[Iaude] CBET 5367: COMET P/2020 Y6 = P/2016 J1
quai at eps.harvard.edu
quai at eps.harvard.edu
Wed Mar 13 15:16:45 EDT 2024
Electronic Telegram No. 5367
Central Bureau for Astronomical Telegrams
Mailing address: Hoffman Lab 209; Harvard University;
20 Oxford St.; Cambridge, MA 02138; U.S.A.
e-mail: cbatiau at eps.harvard.edu (alternate cbat at iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network
COMET P/2020 Y6 = P/2016 J1 (PANSTARRS)
On 2022 Aug. 17, H. H. Hsieh, Planetary Science Institute and Academia
Sinica Institute of Astronomy and Astrophysics; and M. Micheli, European Space
Agency Near-Earth Object Coordination Centre, reported that r'-band exposures
taken on 2022 Apr. 25 with the Gemini North Observatory (six 100-s exposures;
queue observer T. Seccull) show that fragment A of comet P/2016 J1 (CBET 4276)
was then currently active. In those observations, the object had a point-
spread-function size of 0".71 (full-width-at-half-maximum) compared to typical
FWHM values of 0".65 for nearby stellar sources (as measured in the direction
perpendicular to the non-sidereal motion of the object on the sky), and it
exhibited a short, faint tail extending approximately 1".5 from the nuclear
condensation in p.a. 255 degrees, close to the projected direction of the
anti-solar vector (258 degrees) on the sky. The object had a measured mean
magnitude of r' = 22.8 (measured using a photometry aperture enclosing all of
the total visible flux from the fragment). In follow-up observations with
the 8.1-m "Gemini North" telescope at Mauna Kea on 2022 June 19 (two 100-s
exposures; queue observer C. Figura), component A exhibited a tail extending
approximately 3".5 from the nuclear condensation in p.a. about 230 degrees,
close to the projected direction of the anti-solar vector (217 degrees) on
the sky, with a measured mean magnitude of r' = 21.9. Hsieh notes that this
object appeared apparently inactive in earlier observations obtained with the
same telescope on 2021 Apr. 14 and 17 and 2021 May 17 (six 300-s exposures,
three 300-s exposures, and three 300-s exposures, respectively; queue
observers J. Cortes, T. Rudyk, T. Mocnik, J. Andrews, and T. Seccull;
measured mean r'-band magnitudes of 24.7, 24.8, and 25.0, respectively).
This suggests that the object's absolute magnitude brightened by about 1.6
mag between 2021 (mean derived absolute magnitude 19.8) and 2022 (mean
derived absolute magnitude about 18.2), independently indicating that
activity strength increased between the two epochs. Selected observations
for component A dating back to 2020 from Micheli and Hsieh (full astrometry
on MPEC 2024-E142):
2020 UT R.A. (2000) Decl. Mag. Observer
Dec. 24.52035 10 45 38.52 - 6 28 44.7 25.2 Hsieh
24.52422 10 45 38.58 - 6 28 45.8 25.0 "
2021 UT R.A. (2000) Decl. Mag. Observer
Feb. 17.42188 10 31 43.48 - 6 10 20.5 23.7 Hsieh
17.42961 10 31 43.14 - 6 10 17.8 24.0 "
May 17.27640 10 14 53.61 + 3 32 40.5 24.5 "
17.28412 10 14 53.92 + 3 32 41.3 24.4 "
2022 UT R.A. (2000) Decl. Mag. Observer
Mar. 13.60427 18 22 38.17 -12 01 29.7 23.3 Hsieh
13.60581 18 22 38.31 -12 01 29.1 23.1 "
June 19.36086 19 05 21.22 + 0 17 22.9 21.8 "
19.37324 19 05 20.71 + 0 17 25.2 21.7 "
Hsieh and Micheli also reported the recovery of component B on 2022 June 24
and July 7 in observations obtained with the 8.1-m "Gemini North" telescope
(three 100-s and four 100-s exposures, respectively; queue observers Z.
Hartman and E. P. Farina), and on 2022 July 7 in observations from the Gemini
South Observatory (two 300-s exposures; queue observer L. Magill).
Unfortunately, component B was too faint in these observations to allow
definitive assessment of whether activity was present in any of those data.
