Brown Dwarf search in the Pleiades - Colour Cut method

This workflow is broken up into slightly more Sequences etc. than strictly necessary in order to make the main stages modular.

1. Preparation
   1. Create MySpace subdirectories as needed
   2. Upload SExtractor configuration (.sex) and output parameter (.param) files containing constant input quantities like the mesh size for estimating the background. Other auxillary files can also be supplied but the Portal posesses defaults. Variable parameters are inserted dynamically, see 3.
   3. Use Query page to build catalogue queries and save them to MySpace (SQL is shown below, queries are saved as ADQL).

1. Flow Get initial data using box blc 55.25, 22.6167; trc 58.25, 25.6167 in decimal degrees - the two datasets can be queried in parallel
   1. Step Query 2MASS catalogue of sources
      SELECT * FROM twomass_psc as o where (o.ra > 55.25) and (o.ra < 58.25) and (o.dec > 22.6167) and (o.dec < 25.6167)
   2. Sequence Query INT-WFS DQC (Data Quality) observing log
      1. Step for z image metadata
         SELECT * FROM dqc as o where (o.run >= 197434) and (o.ramas > 198900000) and (o.ramas < 209700000) and (o.decmas > 81420120) and (o.decmas < 92220120) and (o.magzrr > 0.0) and (o.magzrr < 0.2) and (o.stdrms <= 0.5) and (o.ccdno=1) and (o.filter="z")
         • Run numbers > 197434 have standard size images
         • Catalogue RA and Dec are in milliarcsec
         • Mag zeropoint and pointing (stdrms) ranges exclude bad data (magzrr <0) and inaccurate data
         • Each Run contains 4 approximately contiguous CCD frames; metadata for ccdno=1 can be used for all 4
      2. Step repeat for i image metadata
      3. Step Cross-match resulting lists of z and i metadata to obtain a catalogue of z and i matching exposures
2. Sequence The INT-WFS metadata are used to evaluate variables for each Run, which are then inserted into the SExtracor parameter file for that Run.
   1. Set Initialise variables for each pair of runs
   2. Script For each z run and corresponding i run, calculate the EffectiveZeroPoint and record this, the Seeing and housekeeping parameters in the relevant variables.
      1. For loop Iterate over all z / i run pairs
         1. Sequence This will produce one file per run per ccdno containing the position, magnitude and (noise-based) uncertainties for each source in the z band image and corresponding measurements from the i band image at the position of each z band source.
            1. Set ccdno variable (1...4)
            2. For loop Iterate over all ccdno's for each run pair
               1. Sequence (this may require only one call to SExtractor depending on the Script). In each case the z band image is used as the detection image.
                  1. Step Run SExtractor using the z band image as the measurement image
                  2. Step Run SExtractor using the corresponding i band image as the measurement image
      2. Script Concatenate all the z band source files and all the i band source files into two source catalogues
3. Step Cross-match 2MASS sources with INT-WFS extracted source catalogues. This is set up to find the closest z band source within 5" of a 2MASS source and then find the i band source within 2" of the z band source
4. TopCat via Java Webstart Applications which can access MySpace. Make J-K and i-z colours and plot. This could also be done using a script, propagating errors and making the final colour-based selection.

-- AnitaRichards - 07 Feb 2005