The discovery of 2003 SU224

Juan Lacruz, 7 Oct 2003

(espaŮol)

 

 

Serendipity

 

On September the 23rd Seiichi Yoshida posted a message to comets-ml with comets awaiting for the first observation, one of them was P/1999 DN3.

 

The next weekend (2003.09.28) I went to the observatory and tried to image the comet starting a series of 40 pictures 60 seconds each. Then I tracked and stacked the frames using Astrometrica. Thatís where serendipity comes into the scene, blinking the stacks I didnít find any trace of the comet but I noticed a, faint, moving object some 8 arc min. off the cometís position.

 

I Thought it could be the comet so did the astrometry and sent the observations to the minor planet center (MPC in short) with the cometís designation. I sent another e-mail to Seiichi asking him to check the observations, the result was that Akimasa Nakamura and Kenji Muraoka did some calculations to confirm that the object was NOT the comet and proposing it could be an asteroid.

 

Was it a new object then?, I needed more observations to try to confirm it, I entered my observations into the new object ephemeris generator service of the MPC to get the predictions for further observations, this service computes an approximate orbit (Všisšlš) based on two or more positions provided by the observer, the predictions are valid up to about three weeks, then the object starts to depart more and more from the predicted position until it gets eventually lost.

 

The confirmation

 

All the week long was raining. Finally, the 2003.10.03, some holes appeared in between the clouds and I started another imaging session, after reduction I blinked the images and saw nothing I thought it could have been just noise in the first images or the object had been lost after a week without follow up.

 

The next day I was analysing at home the latest images, when I noticed a very faint moving object, I did the astrometry to find that the position and movement was in agreement with that predicted by the MPCís ďNew Object Ephemeris GeneratorĒ based on the initial observations. I sent then the additional observations together with these from the first night to MPC under my own temporary designation.

 

 COD J87
OBS J. Lacruz
MEA J. Lacruz
NET UCAC2
TEL SC 0.30 m + CCD
ACK UNIDED 2003.10.03
AC2
juan_lacruz@yahoo.com

 

 

     LC30928  C2003 09 28.02198 23 33 54.54 -08 34 57.8          19.2 R      J87
     LC30928  C2003 09 28.02929 23 33 54.22 -08 34 59.2          19.6 R      J87
     LC30928  C2003 09 28.03660 23 33 54.08 -08 34 59.6          19.6 R      J87
     LC30928  C2003 09 28.04391 23 33 53.48 -08 35 02.0          19.4 R      J87
     LC30928  C2003 10 03.95574 23 29 40.01 -08 48 56.2          19.9 R      J87
     LC30928  C2003 10 03.96306 23 29 39.87 -08 48 56.3          19.5 R      J87
----- end -----

 

 

 

Some days passed and I had no input from the MPC (later on I realized that my e-mail had changed and the feedback was being sent to a no longer valid address), I e-mailed Timothy Spahr at the MPC asking him about the object, he answered that in a first instance he didnít give a designation to the object due to large residuals (errors in the position determination) but he did when he found a couple of additional nights of observations and that the object discovery was credited to J87. The packed provisional designation is K03SM4U.

 

Below is a picture, courtesy of JPL, with the relative positions at the discovery date, click on it to have a dynamical view of the orbit.

 

 

 

Below are the orbital elements after these observations, according to the MPC minor planet ephemeris service. A semimajor axis (a) about 3 together with an eccentricity (e) very low (orbit nearly circular) and a not too high inclination (i) means this asteroid is on the main belt between mars and jupiter.

 

 

2003 SU224

Epoch 2003 Sept. 18.0 TT = JDT 2452900.5††††††††††††††† MPC
M 104.92695††††††††††††† (2000.0)††††††††††† P†††††††††††††† Q
n†† 0.18263485†††† Peri.211.30082†††† -0.48430652†††† +0.87316328
a†† 3.0766655††††† Node††† 29.83611†††† -0.77809142†††† -0.40108249
e†† 0.0647998††††† Incl.††† 6.35542†††† -0.40002617†††† -0.27698143
P†† 5.40†††††††††† H†† 15.2†††††††††† G†† 0.15
From 14 observations 2003 Sept. 16-Oct. 3.
Residuals
200309166440.1-0.0+††† 20030928J872.2+0.2+††† 200309287040.2-0.6+
200309166440.1-0.0+††† 20030928J871.8-1.1-††† 200309287040.2- 0.6+
200309166440.0+0.1-††† 200309287040.3+0.0+††† 200309287040.7+0.7+
200309166440.0+0.1-††† 200309287040.3+0.0+††† 200309287040.7+0.7+
200309166440.0+0.1+††† 200309287040.6+0.5+††† 20031003J871.3-0.4-
200309166440.0+0.1+††† 200309287040.6+0.5+††† 20031003J871.2+0.4+
20030928 *J870.9-0.4-††† 200309287040.1-0.1+
20030928J870.7-0.6-††† 200309287040.1-0.1+

Last observed on 2003 Oct. 3. Ephemeris below based on elements from MPEC 2003-T49.

