Astrophysical Journal Formatting Requirements: Complete Author Guide

ApJ follows AAS conventions for abstracts.

• Word limit: 250 words for Regular Articles and Letters (150 words for Research Notes). The AAS manuscript preparation page says not more than 250 words, while its pre-submission checklist says shorter than 250 words, so aim for fewer than 250

• Structure: Unstructured (single paragraph)

• Citations: Parenthetical citations are not allowed in the abstract (per the AAS style guide)

The abstract should state the scientific question, describe the data or methods, and present the main results. Astronomy abstracts routinely include specific numerical results: distances, velocities, temperatures, luminosities, masses. "We detect a transit signal with a depth of 0.8% and derive a planetary radius of 1.3 R_Earth" is standard.

Keywords: ApJ uses the Unified Astronomy Thesaurus (UAT) for keywords. During submission, you select keywords from the UAT rather than providing free-text keywords. The UAT is a controlled vocabulary. Select between 1 and 12 UAT concepts that best describe your paper's content.

This keyword system is different from most other journals. You can browse the UAT at Unified Astronomy Thesaurus before submission to identify the best terms for your paper.

ApJ has well-established figure standards, and the astronomy community generally produces high-quality publication figures.

Figure specifications:

Figure best practices in astronomy:

• Multi-panel figures are very common (4-panel, 6-panel, even 16-panel grids)

• Label axes clearly with units

• Use colorbar legends for heat maps and images

• For spectral plots, label emission/absorption lines directly

• For sky images, include a scale bar and compass (N/E orientation)

Machine-readable tables (MRTs): The AAS strongly encourages long tables to be delivered in machine-readable format at submission: when a table has more than about 200 data rows or contains critical object-related data.

MRT specifications:

• Standardized CDS MRT format, or raw ASCII (formatted or delimited), or a LaTeX table; Word users save the table as tab-delimited ASCII

• Standardized header with column descriptions, units, and data types

• ASCII tables named tab#.txt, where # is the table number

• Included with the submission so the data can be evaluated during review

• Harvested by VizieR, which makes AAS MRTs discoverable and searchable

The MRT format is unfamiliar to most first-time ApJ authors. AAS provides tools and documentation for creating MRTs, and the AASTeX template includes commands for generating them. A typical MRT might contain photometric measurements, spectral line parameters, or catalog entries for hundreds or thousands of objects.

Shorter tables can use standard LaTeX table format. The AAS says tables with critical object-related data are also candidates for machine-readable format.

Table formatting for standard tables:

• Every column must have a header with units

• Use \tablehead and \startdata/\enddata in AASTeX

• Notes below tables using \tablenotetext

• Table title above using \tablecaption

ApJ uses the AAS author-year reference style. This is different from the numbered systems used by ACS, Elsevier, and Wiley journals.

In-text citations: Author-year format.

• One author: (Smith 2024) or Smith (2024)

• Two authors: (Smith & Jones 2024) or Smith & Jones (2024)

• Three or more authors: (Smith et al. 2024) or Smith et al. (2024)

The AAS manuscript preparation page shows in-text citations as (Hale 1929), while the AAS reference instructions show first initials, as in (G. E. Hale 1929). The AAS documents differ, so follow the AAS BibTeX style file, which encodes the journal's citation style.

Reference list format (alphabetical by first author):

Smith, A. B., Jones, C. D., & Williams, E. F. 2024, ApJ, 950, 123

Key formatting details:

• Author names: Last name, initials (Smith, A. B.)

• Ampersand before last author

• Year after the author list

• Journal abbreviation (ApJ, MNRAS, A&A, etc.)

• Volume number, then page or article number

• DOIs are included if available (the AAS asks for them in the reference list of accepted manuscripts)

• arXiv preprints cited with eprint number

Astronomy has a unique referencing culture because of the NASA Astrophysics Data System (ADS). BibTeX entries for virtually every astronomy paper are available on ADS, and most astronomers build their .bib files by exporting directly from ADS. If you do this, the formatting is automatically correct.

Use the AAS BibTeX style file that comes with AASTeX (aasjournal.bst for v6 manuscripts; the AAS lists a newer aasjournalv7.1.bst for AASTeX v7+). It handles all AAS formatting conventions, including the distinctive journal abbreviation macros (\apj, \mnras, \aap, etc.).

There's no reference cap. Published ApJ papers typically cite 30-60 references, but survey papers and reviews can cite 100+.

AAS journals have a well-developed system for supplementary data products, reflecting astronomy's culture of data sharing.

Types of supplementary content:

1. Figure sets: If you have many similar figures (e.g., spectra of 50 objects), AASTeX supports "figure sets" where the full set is published online but only representative examples appear in the printed article.

1. Machine-readable tables: Large data tables published in MRT format (described above).

1. Animations and videos: Supported for online publication. MPEG-4 with the H.264 codec is recommended; animated GIFs are not accepted.

1. Data behind figures: AAS encourages authors to provide the data underlying each figure as supplementary material.

1. Supplemental text and appendices: Extended derivations, additional analysis, and supporting material.

Data hosting: AAS provides data hosting through the journal's online infrastructure. Large datasets can also be deposited in persistent repositories such as Zenodo or Harvard Dataverse, where the AAS asks you to submit the deposit to its AAS Journals community.

Data availability: The AAS Data Guide encourages authors to enrich articles with data and other digital materials, and asks authors who use repositories to follow its documentation and licensing guidance. The submission form also asks whether you used datasets hosted in astronomy data archives and, if so, for their DOIs.

