5.1   Search for objects around a position

For rectangular queries one can use:

--- Retrieve all objects in a rectangle
SELECT * FROM
  PhotoObj as P
WHERE
  P.ra > 15.4 AND P.ra < 15.6
  AND
  P.dec > 59.0 AND P.dec < 60.1

The table getObjCirc is used in the following example to retrieve all objects within a radius of 10 arcmin from the position RA=15.45, Dec=60.50:

--- Retrieve all objects within 10 arcmin of
--- the position RA=15.45, Dec=60.50
--- uses HTM to speed the query
SELECT * FROM 
  PhotoObj as P, getObjCirc as G
WHERE
  --- Insert here the ra, dec and radius in arcmin
  G._ra=15.45 AND G._dec=60.50 AND G._radius=10.0 
AND
  --- getObjCirc returns a table with id numbers
  --- satisfying the circular query
  G.id = P.id

The image below shows the result ra, dec distribution of the returned sources as well as their r band magnitude distribution.

5.2   Extracting colours

The following example selects positions and colours for sources observed in fields which match '7300':

SELECT 
   P.ra, P.dec, 
   P.coremag_r, P.coremag_i, P.coremag_ha,
   F.name
FROM PhotoObj as P, FieldsAll as F
--- ADQL does not support JOIN keyword
WHERE P.field_id = F.id AND F.name LIKE '%7300o%'

The following plot shows a colour-colour diagram extracted for the field 7300o. The plot on the right shows different objects as function of their magnitude (magenta: r<14, blue: r<16, grey: r<18 and green: r<20).

5.3   Selecting by magnitude limit

The following query selects all the objects which are observed in frames where the r-band magnitude is greater or equal to 22.0 (the result is 366763 objects):

SELECT
   P.ra, P.dec, P.coremag_r, P.coremag_i, P.coremag_ha, F.name
FROM PhotoObj as P, PhotoPtr as T, FieldsAll as F, ChipAll as C 
WHERE P.pptr_id=T.id And T.chip_r_id=C.id And T.field_id=F.id and C.maglim>22.0

5.4   Adding additional constrains

In some cases you will want to retrieve objects which have been observed in a particular field, or only in those observations with a good seeing and/or good photometric conditions:

--- Select objects which have been observed in good conditions
SELECT TOP 1000 * FROM PhotoObj as P
WHERE
   --- Only objects observed in seeing <= 1.7 arcsec
   --- we may add more codes to different seeing values
   seeing_flag =1
AND
   --- Only objects observed with ellipticity <= 0.25
   --- we may add more codes to different ellipt values
   ellipt_flag = 1
AND
   --- Skip objects saturated in one or more bands
   class_flag <> -9
AND
   --- Only objects for which r, i and Ha have been obtained the same night
   night_flag = 1

5.5   Example Query Files

In order to load these queries follow this tutorial.

1. iphas_rect.q performs a simple selection in ra and dec
2. iphas_cone.q performs a simple cone search query using the HTM tree.
3. iphas_field.q resturns all objects observed in a particular field.