1997 DP 1997 GY3 1997 LD4 1997 PD2
UT Discovery Date: 06:58:00 UT February 16, 1997 (confirmed on March 3-4 UT, 1997)
Our Initial Designation: FBAC18
Discoverers: Bill Dillon, John Harrison, Dennis Borgman, Keith Rivich
Our Astrometry
Orbital Elements
Next Opposition:
Comments: We discovered this asteroid on the night of February 15-16. On the night of February 16-17, Dennis, Keith, and Randy went out to the George to confirm the discovery. Unfortunately, I had computed predicted positions using our calendar dates, and not UT calendar dates, and my fellow team members ended up imaging "tomorrows" position. After that, the weather turned bad and waxing moonlight put an end to further recovery attempts.
I was hopefull that we would be able to recover the asteroid , as we discovered the asteroid near opposition, our astrometry was good to half an arcsecond, and we had a two hour track. On the night of March 2-3, we recovered the asteroid about two arcminutes east of it's predicted position. Successfully extrapolating a two-hour arc 15 days into the future is a record for us (previous record was extrapolating VA3's position a week into the future from a 45 or so minute arc).
The asteroid is fading fast, perhaps part of an opposition effect. Hopefully we'll be able to add a few more weeks of arc length to it's path.
Epilog: This asteroid was recovered by someone in early September, 2000, for its second opposition.
UT Discovery Date: 04:35:00 UT April 7, 1997 (possibly on April 6 UT)
Our Initial Designation: FBAC21
Discoverers: Dennis Borgman, Bill Dillon, Keith Rivich, Frances Smith
Our Astrometry
Orbital Elements
Next Opposition:
Next Opposition Ephemeris
Comments: Frances and I observed a moving object on April 6(UT). It was given the preliminary designation FBAC20. The next night, Dennis, K2, and Frances went out to confirm the discovery. They found an asteroid, but it seemed a bit far from the predicted position (~1.5 arcminutes), and it did not backtrack well to the April 6 position. We called the April 7 object FBAC21.
Then we found a CDT->UT conversion problem (that was the weekend change to Daylight savings time), and FBAC21 could be backtracked to FBAC20's position. However, there was still a bust in going from FBAC20 to FBAC21'sposition, and my linear spacetime fit showed large (~2.5 arcseconds), systematic residuals in the FBAC20 positions when fitting both nights.
I asked Dan Kaiser and Paul Comba for help, providing them with Vaisala predictions just based on the April 7 data (which had the highest quality). Paul Comba had clear skies on April 9 UT, and was able to image FBAC21 near it's predicted position. I sent our combined data into the MPC (excluding the April 6 data, which we need analyze further.
Paul Comba observed it again while tracking one of his own discoveries on D-Day +5 and we recovered it after the bight-moon on April 28-29 at magnitude 20 plus! Dennis was able to fit an orbit with small residuals to all the known data. K2 did a super job of astrometry, and I also did the linear spacetime fit and delta O-C to be sure we had it.
Unfortunetly, we captured this asteroid under near optimal conditions. Unless we get really good at tracking along a predicted orbit while imaging, the next opposition will be too faint. The next opposition after that around Christmas of 1999, the magnitude will be 20.6 (opposition the summer of 2001 will be a mag +21). It may be a while before we see our friend again!
UT Discovery Date: 04:13 UT June 4, 1997
Our Initial Designation: FBAC22
Discoverers: Randy Pepper, Jennifer Sutton, Bill Dillon
Our Astrometry
Orbital Elements
Next Opposition: July 17, 2001 (Mag 21.2, ouch!)
Comments: Randy and Jennifer shot the discovery images, but didn't have time to process them. I blinked their images and found a moving object. It was interesting that the asteroid's motion appeared highly inclined to the ecliptic. Follow up was a problem because clouds settled in. I contacted Paul Comba in Arizona for his help, but he was clouded in too.
On June 7 (UT), Paul was able to get one good astrometric point. I computed a Vaisala ephemeris based on all our data. On June 10 (UT), Randy and Frances were able to recover the asteroid, and shoot two good images. Dennis fit an orbit to all the data, showing that the residuals were quite small, and I sent the observations off to the MPC.
Our preliminary orbit shows a very high inclination (almost 28 degrees!). This asteroid appears to be in a 3:1 resonance with Jupiter, which could account explain the odd orbit.
Epilog: On 15 November, 2000, DOU-V39 announced that LD4 had been linked with 1999 XA136, and we kept primary designation! This was our 14th multi-oppositional asteroid. Of our 35 designated asteroids to date, it has the highest orbital inclination (about 25 degrees). Its peroid is closer to a 10:3 ratio with Jupiter.
UT Discovery Date: 03:22:30 August 6 (UT), 1997
Our Initial Designation: FBAC23
Discoverers: Bill Dillon, Randy Pepper
Our Astrometry
Orbital Elements
Next Opposition:
Comments: Randy and I found this asteroid using a telecompressor (Celestron f6.3) for the first time. Had we not used it, we might have missed the asteroid.
This asteroid is the brightest of our 1997 discoveries (so far!), at magnitude 18.5. We should be able to following this guy another month.
We made the confirmation observations on August 9 (UT), shooting the asteroid between breaks in high-altitude cirrus. The magnitude on the second night was 18.3.
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