SWAN COMET DISCOVERIES

 

9) C/2021 D1 SWAN

COMET C/2021 D1 (SWAN) was announced on CBET 4939
On 2021 Feb. 25 I reported a possible comet in SWAN comet tracker maps freely available online.
The comet appeared to have been brightening from magnitude 12 to 11 between Feb. 19 to 23.
2021 UT R.A. (2000) Decl.
Feb. 19.5 22 54 + 7 40
20.5 22 59 + 8 40
21.5 23 04 + 9 35
22.5 23 10 +10 35
23.5 23 15 +11 45
24.5 23 20 +12 30
25.5 23 25 +13 20
I was unable to verify from the ground as it was not visible from my location and so I requested confirmation on
the comets-ml discussion group.
M Jager (Austria) confirmed the comet on Feb. 28.7 UT, noting a well condensed 3'.5 coma of total mag 10.5
The comet showed a 4' coma of total mag 10.8  on Mar. 1.7UT. (as shown in the above image)
The comet arrived at perihelion on 2021 Feb 27 at a distance of 0.90AU.
Its orbital period is 947 years
 

8) C/2020 F8 SWAN


Click HERE for detailed description on my discovery


7) C/2015 P3 SWAN


On 2015 Aug 9 at 03UT, I downloaded the latest SWAN comet tracker maps at http://swan.projet.latmos.ipsl.fr/
and noted a suspicious object located on the Leo-Coma Berenices border on images dated Aug 3 and 4.
I measured very approximate positions on these dates, as well as a possible earlier detection on July 28:
Position accuracy is generally in the order of 1 to 2 degrees of sky.
Since the comet tracker maps are posted with a time delay of nearly a week, I had to predict where the comet may have advanced in the sky.
I covered a 10 degree square patch of sky in Virgo, situated around Rho Virginis that evening, at 09:11UT, and confirmed the comet
photographically after the third sweep, using a Canon 60Da + Sigma 200mm F/2.8 lens, tracking on a Vixen polarie star tracker.
The comet appeared slightly condensed, of photometric magnitude 11.8, with a coma diameter of 2 arcminutes.
The blue green colour of the comet stood out from the white appearance of the Virgo supercluster of galaxies.
Rapid motion was evident as I imaged the comet for the hour following discovery.
I measured its positions using Astrometrica software and sent it through to CBAT for posting on the Possible Comet Confirmation page.
The discovery was announced on CBET 4136 and the comet designated C/2015 P3 SWAN.
The preliminary orbit indicated that perihelion had already occurred on 2015 July 27 at 0.71AU.
The comet was not expected to become much brighter than magnitude 11.
It was very faint intrinsically (mag 14) and I'm surprised it even survived perihelion.
But a clue lies in its revised orbit - it is a dynamically evolved object, orbiting the Sun every 3,000 years.



 

6) C/2015 C2 SWAN
Independently discovered by Rob Matson. myself and Vladimir Bezugly using the SWAN comet tracker maps.

Ground based Confirmation image. Taken at 10:30UT on Feb 25.
Terry Lovejoy in Queensland confirmed the comet earlier that same evening.

2015 Feb 26.
Visual estimate of magnitude 11.5 through a 20 cm reflector at 130x.

2015 March 3.
Comet was situated at 12 degrees altitude in twilight.
It was heading northwards and only visible from the Northern Hemisphere by mid March.
 

5) C/2006 M4 SWAN
IAUC 8729: R. D. Matson, Irvine, CA; and M. Mattiazzo, Adelaide, S.Australia, report independently that they found images of a moving
object at small solar elongations on SOHO/SWAN images from late June, and both men asked southern-hemisphere observers to try
confirming a possible comet in that vicinity (averaged SWAN positions from Matson and Mattiazzo are provided below).
In response to Mattiazzo's request, T. Lovejoy (Thornlands, Qld.,Australia) found an image of the suspected comet on CCD frames
taken on June 30 with a Canon 350D camera (+ 100-mm-focal-length f/3.5 lens), noting the object to have a distinct greenish hue and
an apparent circular coma of diameter about 0'.5. Confirming images taken by R. H. McNaught with the 0.5-m Uppsala Schmidt
telescope on July 12 show a strongly condensed coma and a tail 80" long in p.a. 205 deg.

