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Global Sky Model for LOFAR andMSSS catalog
A. Mints
Hamburger Sternwarte
September 21, 2012
A. Mints, Global Sky Model for LOFAR and MSSS catalog 1 / 13
GSM components
DatabaseI Storage only (all logic in the pipeline);
I MonetDB or PostgreSQL support;
PipelinePython code with unified database binding.
Front-ends (planned)I Web-interface;
I Python API;
I Direct DB access;
A. Mints, Global Sky Model for LOFAR and MSSS catalog 3 / 13
Data
Observations (pyBDSM output)Time, frequency, Stokes parameter, position(+size/orientation), peak/total flux, errors.
Catalogrunningcatalog Position, spectral parameters,classification, errors, (+Frequency, Stokesparameter, size/orientation).runningcatalog fluxes Frequency, Stokesparameter, peak/total flux, errors
A. Mints, Global Sky Model for LOFAR and MSSS catalog 4 / 13
Point and extended sources
Point sources1 record in positions table and N records in fluxestable.
Extended sourcesN+1 record in positions table and N records influxes table.
A. Mints, Global Sky Model for LOFAR and MSSS catalog 5 / 13
Matching
Matching criteria for point sources is based on deRuiter distance:
R2deRuiter =
(α1 cos δ1 − α2 cos δ2)2
(∆α1)2 + (∆α2)2+
(δ1 − δ2)2
(∆δ1)2 + (∆δ2)2
A. Mints, Global Sky Model for LOFAR and MSSS catalog 6 / 13
Extended source matching
1. Search for a match in the same band;
2. If 1. failed – search for a cross-band match.
R∗2deRuiter =
(α1 cos δ1 − α2 cos δ2)2 + (δ1 − δ2)2
g 2major ,1 + g 2
major ,2
A. Mints, Global Sky Model for LOFAR and MSSS catalog 7 / 13
First snapshot
-1
0
1
2
3
4
5
6
-1 0 1 2 3 4 5 6
A. Mints, Global Sky Model for LOFAR and MSSS catalog 8 / 13
Second snapshot
-1
0
1
2
3
4
5
6
-1 0 1 2 3 4 5 6
1
2
34
A. Mints, Global Sky Model for LOFAR and MSSS catalog 9 / 13
Resolved source
For point sources a “flux splitting” technique isapplied.
For extended sources flux splitting is applied onlyat per-band level.
A. Mints, Global Sky Model for LOFAR and MSSS catalog 10 / 13
Merged source
In this case the nearest source is chosen.Exception: extended sources are merged if possible:
A1, 2, 3 + B5, 6, 7 + X4 = A1, 2, 3, 4, 5, 6, 7 (1)
A. Mints, Global Sky Model for LOFAR and MSSS catalog 11 / 13
Groups
Assigned a unique group ID(all detections in the group).
A. Mints, Global Sky Model for LOFAR and MSSS catalog 12 / 13
Code features
I Coding style: Python PEP8 style rules;
I In-code documentation (docstrings);
I Unit testing (34 tests unified forMonetDB/PostgreSQL);
I SQL mini-preprocessor:1. Queries stored in SQL-file, called by unique Id;2. Parameters can be passed;3. Global parameters can be set;4. Arbitrary Python-code can be called and result
substituted:
A. Mints, Global Sky Model for LOFAR and MSSS catalog 13 / 13