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01_query.html
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@@ -253,11 +253,6 @@
Using Jupyter
</a>
</li>
<li class="toc-h2 nav-item toc-entry">
<a class="reference internal nav-link" href="#installing-libraries">
Installing libraries
</a>
</li>
<li class="toc-h2 nav-item toc-entry">
<a class="reference internal nav-link" href="#connecting-to-gaia">
Connecting to Gaia
@@ -396,24 +391,6 @@ But you might find it easier to learn from <a class="reference external" href="h
</ul>
<p>Before you go on, you might want to explore the other menus and the toolbar to see what else you can do.</p>
</div>
<div class="section" id="installing-libraries">
<h2>Installing libraries<a class="headerlink" href="#installing-libraries" title="Permalink to this headline"></a></h2>
<p>If you are running this notebook on Colab, you should run the following cell to install the libraries we’ll need.</p>
<p>If you are running this notebook on your own computer, you might have to install these libraries yourself.</p>
<div class="cell docutils container">
<div class="cell_input docutils container">
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># If we&#39;re running on Colab, install libraries</span>
<span class="kn">import</span> <span class="nn">sys</span>
<span class="n">IN_COLAB</span> <span class="o">=</span> <span class="s1">&#39;google.colab&#39;</span> <span class="ow">in</span> <span class="n">sys</span><span class="o">.</span><span class="n">modules</span>
<span class="k">if</span> <span class="n">IN_COLAB</span><span class="p">:</span>
<span class="o">!</span>pip install astroquery
</pre></div>
</div>
</div>
</div>
</div>
<div class="section" id="connecting-to-gaia">
<h2>Connecting to Gaia<a class="headerlink" href="#connecting-to-gaia" title="Permalink to this headline"></a></h2>
<p>The library we’ll use to get Gaia data is <a class="reference external" href="https://astroquery.readthedocs.io/en/latest/">Astroquery</a>.
@@ -425,6 +402,20 @@ Astroquery provides <code class="docutils literal notranslate"><span class="pre"
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output stream highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>Created TAP+ (v1.2.1) - Connection:
Host: gea.esac.esa.int
Use HTTPS: True
Port: 443
SSL Port: 443
Created TAP+ (v1.2.1) - Connection:
Host: geadata.esac.esa.int
Use HTTPS: True
Port: 443
SSL Port: 443
</pre></div>
</div>
</div>
</div>
<p>This import statement creates a <a class="reference external" href="http://www.ivoa.net/documents/TAP/">TAP+</a> connection; TAP stands for “Table Access Protocol”, which is a network protocol for sending queries to the database and getting back the results.</p>
</div>
@@ -442,15 +433,160 @@ Astroquery provides <code class="docutils literal notranslate"><span class="pre"
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output stream highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>INFO: Retrieving tables... [astroquery.utils.tap.core]
INFO: Parsing tables... [astroquery.utils.tap.core]
INFO: Done. [astroquery.utils.tap.core]
</pre></div>
</div>
</div>
</div>
<p>The following <code class="docutils literal notranslate"><span class="pre">for</span></code> loop prints the names of the tables.</p>
<div class="cell docutils container">
<div class="cell tag_hide-output tag_truncate-output docutils container">
<div class="cell_input docutils container">
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="k">for</span> <span class="n">table</span> <span class="ow">in</span> <span class="n">tables</span><span class="p">:</span>
<span class="nb">print</span><span class="p">(</span><span class="n">table</span><span class="o">.</span><span class="n">name</span><span class="p">)</span>
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output stream highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>external.apassdr9
external.gaiadr2_geometric_distance
external.gaiaedr3_distance
external.galex_ais
external.ravedr5_com
external.ravedr5_dr5
