C/2008 Y12

I found this comet in SOHO LASCO C2 images of 2008 December 22 16:54 - 18:54 UTC.

Karl Battams confirmed it as SOHO-1594, his measurements are here.

Brian Marsden published a retrograde orbit on MPEC 2009-F17:

Orbital elements:
Comet            T              q       e       Peri.    Node     Incl.     C
CK08Y120   2008 Dec.  22.65   0.0533   1.0     140.06    35.03   154.34     X

Brian G. Marsden             (C) Copyright 2009 MPC           M.P.E.C. 2009-F17

On 2012 Febuary 01 Karl Battams wrote to the sohohunter list:

"Andrew Steffl from SWRI (Boulder) found a small object in the HI-1A data in 2008,
and he was able to link it to the tiny SOHO non-group comet C/2008 Y12 (SOHO)"

With these additional observations from STEREO-A Gareth Williams published a new orbit on MPEC 2012-B23:

    C/2008 Y12 (SOHO)
T 2008 Dec. 22.60543 TT                                 MPC
q   0.0658983            (2000.0)            P               Q
                   Peri.  145.62274     -0.16888872     -0.94058046
                   Node   312.10406     +0.79141647     +0.04873942
e   1.0            Incl.   23.39475     +0.58748326     -0.33605486
From 22 observations 2008 Dec. 21-22.
Michal Kusiak replied: "...this solution almost perfectly match with the orbit
of the Southern Delta Aquarids (corelated with 96P Machholz/Kracht group comet).
So maybe this one is corelated with this complex?"

Figure 2 from Sekanina & Chodas, Astrophys. J., Suppl. Ser., vol. 161, pp. 551-586 (2005) with C/2008 Y12 added.
 L/B for C/2008 Y12 is 100/+10 deg. - a perfect match for the Machholz complex. The small cross indicates the longitude of ascending node/inclination of C/2008 Y12.
As part of the Machholz complex C/2008 Y12 should be of short period.
Using all observations FindOrb converges to:
Orbital elements:
C/2008 Y12
   Perihelion 2008 Dec 22.612890 TT = 14:42:33 (JD 2454823.112890)
Epoch 2008 Dec 22.0 TT = JDT 2454822.5   Earth MOID: 0.0574   Ve: 0.0303
M 359.81520              (2000.0)        Me: 0.0889   Ma: 0.0895
n   0.30151293     Peri.  146.40435     -0.18015327     -0.93832952     
a   2.20258200     Node   312.01038      0.79224466      0.03939800     
e   0.9699842      Incl.   23.40060      0.58300358     -0.34349017     
P   3.27            q 0.06611220  Q 4.33905180
From 22 observations 2008 Dec. 21-22; mean residual 23".653.
# State vector (heliocentric ecliptic J2000):
#    0.041204597088   0.057926845002   0.030026186786 AU
#  -81.151769737517  24.185502380077 -19.089156303052 mAU/day
# MOIDs: Me  0.0889 Ve  0.0303 Ea  0.0574 Ma  0.0895
# MOIDs: Ju  1.4224 Sa  5.9425 Ur 15.1917 Ne 26.0423
# Elements written:  8 Feb 2012 15:49:47 (JD 2455966.159572)
# Full range of obs: 2008 Dec. 21-22 (22 observations)
# Find_Orb ver: Apr 29 2011 11:56:25
# Perturbers: 00000000 (unperturbed orbit)
# Tisserand relative to Earth: 1.11642
# Tisserand relative to Jupiter: 2.65276
081221 C49 54.5- 20.7-    081221 C49  7.8+ 26.4-    081222 249  1.1+  4.0+ 
081221 C49 29.9- 52.1-    081221 C49  2.4+  .49+    081222 249  1.2+  .02+ 
081221 C49 23.1+ 44.1+    081222 C49  5.0+ 23.3+    081222 249  2.9-  1.4- 
081221 C49  8.5+ 25.2+    081222 C49 49.3+  6.9-    081222 249  1.3+  3.0- 
081221 C49  6.5- 21.2+    081222 C49 43.7- 31.9-    081222 249  2.4-  .25+ 
081221 C49  4.5+ 39.2+    081222 C49 16.0- 17.7-    081222 249  2.2-  4.0+ 
081221 C49 50.5+  6.4-    081222 C49 33.6-  7.9+    
081221 C49 34.1+  3.7-    081222 249  4.7+  3.2+    

Station data:
(249) SOHO.
(C49) STEREO-A.
As a short period comet it should have been visible in SOHO LASCO images before 2008, but I have found no candidates among the known SOHO comets.
The tracks through C2 are unfavourable in March/April and September/Oktober:

The tracks are drawn for the 15th day of each month.
Numbers are drawn every 30 minutes.
The numbers give the velocities in pixel/hour for the C2 1024*1024 images.

