C/2009 R1 (McNaught)

In early June 2010, C/2009 R1 was visible with binoculars in the constellations Andromeda and Perseus, and by June 8 it was visible to the unaided eye in a dark sky with little light pollution.{{cite web|url=http://www.space.com/spacewatch/new-comet-mcnaught-visible-100608.html |title=New Comet Visible in Early Morning Sky |access-date=2010-06-09 |date=2010-06-08 |last=Rao |first=Joe |publisher=Space.com}} Astronomers predicted the comet to grow brighter and become widely visible in the northern hemisphere to the unaided eye by mid- or late-June,{{r|APOD}} at which time it appeared between the constellations Auriga and Gemini.{{cite web|url=http://www.aerith.net/comet/catalog/2009R1/2009R1.html |title=C/2009 R1 ( McNaught ) |access-date=2010-06-09 |work=Multitudinous Image-based Sky-survey and Accumulative Observations}} Because the new moon on June 12 provided a particularly dark night sky, the weekend of Friday, June 11 to Sunday, June 13 was expected to be the best time to view the comet,{{cite web|url=http://www.astronomy.com/asy/default.aspx?c=a&id=9917 |title=A comet flies through June's sky |access-date=2010-06-09 |last=Bakich |first=Michael |date=2010-06-04 |work=Astronomy Magazine |publisher=Kalmbach Publishing}} and it was expected to be "an easy skywatching target for most people." Late the following week, the comet remained "easy to spot in binoculars".{{r|APOD2}}

Cometary brightness is difficult to predict, especially when, as in this case, it is the first known appearance of the comet. C/2009 R1 proved to be brighter than expected, so much so that Sky and Telescope retitled an online article from "Faint Comet in the June dawn" to "Comet in the June dawn".[https://archive.today/20121201044836/http://www.skyandtelescope.com/observing/objects/comets/94277259.html Faint Comet in the June Dawn (Google cache of the original article)]; [http://www.skyandtelescope.com/observing/highlights/94277259.html Comet in the June Dawn (updated and retitled article)] {{Webarchive|url=https://web.archive.org/web/20100522021617/http://www.skyandtelescope.com/observing/highlights/94277259.html |date=2010-05-22 }} Predictions expected C/2009 R1 to eventually reach a brightness as high as magnitude 2 from June 30 to July 2, 2010, the latter date marking perihelion. However, as it grew brighter, its proximity to the Sun made it difficult to see, and would make it likely only visible near the horizon at dawn and dusk. The exception to this was the total solar eclipse on July 11 in the Southern Hemisphere (visible in the South Pacific, touching land at Mangaia, Easter Island, and far southern Chile and Argentina{{cite web|url=http://eclipse.gsfc.nasa.gov/SEmono/TSE2010/TSE2010.html |title=Total Solar Eclipse of 11 July 2010 |access-date=2010-06-09 |publisher=NASA}}), which allowed the comet to be seen during the day. The comet was notable for its "impressive green coma and long ion tail", which spanned 5 degrees as of 6 June 2010,{{r|APOD}} and its appearance was likened to an "apple on a stick." By June 13, a second tail created by dust from the comet, was also visible, sharing the same green hue of the coma.{{r|APOD2}} The green colors in the coma were caused by the presence of cyanogen and diatomic carbon, while bluish hues in the ion tail were produced by positively charged carbon monoxide and carbon dioxide ions.

{{Reflist|refs=

{{Cite APOD

| title= Comet McNaught Becoming Visible to the Unaided Eye

| date= 7 June 2010

| access-date= 8 June 2010 }}

{{Cite APOD

| title= Comet McNaught Passes NGC 1245

| date= 17 June 2010

| access-date= 18 June 2010 }}

{{cite web

| author= Horizons output

| url= https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%272009+R1%27&TABLE_TYPE=%27ELEMENTS%27&START_TIME=%271800-01-01%27&STOP_TIME=%272200-01-01%27&STEP_SIZE=%27200%20years%27&CENTER=%27@0%27&OUT_UNITS=%27AU-D%27

| title= Barycentric Osculating Orbital Elements for Comet C/2009 R1 (McNaught)

| website= ssd.jpl.nasa.gov

| access-date= 12 March 2011 }}

{{cite web

| author1= G. W. Kronk

| title= C/2009 R1 (McNaught)

| url= http://cometography.com/lcomets/2009r1.html

| website= Cometography.com

| access-date= 8 June 2010 }}

{{cite web

| title= C/2009 R1 (McNaught) – JPL Small-Body Database Lookup

| url= https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2009R1

| website= ssd.jpl.nasa.gov

| publisher= Jet Propulsion Laboratory

| access-date= 15 April 2025 }}

{{cite web

| title= C/2009 R1 (McNaught)

| url= http://www.minorplanetcenter.net/db_search/show_object?object_id=C/2009+R1

| publisher= Minor Planet Center

| access-date= 26 May 2011 }}

}}

{{Commons category}}

• {{JPL Small Body|id=1003036}}
• NASA Astronomy Picture of the Day:
• June 17, 2010, [http://antwrp.gsfc.nasa.gov/apod/ap100617.html Comet McNaught Passes NGC 1245]
• June 7, 2010, [http://antwrp.gsfc.nasa.gov/apod/ap100607.html Comet McNaught Becoming Visible to the Unaided Eye]
• [http://www.perseus.gr/Astro-Comets-2009-R1-McNaught-20100608.htm Comet C/2009 R1 (McNaught) in Andromeda]
• [http://remanzacco.blogspot.com/2010/05/comet-c2009-r1-mcnaught-animation.html Comet C/2009 R1 (McNaught) - Animation & Images] (disconnection event 26 May 2010 / Remanzacco Observatory)

{{Comets}}

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Category:Non-periodic comets

Category:Hyperbolic comets

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