J/AJ/168/286 Observed apparent magnitudes of C/2023 RN3 (Dobson+, 2024)
Analyzing the onset of cometary activity by the Jupiter-family comet 2023 RN
Dobson M.M., Schwamb M.E., Fitzsimmons A., Kelley M.S.P., Holt C.E.,
Murtagh J., Hsieh H.H., Denneau L., Erasmus N., Heinze A.N.,
Shingles L.J., Siverd R.J., Smith K.W., Tonry J.L., Weiland H.,
Young D.R., Lister T., Gomez E., Chatelain J., Greenstreet S.
<Astron. J., 168, 286 (2024)>
=2024AJ....168..286D 2024AJ....168..286D
ADC_Keywords: Comets; Photometry, UBVRI; Solar system
Keywords: Comets ; Comae ; Small Solar System bodies ; Centaur group ;
Broad band photometry ; Wide-field telescopes ; Orbital evolution
Abstract:
We utilize serendipitous observations from the Asteroid
Terrestrial-impact Last Alert System (ATLAS) and the Zwicky Transient
Facility in addition to targeted follow-up observations from the Las
Cumbres Observatory (LCO) and Liverpool Telescope to analyze the first
observed instance of cometary activity by the newly discovered
Jupiter-family comet C/2023 RN3 (ATLAS), whose orbital dynamics place
it close to residing on a Centaur-like orbit. Across our 7 month
baseline, we observe an epoch of cometary activity commencing in 2023
August with an increase in brightness of >5.4 mag. The lightcurve of
2023 RN3 indicates the presence of continuous cometary activity across
our observations, suggesting the onset of a new period of sustained
activity. We find no evidence of any outbursts on top of the observed
brightening nor do we find any significant color evolution across our
observations. 2023 RN3 is visibly extended in LCO and Liverpool
Telescope observations, indicating the presence of a spatially
extended coma. Numerical integration of 2023 RN3's orbit reveals the
comet to have recently undergone a slight increase in semimajor axis
due to a planetary encounter with Jupiter; however, whether this
orbital change could trigger 2023 RN3's cometary activity is unclear.
Our estimate for the maximum dust production metric of Afρ∼400cm
is consistent with previous measurements for the Jupiter-family comet
and Centaur populations.
Description:
Our data set consists of both targeted follow-up observations of 2023
RN3 (LOOK and Liverpool Telescope) and serendipitous observations of
the object from the Asteroid Terrestrial-impact Last Alert System
(ATLAS) and the Zwicky Transient Facility (ZTF) automated surveys. Our
observations extend in time from 2023 June 6 to 2024 February 2. The
serendipitous observations from ATLAS and the ZTF make up the majority
of our data set and cover the onset of 2023 RN3's cometary activity
first observed on 2023 August 26. Our observations from the Las
Cumbres Observatory Outbursting Objects Key (LOOK) project and the
Liverpool Telescope sample 2023 RN3 after its activity commenced.
ATLAS regularly observes the entire night sky to a limiting magnitude
of 19.5mag using 30s exposures in two nonstandard filters, cyan (c,
420-650nm) and orange (o, 560-820nm). ATLAS consists of four telescope
units, two of which are located in Hawaii (Mauna Load and Haleakala),
one in Chile (El Sauce), and one in South Africa (Sutherland). Each of
the four ATLAS units consists of a 0.5m Schmidt telescope with a field
of view (FOV) of 28.9 deg2. We use both c and o filter observations
of 2023 RN3 from all four ATLAS telescopes between 2023 June 6 and
2024 February 2.
Using the 48inch (1.2m) Samuel Oshin telescope at Palomar Observatory
in CA, USA, ZTF is a wide-field time domain survey that has been
observing the visible sky since 2017 October with a cadence of
approximately 3 days. Each observation has an exposure time of 30s,
with an FOV of 43 deg2, and is obtained using three broadband
filters ZTF-g, ZTF-r, and ZTF-i. We query the ZTF observations of 2023
RN3 via the Infrared Science Archive (IRSA) of the NASA Infrared
Processing and Analysis Center (IPAC). These observations range in
time from 2023 August 3 to 2024 January 7 in the broadband filters
ZTF-g and ZTF-r.
