NGC 6366

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

{{Infobox globular cluster

| name = NGC 6366

| image = NGC 6366 HST 10775 R814B606.png

| caption = NGC 6366 as seen through the Hubble Space Telescope

| epoch = J2000

| pronounce =

| constellation = Ophiuchus

| class = XI

| ra = {{RA|17|27|44.3}}

| dec = {{DEC|-05|04|36}}

| z =

| h_radial_v = {{val|-122|0.5|u=km/s}}

| gal_v =

| dist_pc =

| dist_ly =

| group_cluster =

| type = XI

| mass =

| mass_light_ratio =

| size =

| stars =

|metal_fe== −0.60{{±|0.03}}{{citation|arxiv=1801.09968|year=2018|title=Chemical analysis of eight giant stars of the globular cluster NGC 6366|doi=10.1093/mnras/sty267 |last1=Puls |first1=Arthur A. |last2=Alves-Brito |first2=Alan |last3=Campos |first3=Fabíola |last4=Dias |first4=Bruno |last5=Barbuy |first5=Beatriz |journal=Monthly Notices of the Royal Astronomical Society |volume=476 |pages=690–704 |doi-access=free }}

| appmag_v = 9.5

| absmag_v = -5.47

| size_v = 13.0'

| notes =

| names = GCL 65

| references = NASA/IPAC extragalactic datatbase, http://spider.seds.org/

}}

NGC 6366 is a globular cluster located in the constellation Ophiuchus. It is designated as XI in the Shapley–Sawyer Concentration Class and was discovered by the German astronomer Friedrich August Theodor Winnecke on 12 April 1860.{{cite web|title=NGC 6366 (= GCL 65)|url=http://cseligman.com/text/atlas/ngc63a.htm#6366|website=cseligman|access-date=19 October 2015}} It is at a distance of 11,700 light years away from Earth.{{cite web|title=Object No. 1 - NGC 6366|url=http://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=NGC+6366&extend=no&hconst=73&omegam=0.27&omegav=0.73&corr_z=1&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES|website=NASA/IPAC extragalactic database|publisher=NASA/IPAC|access-date=19 October 2015}}{{cite web|title=Revised NGC Data for NGC 6366|url=http://spider.seds.org/ngc/revngcic.cgi?NGC6366|website=Seds|access-date=19 October 2015}}{{cite web|title=NGC 6366|url=http://spider.seds.org/spider/MWGC/n6366.html|website=Seds|access-date=19 October 2015}}{{cite web|title=The globular cluster NGC 6366|url=https://in-the-sky.org/data/object.php?id=5117|website=In-the-sky|access-date=19 October 2015}}

NGC 6366 is similar in composition to M 71 or NGC 6342.{{citation|arxiv=1606.08491|year=2016|title=The Chemical Composition of Red Giant Branch Stars in the Galactic Globular Clusters NGC 6342 and NGC 6366|doi=10.3847/0004-6256/152/1/21 |last1=Johnson |first1=Christian I. |last2=Caldwell |first2=Nelson |last3=Rich |first3=R. Michael |last4=Pilachowski |first4=Catherine A. |last5=Hsyu |first5=Tiffany |journal=The Astronomical Journal |volume=152 |issue=1 |page=21 |bibcode=2016AJ....152...21J |s2cid=19812549 |doi-access=free }} It is metal-rich for a globular cluster, and all of its stars appears to have formed in the same epoch.