Search form

AAS Journal Author Instruction Updates

The AAS Journals, guided by a Task Force on the Future of our Journals, are undergoing important changes that will affect the way authors prepare, submit, review, and publish articles. Concomitant changes to the author instructions on this page are forthcoming. If you have questions about appropriateness of the extant instructions then please email our Authoring Support team <>. 

Citations in Text

References should be cited in text by the last name of the author(s) and the date of publication (Hale 1929). There is no comma before the date. For papers with two authors, join author names with an ampersand (Press & Rybicki 1992). Papers by three or more authors are cited by the first author followed by "et al." and the date (Goodman et al. 2003).

Reference List


All sources cited in the text and tables must appear in the reference list at the end of the paper, and all entries in the reference list must be cited in the text. Reference entries should be ordered alphabetically, starting with the last name of the first author, followed by the first author's initial(s), and so on for each additional author. For papers with more than five authors, the last name and initials of the first three authors only should be listed, followed by a comma and "et al." References listed as "et al." are grouped together and last, as if the fourth author started with "z"; they are not alphabetized by the name of the actual fourth author. Multiple entries for one author or one group of authors should be ordered chronologically, and multiple entries for the same year should be distinguished by appending sequential lower-case letters to the year, even if the author groups are not identical: e.g., Smith, E., Rowe, T., & Jones, A. B. 1999a; Smith, A. B., Thomas, J. R., & Peebles, P. J. E. 1999b; Smith et al. 1999c (because all will appear as "Smith et al. 1999" in the text).

Citation of Electronic Sources

Electronic catalogs, databases, observers' guides, instrument documentation, electronic conference proceedings, electronic journals, and other stable (non-changing) documents available online should be listed in the reference list in the same manner as other references. These should give the author(s) or authoring agency, title of the document, location and name of the hosting organization (e.g., Pasadena, CA: JPL), version consulted if any, page or document number if any, and the URL (see examples below). References in this class include databases, manuals, conference proceedings, and similar documents, but not general informational sites for instruments or projects, sites for downloading computer code, or papers posted on personal web pages. Citations of electronic journals should follow normal journal format, omitting page number if none are used, followed by the URL. See below for examples.

Note that URLs for all other electronic resources, such as personal web pages, general informational sites for organizations, telescopes, surveys, projects, proposals, sites for uploading computer or mathematical code, and other sites whose content regularly changes, should be given in a footnote at first mention in the text, but not listed in the reference list.

Unpublished Material

References to papers in preparation, preprints, or other sources generally not available to readers should be avoided if possible. If no published form is available, preprints may be listed in the reference list. Private communications, unpublished works, and papers in preparation should be cited only in the run of text, giving authors' initials and the year if completion is imminent, e.g., F. Carlon et al. (2009, in preparation).


Authors will be queried for missing, incomplete, or incorrect information in the reference list. It is especially important that authors recheck reference lists after each revision of the text, to be certain that all references cited in the text are in the reference list, and all references given in the reference list are cited.


Examples are given here of some of the most common citation formats.

Journal Paper

Martín, E. L., Rebolo, R., & Zapatero Osorio, M. R. 1996, ApJ, 469, 706
Aguirre, J. E., Ginsburg, A. G., Dunham, M. K., et al. 2011, ApJS, 192, 4


Donat, W., III, & Boksenberg, A. J. 1993, The Astronomical Almanac for the Year 1994, Vol. 2 (2nd ed.; Washington, DC: GPO)

Where specific pages of a book are cited, these should be given at the text citation, not in the reference list.

Paper or Chapter in an Edited Collection

Huchra, J. P. 1986, in Inner Space/Outer Space, ed. E. W. Kolb et al. (Chicago, IL: Univ. Chicago Press), 65

Conference Proceedings

Salpeter, E. E., & Wasserman, I. M. 1993, in ASP Conf. Ser. 36, Planets around Pulsars, ed. J. A. Phillips, S. E. Thorsett, & S. R. Kulkarni (San Francisco, CA: ASP), 345

Electronic Conference Proceedings (published only online)

Gomez, M. 2000, in Cosmology 2000, ed. M.C. Bento, O. Bertolami, & L. Teodoro (Lisbon: Inst. Superio Tecnico), 57,

Star Catalogs

Hoffleit, D. 1982, The Bright Star Catalogue (New Haven, CT: Yale Univ. Obs.)

Electronic Newsletters (published only online)

Hermoso, D. 1996, ESA IUE Electron. Newsl. 46,
Bersier, D., et al. 2004, GCN Circ. 2544,

Instrument Documentation

Gussenhoven, M. S., Mullen, E. G., & Sagalyn, R. C. 1985, CRRES/SPACERAD Instrument Description, Document AFGL-TR-85-0017 (Hanscom, MA: Air Force Geophys. Lab.)
Spitzer Science Center. 2004, Spitzer Observers' Manual (Pasadena, CA: SSC),


Smith, A. B. 1999, arXiv:astro-ph/9812345 (style for preprints before April 2007)
Smith, A. B. 2007, arXiv:0702.1234 (style for preprints after April 2007)
Lockwood, G. W., & Skiff, B. A. 1988, Air Force Geophys. Lab. preprint (AFGL-TR-88-0221)

References to preprints are acceptable only for papers not yet published. For papers that have been accepted but are not yet published, the preprint number may be given at the end of a reference submitted or in press (i.e., Smith, A. B. 1999, AJ, in press (arXiv:astro-ph/9912345)).

Papers Submitted or In Press

Wolk, S. J., & Walter, F. M. 1999, AJ, submitted
Wolk, S. J., & Walter, F. M. 1999, AJ, in press

"Submitted" should be used for manuscripts not yet accepted for publication, and "in press" for manuscripts accepted but not yet published.

Journal Abbreviations

See ADS Bibliographic Codes: Refereed Publications on the ADS site for the appropriate journal abbreviations.