Further observations? Desirable between 2003 Nov. 13-22.

 

 

Below is the observability chart prepared, using the Lowell observatory online services, after the first observations the nights of 28 Sept and 3 Nov, note the rapidly growing uncertainty reaching beyond 1000 ď (lost?) after a few months,

 

 

According to the Lowell online services, The observation strategy to get the asteroid numbered with a minimum of observations consisted of six, from 2003 Dec 22 to 2014 Sep 30.

 

 

 

After some more days of heavy rain, additional observations were done on the night of October the 23rd and sent to the MPC with the new provisional designation,

 

 

COD J87
OBS J. Lacruz
MEA J. Lacruz
TEL SC 0.30 m + CCD
ACK MBA 2003 SU224

AC2 juan_lacruz@yahoo.com
NET UCAC-2


     K03SM4U  C2003 10 23.80386 23 19 13.37 -09 05 22.9          20.7 R      J87
     K03SM4U  C2003 10 23.81630 23 19 13.02 -09 05 22.2          21.1 R      J87
     K03SM4U  C2003 10 23.82987 23 19 12.81 -09 05 21.5          20.8 R      J87
----- end -----

 

  

 

To reach such a magnitude (about 21 in the red band) I had to track and stack 3 x 20 x 60 sec exposures i.e. one hour integration time.

The next day, observations since April 1996 were linked by the MPC spanning a total of four oppositions (the opposition is when the Earth passes in between the Sun and the Asteroid, itís the best time to view it). Here follows an extract from the MPES service, note that the uncertainty parameter U is equal to 1 meaningsmall uncertainty (in this logarithmic scale 0 is very small uncertainty and 9 is extremely large), according to the current mpc guidelines, in order to get the asteroid numbered and then named, observations at four oppositions(various nights in each) and a value of U less than or equal to 2 are needed.

 2003 SU224

Epoch 2003 Dec. 27.0 TT = JDT 2453000.5†††††††††††††††† MPC
M 122.72639††††††††††††† (2000.0)††††††††††† P†††††††††††††† Q
n†† 0.18270166†††† Peri.210.22066†††† -0.50498010†††† +0.86137045
a†† 3.0759154††††† Node††† 29.55241†††† -0.76785792†††† -0.41916878
e†† 0.0820227††††† Incl.††† 6.41423†††† -0.39419450†††† -0.28694683
P†† 5.39†††††††††† H†† 15.5†††††††††† G†† 0.15†††††††††† U†† 1
From 23 observations at 4 oppositions, 1996-2003, mean residual 0".59.
Residuals
19960413 6910.1-0.1+††† 200309166440.5-0.0†††† 200309287040.1-0.1+
199604136910.4+0.1+††† 200309166440.3-0.1-††† 200309287040.2-0.6+
199604136910.1-0.3+††† 200309166440.3-0.1+††† 200309287040.7+0.7+
199810296910.3-0.0†††† 20030928J870.9-0.4-††† 20031003J87 (3.1-0.5+)
199810296910.1+0.1-††† 20030928J870.6-0.6-††† 20031003J870.6-1.3+
199810296910.1+0.4+††† 20030928J87 (2.3+0.2+)†† 20031023J871.3+0.3-
200103197040.2+0.9+††† 20030928J871.7-1.1-††† 20031023J870.2+0.1+
200103197040.5+0.4+††† 200309287040.4+0.0†††† 20031023J871.4+0.4+
20010319704 (2.6+1.0+)†† 200309287040.6+0.5+

Last observed on 2003 Oct. 23. Perturbed ephemeris below based on elements from MPEC 2003-U57.

Further observations? Very desirable between 2003 Nov. 22-Dec. 22.

 

 

After the observations on the night of 23 October when it was linked to observations in 1986 the Uncertainty reduced dramatically to about 1Ē or less over many years on, anyhow the orbit didnít change that much.

 

 

The resulting strategy to get the asteroid numbered, according to Lowell asteroid services didnít prompt for any observations needed.

