Make your own free website on Tripod.com

1999 RB35 = 20517


The evening of Friday, September 10-11, 1999 started off a little cloudy but I opened up the Sunflower Observatory in the backyard anyway hoping it would clear off. I was going to run Frank B Zoltowski's program, CCDTRACK for the first time.

Mark Abraham joined me to get some time learning the ropes before his new LX200 arrived for his Everstar Observatory. He also helped me to get my network installed in the control room of Sunflower Observatory. First we imaged a few of the recently discovered near earth asteroids, including C79312 and C79317 which we were able to help confirm and were listed the next day on the Minor Planet Circulars as these objects achieved the designations 1999RB32 and 1999RD32. Then we decided to run CCDTRACK and image galaxies starting with Scheat, the bright corner star in Pegasus as our first alignment star. We purposely wrote the script to take 120 second images of three galaxies in a row before returning to our alignment star and then repeat this sequence three times. This way we would have a series of three images of each galaxy and its surrounding area spaced about ten minutes apart. This would allow us to blink the images and look for moving objects like comets or asteroids. In addition we could add the three images together and get a nice six minute deep sky photo of the galaxy. By imaging the same area about every two weeks we could then compare two images of the same galaxy to see if any supernova had developed. This system would allow us to see asteroids, comets and supernova and perhaps even variable stars.

The first three galaxies in the script were NGC 7487, UGC 12352, and CGCG 475-39. It took us awhile to master the program and we ended up repeating the script four times! However, we saved every image. This would prove to be a wise decision later. We finally got the script running and took our final series of images.

It was the next morning after fours of sleep that I blinked the images of the galaxies and found the moving object. It was in the images of CGCG 475-39. Using Computer Aided Astrometry, I was able to get seven good positional measurements from the many images we had taken the night before.

Knowing that we needed two nights of observations I was a little worried by the cloud bank moving in as the sun set. Mark came over again and after several hours of clouds we finally got a break and were able to get many more images of the object finding it the first time slightly behind where the New Object Orbit Generator web page of the Minor Center had computed it to be.

I immediately did the reductions and turned the measurements in as SF9001. The next day, Sunday, September 12, the minor planet center assigned it designation 1999RB35. However, it would be another day before the official circular was released and there was still a chance the object could be linked to a previous discovery.

I imaged it again Sunday night and turned those positions in to the MPC and got to bed a little earlier.

Monday Mark's LX200 came and I went over to his house and helped him get it polar aligned and set up with his camera and we took many asteroid pictures. I left him slewing and snapping image after image of bright asteroids.

On Monday night I reacquired 1999RB35 and got a fourth night of observations and turned those in to the Minor Planet Center. I ran the CCDTRACK script again after adding more galaxies to the list getting it up to two hours of continuous automated operation. I slept on the couch nearby, while it ran for the next two hours in automatic mode. I got up at 430 to turn it off and take some pictures of the horse head nebula in automatic mode while I blinked the galaxy images. Nothing new this time. Another two hours of sleep and then off to work.

During the day, Monday, September 13, 1999 the MPC published Minor Planet Circular 1999-R40 and there at the very end of the list of New One-opposition orbits was J99R35B, which is shorthand for 1999RB35. It had not been linked!

I guess it always could be linked sometime in the future, but it is not as likely as some since 1999RB35 is in an orbit inclined 20 degrees from the solar system and just past the orbit of Mars. It will be visible and bright enough to follow for several months. If others and I can keep track of it we may someday define its orbit well enough to get it officially named and numbered. With four days of arc the orbit is now fairly good for the next month and will get better with more observations. It will stay in Pegasus for the next several months as it appears to loop back through the great square ending up in front of the beehive cluster, M44 in September 2000.

1999RB35 current orbital elements and ephimerides from the MPC:

1999 RB35

Epoch 1999 Aug. 30.0 TT = JDT 2451420.5 Williams
M 285.79818 (2000.0) P Q
n 0.21938439 Peri. 169.23174 -0.12165551 -0.93218663
a 2.7226944 Node 287.07842 +0.88210686 +0.05593499
e 0.2441590 Incl. 20.89456 +0.45506859 -0.35763022
P 4.49 H 14.8 G 0.15

From 13 observations 1999 Sept. 11-13.

Last observed on 1999 Sept. 13. Elements from MPEC 1999-R40.

