Trans-Neptunian Objects (TNOs) and Centaurs
The Trans-Neptunian objects are the small Solar System bodies orbiting beyond Neptune, between 30 and 50AU far from the Sun. They form the Kuiper Belt. A large fraction of them has been discovered by D. Jewitt and his colleagues using UH8k on the 2.2-m of University of Hawaii close to the CFHT. A very nice site on the Kuiper belt has been prepared by Joel Parker at the Southwest Research Institute in Boulder, Colorado. If you are interested in the TNOs, you should definitely visit it!
The search for TNOs is done using wide field imaging. The larger is the field observed, the more likely is the discovery of a TNO. As the TNOs are faint objects (most of them fainter than 22), you need also a large aperture! UH8k, with its large field, was certainly a good detector for this search, and CFH12k on the 3.6-m CFHT is a still better instrument, waiting for the new generation wide-field camera (as MegaCam on MegaPrime).
Once they are discovered, and followed on a short period of time after their discovery, they need to be observed at their next opposition in order to allow a better orbit determination. A very large field is no longer needed, as the rough orbit computed on the short arc around the discovery is good enough for recovering them one year later. MOS in imaging mode is then an ideal combination, able to reach in 10 to 15 minutes mg=24 with a 8' field. Wide-field imaging is still good too, even if at that time only a small part of the field is really used. One can still examine the whole field searching for new TNOs, and get all the more classical asteroids in the field!
The recovery of TNO's started with MOS in 1997, and for some time used
only D-Time. A first normal run was scheduled in May 1998, and allowed
the observations of 5 other TNO's. Another one was scheduled in December
1998, but took place in October due to programming changes in the observation
schedule at CFHT... Then other runs were scheduled following the changing
moods of the TAC's, with additional observations made from time to time
using Discretionary Time...
2001 Observations - D time with CFH12K
Processing of December images (00BF52)
February 3-4, 2001
2000 CK105, 2000 CL105
January 1, 2001
This run, with A. Doressoundiram, was scheduled for four nights on Dec. 20-24, 2000. Its main purpose was the multi-color photometry of a ser of selected TNO's, with a fraction of the observing time devoted to TNO recovery. Six TNO's were recovered, (two of them two years after their discovery), and one new TNO was doscovered and confirmed later on D time.
2000 CL104, 2000 CE105, 2000
CG105, 2000 CM105
This run, with A. Doressoundiram, was scheduled for four nights in two differents runs (on May 24-25 and June ). Its main purpose was the multi-color photometry of a ser of selected TNO's, with a fraction of the observing time devoted to TNO and NEO recovery. Two TNO's were recovered on the first run (with some time taken on another program) and three more on the second one.
|December 28-31, 1999
Nearly an hour of observation has been devoted to TNO revovery at the end of eacht these three nights. High wind caused strongly elongated images on a couple of nights. Six TNOs have been recovered though... 1999 CL119, 1999 CN119, 1999 CX131 MPEC circular is here , and 1999 CV118, 1999 CF119, 1999 CG119 MPEC circular is here.
1999 CF119, 1999 CG119
While CF1999 had been observed over three months (February to May), CG119 had been observed only in February and two nights in April. They were both on a same image of CFH12K, CF119 at around 45" from its predicted position and CG119 at more than 3' .
Observed for at least once per month over three months (February to April), CL119 was an easy target (R<23), found roughly 1' from its predicted position.
1999 CN119, 1999 CX131
CX131 had been observed prior to its recovery as CL119 . CX131 however had been observed only on two nights (Feb 11 and 18, 1999). They were bot recovered on the same CFH12K image at nearly 1' from their predicted position.
|October 6 & 9, 1999
An hour of D time over two nights allowed the recovery of three TNOs, in spite of a very poor weather the second night...
US43 has been observed for two months back in November1998/January 1999. It has been recovered at one minute of arc from its predicted position. Go here for the US43 circular.
Observed on only 9 days in November 1998, this TNO has been recovered at one minute of arc from its predicted position. Go here for the WA25 circular.
|July 10-12, 1999
1998 KR65 - 1998 KS65
This Centaur has been recovered for its second opposition on two pairs of frames on July 11 and 12. The corresponding MPEC is here.
This two nights run hasn't been very successful due to a poor weather for the first night...
Discovered in May of this year and observed on an arc only 40 days long, KG62 has been reobserved using a pair of images taken on the first and second night of the run. The arc available now is 150 days long. Positions are here.
? Yes! (1998
What is probably SZ10 has been observed on the second night of the run on five exposures covering 4.3 hours. Nothing has been found on a 10' diameter field centered on the predicted position. Adjacent fields East and West have been also imaged and one of them gave a moving object with the SZ10 rate. Go here for the positions.
It was SZ10... You can view the MPEC here... It seems to be the first TNO in 1:2 mean-motion resonance with Neptune.
|A new TNO, or 1997 TX8 ?...
Trying to recover 1997 TX8, we found a moving object not far from the TX8 predicted position. It has been followed for the two nights of the run. The measured positions don't fit very well with the 1997 observations of 1997 TX8. We hope that additional observations will be made at another place to check the nature of what is called for the moment CFH500. If you want to play with the positions, you will find them here...
- 1998 KS65
Discovered in May
and only observed for the last ten days of May, 1998 KR65 and KS65 are
close to each other for the moment. Three positions of each of them have
been obtained using Telescope Control System Engineering time on Aug.14.
The available arc jumped from 10 to 86 days, and the recovery at the next
opposition shouldn't be a problem.
- KR65 is in the lower left box, KS65 in the other one.
This bright TNO has been observed for one more opposition..., only on one night. Positions are here.
Discovered in 1994, and not observed since 1995, 1994 ES has been seen for the three consecutive nights of the run. Its position can be found here.
In spite of many efforts, 1996KV1 has not been found at its 1997 opposition. It has been found again in a very crowded field, far from its predicted position by more than 6'. Positions and new orbital elements are here.
These are the first second opposition of this object, observed at high air-mass and with a thin layer of cirrus. Positions and new orbital elements are here.
These are the first second opposition observations of this object.
Seen only one night, its identification could have been wrong... Unfortunately,
these observations have not been included for generating a new orbit at
MPC after two nights of observations one month later by Jewitt et al. (MPEC
The first TNO to be recovered in this program. Only one night of observations (not enough for a new orbit to be publiched in an MPC), but the demonstration of the feasibility of the program.
This 23.5mg TNOs has been discovered in Spet 1996, and reobserved for a few days in November. It is the first really recovered with more than one night of observation with MOS at CFHT. The corresponding positions and orbit determination by Gareth V. Williams at MPC can be found here .
With a V magniotude of 22.7, 1997CQ29 has been discovered and observed for two months in February and March 1997, it has been recovered, together with the next two objects of this list, on consecutive hal D-nights in February 1998. Positions and subsequent orbit by Gareth V. Williams can be found here here
With magnitude and first opposition observations similar to CQ29,
1997CR29 has been found in the MOS field centered on its predicted position.
Positions and subsequent orbit by Gareth V. Williams can be found here.
The last in the series of 1997 discovered objects, CV29 is slightly
fainter than the two previous ones. The positions and the orbit computed
by Brian G. Marsden can be found here.
This object is librating about the 4:7 mean-motion resonance with Neptune,
the minimum distance from Neptune within 7000 years of the present being
More to come later... Visit us again!Christian Veillet - CFHT