Arp-Madore 1

{{Short description|Globular cluster in the constellation Horologium}}

{{Infobox globular cluster

| name = Arp-Madore 1

| image = 250px

| caption = Globular cluster Arp-Madore 1

| credit =

| epoch = J2000.0

| class =

| constellation = Horologium

| ra = {{RA|03|55|02.70}}{{cite simbad |title = NAME E 1 |accessdate = 29 January 2014}}

| dec = {{dec|-49|36|52.0}}

| dist_ly = 398,000

| dist_pc = 122,000

| appmag_v = 15.07

| size_v = 1.288 by 0.691 {{prime}}

| mass_msol =

| mass_kg =

| radius_ly =

| v_hb =

| metal_fe =

| age =

| notes =

| names = E1, AM 0353-094, C 0353-497, C 0354-498, AM 1, ESO 201-10, LEDA 14098, SGC 035336-4945.6

}}

Arp-Madore 1 (also known as AM 1) is a globular cluster visible in the constellation Horologium, located {{convert|123.3|kpc|ly|abbr=off}} away from Earth.{{Cite journal |doi = 10.1093/mnras/stz171|title = Proper motions and dynamics of the Milky Way globular cluster system from Gaia DR2|journal = Monthly Notices of the Royal Astronomical Society|volume = 484|issue = 2|pages = 2832–2850|year = 2019|last1 = Vasiliev|first1 = Eugene| doi-access=free |bibcode = 2019MNRAS.484.2832V|arxiv = 1807.09775}} It is one of the most distant known globular clusters of the Milky Way galaxy's halo;{{citation|bibcode=1984ApJ...276..221A|journal=Astrophys. J.|volume=276|pages=221–228|year=1984|title=AM-1 : a very distant globular cluster|last1=Aaronson|first1=M.|last2=Schommer|first2=R. A.|last3=Olszewski|first3=E. W.|doi = 10.1086/161605|doi-access=free}}.{{citation|bibcode=2008AJ....136.1407D|journal=Astron. J.|volume=136|issue=4|pages=1407–1414|year=2008|title=Globular clusters in the outer galactic halo: AM-1 and Palomar 14|last1=Dotter|first1=A.|last2=Sarjedini|first2=A.|last3=Yang|first3=S.-C.|arxiv = 0807.1103 |doi = 10.1088/0004-6256/136/4/1407 |s2cid=119153331 }}. its distance gives it interest as a test case for gravitational theories.{{citation|bibcode=2006A&A...448..171H|journal=Astron. Astrophys.|volume=448|issue=1|pages=171–180|year=2006|title=Probable member stars of the gravitational theory-testing globular clusters AM 1, Pal 3 and Pal 14|last=Hilker|first=M.|arxiv = astro-ph/0510679 |doi = 10.1051/0004-6361:20054327 |s2cid=15832632 }}. AM 1 has a visual magnitude of 15.07.{{Cite web |title=AM 1 |url=https://people.smp.uq.edu.au/HolgerBaumgardt/globular/fits/am1.html |access-date=2024-05-10 |website=people.smp.uq.edu.au}}

It is named after Halton Arp and Barry F. Madore, who identified it as a distant globular cluster in 1979, using the UK Schmidt Telescope,{{citation|bibcode=1979ApJ...227L.103M|journal=Astrophys. J.|volume=227|pages=L103–L104|year=1979|title=Three new faint star clusters|last1=Madore|first1=B. F.|last2=Arp|first2=H. C.|doi = 10.1086/182876 }}. after previous researchers at the European Southern Observatory had observed its existence but not its classification.{{citation|bibcode=1975A&AS...22..327H|journal=Astron. Astrophys.|series=Suppl.Ser.|volume=22|pages=327–402|year=1975|title=The ESO/Uppsala survey of the ESO (B) atlas of the southern sky. III|last1=Holmberg|first1=E. B.|last2=Lauberts|first2=A.|last3=Schuster|first3=H. E.|last4=West|first4=R. M.}}.