Rainer Kracht, 2012 February 08

The Return of C/2008 Y12

Zhijian Xu reported a non group comet in real time C2 images of 2014 May 17 and Michal Kusiak measured some positions and derived an orbit similar to that of C/2008 Y12. 
Michal posted his results to the Sohohunter group on the same day. I could link his measurements with those of C/2008 Y12:
 2008/12/21  JD=2454822.2395440   (ref. J2000.0)    File: CK08Y120.POS
 Equat. Pos. & Vel.               Ecliptic Oscul. Elements
     (Gm, km/s)                           (deg, AU)
Itr:  5   Converged             sw= 4.6135E-03
 e :    0.97849436  s= 1.5E-04          X0 :  9.21683660E+00  s= 3.0E-02
 i :   23.36540876  s= 3.4E-02          Y0 :  4.82029158E+00  s= 2.6E-02
 w :  145.49964218  s= 3.9E-01          Z0 :  7.67048013E+00  s= 7.3E-03
Nod:  311.88263773  s= 3.8E-01          Vx0: -1.28099836E+02  s= 2.4E-01
 a :    3.07986616  s= 2.0E-05          Vy0:  6.19695305E+01  s= 7.2E-01
 M0:  359.84294412  s= 1.6E-03          Vz0: -1.92272328E-01  s= 2.7E-01
Rj0: -2.88615E-08     DataPoints:   36          Time Span:  1972.845 d
 A1:  0.00000000E+00              M. Motion:    0.1823502273  s= 1.8E-06
 A2:  0.00000000E+00              Perih Dist :    0.06623450  s= 4.7E-04
 A3:  0.00000000E+00              Perih Long :   97.38227990  s= 5.4E-01
 AF:  1.11300000E-01              Period (JY):       5.40513  s= 5.3E-05
                                  Perih Time :       0.86129  s= 2.8E-02

This solution has T = 2014 May 17.9 and T = 2008 December 22.6 with previous perihelion times of 2003 July 23 and 1998 February 16.
(results posted to
Sohohunter)

One week later MPEC 2014-K37 appeared with a lot of new measurements from Karl Battam's student T. Kozlowski and this linkage:

Orbital elements:
    P/2008 Y12 = 2014 K3 (SOHO)
Epoch 2009 Jan. 9.0 TT = JDT 2454840.5
T 2008 Dec. 22.56333 TT                                 MPC
q   0.0679228            (2000.0)            P               Q
n   0.18234961     Peri.  144.03072     -0.10962655     -0.94643285
a   3.0798731      Node   310.13666     +0.79364939     +0.10061696
e   0.9779462      Incl.   23.40805     +0.59841679     -0.30682421
P   5.41
From 67 observations 2008 Dec. 21-2014 May 17.

    P/2008 Y12 = 2014 K3 (SOHO)
Epoch 2014 May 23.0 TT = JDT 2456800.5
T 2014 May 17.88582 TT                                  MPC
q   0.0671057            (2000.0)            P               Q
n   0.18272247     Peri.  144.30899     -0.10984942     -0.94530154
a   3.0756818      Node   309.84545     +0.79359461     +0.10264158
e   0.9781819      Incl.   23.58102     +0.59844857     -0.30962833
P   5.39
From 67 observations 2008 Dec. 21-2014 May 17.

The return in 2003 July should have been quite favourable.

The next return around 2019 October 10 was outside the C2 fov.

Update

The comet was recovered by Z. Xu on 2019 August 26 in LASCO C2 images, but the identity got unnoticed because the comet appeared seven weeks earlier than computed from the pure gravitational solution for 2008 Y12 = 2014 K3. In 2023 February I have compared the path of SOHO-3819 in LASCO C2 with the paths of the other non-group comets and found that it was very similar th that of 2008 Y12. My measurements with Astrometrica confirmed that SOHO-3819 has very similar orbital elements as 2008 Y12 and 2014 K3. I could link all three apparitions with A2 = -1.0E-08 with small residuals.

