WEBDA Interrogation

Contents

Query design

Cluster selection

Cluster page

Bibliography

Data sources

Cross-identifications

However, no facilities is yet proposed to search all clusters in the database for some characteristics, or, for example, to list all stars in open clusters that are brighter than a given magnitude.

Cluster selections

the quantity of available data.

This is mostly useful to identify the clusters with the largest number of observations for a given project or to locate the clusters requiring modern observations and prepare an observing program.

the cluster parameters.

Cluster parameters include coordinates, distances, ages and diameters.

easons to do selections on the cluster parameters are the same as those described in the previous item.

the cluster names

This permits to display the properties of all the clusters in the list of any author, like, for example, Trumpler or Stock.

A) On the quantity of available data

1) Select the kind of selection you want to perform among the three possibilities:

• more than N stars observed
• less than N stars observed
• between N1 and N2 stars observed

2) Enter the limiting value(s) in the corresponding text area.

3) Indicate on which type of data the selection should be made in the last area.

4) Press Submit Query to activate the selection.

B) On the quantity of available data and cluster parameters

1) Enter the lower and upper limits, when relevant, corresponding to your criteria,

• Any number of parameters can be used simultaneously, but do not fill both the distance in [pc] and the distance modulus in [mag].
• The right ascension is given in hours and minute with a space, like 11 30
• The declination is entered in a similar fashion: -30 15
• The other parameters require decimal (floating) numbers.

2) Select the kind of selection you want to perform among the three possibilities:

• more than N stars observed
• less than N stars observed
• between N1 and N2 stars observed

3) Enter the limiting value(s) in the corresponding text area.

4) Indicate on which type of data the selection should be made in the last area.

5) Press Submit Query to activate the selection.

C) On cluster parameters

1) Enter the lower and upper limits, when relevant, corresponding to your criteria,

• Any number of parameters can be used simultaneously, but do not fill both the distance in [pc] and the distance modulus in [mag].
• The right ascension is given in hours and minute with a space, like 11 30
• The declination is entered in a similar fashion: -30 15
• The other parameters require decimal (floating) numbers.

2) Press Submit Query to activate the selection.

D) On cluster names

1) Enter a name in the text area,

2) Press Submit Query to activate the selection.

E) On colour maps

1) Select the plot in the right-hand frame,

2) Fill the form:

• Indicate the limits of the plot in the system of coordinates. Both normal (hour, minute and degree, minute) or decimal (hh.mm, dd.mm) modes can be used.
• If no criteria are gievn for the declination or latitude, a selection is made with l = 15°.
• Cluster names may be written on the map if the chosen scale is appropriate. Use the radio buttons to select the desired mode.

Enter its name in the text area and press Return.

You can use any NGC or IC numbers, anon. designations, Messier names or IAU official identifications, in upper or lower cases and with or without space between the name and cluster number. You can also use the name of nearby clusters, like Hyades and so on.

Examples

• NGC 2516 or NGC 2516 or ngc2516
• IC 2602 or IC2602 or ic2602
• Trumpler 16 or Tr16 or tr 16
• Messier 6 or M6 or m6
• C0424+151
• Hyades or hyades
• Pleiades, Praesepe, Coma, Alpha Persei, Orion, ...

Query

A) Search by star numbers

To use the query form

• Select one or more data types (multiple selection),
• Enter a list of star numbers,
• Submit query.

The output will group the data of one kind for all stars. The field labelled Ref has a link which allows to get the reference of the source for the data.

To perform selection on star numbers use the selection form described below.

B) Selection on data

To get more information on this facitility, look at the usage explanation.

Bibliography query

A) Query by keywords

1) Enter the initial and final years,

2) Enter up to three keywords,

• In addition to the cluster names, there is a large list of keywords and
• it is possible to use a form to search the possible keywords describing a concept.

3) Press Submit Query to activate the query.

B) Query by authors'names

1) Enter up to three astronomer names, separated by a space,

2) Press Submit Query to activate the query.

How to perform a search

1. Select ONE type of data in the upper windows. The data types are separated in three main groups: fundamental data, photometric data and spectroscopic data.
   Information on the data types can be obtained by following the link Datatypes in the bottom of the form.
2. Choose on which criterion the search will be done: reference number, author's name or word in the titles.
3. Enter the appropriate information in the text field,
4. Press submit query

If the answer is psitive, the output will give the cluster name and the number of the star in the adopted numbering system. The link under the cluster name leads to the cluster page, and that under the star number displays a new form to query the database for that star. The star number is already entered in the form.

The form page provides a few examples of the accepted syntaxes.