Galactic 1

Tutors: Deborah BAINES, Nic WALTON, Paul HARRISON, Gary GILCHRIST

Participants

Belcheva (Linux), Borisova (Linux), Bragaglia (Mac OS X), Follert (Windows/Linux), Graefe (Linux), Nikolov (Linux), Raddi (Mac OS X), Stiele (Linux), Tempel (Mac OS X), Tuvikene (Windows)

Notes from Gal group One

The page GalOneNotes lists feedback from the group - and contains some screen shots of what the attendees did over the two days of hands-on practicals.

AstroGrid Sample SQL Queries to IPHAS:

http://www.astrogrid.org/wiki/Help/UsageExamples/DataAccess/ExampleQueries/IPHAS

USE CASES

Use Case 1

The Pleiades open cluster, from the AIDA WP5 use cases (uses Aladin, VOPlot).

• Launch Aladin
• Open the server selector (File -> Load from the Virtual Observatory).
• Enter target 'pleiades', radius '30 arcmin' and deselect the catalogues and spectra servers.
• Load POSS II J image 6.5 x 6.5 degrees.
• To make the image clearer, modify the pixel distribution ( "pixel" button, 3rd from the bottom, vertical tool bar, right next to the display window -> sqrt) .
• Select 'all VizieR' at the top right hand side of the Server selector window.
• In the free text field enter 'parallax' and click 'submit'.
• Select The Hipparcos and Tycho Cat, I/239, return to the server selector window and add “/hip_main' to the Catalogue field, after 'I/239' and input a radius of 5 degrees. Then click 'SUBMIT' in the catalogue window.
• The catalogue points are overlaid on the pleiades J image in the main Aladin window.
• Open the VOPlot tool (Tool -> VO tools -> VOPlot).
• Right click on the catalogue plane and select 'broadcast selected tables to VOPlot'.
• Switch to the VOPlot window and in the x-axis coordinate field select parallaxes (plx) and click 'histogram'. Notice that the parallax for this cluster is around 8-9 mas, with many background stars and a few foreground ones.
• Add a new column to the catalogue (functions -> Create New Columns). Correct the data for reddening using the relation (B-V)o = (B-V) – E(B-V) = (B-V) -0.04, for this cluster by inserting '(B-V)o into the 'Enter column name' field and in the 'Enter expression' field choose the (B-V) column and add '-0.04'. Then click 'Add'.
• Check that the new column has been added by selecting 'Data in Table Format', which will ooen a new window showing the table data.
• In the main VOPlot window select '(B-V)o' for the x-axis, 'Vmag' for the y axis, check the Rev button above the y-axis and then click 'Plot'.
• In the resulting plot the main sequence is clearly visible.
• Match sources between Aladin and VOPlot by selecting points in the top left corner of the VOPlot plot. These are then highlighted in both VOPlot and Aladin. Note that they are mainly in the centre and most of them have parallaxes of 8 - 9 mas.
• Select points in the bottom right corner of the VOPlot plot. The corresponding sources in the image are mainly at the edge of the field and from the parallaxes can be seen that they are mostly background sources.
• Select data available in diffferent missions by doing the following: go back to the Aladin Server selector window and select 'Missions' in to the right of the window.
• Type 'pleiades' into the Target field and select logHST then click 'SUBMIT'. The pointings for the HST are overlaid in the image. Do the same for the logIUE and logESO.
• Select one HST pointing in the image.
• The table below the image gives links to images, data archives, web pages, and other information.

