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J/ApJ/603/584       Polarimetry toward Musca dark cloud      (Pereyra+, 2004)

Polarimetry toward the Musca dark cloud. I. The catalog. Pereyra A., Magalhaes A.M. <Astrophys. J., 603, 584-594 (2004)> =2004ApJ...603..584P
ADC_Keywords: Molecular clouds ; Polarization Keywords: catalogs - ISM: clouds - ISM: magnetic fields - polarization - ISM: individual (Chamaeleon-Musca Dark Cloud Complex) - Abstract: We have used CCD imaging polarimetry to obtain linear polarization measurements of background stars toward the filamentary Musca dark cloud. We present a catalog of 2497 objects with polarization signal-to-noise ratio larger than 5. This allows us to build polarization maps to infer the detailed geometry of the local magnetic field. We show composite polarization maps along the cloud and explore general correlations of the polarimetric data with the morphology of the region. We find the overall field to be strikingly aligned with the projected small axis of the filamentary cloud. We detect a lower limit for the polarization across the cloud of ∼2%, with an enhanced polarization of 6%-7% in the central region. We find evidence that the polarization pattern is altered in the inner regions, those associated with higher extinction. Description: The observations were made using IAGPOL, the IAG-USP imaging polarimeter, at the f/13.5 Cassegrain focus of the 0.6m IAG telescope at the Observatorio do Pico dos Dias, operated by the Laboratorio Nacional de Astrofisica, Brazil. We obtained linear polarization data for 35 CCD fields along the Musca dark cloud obtained in runs in 1996 April and 1997 April through a standard V filter. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 45 35 Field CCD positions table3.dat 59 2555 Field data notes.dat 64 116 Notes table5.dat 27 35 Analysis of 35 fields in Musca dark cloud
See also: J/A+AS/93/373 : uvby-beta photometry in SA 203 (Franco 1992) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 2 I2 --- FNum Field number 4- 5 I2 h RAh Right ascension (J2000.0) 7- 8 I2 min RAm Right ascension (J2000.0) 10- 14 F5.2 s RAs Right ascension (J2000.0) 16 A1 --- DE- Declination sign (2000.0) 17- 18 I2 deg DEd Declination (2000.0) 20- 21 I2 arcmin DEm Declination (2000.0) 23- 27 F5.2 arcsec DEs Declination (2000.0) 29- 30 I2 --- Run Run number 32- 45 A14 --- Region Region
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 2 I2 --- FNum Field number (1) 4- 6 I3 --- ID Object identification number (1) 8- 10 A3 --- n_ID Note detailled in file "notes.dat" 12- 13 I2 h RAh Hour of Right Ascension (J2000) 15- 16 I2 min RAm Minute of Right Ascension (J2000) 18- 22 F5.2 s RAs Second of Right Ascension (J2000) 24 A1 --- DE- Sign of the Declination (J2000) 25- 26 I2 deg DEd Degree of Declination (J2000) 28- 29 I2 arcmin DEm Arcminute of Declination (J2000) 31- 35 F5.2 arcsec DEs Arcsecond of Declination (J2000) 37- 41 F5.3 % PolV Percent linear polarization in the V band 43- 47 F5.3 % e_PolV Measured error in PolV (2) 49- 53 F5.1 deg PA Polarization position angle (3) 55- 59 F5.2 mag Vmag The V band magnitude
Note (1): Objects are identified in Simbad as [PM2004] FNum ID Note (2): The latter are obtained from the residuals of the observations at each waveplate position angle (ψi) with respect to the expected cos(4ψi) curve; they are consistent with the photon noise errors (Magalhaes, Benedetti & Roland, 1984, ASP Conf. Ser. 97, 118). Note (3): Measured from North to East.
Byte-by-byte Description of file: notes.dat
Bytes Format Units Label Explanations
1- 3 A3 --- Note Note designation 5- 64 A60 --- Text Text of the note
Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 2 I2 --- FNum Field number 4- 5 I2 --- N Number of objects with Pol/e_Pol>10 in the field 7- 10 F4.2 % Pol Mean polarization value 12- 15 F4.2 % e_Pol Associated error to Pol 17- 22 F6.2 deg PA Mean polarization position angle 24- 27 F4.2 deg e_PA Associated error to PA
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 07-May-2004
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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