Hsieh notes, however, that component B did exhibit clear activity in earlier
observations obtained with the "Gemini North" telescope on 2021 May 29, 30,
and 31 (four 300-s exposures, three 300-s exposures, and one 300-s exposure,
respectively; queue observer A. Smith). In the data obtained on 2021 May 29,
component B had a point-spread function of size 1".0 (FWHM) as compared to
typical FWHM values of 0".6 for nearby stellar sources (as measured in the
direction perpendicular to the non-sidereal motion of the object on the sky),
and it exhibited a short, faint tail extending about 2".5 from the nuclear
condensation in p.a. 125 degrees, close to the projected direction of the
anti-solar vector (112 degrees) on the sky. Photometric measurements of
component B indicate that it had mean r'-band magnitudes of 23.9, 23.9, and
24.1 on 2021 May 29, 30, and 31, respectively, and 24.7 on 2022 July 7 (from
the "Gemini South" telescope). Selected astrometry for component B:
2021 UT R.A. (2000) Decl. Mag. Observer
May 29.28264 10 24 26.01 + 3 44 41.7 23.6 Hsieh
29.28649 10 24 26.20 + 3 44 41.8 23.9 "
29.29035 10 24 26.41 + 3 44 41.7 23.9 "
30.33112 10 25 21.59 + 3 44 48.9 22.8 "
31.32214 10 26 15.06 + 3 44 47.6 22.8 "
2022 UT R.A. (2000) Decl. Mag. Observer
June 24.50698 19 02 06.27 + 0 30 33.9 24.4 Hsieh
July 7.17327 18 52 39.69 + 0 35 23.6 23.8 "
Additional astrometry for component B is given on MPEC 2024-E143 (where the
Minor Planet Center inadvertently designated component B as "P/2021 K5-B"
instead of the proper designation "P/2020 Y6, component B").
Also in 2022, as a result of Hsieh's report, S. Nakano (Central Bureau)
found the following suspected observations of this comet from 2004 in Catalina
Sky Survey observations in the MPC's "isolated tracklet file":
2004 UT R.A. (2000) Decl. Mag.
June 20.14644 10 21 58.14 + 4 08 19.4 17.7
20.15015 10 21 58.47 + 4 08 17.7 17.8
20.15385 10 21 58.66 + 4 08 17.8 17.6
20.15756 10 21 58.94 + 4 08 17.0 17.5
Nakano notes that he found these observations from a linked orbit from
2016-2022 observations, and the residuals were only +6" (mainly in R.A.) in
2004 with a corresponding correction of Delta(T) = -0.007 day.
S. Deen (Simi Valley, CA, USA) was unable to find images of the comet in
CSS observations from 2004 Apr. 22 down to red mag around 21.0, suggesting an
outburst in brightness in June. He was also unable to find the comet in
Canada-France-Hawaii Telescope exposures from 2002 Dec. 6 down to around
magnitude r = 24.0. Deen further reports that he has now found numerous
additional observations of this comet in publicly available data, including
the following observations obtained with the Pan-STARRS1 1.8-m reflector at
Haleakala, Hawaii, from 2010 and 2011:
2010 UT R.A. (2000) Decl. Mag.
Apr. 3.44163 12 14 43.95 - 6 41 15.6 21.3
3.44992 12 14 43.64 - 6 41 10.5 21.3
12.42586 12 09 12.13 - 5 07 15.3
12.43503 12 09 11.81 - 5 07 09.8
17.39984 12 06 33.96 - 4 16 47.9
17.40903 12 06 33.65 - 4 16 42.0
2011 UT R.A. (2000) Decl.
Aug. 18.37134 21 11 04.19 + 3 30 24.1
18.38363 21 11 03.68 + 3 30 18.9
18.39720 21 11 03.09 + 3 30 12.7
19.35574 21 10 24.00 + 3 23 14.2
19.36792 21 10 23.48 + 3 23 08.7
19.37952 21 10 22.97 + 3 23 03.6
Deen was unable to find two components in 2010 or 2011. On 2010 Apr. 12 and
17, the comet appears noticeably diffuse with an apparent coma of size 1".5
(FWHM) in 0".7 seeing, with no tail; the magnitudes were around g = 22.0
and 21.9 on those two nights, respectively. The 2011 Aug. 18 and 19 images
are incredibly faint. The 2010 Apr. 3 images were from i-band exposures.
Deen also identified the comet in sixteen high-quality W3-band images taken
with the Wide-field Infrared Survey Explorer satellite between 2010 June 21.85
and 23.24 UT, where the comet appears possibly slightly elongated by possibly
6" in p.a. about 115/295 degrees.
The residuals for the recovery observations of component A on 2022 Mar.
13 were +48" in R.A. and +6" in Decl. from the prediction in NK 3987, with a
corresponding correction of Delta(T) = -0.05 day. Nakano has analyzed all of
the available astrometry, leading to the following linked orbital elements
for component A, from 135 observations spanning 2004-2022 (mean residual
0".4), with non-gravitational parameters A_1 = -1.24 +/- 0.13 and A_2 =
-0.0816 +/- 0.0039. The April 2010 observations (above) do not fit well
(systematic residuals of +8" in R.A.) and were excluded. Some of the WISE
observations were excluded also (residuals in the range 3"-6" mostly in R.A.).
