TASS Mark IV patches photometric catalog (Droege+, 2006) ================================================================================ TASS Mark IV Photometric Survey of the Northern Sky Droege, T. F., Richmond, M. W., Sallman, M. < > = ================================================================================ 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. 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 patches.dat 113 4353670 Properties of objects detected repeatedly during the Mark IV survey of northern sky. -------------------------------------------------------------------------------- Byte-by-byte Description of file: patches.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 8 I8 --- Index Index in Mark IV engineering database 10- 13 I4 --- numobs Number of good (V,I) measurement pairs 15- 23 F9.5 deg RA mean Right Ascension (J2000.0) 25- 31 F7.5 deg sig_RA standard deviation from mean RA position 33- 41 F9.5 deg Dec mean Declination (J2000.0) 43- 49 F7.5 deg sig_Dec standard deviation from mean Dec position 51- 56 F6.3 mag Vmag interquartile mean of all V-band measurements 58- 62 F5.3 mag sig_V standard deviation from interquartile mean V 64- 68 F5.3 mag scat_V 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 77- 81 F5.3 mag sig_V standard deviation from interquartile mean I 83- 87 F5.3 mag scat_I standard deviation from mean I value in ensemble analysis of local patch (1) 89- 94 F6.2 --- Dev_V normalized measure of deviation from mean V magnitude in ensemble analysis (2) 96-101 F6.2 --- Dev_I 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 --- proxcode 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 "Dev" 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 (1993, AJ, 105, 1813) for a full description. Large values suggest intrinsic variability 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) -------------------------------------------------------------------------------- Acknowledgements: References: ================================================================================ (End) Michael Richmond [RIT, USA] 16-Sep-2006