IC 438

{{Short description|Galaxy in the constellation Lepus}}

{{Use dmy dates|date=June 2025}}

{{Sky|05|53|00.0676|-|17|52|33.684}}

{{Infobox Galaxy

| name = IC{{nbsp}}438

| image = Luminous in Lepus (potw2404a).jpg

| caption= IC 438 imaged by the Hubble Space Telescope in 2021

| alt = A large spiral galaxy seen close-up. The left side of the image shows the galaxy's core and its tightly-curled inner spiral arms. On the right side, one of the arms reaches down from above, curving across the dark background. There is a bright star inside the arc of the arm, and a couple more next to the galaxy.

| epoch = J2000

| constellation name = Lepus

| ra = {{RA|05|53|00.0676}}{{cite web

| website = NASA/IPAC Extragalactic Database

| publisher = NASA and Caltech

| title=Results for object IC 0438

| url = https://ned.ipac.caltech.edu/byname?objname=IC+0438

| access-date = 9 June 2025}}

| dec = {{DEC|-17|52|33.684}}{{r|ned}}

| z = {{val|0.004256|0.000006}}{{r|ned}}

| h_radial_v = {{val|3123|4|u=km/s|fmt=commas}}{{r|ned}}

| dist_ly = {{convert|41.835 ± 1.314|Mpc|Mly|abbr=on|lk=on|order=flip}}{{r|ned}}

| group_cluster = IC 438 Group (LGG 134)

| type = SA(rs)c{{r|ned}}

| size = ~{{convert|47.55|kpc|ly|abbr=on|lk=on|order=flip}} (estimated){{r|ned}}

| appmag_v = 12.74{{r|ned}}

| size_v = {{Val|2.8|×|2.1|u=arcminute}}{{r|ned}}

| notes =

| names = {{odlist | name= ESO 555- G 009 | IRAS= 05508-1753 | PGC= 18047 | UGCA= 115 | MCG= -03-15-025}}{{r|ned}}

}}

IC 438 is a spiral galaxy in the constellation of Lepus. Its velocity with respect to the cosmic microwave background is {{val|3199|6|u=km/s|fmt=commas}}, which corresponds to a Hubble distance of {{convert|47.18 ± 3.30|Mpc|Mly|abbr=on|lk=on|order=flip}}.{{r|ned}} However, 17 non-redshift measurements give a much closer distance of {{convert|41.835 ± 1.314|Mpc|Mly|abbr=on|lk=off|order=flip}}.{{cite web | url = https://ned.ipac.caltech.edu/cgi-bin/nDistance?name=IC+438 | title = Distance Results for IC 438 | website = NASA/IPAC EXTRAGALACTIC DATABASE | publisher = NASA | access-date = 9 June 2025}} It was discovered by American astronomer Lewis Swift on 7 January 1891.{{cite web | url = https://cseligman.com/text/atlas/ic4.htm#ic438 | title = Index Catalogue Objects: IC{{nbsp}}438 | last = Seligman | first = Courtney | website = Celestial Atlas | access-date = 25 May 2025}}{{cite journal |last=Swift |first=Lewis |title=Catalogue No. 10 of Nebulae discovered at the Warner Observatory |journal=Astronomische Nachrichten |volume=129 |pages=361 |year=1892 |bibcode=1892AN....129..361S}}

IC{{nbsp}}438 is a Seyfert I Galaxy, i.e. it has a quasar-like nucleus with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, the host galaxy is clearly detectable.{{cite journal|bibcode=2022ApJS..258...29C |title=A Uniformly Selected, Southern-sky 6dF, Optical AGN Catalog |last1=Chen |first1=Yan-Ping |last2=Zaw |first2=Ingyin |last3=Farrar |first3=Glennys R. |last4=Elgamal |first4=Sana |journal=The Astrophysical Journal Supplement Series |date=2022 |volume=258 |issue=2 |page=29 |doi=10.3847/1538-4365/ac4157 |doi-access=free |arxiv=2111.13217}}