Solwind-10 Images

I have found a small non-group comet in Solwind images of 1984 September 15/16.

It's well visible in 16 full frame images from Sep 15 05:52:27 to Sep 16 08:50:57 UTC
and two partial frames at Sep 15 07:37:21 and 07:40:15.

From top to bottom: Sep 15 05:52:27, 07:37:21, 07:40:15, 08:55:05, 08:59:59, 09:04:52, 17:06:56, 17:11:49, 18:42:43, 18:47:36,
Sep 16 04:07:32, 04:12:25, 04:17:19, 04:22:12, 07:26:20, 07:31:13, 08:46:04, 08:50:57 UTC.


15 images stacked and aligned on one of the hot spots.

I have measured rough R.A. and Decl:

Time (Sep 15/16) comet x comet y hot spot x hot spot y dx dy new x new y R.A. 2000.0 Decl 2000.0
05:52:27 482 140 491 356 +2 -2 484 138 11 29.4 +04 14
07:37:21 455 137 494 353 -1 +1 454 138 11 30.4 +04 14
08:55:05 431 143 488 359 +5 -5 436 138 11 31.1 +04 13
08:59:59 428 140 490 357 +3 -3 431 137 11 31.2 +04 14
09:04:52 431 140 491 356 +2 -2 433 138 11 31.2 +04 13
17:06:56 298 140 494 353 -1 +1 297 141 11 35.9 +04 11
17:11:49 299 140 496 354 -3 0 296 140 11 35.9 +04 11
18:42:43 273 140 494 353 -1 +1 272 141 11 36.8 +04 11
18:47:36 272 140 495 353 -2 +1 270 141 11 36.9 +04 11
04:07:32 102 147 491 356 +2 -2 104 145 11 42.6 +04 08
04:12:25 104 146 494 353 -1 +1 103 147 11 42.6 +04 07
04:17:19 104 144 496 353 -3 +1 101 145 11 42.7 +04 08
04:22:12 105 146 497 355 -4 -1 101 145 11 42.7 +04 08
07:26:20 44 149 495 354 -2 0 42 149 11 44.7 +04 06
07:31:13 44 148 497 355 -4 -1 40 147 11 44.7 +04 07
08:46:04 11 155 488 359 +5 -5 16 150 11 45.5 +04 06
08:50:57 10 152 491 357 +2 -3 12 149 11 45.7 +04 06

The images were enlarged three times and measured to th nearest pixel. The comet's x,y are measured from the upper left corner of the images (with the pylon on the left side of the images). The measurements of the hot spot are used to compensate for the image shift.
I have used a position angle of celestial north of 7.1 degree and a plate scale of 70.2 arcseconds per pixel (as before) and the suncenter at 118,122 to match the positions of beta Vir in images of 1984 September 20.

Rainer Kracht 2005 July 30

With FindOrb (Bill Gray, www.projectpluto.com) I have derived these orbital elements:

Orbital elements:
Cxxxxxx
   Perihelion 1984 Sep 17.430670 TT
Epoch 2001 Aug 19.0 TT = JDT 2452140.5                  Kracht
q   0.115757             (2000.0)            P               Q
                   Peri.   72.78440     -0.61496609     -0.74259591     
                   Node   153.04165     -0.73268091      0.66246369     
e   1.0007803      Incl.   35.81300      0.29153966      0.09845382     
From 16 observations 1984 Sep. 15-16;   RMS error 62.663 arcseconds


840915 029 83.1+ 43.9+    840915 029 75.0- 30.3-    840916 029 39.5- 15.5+ 
840915 029 66.2+ 53.6+    840915 029 82.5-  7.6-    840916 029 78.7+ 15.4- 
840915 029 14.4+  2.3+    840915 029 36.7-  6.3-    840916 029 34.2+ 47.1+ 
840915 029 61.3+ 62.9+    840916 029  4.2+  9.0+    840916 029 70.8+ 27.4+ 
840915 029 18.5+  3.5+    840916 029 40.2- 48.8-    840916 029( 206+ 30.1+)
840915 029 31.3- 31.4-    840916 029  4.9+ 13.4+    

Station data:
(029) Hamburg-Bergedorf  (N53.4797 E10.2406).

Rainer Kracht 2005 August 02

With these orbital elements the absolute magnitude H10 of the comet was close to mag 12.4.
It could have been visible in the southern evening sky in 1984 October.

Rainer Kracht 2005 August 03

The comet was announced as C/1984 R1 on IAUC 8583 with these orbital elements:

The following parabolic orbital elements are by B. G. Marsden. The comet seems not to belong to a known group.

T = 1984 Sept.17.42 TT      Peri. =  78.74
                            Node  = 152.84    2000.0
q = 0.1051 AU               Incl. =  36.92

With these orbital elements the absolute magnitude H10 of the comet was close to mag 12.8.

Rainer Kracht 2005 August 13