C/2017 O1 (ASASSN) |
ephemeris |
date |
magn |
radius |
delta |
ra |
dec |
elong |
phase |
PA |
Perihelion | 16 Oct 2017 | 10.8 | 1.491 AU | 0.697 AU | 04h33m | +51°36' | 122.3° | 34.4° | 240° |
Nearest approach | 17 Oct 2017 | 10.8 | 1.491 AU | 0.696 AU | 04h35m | +53°25' | 122.4° | 34.3° | 238° |
Today | 16 Sep 2025 | 29.7 | 20.814 AU | 21.724 AU | 13h12m | -01°08' | 24.4° | 1.1° | 99° |
C/2017 O1 (ASASSN)- 2025-09-16
astro.vanbuitenen.nl
The interactive orbit chart above shows the comet's path through the solar system and its position at the given date.
Green and blue lines are shown perpendicular to the ecliptic plane: Green if the path is above the ecliptic plane, blue if it is below.
(Left-click and drag to rotate the view; Right-click and drag to move the view; Use scroll wheel to zoom in our out.)
The orbital elements of C/2017 O1 (ASASSN) are:
e (Eccentricity) : 0.9961060
q (Perihelion distance) : 1.4906670
i (Inclination) : 39.99240
Ω (Longitude of ascending node) : 25.71300
ω (Argument of perihelion) : 20.84740
L (Longitude of perihelion) : 41.97765
B (Latitude of perihelion) : 13.22168
T (Time of perihelion passage) : 2458042.56890
P (Orbital period in years) : 7489.92
Epoch : 2022 Nov 15
Reference : MPEC 2022-OB6
Classification(s): : Nearly isotropic; Returning (a < 10000 AU); External (P > 200 years)
The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations respectively from COBS or the MPC.
The gray curve is based on the absolute magnitude and slope parameter as calculated from the original MPEC, or the latest values provided by the MPC (11.00 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 9.86 + 5 log[∆] + 10.00 log[r]).
The all-sky chart below shows the path of the comet over the same period as the light curve. The comet's current position is marked yellow.
The following chart shows the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.
A more printer-friendly version of the same chart can be found further down this page as well.
The following chart shows the current location of the comet in a smaller, upside-down telescopic field of view.
A printable version of the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.
Ephemerides:
Date Time RA (2000) DEC (2000) delta radius elong phase PA magn
2025-09-16 00:00 UT 13 12 02.7 -01 08 16 21.720 20.812 24.7 1.2 99 29.7
2025-09-16 07:32 UT 13 12 05.6 -01 08 40 21.724 20.814 24.4 1.1 99 29.7
2025-09-17 00:00 UT 13 12 12.2 -01 09 31 21.732 20.817 23.8 1.1 99 29.7
2025-09-18 00:00 UT 13 12 21.9 -01 10 47 21.743 20.822 22.9 1.1 98 29.7
2025-09-19 00:00 UT 13 12 31.6 -01 12 02 21.755 20.827 22.0 1.0 97 29.7
2025-09-20 00:00 UT 13 12 41.3 -01 13 17 21.765 20.832 21.1 1.0 97 29.7
2025-09-21 00:00 UT 13 12 51.1 -01 14 33 21.776 20.837 20.2 1.0 96 29.7
2025-09-22 00:00 UT 13 13 01.0 -01 15 48 21.786 20.842 19.3 0.9 95 29.7
2025-09-23 00:00 UT 13 13 10.9 -01 17 04 21.796 20.847 18.5 0.9 94 29.7
2025-09-24 00:00 UT 13 13 20.9 -01 18 19 21.806 20.852 17.6 0.8 93 29.7
2025-09-25 00:00 UT 13 13 30.9 -01 19 35 21.816 20.857 16.7 0.8 92 29.7
2025-09-26 00:00 UT 13 13 41.0 -01 20 50 21.825 20.863 15.8 0.8 91 29.7
Terminology:
delta: distance between comet and earth in AU
radius: distance between comet and sun in AU
magn: magnitude (brightness) estimate
ra: right ascension in hours (24h = 360deg)
dec: declination in degrees
elong: elongation in degrees (angle sun-earth-comet)
phase: phase angle in degrees (angle sun-comet-earth)
AU: Astronomical Unit (mean distance between earth and sun: 149597870.7 km
Orbital elements usually provided by the MPC (Minor Planet Center).
Observations contributed by observers worldwide, via COBS (Comet Observation Database) or the MPC (Minor Planet Center)
Calculations by a modified version of AAPlus, a C# implementation of the AA+ project by PJ Naughter from the algorithms presented in the book "Astronomical Algorithms" by Jean Meeus.
NGC2000 dso catalog and star labels from VizieR as provided by the Strasbourg astronomical Data Center.
Tycho2 catalog from the ESO archive.