MAXI/GSC Catalogs (gdt.missions.maxi.gsc.catalogs)

The HEASARC hosts a couple of MAXI/GSC catalogs: a high Galactic Latitude catalog of sources from the first 37 months of observations, and a more complete catalog of the first 7 years of sources. HEASARC provides a way to search these catalogs online through their Browse interface, but we offer a way to do it in Python through the Data Tools.

Let’s look at accessing the 7-year catalog (MaxiGsc7YearCatalog):

>>> from gdt.missions.maxi.gsc.catalogs import MaxiGsc7YearCatalog
>>> cat = MaxiGsc7YearCatalog()
Sending request and awaiting response from HEASARC...
Downloading maxigsc7yr from HEASARC via w3query.pl...
Finished in 2 s
>>> cat
<MaxiGsc7YearCatalog: 38 columns, 907 rows>

Depending on your connection, initialization may take a few seconds. We can see what columns are available in the catalog:

>>> print(cat.columns)
('NAME',
 'RA',
 'DEC',
 'ERROR_RADIUS',
 'FLUX_4_10',
 'FLUX_4_10_ERROR',
 'FLUX_3_4_LIMIT',
 'FLUX_3_4',
 'FLUX_3_4_ERROR',
 'EXCESS_VARIANCE',
 'EXCESS_VARIANCE_ERROR',
 'CTRPART_NAME',
 'OBJECT_TYPE',
 'BII',
 'CATALOG',
 'CATALOG_SOURCE_NUMBER',
 'CTRPART_DEC',
 'CTRPART_FLAGS',
 'CTRPART_OFFSET',
 'CTRPART_RA',
 'DETSIG_10_20',
 'DETSIG_3_4',
 'DETSIG_4_10',
 'FLUX_10_20',
 'FLUX_10_20_ERROR',
 'FLUX_10_20_LIMIT',
 'FLUX_3_10',
 'FLUX_3_10_ERROR',
 'HARDNESS_RATIO_1',
 'HARDNESS_RATIO_1_ERROR',
 'HARDNESS_RATIO_2',
 'HARDNESS_RATIO_2_ERROR',
 'HARDNESS_RATIO_3',
 'HARDNESS_RATIO_3_ERROR',
 'LII',
 'NOTE_FLAG',
 'REDSHIFT',
 'TIMEVAR')

We can also return the range of values for a given column:

>>> cat.column_range('FLUX_4_10')
(4.33e-12, 1.8192e-07)

If we only care about specific columns in the table, we can return a numpy record array with only those columns. Let’s return a table with the RA, Dec, and error radius for every source:

>>> cat.get_table(columns=('RA', 'DEC', 'ERROR_RADIUS'))
rec.array([(3.47146e+02, -8.9383e+01,  709.2),
           (2.87090e+01, -8.3889e+01,  504. ),
           (2.96915e+02, -8.3585e+01, 1184.4), ...
           (3.19187e+02,  8.2221e+01,  406.8),
           (2.39155e+02,  8.4996e+01,  720. ),
           (2.59998e+02,  8.6165e+01,  536.4)],
          dtype=[('RA', '<f8'), ('DEC', '<f8'), ('ERROR_RADIUS', '<f8')])

Importantly, we can make slices of the catalog based on conditionals. Let’s only select triggers with positive declinations:

>>> sliced_cat = cat.slice('DEC', lo=0.0, hi=90.0)
>>> sliced_cat
<MaxiGsc7YearCatalog: 38 columns, 361 rows>

We can also slice on multiple conditionals, simultaneously. Select everything that has a positive declination and has an error radius less than 0.1 degree:

>>> sliced_cat2 = cat.slices([('DEC', 0.0, 90.0), ('ERROR_RADIUS', 0.0, 0.1)])
>>> sliced_cat2
<MaxiGsc7YearCatalog: 38 columns, 63 rows>

>>> sliced_trigcat2.get_table(columns=('trigger_name', 'trigger_time', 'error_radius'))
rec.array([(287.824,  0.577, 0.), (285.442,  1.475, 0.),
           (284.579,  3.335, 0.), (287.989,  4.939, 0.),
           (279.994,  5.029, 0.), (287.675,  7.684, 0.), ...
           (343.29 , 62.617, 0.), (338.912, 63.401, 0.),
           ( 19.566, 63.711, 0.), (  6.308, 64.132, 0.),
           ( 19.492, 65.268, 0.)],
          dtype=[('RA', '<f8'), ('DEC', '<f8'), ('ERROR_RADIUS', '<f8')])

For more information on working with catalogs, see The BrowseCatalog Class.

Reference/API

gdt.missions.maxi.gsc.catalogs Module

Classes

MaxiGsc37MonthCatalog([cache_path])

High-Galactic latitude catalog of X-ray sources based on the first 37 months of GSC observations.

MaxiGsc7YearCatalog([cache_path])

High- and Low-Galactic latitude catalog of X-ray sources based on 7 years of GSC observations.

Class Inheritance Diagram

Inheritance diagram of gdt.missions.maxi.gsc.catalogs.MaxiGsc37MonthCatalog, gdt.missions.maxi.gsc.catalogs.MaxiGsc7YearCatalog