2006 UT R.A. (2000) Decl. Mag. Observer
June 20 8 42.0 - 9 29 SWAN
22 8 44.0 - 8 48 "
25 8 46.8 - 8 00 "
29 8 50.0 - 6 09 "
30.363 8 52.49 - 6 20.8 12 Lovejoy
July 2 8 52.4 - 5 14 SWAN
4 8 54.2 - 4 38 "
5 8 54.8 - 3 42 "
July 12.35695 9 05 59.07 - 1 55 43.8 12.3 McNaught
12.35925 9 05 59.27 - 1 55 41.0 "
12.36157 9 05 59.46 - 1 55 38.5 "
12.36387 9 05 59.63 - 1 55 35.6 "

The ephemeris below is provided to aid observers, taken from very uncertain parabolic orbital elements (T = 2006 Aug. 24.2 TT, q
= 0.132 AU, Peri. = 112.9, Node = 162.6, i = 98.8, equinox 2000.0).

2006 TT R. A. (2000) Decl. Delta r Elong. Phase Mag.
July 4 8 56.02 - 4 43.2 1.994 1.398 41.1 28.6 13.0
9 9 01.84 - 3 03.4 1.958 1.299 37.0 28.1 12.6
14 9 08.08 - 1 22.2 1.915 1.196 32.9 27.5 12.2
19 9 14.74 + 0 22.2 1.864 1.089 28.7 26.7 11.7
24 9 21.88 + 2 12.0 1.805 0.977 24.6 25.6 11.2

4) P/2005 T4  SWAN

Image taken 2005 October 27

IAUC 8619: R. D. Matson, Newport Coast, California; and M. Mattiazzo, Wallaroo, South Australia,
have independently reported the presence of a comet in SOHO SWAN images during the first half of October
The SWAN positions below are from Matson.
E. J. Christensen reports that Catalina Sky Survey (0.68-m Schmidt telescope) images on Oct. 22.1 UT show a moderately condensed,
roughly circular coma of diameter about 2' in three coadded 20-second exposures.
R. H.McNaught, observing with the 1.0-m f/8 reflector at Siding Spring Observatory on Oct. 22.4, reports a diffuse 1' coma with a 3" (FWHM)
central condensation (used for the magnitude estimates below). J. E. McGaha (Tucson, Arizona, 0.62-m f/5.1 reflector) reports that
his images on Oct. 23.1 show a fan-shaped coma of size 20" x 30" toward p.a. 120 deg. A. Hale (Cloudcroft, New Mexico, 0.41-m
reflector) writes that a visual observation on Oct. 23.08 showed a diffuse coma of diameter 1'.5 and total mag 12.1.

2005 UT R.A. (2000) Decl. Mag. Observer
Oct. 6 15 00.7 - 0 20 SWAN
9 15 29.2 - 3 28 "
11 15 47.9 - 5 10 "
13 16 06.9 - 6 43 "
Oct. 22.06892 16 27 47.50 - 9 13 25.2 12.4 Christensen
22.07064 16 27 47.68 - 9 13 27.0 "
22.07230 16 27 47.91 - 9 13 28.7 "
22.39354 16 28 24.32 - 9 17 53.4 18.1 McNaught
22.39504 16 28 24.50 - 9 17 55.1 18.0 "
22.39654 16 28 24.67 - 9 17 56.3 18.0 "
22.39809 16 28 24.83 - 9 17 57.4 17.9 "
22.39960 16 28 24.99 - 9 17 58.8 17.9 "
22.40110 16 28 25.18 - 9 18 00.0 17.7 "

Additional precise positions, the following preliminary parabolic orbital elements by B. G. Marsden (from 12 precise
positions, Oct. 22-23), and an ephemeris appear on MPEC 2005-U19:
T = 2005 Oct. 9.602 TT Peri. = 40.696
Node = 25.945 2000.0
q = 0.64699 AU Incl. = 160.126

3) C/2005 P3 SWAN

IAUC 8587: Several people reported the appearance of a possible comet in ultraviolet SWAN website images taken with the SOHO spacecraft,
including H. Sato (Sukagawa, Fukushima-ken, Japan; via S. Nakano, Sumoto, Japan), M. Suzuki (Utsunomiya, Tochigi, Japan), M.
Mattiazzo (Adelaide, S. Australia), M. Jaeger (Vienna, Austria), and V. Bezugly (Dnepropetrovsk, Ukraine).
Following requests for confirmation by the Central Bureau, A. Hale (Cloudcroft, NM) reported a visual observation of the object on Aug. 25.142 UT with
a 0.41-m reflector, which had a moderately condensed 3' coma and a guessed total mag of roughly 9.5; his observation was combined with
the necessarily very rough SWAN positions below measured by Sato to produce an ephemeris for the 'NEO Confirmation Page'. Available
positions follow (Aug. 4 and 7 positions from Mattiazzo):

