398P/Boattini
Jupiter-family comet discovered by Andrea Boattini in 2009.
398P/Boattini, designated Comet Boattini 5, is a Jupiter-family comet that orbits the Sun every 5.53 years. It is the tenth comet found by Italian astronomer Andrea Boattini.
The comet was first spotted by Boattini on the night of 26 August 2009, appearing as a 19th-magnitude object with a strongly condensed coma in the constellation Taurus. It was initially labeled P/2009 Q4. Later, precovery images from as early as January 2004 were identified. Astrometric measurements from October 2009 confirmed it was periodic, with a 5.5-year orbital period. Its predicted return in June 2015 went unobserved, but in August 2025, the COIAS project found archival images from the Subaru Telescope showing the comet during that apparition. The comet was recovered on its next return as P/2020 P2, using CCD images from the ATLAS facility at Mauna Loa Observatory. On 28 September 2020, it experienced an outburst, brightening by 1.4 magnitudes for four days. Observations from TESS later recorded a two-phase brightening during another outburst in early 2021. The comet received its permanent numerical designation, 398P/Boattini, in December 2020.
Infrared observations by the Wide-field Infrared Survey Explorer (WISE) in 2010 measured the nucleus’s effective radius at about 0.6 km (0.37 mi). Narrowband-filter observations at the TRAPPIST-North facility of the Oukaïmeden Observatory in November 2020 detected cyanogen (CN) emissions in its coma, but the comet was notably depleted in carbon compounds (C2 and C3), making it one of the few known carbon-chain poor Jupiter-family comets.
Quick Facts
- Discovery Ref
- IAUC_9069
- Discoverer
- Andrea Boattini
- Discovery Site
- Catalina Sky Survey
- Discovery Date
- 26 August 2009
- Mpc Name
- P/2009 Q4, P/2020 P2
- Designations
- Boattini 5nasa-pds
- Orbit Ref
- jpldata · MPC
- Epoch
- 9 June 2026 (JD 2461200.5)
- Earliest Precovery Date
- 31 January 2004
- Obs
- 2,560
- Perihelion
- 1.300 AU
- Aphelion
- 4.947 AU
Facts from the source article.
Lore & Background
Italian astronomer Andrea Boattini spotted this comet on the night of 26 August 2009 as a 19th-magnitude object with a strongly condensed coma in the constellation Taurus. It was initially designated P/2009 Q4. Precovery images from as early as January 2004 were later found, and astrometric measurements in October 2009 confirmed it as periodic with a 5.5-year orbit.
The comet was predicted to return in June 2015, but no observations were reported at that time. However, in August 2025, the COIAS project discovered archival images of the 2015 apparition taken by the Subaru Telescope. It was later recovered on its next apparition as P/2020 P2 from CCD images taken at the ATLAS facility of the Mauna Loa Observatory. An outburst on 28 September 2020 temporarily brightened it by 1.4 magnitudes for four days, and TESS observations noted a two-phase brightening during another outburst in early 2021. The comet received its permanent numerical designation 398P/Boattini in December 2020.
Infrared observations by the Wide-field Infrared Survey Explorer (WISE) in 2010 measured the nucleus effective radius at about 0.6 km. Narrowband-filter observations at the TRAPPIST-North facility of the Oukaïmeden Observatory in November 2020 detected cyanogen (CN) emissions in its coma, but it was noticeably depleted in carbon compounds (C2 and C3), placing it among a small number of known carbon-chain poor Jupiter-family comets.
Reader's Guide
398P/Boattini holds significance as the 10th comet discovered by Italian astronomer Andrea Boattini, adding to the catalog of Jupiter-family comets with well-determined orbits. Its 5.53-year orbital period and recovery across multiple apparitions—including the later identification of unobserved 2015 images by the COIAS project—demonstrate the value of archival searches in cometary astronomy. The comet's physical characterization, particularly the nucleus radius of 0.6 km from WISE observations, contributes to the understanding of typical Jupiter-family comet sizes. More notably, its depletion in carbon-chain molecules (C2 and C3) as detected by TRAPPIST-North marks it as one of the few known carbon-chain poor Jupiter-family comets, a rare compositional class that may offer insights into the diversity of cometary material and formation conditions in the early solar system. The outburst events observed in 2020 and 2021, including a two-phase brightening recorded by TESS, provide data on the activity mechanisms of such comets.
Did You Know?
- 398P/Boattini was discovered by Italian astronomer Andrea Boattini on 26 August 2009 as a 19th-magnitude object.
- Its nucleus has an effective radius of about 0.6 km, measured by WISE in 2010.
- The comet is one of a few known carbon-chain poor Jupiter-family comets, depleted in C2 and C3 compounds.
- An outburst on 28 September 2020 temporarily brightened the comet by 1.4 magnitudes for four days.
Frequently Asked Questions
What is 398P/Boattini?
398P/Boattini, also called Comet Boattini 5, is a Jupiter-family comet that completes one full orbit around the Sun roughly every 5.53 years. It was first seen as a faint 19th-magnitude smudge with a tightly condensed coma in the constellation Taurus.
Who discovered 398P/Boattini and when?
Italian astronomer Andrea Boattini first detected the object on the night of 26 August 2009. It was his tenth comet discovery and was initially catalogued under the provisional designation P/2009 Q4.
What is 398P/Boattini's orbital period?
The comet circles the Sun on an elliptical path with a period of approximately 5.53 years. That figure was confirmed by astrometric measurements taken in October 2009, which established the object as genuinely periodic.
What other designations does 398P/Boattini carry?
Before receiving its permanent number, the comet was known by the provisional labels P/2009 Q4 and P/2020 P2. In fan and enthusiast circles it is also simply referred to as Comet Boattini 5.
Why is 398P/Boattini considered notable?
It represents a personal milestone for Andrea Boattini, being the tenth periodic comet he has identified. Precovery images dating back to January 2004 also revealed that the comet had been observable well before its formal discovery, extending its known observational history by several years.
More in Periodic Comets 1-24
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