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.