Epoch = 2005 Mar. 11.0 TT
T = 2005 Mar. 15.86557 TT Peri. = 45.59805
e = 0.2359634 Node = 200.37541 2000.0
q = 2.4153410 AU Incl. = 14.35626
a = 3.1612896 AU n = 0.17535076 P = 5.62 years
Epoch = 2010 Nov. 20.0 TT
T = 2010 Nov. 1.08713 TT Peri. = 45.87088
e = 0.2348393 Node = 200.33184 2000.0
q = 2.4195771 AU Incl. = 14.35335
a = 3.1621815 AU n = 0.17527658 P = 5.62 years
Epoch = 2016 June 21.0 TT
T = 2016 June 24.21905 TT Peri. = 46.58721
e = 0.2282575 Node = 199.85614 2000.0
q = 2.4479989 AU Incl. = 14.33013
a = 3.1720411 AU n = 0.17446000 P = 5.65 years
Epoch = 2022 Mar. 2.0 TT
T = 2022 Feb. 20.66426 TT Peri. = 46.98806
e = 0.2277366 Node = 199.81128 2000.0
q = 2.4496763 AU Incl. = 14.32870
a = 3.1720735 AU n = 0.17445733 P = 5.65 years
Epoch = 2027 Nov. 11.0 TT
T = 2027 Nov. 14.76910 TT Peri. = 50.40485
e = 0.2209317 Node = 198.73356 2000.0
q = 2.4838098 AU Incl. = 14.19743
a = 3.1881796 AU n = 0.17313700 P = 5.69 years
Epoch = 2033 July 22.0 TT
T = 2033 July 29.27836 TT Peri. = 50.89357
e = 0.2211751 Node = 198.68620 2000.0
q = 2.4824343 AU Incl. = 14.19692
a = 3.1874099 AU n = 0.17319972 P = 5.69 years
The residuals for the recovery observations of component B above are +140" in
R.A. and +18" in Decl. from the prediction in NK 3988, with a corresponding
correction of Delta(T) = -0.09 day. The following linked orbital elements for
component B by Nakano are from 76 observations spanning 2004-2022 (mean
residual 0".5), with non-gravitational parameters A_1 = -5.98 +/- 0.56 and A_2
= -0.9406 +/- 0.0217. He notes that A_1 has notable uncertainty. Nakano
included the 2004 observations, which fit well and suggest that the splitting
occurred at or after that apparition. The April 2010 observations were
included as component B (see discussion on residuals for component A, above).
There are no close approaches to major planets.
Epoch = 2005 Mar. 11.0 TT
T = 2005 Mar. 15.74615 TT Peri. = 45.57086
e = 0.2359512 Node = 200.37484 2000.0
q = 2.4154351 AU Incl. = 14.35742
a = 3.1613623 AU n = 0.17534471 P = 5.62 years
Epoch = 2010 Nov. 20.0 TT
T = 2010 Nov. 1.01424 TT Peri. = 45.85305
e = 0.2348116 Node = 200.33128 2000.0
q = 2.4196650 AU Incl. = 14.35451
a = 3.1621822 AU n = 0.17527652 P = 5.62 years
Epoch = 2016 June 21.0 TT
T = 2016 June 24.11589 TT Peri. = 46.57644
e = 0.2282189 Node = 199.85585 2000.0
q = 2.4480697 AU Incl. = 14.33130
a = 3.1719740 AU n = 0.17446553 P = 5.65 years
Epoch = 2022 Mar. 2.0 TT
T = 2022 Feb. 20.47538 TT Peri. = 46.98588
e = 0.2276851 Node = 199.81101 2000.0
q = 2.4497382 AU Incl. = 14.32988
a = 3.1719421 AU n = 0.17446816 P = 5.65 years
Epoch = 2027 Nov. 11.0 TT
T = 2027 Nov. 14.44795 TT Peri. = 50.41359
e = 0.2208816 Node = 198.73330 2000.0
q = 2.4838097 AU Incl. = 14.19849
a = 3.1879745 AU n = 0.17315371 P = 5.69 years
Epoch = 2033 July 22.0 TT
T = 2033 July 28.73636 TT Peri. = 50.90973
e = 0.2211160 Node = 198.68597 2000.0
q = 2.4824190 AU Incl. = 14.19799
a = 3.1871485 AU n = 0.17322103 P = 5.69 years
The photometric power-law parameters for component A from the 2016 apparition
(H = 16.0, 2.5n = 10) represent the 2020-2022 observations well and suggest
that the comet is currently near mag 25.
NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.
(C) Copyright 2024 CBAT
2024 March 13 (CBET 5367) Daniel W. E. Green
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