external.ravedr5_gra
external.ravedr5_on
external.sdssdr13_photoprimary
external.skymapperdr1_master
external.skymapperdr2_master
external.tmass_xsc
public.hipparcos
public.hipparcos_newreduction
public.hubble_sc
public.igsl_source
public.igsl_source_catalog_ids
public.tycho2
public.dual
tap_config.coord_sys
tap_config.properties
tap_schema.columns
tap_schema.key_columns
tap_schema.keys
tap_schema.schemas
tap_schema.tables
gaiaedr3.gaia_source
gaiaedr3.agn_cross_id
gaiaedr3.commanded_scan_law
gaiaedr3.dr2_neighbourhood
gaiaedr3.frame_rotator_source
gaiaedr3.allwise_best_neighbour
gaiaedr3.allwise_neighbourhood
gaiaedr3.apassdr9_best_neighbour
gaiaedr3.apassdr9_join
gaiaedr3.apassdr9_neighbourhood
gaiaedr3.gsc23_best_neighbour
gaiaedr3.gsc23_join
gaiaedr3.gsc23_neighbourhood
gaiaedr3.hipparcos2_best_neighbour
gaiaedr3.hipparcos2_neighbourhood
gaiaedr3.panstarrs1_best_neighbour
gaiaedr3.panstarrs1_join
gaiaedr3.panstarrs1_neighbourhood
gaiaedr3.ravedr5_best_neighbour
gaiaedr3.ravedr5_join
gaiaedr3.ravedr5_neighbourhood
gaiaedr3.sdssdr13_best_neighbour
gaiaedr3.sdssdr13_join
gaiaedr3.sdssdr13_neighbourhood
gaiaedr3.skymapperdr2_best_neighbour
gaiaedr3.skymapperdr2_join
gaiaedr3.skymapperdr2_neighbourhood
gaiaedr3.tmass_psc_xsc_best_neighbour
gaiaedr3.tmass_psc_xsc_join
gaiaedr3.tmass_psc_xsc_neighbourhood
gaiaedr3.tycho2tdsc_merge_best_neighbour
gaiaedr3.tycho2tdsc_merge_neighbourhood
gaiaedr3.urat1_best_neighbour
gaiaedr3.urat1_neighbourhood
gaiaedr3.gaia_source_simulation
gaiaedr3.gaia_universe_model
gaiaedr3.tycho2tdsc_merge
gaiadr1.aux_qso_icrf2_match
gaiadr1.ext_phot_zero_point
gaiadr1.allwise_best_neighbour
gaiadr1.allwise_neighbourhood
gaiadr1.gsc23_best_neighbour
gaiadr1.gsc23_neighbourhood
gaiadr1.ppmxl_best_neighbour
gaiadr1.ppmxl_neighbourhood
gaiadr1.sdss_dr9_best_neighbour
gaiadr1.sdss_dr9_neighbourhood
gaiadr1.tmass_best_neighbour
gaiadr1.tmass_neighbourhood
gaiadr1.ucac4_best_neighbour
gaiadr1.ucac4_neighbourhood
gaiadr1.urat1_best_neighbour
gaiadr1.urat1_neighbourhood
gaiadr1.cepheid
gaiadr1.phot_variable_time_series_gfov
gaiadr1.phot_variable_time_series_gfov_statistical_parameters
gaiadr1.rrlyrae
gaiadr1.variable_summary
gaiadr1.allwise_original_valid
gaiadr1.gsc23_original_valid
gaiadr1.ppmxl_original_valid
gaiadr1.sdssdr9_original_valid
gaiadr1.tmass_original_valid
gaiadr1.ucac4_original_valid
gaiadr1.urat1_original_valid
gaiadr1.gaia_source
gaiadr1.tgas_source
gaiadr2.aux_allwise_agn_gdr2_cross_id
gaiadr2.aux_iers_gdr2_cross_id
gaiadr2.aux_sso_orbit_residuals
gaiadr2.aux_sso_orbits
gaiadr2.dr1_neighbourhood
gaiadr2.allwise_best_neighbour
gaiadr2.allwise_neighbourhood
gaiadr2.apassdr9_best_neighbour
gaiadr2.apassdr9_neighbourhood
gaiadr2.gsc23_best_neighbour
gaiadr2.gsc23_neighbourhood
gaiadr2.hipparcos2_best_neighbour
gaiadr2.hipparcos2_neighbourhood
gaiadr2.panstarrs1_best_neighbour
gaiadr2.panstarrs1_neighbourhood
gaiadr2.ppmxl_best_neighbour
gaiadr2.ppmxl_neighbourhood
gaiadr2.ravedr5_best_neighbour
gaiadr2.ravedr5_neighbourhood
gaiadr2.sdssdr9_best_neighbour
gaiadr2.sdssdr9_neighbourhood
gaiadr2.tmass_best_neighbour
gaiadr2.tmass_neighbourhood
gaiadr2.tycho2_best_neighbour
gaiadr2.tycho2_neighbourhood
gaiadr2.urat1_best_neighbour
gaiadr2.urat1_neighbourhood
gaiadr2.sso_observation
gaiadr2.sso_source
gaiadr2.vari_cepheid
gaiadr2.vari_classifier_class_definition
gaiadr2.vari_classifier_definition
gaiadr2.vari_classifier_result
gaiadr2.vari_long_period_variable
gaiadr2.vari_rotation_modulation
gaiadr2.vari_rrlyrae
gaiadr2.vari_short_timescale
gaiadr2.vari_time_series_statistics
gaiadr2.panstarrs1_original_valid
gaiadr2.gaia_source
gaiadr2.ruwe
</pre></div>
</div>
</div>
</div>
<p>So that’s a lot of tables. The ones we’ll use are:</p>
<ul class="simple">
@@ -466,6 +602,16 @@ Astroquery provides <code class="docutils literal notranslate"><span class="pre"
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output stream highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>Retrieving table &#39;gaiadr2.gaia_source&#39;
Parsing table &#39;gaiadr2.gaia_source&#39;...
