 1, 49)] is included in the SDSS Data Archive Server (DAS), but data for the object are unavailable through the Catalog Archive Server (CAS).
Byte-by-byte Description of file: refs.dat
Bytes Format Units Label Explanations
1- 2 I2 --- Ref Reference number 4- 22 A19 --- BibCode BibCode 24- 41 A18 --- Aut Author's name 43- 60 A18 --- Com Comments
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 25-Sep-2010
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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