Here is the same case as above, but using TOPCAT instead of VOPlot:

• Launch Aladin
• Open the server selector (File -> Load from the Virtual Observatory).
• Enter target 'pleiades', radius '30 arcmin' and deselect the catalogues and spectra servers.
• Load POSS II J image 6.5 x 6.5 degrees.
• To make the image clearer, modify the pixel distribution ( "pixel" button, 3rd from the bottom, vertical tool bar, right next to the display window -> sqrt) .
• Select 'all VizieR' at the top right hand side of the Server selector window.
• In the free text field enter 'parallax' and click 'submit'.
• Select The Hipparcos and Tycho Cat, I/239, return to the server selector window and add “/hip_main' to the Catalogue field, after 'I/239' and input a radius of 5 degrees. Then click 'SUBMIT' in the catalogue window.
• The catalogue points are overlaid on the pleiades J image in the main Aladin window.
• Open TOPCAT (Tool -> VO tools -> TOPCAT).
• Right click on the catalogue plane and select 'broadcast selected tables to TOPCAT'.
• Switch to the TOPCAT window and select the Histogram plot from Graphics -> Histogram. In the Histgram window change the x-axis coordinate field to parallaxes (plx). Notice that the parallax for this cluster is around 8-9 mas, with many background stars and a few foreground ones.
• Add a new column to the catalogue by selecting Views -> Column Info. In the Table Columns window that opens, select Columns -> New Synthetic Column. Correct the data for reddening using the relation (B-V)o = (B-V) – E(B-V) = (B-V) -0.04, for this cluster by inserting '(B-V)o into the 'Name' field. In the 'Expression' field choose the (B-V) column and add -0.04, i.e. type '$Number -0.04', where Number is the (B-V) column number. Input 'mag' into the 'Units' field and click 'OK'.
• Check that the new column has been added by selecting 'Views -> Table Data', which will open a new window showing the table data.
• In the main TOPCAT window select 'Graphics -> Plot', '(B-V)o' for the x-axis, 'Vmag' for the y axis and check the 'Flip' button for the y-axis.
• In the resulting plot the main sequence is clearly visible.
• Match sources between Aladin and TOPCAT by selecting points in the top left corner of the TOPCAT plot by selecting 'Subsets -> Draw Subset Region'. Draw the region to be selected then go to 'Subsets -> Finish Drawing Region'. A 'New Subset' window appears. Type in the subset name 'TopLeft' and click 'Add Subset'. This subset appears in the plot as different coloured points. Broadcast this subset to Aladin by going back to the main TOPCAT window and changing the 'Row Subset' field to 'TopLeft'. Then select 'File -> Send table to Aladin. These stars appear in a third layer in Aladin. Note that they are mainly in the centre and most of them have parallaxes of 8 - 9 mas.
• Repeat the above step and select points in the bottom right corner of the TOPCAT plot. Broadcast this subset to Aladin. The corresponding sources in the image are mainly at the edge of the field and from the parallaxes can be seen that they are mostly background sources.
• Select data available in diffferent missions by doing the following: go back to the Aladin Server selector window and select 'Missions' in to the right of the window.
• Type 'pleiades' into the Target field and select logHST then click 'SUBMIT'. The pointings for the HST are overlaid in the image. Do the same for the logIUE and logESO.
• Select one HST pointing in the image.
• The table below the image gives links to images, data archives, web pages, and other information.

Use Case 2

Based on the case developed by Evanthia, based on the VO-TECH Science Framework Document (see http://www.euro-vo.org/pub/fc/workflows/IMF.htm)

Use Case 3

Proposed by Angela Bragaglia: Building the Spectro-Photometric Standard Stars grid for GAIA Targets.

We require SPSS in the magnitude range V=9-15 that must be: single stars (or members of wide, well separated binaries); non intrinsically variable; as featureless as possible (e.g. WDs, sds metal-poor stars) with only a few cases of red spectral types; in uncrowded regions of the sky. We would also require a few hot, but heavily reddened objects. Stars lying within 1-2 degrees of the two bands at +/- 45 degrees ecliptic latitude (the zones more frequently sampled by Gaia) would be an asset. OUTPUT FROM THE VO: Stars with precise absolute photometry, known to be single, with variability checked (or checkable) by repeated photometry, with known spectral type. Other desirable outputs: spectrophotometry, atmospheric parameters.