Done.
</pre></div>
</div>
<div class="output text_plain highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>&lt;astroquery.utils.tap.model.taptable.TapTableMeta at 0x7f50edd2aeb0&gt;
</pre></div>
</div>
</div>
</div>
<p>Jupyter shows that the result is an object of type <code class="docutils literal notranslate"><span class="pre">TapTableMeta</span></code>, but it does not display the contents.</p>
<p>To see the metadata, we have to print the object.</p>
@@ -475,18 +621,129 @@ Astroquery provides <code class="docutils literal notranslate"><span class="pre"
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output stream highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>TAP Table name: gaiadr2.gaiadr2.gaia_source
Description: This table has an entry for every Gaia observed source as listed in the
Main Database accumulating catalogue version from which the catalogue
release has been generated. It contains the basic source parameters,
that is only final data (no epoch data) and no spectra (neither final
nor epoch).
Num. columns: 96
</pre></div>
</div>
</div>
</div>
</div>
<div class="section" id="columns">
<h2>Columns<a class="headerlink" href="#columns" title="Permalink to this headline"></a></h2>
<p>The following loop prints the names of the columns in the table.</p>
<div class="cell docutils container">
<div class="cell tag_hide-output tag_truncate-output docutils container">
<div class="cell_input docutils container">
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="k">for</span> <span class="n">column</span> <span class="ow">in</span> <span class="n">meta</span><span class="o">.</span><span class="n">columns</span><span class="p">:</span>
<span class="nb">print</span><span class="p">(</span><span class="n">column</span><span class="o">.</span><span class="n">name</span><span class="p">)</span>
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output stream highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>solution_id
designation
source_id
random_index
ref_epoch
ra
ra_error
dec
dec_error
parallax
parallax_error
parallax_over_error
pmra
pmra_error
pmdec
pmdec_error
ra_dec_corr
ra_parallax_corr
ra_pmra_corr
ra_pmdec_corr
dec_parallax_corr
dec_pmra_corr
dec_pmdec_corr
parallax_pmra_corr
parallax_pmdec_corr
pmra_pmdec_corr
astrometric_n_obs_al
astrometric_n_obs_ac
astrometric_n_good_obs_al
astrometric_n_bad_obs_al
astrometric_gof_al
astrometric_chi2_al
astrometric_excess_noise
astrometric_excess_noise_sig
astrometric_params_solved
astrometric_primary_flag
astrometric_weight_al
astrometric_pseudo_colour
astrometric_pseudo_colour_error
mean_varpi_factor_al
astrometric_matched_observations
visibility_periods_used
astrometric_sigma5d_max
frame_rotator_object_type
matched_observations
duplicated_source
phot_g_n_obs
phot_g_mean_flux
phot_g_mean_flux_error
phot_g_mean_flux_over_error
phot_g_mean_mag
phot_bp_n_obs
phot_bp_mean_flux
phot_bp_mean_flux_error
phot_bp_mean_flux_over_error
phot_bp_mean_mag
phot_rp_n_obs
phot_rp_mean_flux
phot_rp_mean_flux_error
phot_rp_mean_flux_over_error
phot_rp_mean_mag
phot_bp_rp_excess_factor
phot_proc_mode
bp_rp
bp_g
g_rp
radial_velocity
radial_velocity_error
rv_nb_transits
rv_template_teff
rv_template_logg
rv_template_fe_h
phot_variable_flag
l
b
ecl_lon
ecl_lat
priam_flags
teff_val
teff_percentile_lower
teff_percentile_upper
a_g_val
a_g_percentile_lower
a_g_percentile_upper
e_bp_min_rp_val
e_bp_min_rp_percentile_lower
e_bp_min_rp_percentile_upper
flame_flags
radius_val
radius_percentile_lower
radius_percentile_upper
lum_val
lum_percentile_lower
lum_percentile_upper
datalink_url
epoch_photometry_url
</pre></div>
</div>
</div>
</div>
<p>You can probably infer what many of these columns are by looking at the names, but you should resist the temptation to guess.
