TN 0080: Data to be kept in Mark IV databases

Author: Robert Creager
Address: robert@carolinecreager.com
Date: 20010625
Revision: #0 20010625
Revision: #1 20010717
Revision: #2 20020121
Key Words: databases
Contributors: Chris Albertson and Arne Henden via e-mail and e-mail archives

Introduction

In 1997, Chris Albertson led a discussion concerning databases for Mark III data. The information is contained within e-mail archives and software that Chris has made available (http://www.tass-survey.org/tass/software/software.html#dbms). This tech note is an effort to consolidate the information from those sources, and to add new information based on changing requirements. The intent here is not to produce a database schema per say, but rather identify what information is required for long term database viability.

Data Definitions

For each telescope setup:

• Frame orientation:
• X zero point
• 0 -> lowest x is east
• 1 -> lowest x is west
• Y zero point
• 0 -> lowest y is north
• 1 -> lowest y is south
• Orientation
• 0 -> x is E/W, y is N/S
• 1 -> x is N/S, y is E/W

For each detector

• Name of detector
• Size of detector - X, Y
• Bias over scan columns in original image
• Actual image area in original image
• Read noise (e-)
• Gain (e-/ADU)
• Pixel size (microns)

For each night:

• Extraction Software Version Number
• Astrometric Software Version Number
• Processing Comments
• For each filter
• Dark image files - file names which went into creation of the dark frame
• Flat field image files - file names which went into creation of the flat field

For each image file processed

• File name - original fits file name
• Object/field name - 'survey' for survey mode, otherwise specific field name
• Universal Time - exposure start
• Exposure duration - in seconds
• Filter
• Central RA, Dec
• CCD Temp
• Coordinate Epoch
• Aperture Radii
• Sky Annulus - inner and outer radii
• Median FWHM for the Frame
• Threshold above sky for photometric extraction
• Plate Constants for the Frame
• Pixel Scale - in arc seconds
• Catalog used for solution
• Number of reference stars in frame
• Number of reference stars used for astrometry solution
• RMS error (arcsec) per star used for astrometry solution
• Pate transformations a, b, c, d, e, f: X = a + bx + cy, Y = d + ex + fy where a, d are offsets; b, c, e, f give scale and rotation.  Can extend to cubic or quatratic.
• PSF data
• FWHM
• Index numbers of stars used for profile generation
• Radius of profile for fit Radius of profile for magnitude determination
• Aperture for zero point adjustment

For each star - Note that, while the astrometry is final, the photometry is instrumental only

• RA, RA error
• Dec, Dec error
• CCD X, Y coordinates
• FWHM X, Y - instrumental in answering future question about source (galaxy, star, satellite track) and quality of reduction
• Roundness - instrumental in answering future question about source (galaxy, star, satellite track) and quality of reduction
• Peak Star Signal - for determining if saturation has been reached
• Background Sky Value - instrumental in answering future question about source (galaxy, star, satellite track) and quality of reduction
• Magnitude, sigma - in X (at least 7, more likely a variable number, but consistent for a site?) apertures of increasing size (or 1 for PSF), adjusted to Tycho2 color.  These apertures are included so that a curve of growth may be calculated and then determine what the optimal aperture for an evening based on seeing or tracking considerations, and also calculate aperture corrections to use smaller apertures for fainter objects or crowded objects