由於天琴座RR型變星本質的光度微弱,很難在銀河系以外的星系中觀察到。事實上,沃爾特·巴德因為未能在仙女座星系中找到它們,使他懷疑該星系比預測的遠得多,而考慮重新校準造父變星,並提出星族的概念[1]。在1980年代,普里切特(Pritchet)和范登伯格(van den Bergh)使用加法夏望遠鏡才在仙女座星系的暈中發現天琴座RR型變星[2];最近也在它的球狀星團中發現[3]。
^Pritchet, Christopher J.; Van Den Bergh, Sidney. Observations of RR Lyrae stars in the halo of M31. Astrophysical Journal. 1987, 316: 517. Bibcode:1987ApJ...316..517P. doi:10.1086/165223.
^Clementini, G.; Federici, L.; Corsi, C.; Cacciari, C.; Bellazzini, M.; Smith, H. A. RR Lyrae Variables in the Globular Clusters of M31: A First Detection of Likely Candidates. The Astrophysical Journal. 2001, 559 (2): L109. Bibcode:2001ApJ...559L.109C. arXiv:astro-ph/0108418. doi:10.1086/323973.
^Layden, A. C.; Hanson, Robert B.; Hawley, Suzanne L.; Klemola, Arnold R.; Hanley, Christopher J. The Absolute Magnitude and Kinematics of RR Lyrae Stars via Statistical Parallax. Astron. J. August 1996, 112: 2110–2131. Bibcode:1996AJ....112.2110L. arXiv:astro-ph/9608108. doi:10.1086/118167.
^Szabó, R.; Kolláth, Z.; Molnár, L.; Kolenberg, K.; Kurtz, D. W.; Bryson, S. T.; Benkő, J. M.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Borucki, W. J.; Koch, D.; Twicken, J. D.; Chadid, M.; Di Criscienzo, M.; Jeon, Y.-B.; Moskalik, P.; Nemec, J. M.; Nuspl, J. Does Kepler unveil the mystery of the Blazhko effect? First detection of period doubling in Kepler Blazhko RR Lyrae stars. Monthly Notices of the Royal Astronomical Society. 2010, 409 (3): 1244. Bibcode:2010MNRAS.409.1244S. arXiv:1007.3404. doi:10.1111/j.1365-2966.2010.17386.x.
^Lee, Jae-Woo; López-Morales, Mercedes; Hong, Kyeongsoo; Kang, Young-Woon; Pohl, Brian L.; Walker, Alistair. Toward a Better Understanding of the Distance Scale from RR Lyrae Variable Stars: A Case Study for the Inner Halo Globular Cluster NGC 6723. The Astrophysical Journal Supplement. 2014, 210: 6. Bibcode:2014ApJS..210....6L. arXiv:1311.2054. doi:10.1088/0067-0049/210/1/6.
^Neeley, J. R.; Marengo, M.; Bono, G.; Braga, V. F.; Dall'Ora, M.; Stetson, P. B.; Buonanno, R.; Ferraro, I.; Freedman, W. L.; Iannicola, G.; Madore, B. F.; Matsunaga, N.; Monson, A.; Persson, S. E.; Scowcroft, V.; Seibert, M. On the Distance of the Globular Cluster M4 (NGC 6121) Using RR Lyrae Stars. II. Mid-infrared Period-luminosity Relations. The Astrophysical Journal. 2015, 808: 11. Bibcode:2015ApJ...808...11N. arXiv:1505.07858. doi:10.1088/0004-637X/808/1/11.
^Clementini, G.; Federici, L.; Corsi, C.; Cacciari, C.; Bellazzini, M.; Smith, H. A. RR Lyrae Variables in the Globular Clusters of M31: A First Detection of Likely Candidates. The Astrophysical Journal. 2001, 559 (2): L109. Bibcode:2001ApJ...559L.109C. arXiv:astro-ph/0108418. doi:10.1086/323973.
^Bono, G. The Cepheid and RR Lyrae instability strip with GAIA. GAIA Spectroscopy: Science and Technology. 2003, 298: 245. Bibcode:2003ASPC..298..245B.