To find out what the columns mean, <a class="reference external" href="https://gea.esac.esa.int/archive/documentation/GDR2/Gaia_archive/chap_datamodel/sec_dm_main_tables/ssec_dm_gaia_source.html">read the documentation</a>.</p>
@@ -496,7 +753,113 @@ To find out what the columns mean, <a class="reference external" href="https://g
<p>One of the other tables we’ll use is <code class="docutils literal notranslate"><span class="pre">gaiadr2.panstarrs1_original_valid</span></code>. Use <code class="docutils literal notranslate"><span class="pre">load_table</span></code> to get the metadata for this table. How many columns are there and what are their names?</p>
<div class="cell tag_hide-cell docutils container">
<div class="cell_input docutils container">
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># Solution goes here</span>
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># Solution</span>
<span class="n">meta2</span> <span class="o">=</span> <span class="n">Gaia</span><span class="o">.</span><span class="n">load_table</span><span class="p">(</span><span class="s1">&#39;gaiadr2.panstarrs1_original_valid&#39;</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="n">meta2</span><span class="p">)</span>
<span class="k">for</span> <span class="n">column</span> <span class="ow">in</span> <span class="n">meta2</span><span class="o">.</span><span class="n">columns</span><span class="p">:</span>
<span class="nb">print</span><span class="p">(</span><span class="n">column</span><span class="o">.</span><span class="n">name</span><span class="p">)</span>
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output stream highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>Retrieving table &#39;gaiadr2.panstarrs1_original_valid&#39;
Parsing table &#39;gaiadr2.panstarrs1_original_valid&#39;...
Done.
TAP Table name: gaiadr2.gaiadr2.panstarrs1_original_valid
Description: The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) is
a system for wide-field astronomical imaging developed and operated by
the Institute for Astronomy at the University of Hawaii. Pan-STARRS1
(PS1) is the first part of Pan-STARRS to be completed and is the basis
for Data Release 1 (DR1). The PS1 survey used a 1.8 meter telescope and
its 1.4 Gigapixel camera to image the sky in five broadband filters (g,
r, i, z, y).
The current table contains a filtered subsample of the 10 723 304 629
entries listed in the original ObjectThin table.
We used only ObjectThin and MeanObject tables to extract
panstarrs1OriginalValid table, this means that objects detected only in
stack images are not included here. The main reason for us to avoid the
use of objects detected in stack images is that their astrometry is not
as good as the mean objects astrometry: “The stack positions (raStack,
decStack) have considerably larger systematic astrometric errors than
the mean epoch positions (raMean, decMean).” The astrometry for the
MeanObject positions uses Gaia DR1 as a reference catalog, while the
stack positions use 2MASS as a reference catalog.
In details, we filtered out all objects where:
- nDetections = 1
- no good quality data in Pan-STARRS, objInfoFlag 33554432 not set
- mean astrometry could not be measured, objInfoFlag 524288 set
- stack position used for mean astrometry, objInfoFlag 1048576 set
- error on all magnitudes equal to 0 or to -999;
- all magnitudes set to -999;
- error on RA or DEC greater than 1 arcsec.
The number of objects in panstarrs1OriginalValid is 2 264 263 282.
The panstarrs1OriginalValid table contains only a subset of the columns
available in the combined ObjectThin and MeanObject tables. A
description of the original ObjectThin and MeanObjects tables can be
found at:
https://outerspace.stsci.edu/display/PANSTARRS/PS1+Database+object+and+detection+tables
Download:
http://mastweb.stsci.edu/ps1casjobs/home.aspx
Documentation:
https://outerspace.stsci.edu/display/PANSTARRS
http://pswww.ifa.hawaii.edu/pswww/
References:
The Pan-STARRS1 Surveys, Chambers, K.C., et al. 2016, arXiv:1612.05560
Pan-STARRS Data Processing System, Magnier, E. A., et al. 2016,
arXiv:1612.05240
Pan-STARRS Pixel Processing: Detrending, Warping, Stacking, Waters, C.
Z., et al. 2016, arXiv:1612.05245
Pan-STARRS Pixel Analysis: Source Detection and Characterization,
Magnier, E. A., et al. 2016, arXiv:1612.05244
Pan-STARRS Photometric and Astrometric Calibration, Magnier, E. A., et
al. 2016, arXiv:1612.05242
The Pan-STARRS1 Database and Data Products, Flewelling, H. A., et al.
