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J/AJ/124/2164       SDSS photometry in the field of L1457    (Andersson+, 2002)

A spectroscopic and photometric survey of stars in the field of L1457: a new distance determination. Andersson B.-G., Idzi R., Uomoto A., Wannier P.G., Chen B., Jorgensen A.M. <Astron. J. 124, 2164 (2002)> =2002AJ....124.2164A
ADC_Keywords: Molecular clouds ; Photometry, SDSS ; Photometry, UBV Keywords: ISM: individual (L1457) Abstract: We present a spectroscopic and photometric survey of a sample of field stars in the region of the molecular cloud L1457. High-quality coude feed spectra, together with five-band photometry in the Sloan Digital Sky Survey system and near-infrared archival data from the Two Micron All Sky Survey, are used to derive color excesses and distances for the stars. Based on these data, a new distance estimate of 360±30pc is derived for the cloud, supporting recent results by K.L. Luhman, 2001ApJ...560..287L. The data further indicate that the north-south velocity gradient seen in the millimeter-wave CO data is mirrored in a distance gradient, with the northern part of the cloud being closer to us. A second, less opaque, layer of extinction is detected at ∼80pc. This distance is consistent with the earlier distance estimates to the cloud, based on Na I absorption. We identify this layer with the wall of the hot Local Bubble. Hence, the dense cloud is not, as previously thought, associated with the Local Bubble. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 84 172 Observational Data for Stars in the L1457 Field table3.dat 96 172 Derived Data for Stars in the L1457 Field table4.dat 57 68 Rejected stars
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 9 A9 --- GSC Guide Star Catalog identification number 11 A1 --- f_GSC [T] Flag GSC (1) 13 I1 h RAh Hour of Right Ascension (J2000) 15- 16 I2 min RAm Minute of Right Ascension (J2000) 18- 21 F4.1 s RAs Second of Right Ascension (J2000) 22 A1 --- DE- Sign of Declination (J2000) 23- 24 I2 deg DEd Degree of Declination (J2000) 26- 27 I2 arcmin DEm Arcminute of Declination (J2000) 29- 32 F4.1 arcsec DEs Arcsecond of Declination (J2000) 34- 39 F6.3 mag u'mag ? The SDSS u'-band magnitude (2) 41- 46 F6.3 mag g'mag ? The SDSS g'-band magnitude (2) 48- 53 F6.3 mag r'mag ? The SDSS r'-band magnitude (2) 55- 60 F6.3 mag i'mag ? The SDSS i'-band magnitude (2) 62- 67 F6.3 mag z'mag ? The SDSS z'-band magnitude (2) 68 A1 --- u_z'mag [:] Uncertainty flag on z'mag (3) 70- 76 A7 mag Kmag ? K-band magnitude, transformed from the 2MASS Ks magnitude 78- 82 F5.3 mag e_Kmag ? Error in Kmag 84 A1 --- f_Kmag [B] Indicates Kmag from Bhatt et al., 1994A&A...289..946B
Note (1): T = BV photometry available from the Tycho database (Hog et al., 2000, Cat. I/259). Note (2): For the SDSS system photometry, the uncertainties are 0.02mag in u'mag and 0.01mag in g'mag, r'mag, i'mag, and z'mag. Note (3): For stars measured on JD 2451960, the z'mag errors are 0.04mag. These z'mag magnitudes have been have been marked by with colons.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 9 A9 --- GSC Guide Star Catalog identification number 11- 15 F5.2 mag Bmag The B-band magnitude 17- 20 F4.2 mag e_Bmag Error in Bmag 22- 26 F5.2 mag Vmag The V-band magnitude 28- 31 F4.2 mag e_Vmag Error in Vmag 33- 37 A5 --- SpType MK Spectral classification 39- 48 A10 --- n_SpType Range of uncertainty for SpType (1) 50- 54 F5.2 mag (B-V)0 The intrinsic (B-V)0 color 56- 59 F4.2 mag e_(B-V)0 Error in (B-V)0 61- 65 F5.2 mag VMAG The absolute V-band magnitude 67- 70 F4.2 mag e_VMAG Error in VMAG 72- 76 F5.2 mag E(B-V) The E(B-V) color excess 78- 81 F4.2 mag e_E(B-V) Error in E(B-V) 83- 88 F6.2 mag R(V) ? The total-to-selective extinction (2) 90- 95 F6.2 mag e_R(V) ? Error in R(V)
Note (1): If no explicit uncertainty is given, the estimated uncertainty in the spectral classification is one subclass. Note (2): R(V)=1.1*E(V-K)/E(B-V).
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 10 A10 --- GSC Guide Star Catalog identification number 12 I1 h RAh Right ascension (J2000.0) 14- 15 I2 min RAm Right ascension (J2000.0) 17- 20 F4.1 s RAs Right ascension (J2000.0) 22 A1 --- DE- Declination sign (J2000.0) 23- 24 I2 deg DEd Declination (J2000.0) 26- 27 I2 arcmin DEm Declination (J2000.0) 29- 32 F4.1 arcsec DEs Declination (J2000.0) 34- 38 F5.2 mag Vmag V magnitude 39 A1 --- n_Vmag [cd] Note on Vmag (1) 41- 51 A11 --- SpType MK Spectral type 53- 57 A5 --- Code Rejection code (2)
Note (1): GSC magnitude unless otherwise noted. c: SDSS photometry. d: Estimated from comparisons with GSC stars. Note (2): Rejection codes: (A) missing/bad photometry data (B) missing/bad spectral data (C) emission-line (T Tauri) star (D) derived color excess unreasonable (significantly less than 0).
History: * 12-Nov-2002: From electronic version of the journal * 22-Jun-2003: Several errors detected in table2, which have been corrected in interaction with the author (Rafal Idzi). They concern les GSC numbers or positions of stars at lines 11, 40, 89, 90, 101, 109, 171. Table3 was corrected accordingly. (Erratum in AJ 126, 2087 (2003))
(End) Greg Schwarz [AAS], Patricia Bauer, Francois Ochsenbein [CDS] 22-Jun-2003
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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