This module sets filter criteria for Object Selection (Figure 10). There are two ways to search for objects - Primary and SQL-like. The first one provides with a special screen where one selects a number of parameters to search by whereas the second uses logical expression for the search.
Internal catalogs may contain same objects with different names, to make sure that search result does not contain the same object several times turn Exclude duplicates option on.
Select object catalogs for a search among all internal object databases and user catalogs
Select either Primary search or SQL-like search.
- Select object types. Use this for selecting object types
- Empty field treatment. For incomplete data sets, when some of the object’s data values are missing, you can select the preferred way to resolve the situation during search (i.e. treat the empty field as zero valued, as a ''very large number'' or regardless count it as a positive or a negative match)
- Primary search parameters
- Filter type. Select a filter or do not use it at all
- Visibility Filter. Objects above or equal to a detection limit are looked for
- Maximum magnitude filter. Objects with a magnitude below or equal to a specified value are looked for.
- No filter. No filter is applied
- Select constellation. Select one or several constellations to search objects in. If no constellation is selected, objects are searched in all constellations
- Object name starts with. Select the beginning of the object name. This option is convenient for catalogs combined from various sources like SAC. As an example, by setting name beginning to ''cr'' you limit your search to Collinder open clusters
- Object minimal size. Search for objects with the dimension above or equal to the specified one
- Lowest altitude. Search for objects which rise above the specified altitude during observation time range
- Detection limit. Set the threshold for the visibility filter
- Set maximum magnitude. Set the threshold for maximum magnitude filter
- Minimum separation. Minimum separation between components when searching in double star catalogs
- Maximum separation. Maximum separation between components when searching in double star catalogs
- Maximum mag2. Maximum magnitude of the second component when searching in double star catalogs
This module contains a list of SQL-like expressions defined by user. Select one to use for a search. Initially the list contains 3 simple basic expressions as examples. Create a new search request with Add new search request button at the bottom of the screen.
SQL-like expression consists of two parts:
The following fields could be used in expression (in any case - upper-case, lower-case or mixed).
- SQL request. The request is used to search any database by its non-calculated fields
- Local request. The request is used to filter by calculated values: altitude and visibility
Any additional user database numeric fields could also be used (e.g. this is the valid expression for LDN database: , and this is for WDS or Bright DS database:
The following operations could be used in expressions
- TYPE. Object type. Could take the standard object type value
- A. Larger object dimension in minutes
- B. Smaller object dimension in minutes
- RA. Right ascension (2000) in hours
- DEC. Declination (2000) in degrees
- MAG. Magnitude
- PA. Position angle
- CON. Constellation (3 symbol Latin abbreviation)
- - a is equal to b
- - a is greater than b
- - a is less than b
- - a is not equal to b
- - logical AND (e.g.
- object magnitude is higher than 12 and its type is equal to GC)
- - logical OR (e.g.
- object is either GC or OC
. All objects from Andromeda constellation with larger axis above 15 minutes
. All globular clusters larger than 10 minutes
. Edge-On galaxies
- . All objects in database
- . Objects that have an altitude above 20 degrees at least once during the observation period
- . Objects with visibility higher than 1
. Both above conditions should hold
Provides standard export/import operations.
- Edit. Edit the selected expression
- Remove. Remove it from the list
This part allows to set conditions common to both Primary and SQL-like search.
- Exclude duplicates. This is an option to remove physically duplicated objects when searching in intersecting databases with the same/different object name notations. As an example, if you select NgcIc and UGC catalogs and turn this option on, then among galaxies NGC2 and UGC59 (which are the same) only NGC2 will be found. Without this option the application finds both NGC2 and UGC59. This feature also excludes duplicated objects from the same catalog (e.g. NGC6/NGC20, NGC17/NGC34)
- Time of observation. Set observation range. In addition to setting the time range manually, one may easily define the ranges with a reference to astro twilight, sun rise and sun setting
- Telescope/Instrument. Select an instrument for observations
- Geographic Location. Select observatory location
- Sky limiting magnitude. The magnitude of faintest stars at zenith. Used for visibility calculations