2016, arXiv:1612.05243
Catalogue curator:
SSDC - ASI Space Science Data Center
https://www.ssdc.asi.it/
Num. columns: 26
obj_name
obj_id
ra
dec
ra_error
dec_error
epoch_mean
g_mean_psf_mag
g_mean_psf_mag_error
g_flags
r_mean_psf_mag
r_mean_psf_mag_error
r_flags
i_mean_psf_mag
i_mean_psf_mag_error
i_flags
z_mean_psf_mag
z_mean_psf_mag_error
z_flags
y_mean_psf_mag
y_mean_psf_mag_error
y_flags
n_detections
zone_id
obj_info_flag
quality_flag
</pre></div>
</div>
</div>
@@ -537,6 +900,11 @@ To find out what the columns mean, <a class="reference external" href="https://g
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output text_plain highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>&lt;astroquery.utils.tap.model.job.Job at 0x7f50edd2adc0&gt;
</pre></div>
</div>
</div>
</div>
<p>The result is an object that represents the job running on a Gaia server.</p>
<p>If you print it, it displays metadata for the forthcoming results.</p>
@@ -546,6 +914,22 @@ To find out what the columns mean, <a class="reference external" href="https://g
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output stream highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>&lt;Table length=10&gt;
name dtype unit description n_bad
--------- ------- ---- ------------------------------------------------------------------ -----
source_id int64 Unique source identifier (unique within a particular Data Release) 0
ra float64 deg Right ascension 0
dec float64 deg Declination 0
parallax float64 mas Parallax 2
Jobid: None
Phase: COMPLETED
Owner: None
Output file: sync_20210315090602.xml.gz
Results: None
</pre></div>
</div>
</div>
</div>
<p>Don’t worry about <code class="docutils literal notranslate"><span class="pre">Results:</span> <span class="pre">None</span></code>. That does not actually mean there are no results.</p>
<p>However, <code class="docutils literal notranslate"><span class="pre">Phase:</span> <span class="pre">COMPLETED</span></code> indicates that the job is complete, so we can get the results like this:</p>
@@ -556,6 +940,11 @@ To find out what the columns mean, <a class="reference external" href="https://g
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output text_plain highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>astropy.table.table.Table
</pre></div>
</div>
</div>
</div>
<p>The <code class="docutils literal notranslate"><span class="pre">type</span></code> function indicates that the result is an <a class="reference external" href="https://docs.astropy.org/en/stable/table/">Astropy Table</a>.</p>
<p><strong>Optional detail:</strong> Why is <code class="docutils literal notranslate"><span class="pre">table</span></code> repeated three times? The first is the name of the module, the second is the name of the submodule, and the third is the name of the class. Most of the time we only care about the last one. It’s like the Linnean name for gorilla, which is <em>Gorilla gorilla gorilla</em>.</p>
@@ -571,6 +960,23 @@ To find out what the columns mean, <a class="reference external" href="https://g
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output text_html"><i>Table length=10</i>
<table id="table139985564118224" class="table-striped table-bordered table-condensed">
<thead><tr><th>source_id</th><th>ra</th><th>dec</th><th>parallax</th></tr></thead>
<thead><tr><th></th><th>deg</th><th>deg</th><th>mas</th></tr></thead>
<thead><tr><th>int64</th><th>float64</th><th>float64</th><th>float64</th></tr></thead>
<tr><td>5887983246081387776</td><td>227.978818386372</td><td>-53.64996962450103</td><td>1.0493172163332998</td></tr>
<tr><td>5887971250213117952</td><td>228.32280834041364</td><td>-53.66270726203726</td><td>0.29455652682279093</td></tr>
<tr><td>5887991866047288704</td><td>228.1582047014091</td><td>-53.454724911639794</td><td>-0.5789179941669236</td></tr>
<tr><td>5887968673232040832</td><td>228.07420888099884</td><td>-53.8064612895961</td><td>0.41030970779603076</td></tr>
<tr><td>5887979844465854720</td><td>228.42547805195946</td><td>-53.48882284470035</td><td>-0.23379683441525864</td></tr>
<tr><td>5887978607515442688</td><td>228.23831627636855</td><td>-53.56328249482688</td><td>-0.9252161956789068</td></tr>
<tr><td>5887978298278520704</td><td>228.26015640396173</td><td>-53.607284412896476</td><td>--</td></tr>
<tr><td>5887995581231772928</td><td>228.12871598211902</td><td>-53.373625663608316</td><td>-0.3325818206439385</td></tr>
<tr><td>5887982043490374016</td><td>227.985260087594</td><td>-53.683444499055575</td><td>0.02878111976456593</td></tr>
