II/271A TASS Mark IV patches photometric catalog, version 2 (Droege+, 2007)
TASS Mark IV Photometric Survey of the Northern Sky Droege, T. F., Richmond, M. W., Sallman, M. <Publ. Astron. Soc. Pac. 118, 1666 (2006)> =2006PASP..118.1666D =2007PASP..119.1083R (Addendum)
ADC_Keywords: Surveys ; Photometry ; Stars, variable Keywords: stars: general -- surveys Abstract: The Amateur Sky Survey (TASS) is a loose confederation of amateur and professional astronomers. We describe the design and construction of our Mark IV systems, a set of wide-field telescopes with CCD cameras which take simultaneous images in the V and I passbands. We explain our observational procedures and the pipeline which processes and reduces the images into lists of stellar positions and magnitudes. We have compiled a large database of measurements for stars in the northern celestial hemisphere with V-band magnitudes in the range 7<V<13. This paper describes data taken over the four-year period starting November, 2001. One of our results is a catalog of repeated measurements on the Johnson-Cousins system for over 4.3 million stars. This Version 2 of the catalog corrects a systematic error in photometry as function of Declination. Description: The Mark IV patches catalog contains summary information for sources detected simultaneously in V and I passbands on at least 5 occasions. The magnitudes in the table are the interquartile mean of all measurements, some of which may have been taken under poor conditions. In addition to the ordinary standard deviation from this mean, the table includes statistics based on ensemble analysis of stars within small patches one degree on a side; this removes some of the systematic errors in photometry and provides a more accurate estimate of intrinsic stellar variability. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file patch2.dat 112 4353670 *Properties of objects detected repeatedly during the Mark IV survey of northern sky (V.2) v1/* 0 29 Version 1 of the catalog
Note on patch2.dat: the full file is split in 24 parts, patch2.dat.00 to patches.dat.23, each corresponding to 1 hour in right ascension.
See also: II/230 : TASS Mark III photometric survey (Richmond+, 2000) http://www.tass-survey.org : TASS Home Page Byte-by-byte Description of file: patch2.dat
Bytes Format Units Label Explanations
1- 8 I8 --- TASS4 Index in Mark IV engineering database 10- 13 I4 --- o_TASS4 Number of good (V,I) measurement pairs 15- 23 F9.5 deg RAdeg Mean Right Ascension (J2000.0) 25- 31 F7.5 deg e_RAdeg Standard deviation from mean RA position 33- 41 F9.5 deg DEdeg Mean Declination (J2000.0) 43- 49 F7.5 deg e_DEdeg Standard deviation from mean Dec position 51- 56 F6.3 mag Vmag Interquartile mean of all V-band measurements (5) 58- 62 F5.3 mag e_Vmag Standard deviation from interquartile mean V 64- 68 F5.3 mag eVmag Standard deviation from mean V value in ensemble analysis of local patch (1) 70- 75 F6.3 mag Imag Interquartile mean of all I-band measurements (5) 77- 81 F5.3 mag e_Imag Standard deviation from interquartile mean I 83- 87 F5.3 mag eImag Standard deviation from mean I value in ensemble analysis of local patch (1) 89- 94 F6.2 --- dVmag Normalized measure of deviation from mean V magnitude in ensemble analysis (2) 96-101 F6.2 --- dImag Normalized measure of deviation from mean I magnitude in ensemble analysis (2) 103-109 F7.2 --- WS Welch-Stetson variability index (3) 111-112 I2 --- Proxy Proximity code (4)
Note (1): Ensemble analysis of stars within a one-degree square patch of sky yields a mean magnitude (with arbitrary zero point) for each star and the standard deviation around that mean. Some measurements may be discarded. Note (2): In each patch, the typical scatter away from mean magnitudes is estimated using all stars. The "Normalized measure of deviation" value is computed by dividing an individual star's standard deviation from its mean by this typical scatter. Note (3): A normalized measure of the degree of correlation of V-band and I-band variations from their mean values. See Welch and Stetson (1993AJ....105.1813W) for a full description. The variability index will be close to zero for stars with random variations which are independent in each passband, or stars which vary by less than the uncertainty of each measurement. It will be a large (greater than 2 or 3) positive value for stars which really do change significantly in brightness. Note (4): Bitwise combination of flags indicating neighbors which may be close enough to contaminate measurements. Flag F4 is set to 1 if at least one brighter star within 30 arcsec. Flag F3 is set to 1 if at least one fainter star within 30 arcsec. Flag F2 is set to 1 if at least one brighter star within 60 arcsec. Flag F1 is set to 1 if at least one fainter star within 60 arcsec. Proximity code is the sum 8*(F4) + 4*(F3) + 2*(F2) + 1*(F1) Note (5): Original version of catalog contained systematic errors depending on Dec position of star, due to a flatfielding effect. The amplitude of the errors ranged from ±0.02mag to ±0.10mag, worse near northern and southern edges of survey. The errors have been modeled and removed for Version 2 of this catalog.
Acknowledgements: Michael Richmond, richmond(at)stupendous.cis.rit.edu History: * 18-Sep-2006: Version 1 of the catalog ("v1" subdirectory) * 28-Jul-2007: Version 2 at CDS (Catalog II/271A)
(End) Michael Richmond [RIT, USA], Francois Ochsenbein [CDS] 30-May-2007
|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|