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J/AJ/121/1192       Proper-motion measurements with the VLA  (McGary+, 2001)

Proper-motion measurements with the VLA. I. Wide-field imaging and pulse-gating techniques. McGary R.S., Brisken W.F., Fruchter A.S., Goss W.M., Thorsett S.E. <Astron. J. 121, 1192 (2001)> =2001AJ....121.1192M
ADC_Keywords: Pulsars ; Proper motions ; Interferometry Keywords: astrometry - pulsars: general - techniques: interferometric Abstract: The pulsar velocity distribution provides information about the binary history of pulsar progenitors, as well as the asymmetries of the supernova events in which pulsars are born. Studies of local pulsars present a biased view of this distribution, because they preferentially select low-velocity pulsars that have remained near their birthplaces in the Galactic plane. Using the VLA, we have studied the proper motions of a large sample of distant pulsars. These pulsars are generally faint, and the expected proper motions are small. In this paper, we describe the data analysis techniques that we have developed to allow precise astrometric measurements of faint sources with the VLA. These techniques include "gating" the VLA correlator to increase the signal-to-noise ratio of the pulsar by gathering data only during the pulse. Wide-field imaging techniques, including multiband imaging to account for bandwidth smearing, were used to allow identification of multiple in-beam background sources for astrometric calibration. We present the analysis of three pulsars and demonstrate that astrometric accuracy of about 10 mas can be obtained for individual sources with our technique, allowing measurement of proper motions with errors of only a few milliarcseconds per year over our 7 year baseline. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 74 44 Reference sources for proper motions table2.dat 69 3 Proper motions of B0919+06, B1237+25 and B1937-26
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Name Pulsar name, Bhhmm+dd (1) 10- 13 F4.1 mJy F20 The 20cm flux density of reference 15- 17 F3.1 mJy e_F20 Uncertainty in F20 19- 20 I2 h RAh Right Ascension of reference (J2000) 22- 23 I2 min RAm Right Ascension of reference (J2000) 25- 29 F5.2 s RAs Right Ascension of reference (J2000) 31- 33 F3.2 s e_RAs Uncertainty in RAs 35 A1 --- DE- Sign of the reference Declination (J2000) 36- 37 I2 deg DEd Declination of reference (J2000) 39- 40 I2 arcmin DEm Declination of reference (J2000) 42- 45 F4.1 arcsec DEs Declination of reference (J2000) 47- 48 F2.1 arcsec e_DEs Uncertainty in DEs 50- 54 I5 arcsec dRA RA offset from pulsar position 56- 60 I5 arcsec dDE Dec offset from pulsar position 62- 64 I3 mas/yr pmRA ? Proper Motion along RA 66- 67 I2 mas/yr e_pmRA ? Uncertainty in pmRA 69- 70 I2 mas/yr pmDE ? Proper Motion along Dec 72- 73 I2 mas/yr e_pmDE ? Uncertainty in pmDE
Note (1): The objects are identified in Simbad as [MBF2001]
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Name Pulsar Name 10- 12 F3.1 mJy F20 The 20cm flux density 14- 16 F3.1 mJy e_F20 Uncertainty in F20 18- 22 F5.1 mJy GF20 Gated 20cm flux density 24- 26 F3.1 mJy e_GF20 Uncertainty in GF20 28- 29 I2 yr Epoch1 Epoch of observation (1900+) 30 A1 --- n_Epoch1 [a] a: gated observation 32- 33 I2 yr Epoch2 Epoch of observation (1900+) 34 A1 --- n_Epoch2 [a] a: gated observation 36- 37 I2 yr Epoch3 Epoch of observation (1900+) 38 A1 --- n_Epoch3 [a] a: gated observation 40- 41 I2 yr Epoch4 ? Epoch of observation (1900+) 42 A1 --- n_Epoch4 [a] a: gated observation 44- 45 I2 --- Num Number of reference objects used 47- 52 F6.1 mas/yr pmRA Proper motion along RA 54- 56 F3.1 mas/yr e_pmRA Uncertainty in pmRA 58- 61 F4.1 mas/yr pmDE Proper motion along Dec 63- 65 F3.1 mas/yr e_pmDE Uncertainty in pmDE 67- 69 F3.1 --- Cov Covariance of RA & Dec proper motion components
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 24-Apr-2001
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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