<tr><td>5887982971205433856</td><td>227.89884570686218</td><td>-53.67430215342567</td><td>--</td></tr>
</table></div></div>
</div>
<p>Each column has a name, units, and a data type.</p>
<p>For example, the units of <code class="docutils literal notranslate"><span class="pre">ra</span></code> and <code class="docutils literal notranslate"><span class="pre">dec</span></code> are degrees, and their data type is <code class="docutils literal notranslate"><span class="pre">float64</span></code>, which is a 64-bit <a class="reference external" href="https://en.wikipedia.org/wiki/Floating-point_arithmetic">floating-point number</a>, used to store measurements with a fraction part.</p>
@@ -580,7 +986,23 @@ To find out what the columns mean, <a class="reference external" href="https://g
<p>Read <a class="reference external" href="https://gea.esac.esa.int/archive/documentation/GDR2/Gaia_archive/chap_datamodel/sec_dm_main_tables/ssec_dm_gaia_source.html">the documentation</a> of this table and choose a column that looks interesting to you. Add the column name to the query and run it again. What are the units of the column you selected? What is its data type?</p>
<div class="cell tag_hide-cell docutils container">
<div class="cell_input docutils container">
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># Solution goes here</span>
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># Solution</span>
<span class="c1"># Let&#39;s add</span>
<span class="c1">#</span>
<span class="c1"># radial_velocity : Radial velocity (double, Velocity[km/s] )</span>
<span class="c1">#</span>
<span class="c1"># Spectroscopic radial velocity in the solar barycentric </span>
<span class="c1"># reference frame.</span>
<span class="c1">#</span>
<span class="c1"># The radial velocity provided is the median value of the </span>
<span class="c1"># radial velocity measurements at all epochs.</span>
<span class="n">query</span> <span class="o">=</span> <span class="s2">&quot;&quot;&quot;SELECT </span>
<span class="s2">TOP 10</span>
<span class="s2">source_id, ra, dec, parallax, radial_velocity</span>
<span class="s2">FROM gaiadr2.gaia_source</span>
<span class="s2">&quot;&quot;&quot;</span>
</pre></div>
</div>
</div>
@@ -622,6 +1044,14 @@ We’ll use this clause to exclude nearby stars that are unlikely to be part of
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output stream highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>INFO: Query finished. [astroquery.utils.tap.core]
</pre></div>
</div>
<div class="output text_plain highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>&lt;astroquery.utils.tap.model.job.Job at 0x7f50edd40f40&gt;
</pre></div>
</div>
</div>
</div>
<p>And here are the results.</p>
<div class="cell docutils container">
@@ -631,6 +1061,23 @@ We’ll use this clause to exclude nearby stars that are unlikely to be part of
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output text_html"><i>Table length=10</i>
<table id="table139986226873968" class="table-striped table-bordered table-condensed">
<thead><tr><th>source_id</th><th>ra</th><th>dec</th><th>parallax</th><th>radial_velocity</th></tr></thead>
<thead><tr><th></th><th>deg</th><th>deg</th><th>mas</th><th>km / s</th></tr></thead>
<thead><tr><th>int64</th><th>float64</th><th>float64</th><th>float64</th><th>float64</th></tr></thead>
<tr><td>5895270396817359872</td><td>213.08433715252883</td><td>-56.64104701005694</td><td>2.041947005434917</td><td>--</td></tr>
<tr><td>5895272561481374080</td><td>213.2606587905109</td><td>-56.55044401535715</td><td>0.15693467895110133</td><td>--</td></tr>
<tr><td>5895247410183786368</td><td>213.38479712976664</td><td>-56.97008551185148</td><td>-0.19017525742552605</td><td>--</td></tr>
<tr><td>5895249226912448000</td><td>213.41587389088238</td><td>-56.849596577635786</td><td>--</td><td>--</td></tr>
<tr><td>5895261875598904576</td><td>213.5508930114549</td><td>-56.61037780154348</td><td>-0.29471722363529257</td><td>--</td></tr>
<tr><td>5895258302187834624</td><td>213.87631129557286</td><td>-56.678537259039906</td><td>0.6468437015289753</td><td>--</td></tr>
<tr><td>5895247444506644992</td><td>213.33215109206796</td><td>-56.975347759380995</td><td>0.390215490234287</td><td>--</td></tr>
<tr><td>5895259470417635968</td><td>213.78815034206346</td><td>-56.64585047451594</td><td>0.953377710788918</td><td>--</td></tr>
<tr><td>5895264899260932352</td><td>213.21521027193236</td><td>-56.78420864489118</td><td>--</td><td>--</td></tr>
<tr><td>5895265925746051584</td><td>213.17082359534547</td><td>-56.74540885107754</td><td>0.2986918215101751</td><td>--</td></tr>