The astronomy community has strong norms around data sharing. ApJ papers routinely include links to reduced data products, code repositories (GitHub, Zenodo), and archival data. If you don't provide access to your data, reviewers will ask for it.

ApJ uses the AAS journals submission portal at aas.msubmit.net.

Files to prepare (the AAS pre-submission checklist gives the exact upload rules):

• Manuscript source files (.tex, .bib, figure files, MRT files)

• Compiled PDF

• Cover letter (the AAS asks you to upload one listing author names, affiliations and acknowledgements if you opt in to dual anonymous review)

AAS-specific points:

• Software citations: AAS strongly encourages citing all software used in the analysis. Use the \software{} command in AASTeX. This is increasingly important and reviewers will note missing software citations.

• Data availability: State where all data can be accessed.

• Object names: Use established names, correctly formatted, and follow the IAU recommendations for newly discovered objects. AASTeX's \objectname{} command creates database links.

• ORCID iDs: with AASTeX 7, the submission system can extract ORCIDs from the author commands to help identify authors already in the system.

arXiv posting: Like PRB, ApJ has no embargo policy regarding arXiv. Most astronomy papers appear on arXiv simultaneously with or before journal submission. This is standard practice and expected in the field. If you opt in to dual anonymous review, the AAS asks you not to submit to arXiv or social media in advance of the review.

These are the details that experienced ApJ authors know:

AASTeX is strongly encouraged. The AAS accepts native Word files too, but says authors are strongly encouraged to use AASTeX; with AASTeX 7 the submission system can also extract the author list, affiliations, emails and ORCIDs automatically.

Machine-readable tables are strongly encouraged for long tables. The AAS says it converts large tables to MRT format after acceptance and asks authors to proof the result, but it strongly encourages delivering long tables in MRT format at submission.

Author-year citations, not numbered. Astronomy uses author-year style while most other physical sciences use numbered citations. If you're submitting to ApJ from a physics or chemistry background, switch your citation style.

Journal abbreviation macros. AASTeX includes macros for common journal names (\apj, \apjl, \apjs, \mnras, \aap, \aj, \pasp, etc.). Use them. They ensure consistent abbreviations and look correct in the typeset output.

Software and data citations. AAS has been a leader in promoting software and data citation. Your paper should cite the specific versions of software packages used (e.g., astropy, numpy, matplotlib). Software packages can be listed in a section below the acknowledgments using the \software macro, and the preferred citations must also appear in the reference list.

Publication charges are required. The AAS sets them by digital quanta and confirms your final charges within a few business days after you submit. Authors who cannot pay can request support from the AAS Publication Support Fund; a request does not guarantee support.

Astronomical nomenclature. Use standard naming conventions from the IAU. Don't invent new names for objects. Refer to existing catalogs (2MASS, Gaia DR3, SDSS, etc.) using standard designators.

Figures of merit. Astronomy papers frequently report uncertainties, and ApJ expects them to be presented correctly. Use symmetric errors (5.2 +/- 0.3) or asymmetric errors (5.2 +0.4/-0.2). State confidence intervals explicitly (1-sigma, 3-sigma, 95%).

For manuscripts targeting The Astrophysical Journal, four patterns generate the most consistent desk-rejection outcomes.

Manuscript not prepared in the AAS format. The Astrophysical Journal is owned and operated by the American Astronomical Society and published with IOP Publishing. The AAS strongly encourages the AASTeX LaTeX package (currently v7) and also accepts native Word files, for which it provides a template. The structure the AAS lists for a manuscript is title page, abstract, text, figures with figure legends, tables, acknowledgments, appendices and references. AASTeX also supports the machine-readable table markup and author-affiliation notation that differ from standard academic LaTeX.

Archival and observational data not documented. The AAS Data Guide encourages authors to enrich articles with data and to deposit data and code in persistent repositories, following its documentation guidance. The submission form asks whether you used datasets hosted in astronomy data archives (such as MAST, IPAC, Rubin or Chandra) and, if so, for their DOIs, and the AAS asks authors to follow each archive's citation preferences. Manuscripts that reference proprietary datasets without a clear account of how they can be accessed are harder for reviewers to assess.

Statistical methodology not meeting current astronomical standards. ApJ reviewers are rigorous about statistical analysis. Bayesian inference must be correctly specified with prior justification. Frequentist tests applied in inappropriate contexts (e.g., chi-squared tests on non-Gaussian data) are flagged. Upper limits must be reported consistently, and non-detection statistics must follow standard astronomical practice.

Papers that report significance in sigma without specifying the tail probability convention, or that claim detections at less than 3-sigma, receive statistical revision requests.

Machine-Readable Tables not formatted in ApJ MRT standard. Any data table that other researchers could reuse is best prepared as a Machine-Readable Table (MRT) in the AAS-defined format; the AAS strongly encourages this for tables longer than about 200 data rows or with critical object-related data. The MRT format includes a header specifying column names, units, and formats in a structured way that enables downstream data use.

Authors frequently submit data tables as standard LaTeX tabular environments and add an MRT as an afterthought; reviewers check that the MRT matches the paper's figures and text. Discrepancies between the paper and MRT data are among the most common revision requests at ApJ.

A Astrophysical Journal submission readiness check evaluates AASTeX compliance, data repository deposition, statistical methodology, and MRT formatting against these patterns.