This section will outline use of the Advanced page of Splatalogue, which offers the full functionality of the Splatalogue database. In the Advanced mode, you are allowed to search across multiple and arbitrary molecular species, and include (or exclude) specific line lists, amongst other features. The search results are fully customizable, with options to include varying forms of line strength quantifiers and other common spectroscopic quantities.

Searching & Navigation

The Advanced page’s primary feature is the Search Parameters frame, which is split into two categories: inputs for searches and inputs for display. The top half of the frame is reserved for the primary filters used to perform searches – molecules, frequency range, intensity lower limits, etc. An image of the input half of the Parameters frame can be found in Figure 3.1 below.

Search Criteria

Splatalogue provides a number of common search criteria for narrowing a typical spectroscopic catalogue search.


Search input half of the Search Parameters frame.

For specific descriptions of each of the search criteria, see the listing below.

  • Select Species: Select one or more molecular species to search for.

    • If transitions for only one species is needed, you can search for it in the Search bar. However, the typical usage is to select the molecule in the mass ordered listing below the Search bar.

    • You can search for an arbitrary number of molecules in the mass-ordered listing by clicking on the molecule in the list you want to search for. The search listing will confirm your choice by highlighting the molecule in the list. If you want to remove a molecule from the query, click it again and it will unhighlight. There is also an “All” choice at the top of the list, which is useful for frequency-limited searches in survey spectra. You can select separate molecules in the listing by holding the “Ctrl” button and selecting each molecule you want to search. If you would like to select a consecutive sublist of molecules, hold the “Shift” button and first select the molecule in the top of the sublist and then select the last molecule in the desired list.

      • NOTE: Each molecular species is catalogued by a tag #, which is a 5 digit number containing the mass of the species in the first 3 digits, and a unique identifer in the last 2 digits. This unique identifier is set in ascending order of recently uploaded, so more recent astronomical detections will likely have a higher identifier. For instance, methanimine has molecular formula CH2 NH, and a mass of 29 amu Therefore its tag’s first 3 digits is 029, and its unique identifier is 26, for a tag number of 02926.
    • There is a mass calculator below the mass ordered listing. This calculator is case sensitive – so for aluminum hydroxide, AlOH is valid but NOT ALOH or aloh.

  • Data Versions: Each major update to a specific molecule’s linelist is categorized with a new version number. A molecule having multiple versioned linelists correspond to differing versions of the source linelist in one of the primary spectral catalogues that Splatlogue draws from. If you need the most accurate and recent frequency information, always use the most recent linelist. However, if you are interested in how specific spectroscopic information has changed across multiple versions of a catalogue’s spectroscopic information, Splatalogue offers the ability to cross-reference old and new catalogue information.

  • Specify Ranges: Specify and limit frequency, lower state energy, and intensities as search criteria for selected molecules.

    • Frequency Range: Limit search results to an arbitrary frequency range. You can provide a lower limit, upper limit, or both in MHz or GHz.
    • Energy Range: Splatalogue offers the ability to limit results to transitions with either upper state or lower state energies within the given range in either wavenumbers or Kelvin. Like the frequency range, you can specify upper, lower or both limits for either quantity.
  • Line Intensity Lower Limits: Specify lower limits for intensities in one of three quantities: CDMS/JPL integrated intensities, dipole-weighted transition dipole matrix elements (Sijμ2), or the base-10 logarithm of the Einstein A coefficient (Aij).

    • NOTE: CDMS/JPL intensities are weighted at 298 K, so limiting your search to strong transitions for spectra with typical astrophysical rotational temperatures, especially in cm-wave data (e.g. JVLA/GBT), might be somewhat misleading. It is, however, useful to limit results to some significantly small quantity in order to filter out the less abundant transitions, say an intensity lower limit of -9 or -10 for a typical polyatomic molecule.
  • Specify a Transition: Search for a transition by its quantum numbers. This is not an especially reliable tool and will likely be redesigned in a future version of the Splatalogue website.

Search Display Options

The second half of the Search frame, shown in Figure 3.2 below, contains options for outputting and displaying specific quantities regarding the molecules being searched for. Detailed information regarding these features can be found in the listing below.


Search output filtering half of the Search Parameters frame.

  • Search Filter: Filter out specific categories of molecules, or show only NRAO recommended frequencies. Each of the exclusion categories are colored in the mass-ordered species select menu in the top half. The color legend can be found in the Color Schemes section below.

    • NOTE: By default, Splatalogue ONLY shows results for astronomically-known molecules. If you are interested in undetected molecules in the database, make sure to deselect all or, at least, the relevant Search Filter criteria.
    • NOTE 2: The NRAO recommended frequencies are only for astronomically-known molecules. Generally, the most recently updated linelist is chosen for recommendation and contains astronomical intensity information, if included.
  • Line List Display: Select which line lists to display. Typically, JPL and CDMS contain the most recent information, but SLAIM and Lovas/NIST can also provide useful information for astronomically known molecules.

  • Line Strength Display: Select which line strength quantifiers to output. By default, only CDMS/JPL integrated intensities and Lovas/AST astronomical intensities are shown.

  • Energy Levels: Select which quantum state energies to output. Default is Eupperin wavenumbers.

  • Frequency Error Limit: Filter out all transitions with errors greater than 50 MHz. Useful for certain molecules at mm-wave that have only low frequency experimental information available to contrain centrifugal distortion parameters.

  • Miscellaneous: Various quantities to output to the search results page. Most are self-explanatory.

Color Schemes

Splatalogue provides visual organization to both species and transitions by color-coding. Species are color-coded based on their status as astronomical molecules, which transitions are color-coded by the telescope band they are located in.

Species Colors


Example of color coding for species.

Species are colored by their status as astronomical molecules. The color coding is:

  • WHITE: Known astronomical molecules
  • RED: Possible astronomical molecules
  • BLUE: Atmospheric molecules
  • GREEN: Probable astronomical molecules – commonly, excited vibrational states and isotopologues of known molecules

Transition Colors


Example of transition color coding by frequency range.

Transitions are colored based on which ALMA band they fall into. The coding is:

  • PINK: ALMA Band 1 (31-45 GHz)
  • ORANGE: ALMA Band 2 (67-86 GHz)
  • SKY BLUE: ALMA Band 3 (86-115 GHz)
  • GREEN: ALMA Band 4 (125-163 GHz)
  • YELLOW: ALMA Band 5 (163-211 GHz)
  • LIGHT PURPLE: ALMA Band 6 (211-275 GHz)
  • PALE GREEN: ALMA Band 7 (275-373 GHz)
  • DARK PURPLE: ALMA Band 8 (385-500 GHz)
  • PASTEL BLUE: ALMA Band 9 (602-720 GHz)
  • GOLD: ALMA Band 10 (787-950 GHz)

Transitions outside of these bands are colored GREY.

Search Exporting


Search result export options.

Like in Basic mode, there is an export option at the bottom of every search result page, where you can export the search results in a variety of formats. All search results can be exported in a variety of common formats, found at the bottom of the search results page. Search results can be exported in comma (CSV) or tab delimited ASCII files, as well as in a Virtual Astronomical Observatory (VAO)-compliant TSV file for use in CASA. NOTE: Due to limitations regarding PHP, only search result files less than 25MB will be exported successfully.

If your search results in a result that is unstable for export, segment your search (e.g. my frequency), export each segment separately, and concatenate them together locally on your computer.