</table></div></div>
</div>
<p>You might notice that some values of <code class="docutils literal notranslate"><span class="pre">parallax</span></code> are negative. As <a class="reference external" href="https://www.cosmos.esa.int/web/gaia/archive-tips#negative%20parallax">this FAQ explains</a>, “Negative parallaxes are caused by errors in the observations.” They have “no physical meaning,” but they can be a “useful diagnostic on the quality of the astrometric solution.”</p>
<div class="section" id="id2">
@@ -646,7 +1093,16 @@ The modified query should fail, but notice that you don’t get much useful debu
</ul>
<div class="cell tag_hide-cell docutils container">
<div class="cell_input docutils container">
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># Solution goes here</span>
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># Solution</span>
<span class="c1"># In this example, the WHERE clause is in the wrong place</span>
<span class="n">query</span> <span class="o">=</span> <span class="s2">&quot;&quot;&quot;SELECT </span>
<span class="s2">TOP 3000</span>
<span class="s2">WHERE parallax &lt; 1</span>
<span class="s2">source_id, ref_epoch, ra, dec, parallax</span>
<span class="s2">FROM gaiadr2.gaia_source</span>
<span class="s2">&quot;&quot;&quot;</span>
</pre></div>
</div>
</div>
@@ -696,7 +1152,27 @@ Be careful to keep your Python out of your ADQL!</p>
<p><a class="reference external" href="https://www.w3schools.com/sql/sql_operators.asp">Read about SQL operators here</a> and then modify the previous query to select rows where <code class="docutils literal notranslate"><span class="pre">bp_rp</span></code> is between <code class="docutils literal notranslate"><span class="pre">-0.75</span></code> and <code class="docutils literal notranslate"><span class="pre">2</span></code>.</p>
<div class="cell tag_hide-cell docutils container">
<div class="cell_input docutils container">
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># Solution goes here</span>
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># Solution</span>
<span class="c1"># Here&#39;s a solution using &gt; and &lt; operators</span>
<span class="n">query</span> <span class="o">=</span> <span class="s2">&quot;&quot;&quot;SELECT </span>
<span class="s2">TOP 10</span>
<span class="s2">source_id, ref_epoch, ra, dec, parallax</span>
<span class="s2">FROM gaiadr2.gaia_source</span>
<span class="s2">WHERE parallax &lt; 1 </span>
<span class="s2"> AND bp_rp &gt; -0.75 AND bp_rp &lt; 2</span>
<span class="s2">&quot;&quot;&quot;</span>
<span class="c1"># And here&#39;s a solution using the BETWEEN operator</span>
<span class="n">query</span> <span class="o">=</span> <span class="s2">&quot;&quot;&quot;SELECT </span>
<span class="s2">TOP 10</span>
<span class="s2">source_id, ref_epoch, ra, dec, parallax</span>
<span class="s2">FROM gaiadr2.gaia_source</span>
<span class="s2">WHERE parallax &lt; 1 </span>
<span class="s2"> AND bp_rp BETWEEN -0.75 AND 2</span>
<span class="s2">&quot;&quot;&quot;</span>
</pre></div>
</div>
</div>
@@ -754,6 +1230,11 @@ That’s not required, but it is a common style.</p>
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output text_plain highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>&#39;SELECT \nTOP 10 \nsource_id, ra, dec, pmra, pmdec\nFROM gaiadr2.gaia_source\nWHERE parallax &lt; 1\n AND bp_rp BETWEEN -0.75 AND 2\n&#39;
</pre></div>
</div>
</div>
</div>
<p>But if you print it, the line breaks appear as… line breaks.</p>
<div class="cell docutils container">
@@ -762,6 +1243,16 @@ That’s not required, but it is a common style.</p>
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output stream highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>SELECT
TOP 10
source_id, ra, dec, pmra, pmdec
FROM gaiadr2.gaia_source
WHERE parallax &lt; 1
AND bp_rp BETWEEN -0.75 AND 2
</pre></div>
</div>
</div>
</div>
<p>Notice that the format specifier has been replaced with the value of <code class="docutils literal notranslate"><span class="pre">columns</span></code>.</p>
<p>Let’s run it and see if it works:</p>
@@ -772,6 +1263,23 @@ That’s not required, but it is a common style.</p>
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output stream highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>&lt;Table length=10&gt;
name dtype unit description
--------- ------- -------- ------------------------------------------------------------------
source_id int64 Unique source identifier (unique within a particular Data Release)
ra float64 deg Right ascension