In March 2023 I got Karl Battam's new measurements of the three apparitions. My new linkage has this solution:

 2008/12/22  JD=2454823.2048544   (ref. J2000.0)    File: SOHO1594.POS
  Ecliptic Oscul. Elements               Equat. Pos. & Vel.
 (deg, AU)                                (Gm, km/s)
Itr:  3   Converged              s = 1.4300E-03
 e :    0.97912242                      X0 : -2.97911417E+00  s= 9.96E-04
 i :   23.38388320  s= 1.58E-02          Y0 :  7.65643395E+00  s= 5.60E-04
 w :  145.99361338  s= 3.01E-02          Z0 :  5.20732697E+00  s= 7.31E-04
Nod:  312.87477631  s= 3.07E-02          Vx0: -1.51836130E+02  s= 1.33E-02
 a :    3.10170271  s= 8.34E-06          Vy0: -3.16536888E+00  s= 6.05E-02
 M0:    0.01579972  s= 6.19E-05          Vz0: -6.27495433E+01  s= 3.31E-02
Rj0: -2.88615E-08     Used Observations:   83     Time Span:  3898.676 d
 A1:  1.00000000E-30               M. Motion:    0.1804279524  s= 7.27E-07
 A2: -1.03545812E-08  s= 5.57E-13  Perih Dist :    0.06475604  s= 1.74E-07
 A3:  1.94415939E-07  s= 1.12E-08  Perih Long :   98.86838969  s= 2.97E-02
 AF:  1.11262000E-01               Period (JY):       5.46271  s= 2.20E-05
                                   Perih Time :      -0.08757  s= 3.43E-04

Not included are the HI1-observations from 2008 as they leave large residuals and do not improve the solution.
 Ecliptic  Osculating Elements (J2000.0) at JD 2450719.500000  Date:   1997/09/28:00:00:00.00
Body           e           i          w          Node          q          Tiss        JD-Tp          T0
SOHO1594   0.97935730  22.232200  144.340216  314.571894   0.06664802    1.9060      -0.981790   5.80148680
Tp = 1997/09/28.98

 Ecliptic  Osculating Elements (J2000.0) at JD 2452796.500000  Date:   2003/06/06:00:00:00.00
Body           e           i          w          Node          q          Tiss        JD-Tp          T0
SOHO1594   0.97929701  22.608713  144.973656  313.875454   0.06571397    1.9308      -0.899772   5.65516449
Tp = 2003/06/06.90

 Ecliptic  Osculating Elements (J2000.0) at JD 2454822.500000  Date:   2008/12/22:00:00:00.00
Body           e           i          w          Node          q          Tiss        JD-Tp          T0
SOHO1594   0.97921814  23.399985  146.044047  312.818492   0.06475637    1.9576      -0.617882   5.50053885
Tp = 2008/12/22.62
L/B = 101.1/+12.8

 Ecliptic  Osculating Elements (J2000.0) at JD 2456794.500000  Date:   2014/05/17:00:00:00.00
Body           e           i          w          Node          q          Tiss        JD-Tp          T0
SOHO1594   0.97914796  23.759386  146.610716  312.220089   0.06396661    1.9813      -0.917588   5.37298326
Tp = 2014/05/17.92
L/B = 101.1/+12.8

 Ecliptic  Osculating Elements (J2000.0) at JD 2458720.500000  Date:   2019/08/25:00:00:00.00
Body           e           i          w          Node          q          Tiss        JD-Tp          T0
SOHO1594   0.97871657  24.001452  146.960460  311.877012   0.06430221    2.0076      -0.859769   5.25151294
Tp = 2019/08/25.86
L/B = 101.2/12.8

 Ecliptic  Osculating Elements (J2000.0) at JD 2460605.500000  Date:   2024/10/22:00:00:00.00
Body           e           i          w          Node          q          Tiss        JD-Tp          T0
SOHO1594   0.97803613  24.411401  147.687882  311.192970   0.06537171    2.0349      -0.638514   5.13487222
Tp = 2024/10/22.64
Due to the large nongravs, the computed perihelion times in 1997, 2003 and 2024 may be inexact (if the nongravs have changed).
Taken as they are, the 1997 perihelion was very unfavourable outside the C2 FOV. 2003 looks better, additional images could
be found around 2003 May/June. 2024 looks even worse than 1997 (also outside the C2 FOV).