 

 

 

Skymorph

 

On November the 1st I was using Skymorph, a service of the Laboratory for High Energy Astrophysics (LHEA) at NASA/ GSFC, to obtain images of the asteroid by the NEAT project, I was lucky to find a triplet of images (2001.03.26) by the AMOS telescope at Haleakala, Hawaii. I did the astrometry and sent it to MPC, note the COD 608 meaning NEAT/Haleakala and MEAsurer J. Lacruz

 

 

COD 608
MEA J. Lacruz
ACK MBA 2003 SU224 2001.03.26 (608)
AC2 http://mail.yahoo.com/config/login?/ym/Compose?To=juan_lacruz@yahoo.com
NET USNO-B1.0


     K03SM4U  C2001 03 26.36747 11 06 15.74 +12 12 25.7          19.6 R      608
     K03SM4U  C2001 03 26.37872 11 06 15.23 +12 12 27.0          20.2 R      608
     K03SM4U  C2001 03 26.38895 11 06 14.79 +12 12 28.0          19.8 R      608
----- end -----

 

 

The observations were included that night, as a result the mpes returned the residuals of the new observations and a refined orbit, not very different from the previous one.

 

2003 SU224

Epoch 2003 Dec. 27.0 TT = JDT 2453000.5†††††††††††††††† MPC
M 122.72635††††††††††††† (2000.0)††††††† ††††P†††††††††††††† Q
n†† 0.18270167†††† Peri.210.22075†††† -0.50497935†††† +0.86137088
a†† 3.0759153††††† Node††† 29.55237†††† -0.76785818†††† -0.41916798
e†† 0.0820226††††† Incl.††† 6.41425†††† -0.39419496†††† -0.28694671
P†† 5.39†††††††††† H†† 15.5†† ††††††††G†† 0.15†††††††††† U†† 1
From 26 observations at 4 oppositions, 1996-2003, mean residual 0".56.
Residuals
199604136910.1-0.1+††† 200103266080.0†† 0.2+††† 20030928704 0.6+0.5+
199604136910.4+0.1+††† 200103266080.3+0.1+††† 200309287040.1-0.2+
199604136910.1-0.3+††† 200309166440.5-0.1+††† 200309287040.2-0.6+
199810296910.3-0.0†††† 200309166440.4-0.1-††† 200309287040.7+0.7+
199810296910.1+0.1-††† 200309166440.4-0.1+††† 20031003J87 (3.1-0.5+)
199810296910.1+0.4+††† 20030928J870.9-0.3-††† 20031003J870.6-1.3+
200103197040.1+0.9+††† 20030928J870.7-0.6-††† 20031023J871.3+0.3-
200103197040.4+0.4+††† 20030928J87 (2.2+0.2+)†† 20031023J870.1+0.1+
20010319704 (2.5+1.0+)†† 20030928J871.7-1.0-††† 20031023J871.4+0.5+
200103266080.2+0.2+††† 200309287040.4+0.1+

Last observed on 2003 Oct. 23. Perturbed ephemeris below based on elements from MPEC 2003-V02.

Further observations? Very desirable between 2003 Nov. 22-Dec. 22.

 

 
 
 

The night of November the 17th the sky was quite clear and there was an interesting object in the NEOCP list (this resulted to be new comet C/2003 W1) I had to expose 90x60 sec pictures to get two stacks with the object barely discernible at an acceptable signal to noise ratio,

 

COD J87
OBS J. Lacruz
MEA J. Lacruz
TEL SC 0.30 m + CCD
ACK MBA K03SM4U

AC2 juan_lacruz@yahoo.com
NET UCAC-2

  

   K03SM4U  C2003 11 17.84220 23 17 02.79 -08 15 06.7          20.7 R      J87
     K03SM4U  C2003 11 17.86970 23 17 03.02 -08 15 01.9          20.5 R      J87
----- end -----

 

 

I was lucky to find more positions in NEAT images available from SkyMorph

 

 

COD 566
MEA J. Lacruz

ACK MBA 2003 SU224
AC2 http://us.f212.mail.yahoo.com/ym/Compose?To=juan_lacruz@telefonica.net

NET USNO-A2.0


     K03SM4U  C1996 03 24.34867 13 46 48.60 -09 17 55.0          20.6 R      566
----- end -----

 

 

COD 608
MEA J. Lacruz
ACK MBA 2003 SU224 2001.03.26 (608)
AC2 http://mail.yahoo.com/config/login?/ym/Compose?To=juan_lacruz@yahoo.com
NET USNO-B1.0


     K03SM4U  C2001 03 26.36747 11 06 15.74 +12 12 25.7          19.6 R      608
     K03SM4U  C2001 03 26.37872 11 06 15.23 +12 12 27.0          20.2 R      608
     K03SM4U  C2001 03 26.38895 11 06 14.79 +12 12 28.0          19.8 R      608
----- end -----

 

And some others were obtained by measuring trails in DSS (Digital Sky Survey) plates

 

