How to use the Quanta service
General tips
- In each of the functions you can combine units in the usual ways (multiplication & division) such as km/s/Mpc or m.s-2.
See what units & constants are available
The function lists the units and constants that are available in this service. It is useful for checking the symbols. Most of the symbols are standard, however some may not what you would expect. This is to avoid ambiguity as some units have the same symbols in common usage. The resulting list of units will appear on a new screen.
Convert from one quantity to another
This function allows you to convert a value from one set of units to another. So for example, you might want to convert from inches to centimetres. In that case you would put the value in inches in the first box 10in and the units you want to convert to in the second box cm, then click convert. Some examples of common units are:
arcmin (arcmin) 0.000290888208666 rad deg (degree) 0.0174532925199 rad Hz (hertz) 1 s-1 Jy (jansky) 1e-26 kg.s-2 rad (radian) 1 rad s (second) 1 s sr (steradian) 1 sr The results from your query will appear below the query boxes, with the answer highlighted in red text, such as: The value of 234.45km converted to m is: 234450 m
Convert a quantity to base units
This function converts a quantity to the base units for that dimensionality (ie: distance, time, temperature). For example, if you enter 10in it will convert it to 0.254 m since the metre is the base unit for distance.
There are 10 base units:
A (ampere) 1 A K (kelvin) 1 K _ (undimensioned) 1 _ cd (candela) 1 cd kg (kilogram) 1 kg m (metre) 1 m mol (mole) 1 mol rad (radian) 1 rad s (second) 1 s sr (steradian) 1 sr The results from your query will appear below the query boxes, with the answer highlighted in red text, such as: The value of 234.45km converted to base units is: 234450 m
Convert a column of data from a table
The function allows you to convert one column of data from a table. The table must be plain text and can have any column separator. The service assumes that the column you want to transform consists of numerical data only. For example:
1,2,3 3,4,5 6,7,8 and
J2134-2345 no 45 J2344-2355 no 234 J2335-9876 yes 234 are both valid formats, the first with comma separated columns and the second with space separated columns. In the first case, if you enter the table name, the column separator (,) the column to translate (3), the original units (km) and the target units (m) the resulting table will be:
1,2,3000 4,5,6000 7,8,9000 At the moment, the program does not deal with comment lines in the table. The resulting table will be displayed as plain text, on a new page so that it is easy to download.
Convert a column from a VOTable
This function allows you to convert a column of data in a VOTable from one set of units to another. It requires the name of the VOTable, the field name of the column you want to convert, and the units you want to convert from and to. Ultimately this function will be able to use the units from the VOTable to determine the current units for the data. However, at the moment no standard for units has been decided on by the IVOA community. The function returns a VOTable.
As an example, using this VOTable you could convert the Declination column from deg (degrees) to s (seconds). The column descriptor from the VOTable looks like this initially:
<FIELD ID="DE" name="Declination" datatype="float" unit="degrees" ucd="POS_EQ_DEC_MAIN"> <DESCRIPTION>Declination J2000</DESCRIPTION> </FIELD> and one row of data looks like this (Declination is the third column):
<TR> <TD>40</TD> <TD>185.5999</TD> <TD>58.07998</TD> <TD>Double Star WNC4</TD> <TD /> <TD>9.599996</TD> <TD>Double Star</TD> <TD>Ursa Major</TD> <TD /> </TR>
After the conversion, the table is returned with the column data modified and also the new unit in the column description:
<FIELD ID="DE" name="Declination" datatype="float" unit="s" ucd="POS_EQ_DEC_MAIN"> <DESCRIPTION>Declination J2000</DESCRIPTION> </FIELD> <TR> <TD>40</TD> <TD>185.5999</TD> <TD>13939.2</TD> <TD>Double Star WNC4</TD> <TD /> <TD>9.599996</TD> <TD>Double Star</TD> <TD>Ursa Major</TD> <TD /> </TR>
The VOTable functionality has only been tested on relatively straightforward VOTable examples. If you find VOTables that do not work, please let me know so that I can modify the service.
Error messages
Descriptions of the error messages you might get when using the Quanta service.
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