117P/Helin–Roman–Alu

{{Short description|Periodic comet with 8 year orbit}}

{{Infobox comet

| name=117P/Helin-Roman-Alu

| image= 117P 2022-06-04 image ZTF-sso-235-zr-fov-7.0arcmin.png

| discoverer=Eleanor F. Helin
Brian P. Roman
Jeff Alu

| discovery_date=October 2, 1989

| designations=1987 XXXVII

| epoch=March 6, 2006

| semimajor=4.08 AU

| perihelion=3.037 AU

| aphelion=5.123 AU

| eccentricity=0.2556

| period=8.24 a

| inclination= 8.7080°

| last_p=2022-Jul-07{{cite web

|title=117P/Helin-Roman-Alu Orbit

|url=http://www.minorplanetcenter.net/db_search/show_object?object_id=117P

|publisher=Minor Planet Center

|accessdate=2014-06-17}}
March 27, 2014{{cite web

|date=2011-04-06

|title=117P/Helin-Roman-Alu 1 (NK 2051)

|publisher=OAA Computing and Minor Planet Sections

|author=Syuichi Nakano

|author-link=Syuichi Nakano

|url=http://www.oaa.gr.jp/~oaacs/nk/nk2051.htm

|accessdate=2012-02-20}}
December 19, 2005

| next_p=2030-Nov-26{{cite web

|title=Horizons Batch for 117P/Helin-Roman-Alu 1 (90001003) on 2030-Nov-26

|publisher=JPL Horizons

|type=Perihelion occurs when rdot flips from negative to positive

|url=https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND=%27DES%3D117P%3BCAP%27&START_TIME=%272030-Nov-26%27&STOP_TIME=%272030-Nov-28%27&STEP_SIZE=%273%20hours%27&QUANTITIES=%2719%27

|accessdate=2023-07-06}} (JPL#K222/63 Soln.date: 2023-Jul-06)

}}

117P/Helin–Roman–Alu, also known as Helin-Roman-Alu 1, is a periodic comet in the Solar System. It is a Quasi-Hilda comet.{{cite journal | title=The quasi-Hilda subgroup of ecliptic comets - an update | last=Toth | first=I. | journal=Astronomy and Astrophysics | volume=448 | issue=3 | pages=1191–1196 | doi=10.1051/0004-6361:20053492 | bibcode=2006A&A...448.1191T |date=March 2006| doi-access=free }}