Name LastName

Use Case 4

Try cross matching 2mass and IPHAS - thus IR and Optical data. See the page at http://www.astrogrid.org/wiki/Help/IntroScripting/AstrogridPython/XMatchADQL

To run this - you need to make sure that you have VODesktop active - and that you have a file in your home directory - .python-acr set up - see the Configuration section at http://www.astrogrid.org/wiki/Help/IntroScripting/AstrogridPython

Use Case 5: The Field of Streams

Star counts from the SDSS DR5 data - followingBelokurov et al, 2006.

In this you'll query the SDSS with SQL queries selecting stars with the appropriate quality flags. You'll repeat the query in 2 deg strips. You'll then use TopCat to generate the RGB colour plots.

Here is the basic python script:

#!/usr/bin/python 

import time, urllib
from astrogrid import acr, DSA, MySpace

# Login in Leicester account
acr.login('leicester')

# Define the service to query
dsa=DSA('ivo://wfau.roe.ac.uk/sdssdr5-dsa/dsa/ceaApplication')

# Construct the SQL
tsql = """SELECT a.ra, a."dec", a.psfMag_g, a.psfMag_r FROM PhotoTag AS a """
tsql += """WHERE a.ra>110 AND a.ra<230 AND a."dec">%s AND a."dec"<=%s AND (a.psfMag_g-a.psfMag_r <0.4 ) AND """
tsql += """a.psfMag_r>20.0 AND a.psfMag_g>0 AND a.mode=1 AND a.probPSF=1"""

m = MySpace() 

# Looop for range of declinations (use range(0, 60, 2) to get full dec range)
for i in range(0, 2, 2):
   sql = tsql % (i, i+2)
   r = dsa.query(sql, saveAs='#eso/ndec%02d-%02d.vot' % (i,i+2))

   # Wait until completed
   time.sleep(10)
   while r.status() not in ['COMPLETED' , 'ERROR']:
      print r.status()
      time.sleep(10)

   print r.status()
   # If completed extract the URL of the saved file and save it to local disk
   # Note: this can change slightly in the next beta release
   if r.status() == 'COMPLETED':
      url = r.results()[0]
       res = m.readfile(url)
       open('ndec%02d-%02d.vot' % (i, i+2),'w').write(res)
   print 'ndec%02d-%02d.vot' % (i,i+2)

The above script will save the output .vot files in both your Myspace and local disk.

If you run the above with say

for i in range(0, 10, 2):

you will get a set of output files: ndec00-02.vot, ndec02-04.vot etc

to concatentate these you can use STILTS.

• in vodesktop - run up task runner - and select the STILTStask.
• choose interface tcat - see the screenshot below for the boxes you need to fill in.
• for the 'in' box you can add more input files to concatenate by hitting the '+' button.

As an exercise you can work out how to script this.

Once you have your concatenated file - download it to your desktop and use this as the input to topcat below.

You can then use Topcat to generate the RGB plots.

• load the vot file
• hit the purple/red dot button to make the r g b subsets:

1. b
2. psfMag_r > 20.0 && psfMag_r < 20.66
3. g
4. psfMag_r > 20.66 && psfMag_r < 21.33
5. r
6. psfMag_r > 21.33 && psfMag_r < 22.00

• remember to flip the ra axis so that it runs big to small in ra. also - resize plot with non of the subsets displayed (also change the colours to rgb with the displays turned off). then tick the row subsets - need to move the cut percentile sliders to ~ 1 and 99 and do a bit of 'blocking' to recreate the belokurov picture.

-- PaoloPadovani - 02 Mar 2009

• streams.png:
  

• stilts.png:
  

• the group hard at work:
• 

Tools used by the Gal 1 group:

• Aladin
• TOPCAT
• VODesktop
• VOSpec
• VOSA
• VOSED
• VOPlot
• Scripting with Python
• STILTS
• VirGO