The Las Cumbres Observatory (LCO) 1.0m telescopes, located in various
countries around the globe, observed 2023 RN3 from 2023 November 26 to
2024 January 10 (including the observations reported in
Hsieh+, 2023RNAAS...7..263H 2023RNAAS...7..263H) as part of the LCO Outbursting Objects
Key Project (LOOK; Lister+, 2022PSJ.....3..173L 2022PSJ.....3..173L). Observations were
taken in Sloan Digital Sky Survey (SDSS) g, r, and i filters with the
original Hsieh+ (2023RNAAS...7..263H 2023RNAAS...7..263H) observations in the w-filter
included in our analysis. The LOOK photometry pipeline then performs a
color correction to transform the instrumental magnitudes to their
corresponding Pan-STARRS1 filters g', r', and i'. Each 1m telescope
has a FOV of 26.6'x26.6'. All observations were obtained with the
telescope in half-rate tracking mode, with exposure times of 245s. Of
these observations, we utilize for our analysis only those that were
obtained with seeing ≤4".
The Liverpool Telescope is a 2m robotic telescope located at the
Observatorio del Roque de los Muchachos, La Palma, Canary Islands. We
obtained observations of 2023 RN3 between 2023 November 26 and 2023
December 14 using the IO:O wide-field camera and its FOV of 10'x10'.
Observations were obtained in SDSS r and i filters for conditions of
airmass <2.0 and seeing <2". We utilize sidereal tracking of 2023 RN3,
with exposure times of 82s for g-filter observations and 70s in r
and i filters. We analyze 2023 RN3 in the 29 observations where it was
detected above 3σ.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 65 269 Apparent magnitudes of 2023 RN3 in each observation
from ATLAS, ZTF, and LOOK
--------------------------------------------------------------------------------
See also:
J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)
J/ApJ/867/105 : ATLAS all-sky stellar ref. cat., ATLAS-REFCAT2 (Tonry+, 2018)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 F18.12 d MJD [60101/60320] Modified Julian Date of
observation
20- 25 F6.3 mag mag [17/20.4] Apparent magnitude
27- 31 F5.3 mag e_mag [0.02/0.33]? mag uncertainty
33 I1 --- Flag [0/1] Flag for observation
(0=3σ upper limit; 1=Detection)
35- 39 A5 --- Filter Filter of observation (1)
41- 45 F5.3 AU HDist [5.22/5.51] Heliocentric distance at time of
observation
47- 51 F5.3 AU GDist [4.33/5.71] Geocentric distance at time of
observation
53- 59 F7.4 deg alpha [0.993/11.18] Solar phase angle at time of
observation
61- 65 A5 --- Survey Survey of Observation (2)
--------------------------------------------------------------------------------
Note (1): Filters as follows:
ZTF_g = Zwicky Transient Facility (ZTF) g filter (472.3nm); 26 occurrences
ZTF_r = Zwicky Transient Facility (ZTF) r filter (634nm); 28 occurrences
c = Asteroid Terrestrial-impact Last Alert System (ATLAS)
cyan filter (420-650nm); 36 occurrences
o = Asteroid Terrestrial-impact Last Alert System (ATLAS)
orange filter (560-820nm); 106 occurrences
gp = Sloan Digital Sky Survey (SDSS) g' filter (477nm) on the Las Cumbres
Observatory (LCO) and Liverpool telescopes; 26 occurrences
rp = Sloan Digital Sky Survey (SDSS) r' filter (621.5nm) on the Las
Cumbres Observatory (LCO) and Liverpool telescopes; 24 occurrences
ip = Sloan Digital Sky Survey (SDSS) i' filter (754.5nm) on the Las
Cumbres Observatory (LCO) and Liverpool telescopes; 19 occurrences
w = Pan-STARRS1 w filter (577.5nm) on the Las Cumbres Observatory (LCO)
telescopes; 4 occurrences
Note (2): Surveys as follows:
ATLAS = Asteroid Terrestrial-impact Last Alert System, with four 0.5m Schmidt
telescopes, two of which are located in Hawaii (Mauna Load and
Haleakala), one in Chile (El Sauce), and one in South Africa
(Sutherland); 142 occurrences
LOOK = LCO Outbursting Objects Key Project, with the Las Cumbres Observatory
(LCO) 1.0m telescopes located around the globe; 73 occurrences
ZTF = Zwicky Transient Facility, with the 48inch (1.2m) Samuel Oshin
telescope at Palomar Observatory in CA, USA; 54 occurrences
History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 11-Sep-2025