dec float64 deg Declination
pmra float64 mas / yr Proper motion in right ascension direction
pmdec float64 mas / yr Proper motion in declination direction
Jobid: None
Phase: COMPLETED
Owner: None
Output file: sync_20210315091929.xml.gz
Results: None
</pre></div>
</div>
</div>
</div>
<div class="cell docutils container">
<div class="cell_input docutils container">
@@ -780,6 +1288,23 @@ That’s not required, but it is a common style.</p>
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output text_html"><i>Table length=10</i>
<table id="table139985564118512" class="table-striped table-bordered table-condensed">
<thead><tr><th>source_id</th><th>ra</th><th>dec</th><th>pmra</th><th>pmdec</th></tr></thead>
<thead><tr><th></th><th>deg</th><th>deg</th><th>mas / yr</th><th>mas / yr</th></tr></thead>
<thead><tr><th>int64</th><th>float64</th><th>float64</th><th>float64</th><th>float64</th></tr></thead>
<tr><td>5895272561481374080</td><td>213.2606587905109</td><td>-56.55044401535715</td><td>0.3894438898301715</td><td>1.2299266281737415</td></tr>
<tr><td>5895261875598904576</td><td>213.5508930114549</td><td>-56.61037780154348</td><td>0.16203641364393007</td><td>-4.672602679543312</td></tr>
<tr><td>5895247444506644992</td><td>213.33215109206796</td><td>-56.975347759380995</td><td>-7.474003156859284</td><td>-3.538080792097856</td></tr>
<tr><td>5895259470417635968</td><td>213.78815034206346</td><td>-56.64585047451594</td><td>-5.287202255231853</td><td>-0.8163762113468646</td></tr>
<tr><td>5895265925746051584</td><td>213.17082359534547</td><td>-56.74540885107754</td><td>-7.880749306158471</td><td>-4.8585444120179595</td></tr>
<tr><td>5895260913525974528</td><td>213.66936020541976</td><td>-56.66655190442016</td><td>-4.7820929042428215</td><td>-1.5566420086447643</td></tr>
<tr><td>5895264212062283008</td><td>213.7755742121852</td><td>-56.51570859067397</td><td>-6.657690998559842</td><td>-1.7616494482071872</td></tr>
<tr><td>5895253457497979136</td><td>213.30929960610283</td><td>-56.78849448744587</td><td>-5.242106718924749</td><td>-0.18655636353898095</td></tr>
<tr><td>4143614130253524096</td><td>269.1749117455479</td><td>-18.53415139972117</td><td>2.6164274510804826</td><td>1.3244248889980894</td></tr>
<tr><td>4065443904433108992</td><td>273.26868565443743</td><td>-24.421651815402857</td><td>-1.663096652191022</td><td>-2.6514745376067683</td></tr>
</table></div></div>
</div>
<p>Good so far.</p>
<div class="section" id="id4">
@@ -788,7 +1313,29 @@ That’s not required, but it is a common style.</p>
<p>Modify <code class="docutils literal notranslate"><span class="pre">query3_base</span></code> to replace <code class="docutils literal notranslate"><span class="pre">1</span></code> with a format specifier like <code class="docutils literal notranslate"><span class="pre">{max_parallax}</span></code>. Now, when you call <code class="docutils literal notranslate"><span class="pre">format</span></code>, add a keyword argument that assigns a value to <code class="docutils literal notranslate"><span class="pre">max_parallax</span></code>, and confirm that the format specifier gets replaced with the value you provide.</p>
<div class="cell tag_hide-cell docutils container">
<div class="cell_input docutils container">
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># Solution goes here</span>
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="c1"># Solution</span>
<span class="n">query_base</span> <span class="o">=</span> <span class="s2">&quot;&quot;&quot;SELECT </span>
<span class="s2">TOP 10</span>
<span class="si">{columns}</span><span class="s2"></span>
<span class="s2">FROM gaiadr2.gaia_source</span>
<span class="s2">WHERE parallax &lt; </span><span class="si">{max_parallax}</span><span class="s2"> AND </span>
<span class="s2">bp_rp BETWEEN -0.75 AND 2</span>
<span class="s2">&quot;&quot;&quot;</span>
<span class="n">query</span> <span class="o">=</span> <span class="n">query_base</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">columns</span><span class="o">=</span><span class="n">columns</span><span class="p">,</span>
<span class="n">max_parallax</span><span class="o">=</span><span class="mf">0.5</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="n">query</span><span class="p">)</span>
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output stream highlight-myst-ansi notranslate"><div class="highlight"><pre><span></span>SELECT
TOP 10
source_id, ra, dec, pmra, pmdec
FROM gaiadr2.gaia_source
WHERE parallax &lt; 0.5 AND
bp_rp BETWEEN -0.75 AND 2
</pre></div>
</div>
</div>