2005 UT R.A. (2000) Decl. Mag. Observer
Aug. 4 11 12.2 +15 20 SWAN
7 11 16.1 +18 31 "
9 11 20.9 +21 08 "
14 11 30.3 +28 07 "
16 11 31.8 +30 11 "
18 11 33.3 +32 34 "
21 11 33.7 +35 22 "
24.83145 11 33 54.79 +37 38 23.5 11.8 Sanchez
24.84571 11 33 53.86 +37 38 57.1 "
24.87452 11 33 53.77 +37 40 21.0 "
25.142 11 33 50 +37 52.0 Hale
26.12613 11 33 38.53 +38 40 13.6 14.4 McGaha
26.12675 11 33 38.51 +38 40 14.8 "
26.43616 11 33 33.75 +38 54 37.7 Kadota
26.43990 11 33 33.73 +38 54 45.8 "
26.44168 11 33 33.67 +38 54 51.4 11.0 "

S. Sanchez, R. Stoss, J. Nomen (Mallorca). 0.07-m f/2.8 refractor
+ CCD. Clearly diffuse.
J. E. McGaha (Tucson). 0.36-m f/10.0 Schmidt-Cassegrain reflector
+ CCD. Inner coma of size 15" x 10", outer coma of size 45" x
32" (elongated in both cases in p.a. 225 deg.
K. Kadota (Ageo, Japan). 0.25-m f/5.0 reflector + CCD. Diffuse
coma of diameter 2' with central condensation, no tail. Comm. by
Nakano.

2) C/2004 V13 SWAN
IAUC 8455: On 2004 Nov. 30, M. Mattiazzo (Adelaide, S. Australia) reported that he noticed images of a faint object moving on SWAN images
 (his positions below have uncertainties of a degree or more due to the poor resolution of the ultraviolet imager on SWAN/SOHO),
speculating then that, if real, the object might become visible in the days ahead in the C3 coronagraph.
On 2004 Dec 16, S. Hoenig reported the appearance of a comet with a tail in C3 images,
which K. Battams reports has brightened slightly from mag about 6.5 on Dec. 16.26 UT to about 6.1 on Dec. 16.70-16.74.

2004 UT R.A. (2000) Decl. Observer
Nov. 9 12 48 -19.5 SWAN
16 13 15 -20.5 "
21 13 41 -21.0 "
25 14 08 -21.5 "
Dec. 16.154 17 04.9 -19 54 SOHO

It does appear that the SWAN object is identical with the SOHO object, and the following very preliminary parabolic orbital
elements by Marsden also appear on MPEC 2004-Y02.

T = 2004 Dec. 21.139 TT Peri. = 94.253
Node = 207.015 2000.0
q = 0.17727 AU Incl. = 34.463

Below an image of C/2004 V13 SWAN post-perihelion.

 

1) C/2004 H6 SWAN
I detected this comet in SWAN comet tracker maps on 2004 May 14, and was the first person to observe this from the ground,
estimating it at magnitude 7.8 on 2004 May 14.39UT using a pair of 25x100mm binoculars.
Unfortunately the comet was located very low on the horizon and was approaching solar conjunction.
I had to wait a further week to reconfirm the comet, now situated in the morning sky.
On 2004 May 20.85UT, I picked up the comet in 25x100mm binoculars and estimated it at mag 7.5
The following morning, I obtained a CCD image as per below and submitted astrometry to MPC


C/2004 H6 SWAN confirmation image on  on 2004 May 21.85UT.
10x10 second exposures through Celestron C11 at f/3.3.
Field of view about 15' wide. Twilight interference.


C/2004 H6 SWAN on 2004 May 25


C/2004 H6 SWAN on 2004 June 7

The comet arrived at perihelion on 2004 May 12 at 0.77AU and probably underwent an outburst
 

210P Christensen
= THE SWAN COMET THAT SHOULD HAVE BEEN
210P was detected in SWAN data during early April 2003 but was not able to be confirmed from the ground.
On 2023 May 26, Eric Christensen (Catalina sky survey) discovered a comet.
Once an orbit was well determined, it was found that the SWAN object and the new comet were the same.
Unfortunately the IAU did not give credit to SWAN