J99R35B Date TT R.A. (J2000) Decl. Delta r El. Ph. V Motion Object Sun
"/min "/min Azi. Alt. Alt.
1999 09 14 00 23 04.98 +27 37.9 1.754 2.663 148.3 11.5 18.9 -0.65 -0.04 249 +18 +5
1999 09 15 00 23 03.94 +27 36.6 1.750 2.660 148.5 11.4 18.8 -0.65 -0.05 249 +19 +5
1999 09 16 00 23 02.91 +27 35.1 1.747 2.658 148.7 11.3 18.8 -0.65 -0.06 250 +20 +5
1999 09 17 00 23 01.87 +27 33.2 1.744 2.655 148.8 11.3 18.8 -0.65 -0.08 251 +21 +4
1999 09 18 00 23 00.84 +27 31.0 1.741 2.653 148.9 11.3 18.8 -0.64 -0.09 251 +22 +4
1999 09 19 00 22 59.81 +27 28.5 1.738 2.650 148.9 11.3 18.8 -0.64 -0.10 252 +22 +4
1999 09 20 00 22 58.79 +27 25.7 1.736 2.647 148.9 11.3 18.8 -0.64 -0.11 253 +23 +3
1999 09 21 00 22 57.78 +27 22.6 1.734 2.645 148.9 11.3 18.8 -0.63 -0.13 253 +24 +3
1999 09 22 00 22 56.78 +27 19.3 1.732 2.642 148.8 11.3 18.8 -0.63 -0.14 254 +25 +3
1999 09 23 00 22 55.78 +27 15.6 1.730 2.640 148.7 11.4 18.8 -0.62 -0.15 255 +26 +2
1999 09 24 00 22 54.80 +27 11.7 1.728 2.637 148.6 11.4 18.8 -0.62 -0.16 256 +27 +2
1999 09 25 00 22 53.82 +27 07.5 1.727 2.634 148.4 11.5 18.8 -0.61 -0.17 256 +28 +2
1999 09 26 00 22 52.86 +27 03.1 1.726 2.632 148.2 11.6 18.8 -0.60 -0.18 257 +29 +1
1999 09 27 00 22 51.91 +26 58.3 1.725 2.629 147.9 11.7 18.8 -0.59 -0.19 258 +30 +1
1999 09 28 00 22 50.98 +26 53.4 1.725 2.627 147.6 11.8 18.8 -0.58 -0.20 258 +30 +1
1999 09 29 00 22 50.07 +26 48.2 1.725 2.624 147.3 11.9 18.8 -0.57 -0.21 259 +31 +1
1999 09 30 00 22 49.17 +26 42.7 1.724 2.621 146.9 12.0 18.8 -0.56 -0.22 260 +32 +0
1999 10 01 00 22 48.28 +26 37.1 1.725 2.619 146.5 12.2 18.8 -0.55 -0.23 261 +33 +0
1999 10 02 00 22 47.42 +26 31.2 1.725 2.616 146.1 12.3 18.8 -0.54 -0.24 261 +34 +0
1999 10 03 00 22 46.58 +26 25.1 1.726 2.613 145.6 12.5 18.8 -0.53 -0.25 262 +35 -1
1999 10 04 00 22 45.75 +26 18.8 1.726 2.611 145.2 12.6 18.8 -0.52 -0.26 263 +36 -1

Here is what Petr Pravec had to say about 1999RB35:

Date: Tue, 14 Sep 1999 23:32:52 +0200 (MET DST)
From: Petr Pravec
To: Larry
Subject: Re: 1999RB35

Larry,

Yes, your object has higher inclination than average, but not extremely unusual. I have not a related literature here at the telescope (I'm observing now), thus I will write only about my personal experience from observations here at Ondrejov.

Among our ca 250 discoveries with good orbits, only five of them have greater inclinations, in the range 21-26 deg. It is 1 out of 50 objects. But our sample is biased against high inclination objects (due to the fact that we do most observations close to the ecliptic where higher inclination object spend lesser time). The true fraction of objects with i>20 deg may be a few times higher, perhaps 1 out of 10. If I remember well, the mean (debiased) inclination of MBAs is something like 10 degrees or a little bit more, thus a 21-deg inclination object like yours is not extremely unusual. An interesting thing is that you have found it close to its most distant (from the ecliptic plane) point at cca 30 deg ecliptic latitude (which is greater than the inclination due to the projection --- you have observed it from the Earth and not from the Sun).

I will look into literature tomorrow and will let you know if there is something further interesting to add.

Congratulations to your somewhat unusual discovery! You had only about 2% chance that your first one will have so high declination, and you got it. A piece of luck and fun for you, I believe.

Petr

Here is what Brian Warner had to say about 1999RB35:

Larry,

Congratulations on 1999 RB35. That is an interesting orbit. Taking a look at a couple of different sources, those that plot AU vs. inclination, there is no real group or family with that combination of 2.7 AU and 20 inclination. In fact, there is a pronounced *decrease* in the number of objects starting near 2.7 AU, reaching a minimum at 2.85 AU.

Checking in Asteroids I and an article by Kozai, the closest family is one with an AU 2.722-2.785 *but* an inclination around 15d. The lead member is 387 Aquitania. The Phocaea group has about the same inclination but is centered on slightly less than 2.5 AU. My best guess is that RB35 is an asteroid in transition, possibly a former or future member of one of these two groups (or another).

Good luck with following your asteroid. I hope more are to follow.

Clear Skies, Brian Warner

Orbit


This is the orbit of 1999 RB35



Update November 2000

On October 7, 2000 LONEOS found 1999 RB35 again on the current opposition just west of the Beehive cluster. This was followed by LINEAR picking it up on November 20. I found it then on November 21 and 23. Meanwhile, Reiner Stoss in Germany went back through some old Polamar plates and found it on plates from July 1990. This was followed by a link to a one night observation by Observatory Code 413 on May 29, 1976. This means that 1999 RB35 now has 4 oppositions and is getting closer to being numbered and named.



Update January 2001

In late December of 2000, 1999 RB35 was picked up again this time by LONEOS. Sunflower found it also and then LINEAR picked it up a couple of times. This was the fifth opposition. On January 10, 2001 1999 RB35 was numbered. It is now numbered asteroid 20517. A name has been submitted and when approved it will be posted here.