COD 260

MEA R. Stoss

NET USNO-B1.0

ACK K03SM4U 260

AC2 rstoss@hrz1.hrz.tu-darmstadt.de

COM Trail very faint, segmented and ends not well defined

†††† K03SM4U†† 1996 04 21.55707 13 24 53.99 -08 11 09.8 260

†††† K03SM4U†† 1996 04 21.60915 13 24 51.40 -08 11 01.8 260

 

 

COD 261

MEA R. Stoss

NET USNO-B1.0

ACK K03SM4U 261

AC2 rstoss@hrz1.hrz.tu-darmstadt.de

COM Trail quite faint and ends not well defined

†††† K03SM4U†† 1993 11 09.27292 03 06 19.57 +20 36 49.7 261

†††† K03SM4U†† 1993 11 09.30070 03 06 18.13 +20 36 46.5 261

 

Now the asteroid is a five oppositions object, further observation is not needed at the moment.

 

2003 SU224

Epoch 2003 Dec. 27.0 TT = JDT 2453000.5†††††††††††††††† MPC
M 122.72734††††††††††††† (2000.0)††††††††††† P†††††††††††††† Q
n†† 0.18270167†††† Peri.210.22066†††† -0.50499417†††† +0.86136221
a†† 3.0759153††††† Node††† 29.55148†††† -0.76784973†††† -0.41918048
e†† 0.0820232††††† Incl.††† 6.41439†††† -0.39419244†††† -0.28695446
P†† 5.39†††††††††† H†† 15.5†††††††††† G†† 0.15†††††††††† U†† 1
From 33 observations at 5 oppositions, 1993-2003, mean residual 0".66.
Residuals
199311096750.9-0.6+††† 200103197040.3+0.3+††† 200309287040.3+0.0
199311096750.2-0.6+††† 20010319704 (2.4+0.9+)†† 200309287040.5+0.5+
199603245660.0†† 1.1-††† 200103266080.2+0.1+††† 200309287040.2-0.1+
199604136910.5-0.8+††† 200103266080.0†† 0.1+††† 200309287040.3-0.6+
199604136910.0†† 0.9+††† 200103266080.2+0.0†††† 200309287040.6+0.6+
199604136910.5-1.1+††† 200309166440.6-0.0†††† 20031003J87 (3.2-0.4+)
199604214130.9+0.1-††† 200309166440.5-0.1-††† 20031003J870.7-1.2+
199604214131.2+0.1+††† 200309166440.5-0.1+††† 20031023J871.3+0.4-
199810296910.1+0.3-††† 20030928J871.0-0.4-††† 20031023 J870.1+0.0
199810296910.6+0.3-††† 20030928J870.7-0.6-††† 20031023J871.4+0.4+
199810296910.6+0.2+††† 20030928J87 (2.1+0.1+)†† 20031117J870.4+1.7+
200103197040.0†† 0.8+††† 20030928J871.8-1.1-††† 20031117J87 0.2+0.8+

Last observed on 2003 Nov. 17. Perturbed ephemeris below based on elements from MPEC 2003-X29.

Further observations? None needed at this opposition.

 

 

 

 

 

 

 

 

 


The current uncertainty is below one arc second for the next ten years

 

The Numbering

 

One year passed and the asteroid was observable again, I did further observations, Rafael Ferrando from observatory Pla díArguines was able to image it as well, with the astrometry at a new opposition, the new minor planet was officially numbered by the MPC on the 2004 October the 27th batch.

 

Conclusions:

 

International collaborative effort over the internet is key point.

 

It is very remarkable how a telescope just 30 cm in diameter is able to capture a magnitude about 21 asteroid by stacking frames with the appropriate software.

 

Recovering positions by carefully inspecting archived images accelerates the process of getting the orbit secure for possible numbering.

 

According to MPC the size of this asteroid given H=15.5 and albedo 0.05 < a < 0.25 should be between 2 and 5 km.

 

Akcnowledgements :

MPC Minor Planet Center

Minor Planet Ephemeris Service has been made possible by Process Software Corporation, and their excellent VMS Web server, Purveyor. These calculations have been performed on the Tamkin Foundation Computing Network.

The Lowell Observatory

†††††††††† ††† Asteroid observability charts and asteroid observing strategy plans thanks to the Lowell Observatory Asteroid Services.

JPL

†††††††††††††† Chart with relative positions at the moment of discovery

†††††††††††† Horizons system

 

NASA/NEAT

 

†††††††††††††† Skymorph system http://skys.gsfc.nasa.gov/skymorph/skymorph.html

†††††††††††††† ††††††††††††††

References :

†††††††††††††† Details at AstDys

†††††††††††††† Guide to Minor Body Astrometry

†††††††††††††† Minor Planet Ephemeris Service

†††††††††††††† Using SkyMorph