Asteroid "86279 Brucegary (1999 UJ1)" Photometric Observations for 2015
B. L. Gary, Last updated 2015.11.02

This web page is devoted to a photometric investigation of asteroid 86279 Brucegary (1999 UJ1).  It was discovered in 1999 by my neighbors and friends Dave Healy and Jeff Medkeff using the Junk Bond Observatory 20" (loaner) Ritchey-Chritien telescope. When Dave named it for me I promised to observe it and characterize it as much as I could. I "detected" 86279 with a 14" Celestron in 2005, when V-mag ~ 20.6, and measured a rotational LC during the 2006 and 2007 apparitions, when V-mag ~ 17.7. Since then my observing techniques have improved, as well as my analysis techniques, so this web page is meant to be an update to the earlier work. The 2015 apparition observations began 2015 Oct 07, when phase angle = 4.2 deg. My goal for this apparition is to combine this apparition's data with data from the 2006 and 2007 apparitions for determining a better rotation period, and construction of a phase curve for a wide range of phase angles, which I will then interpret using the Belskaya and Schevchenko (2000) model. This should yield a solution for geometric albedo, opposition effect and size.
Latest Analysis

Rotation period = 8.8558 0.0014 hr
Geometric albedo = 33 8 %
Diameter = 1860 340 meters
G = 0.34 0.05, H = 15.65 0.03
Range of variation = 0.315 mag

So far measurements from 3 apparitions agree. Geometric albedo, Ag = 34 8 % & diameter = 1820 meters.

Here's a better HG model: H = 15.67, G = 0.38.

Phase folded LC for all of 2015 observations (so far) with P constrained by only the 2015 observations. 

Phase folded LC for all of 2007 observations. P constrained only by 2007 observations. 

Observing Sessions    

------------------------------------------------------------------------------   2015  --------------------------------------------------------------

2015 Nov 02

This 7-hr observing session was under clear skies.

2015 Oct 31

This 2-hr observing session had some dew problems during the first hour.

2015 Oct 22

This 1-hr observing session was stopped by clouds.

2015 Oct 14

This 7-hr observing session was stopped by clouds.

2015 Oct 10

Observing session plagued by clouds, spanning 0.55 rotation. Not very many APASS calibration stars (13), and they exhibited large scatter (26 mmag), so final calibration is more uncertain than usual (12 mmag vs ~ 7 mmag).

2015 Oct 09

A second observing session for the 2015 apparition, aborted after 3 hrs due to clouds.

2015 Oct 07

This is my first observing session for the 2015 apparition.

------------------------------------------------------------------------------   2007 --------------------------------------------------------------

Final phase-folded LC for 2007 has P = 8.8574(5), and range of variation = 0.31 mag and the first peak is slightly brighter than the second one.

2007 Nov 12

2007 Nov 01

This 8.3-hr observing session was made with Celestron 14", with Cb filter, image scale = 0.64 "/px, 120-sec exposures.

2007 Oct 11

This 7-hr observing session with a Celestron 14" and ST-8e CCD (incl focal reducer, I think), with image scale = 0.84 "arc/pixel, used exposure times of 90 sec except for every 10th image, which was 60 sec (by mistake).

This will be my adopted reference date for defining zero phase (since this is the first good quality LC and has essentially the same viewing geometry as for 2015).

Both peaks are about the same, with the 2nd one possibly brighter.

2007 Oct 09

This 2-hr observing session had poor SNR. It's the first usable image set for 86279 for the 2007 apparition, occurring just a few days before smallest phase angle.

2007 Oct 08

This observing session, the first for the 207 apparition, involves two FOVs. 

------------------------------------------------------------------------------   2006 --------------------------------------------------------------

2006 Feb 02


2006 Jan 31

This is the first observation of 86279 that's usable for the creation of a phase curve. The 2006 observations were made with a Celestron 14" on a GEM, with a SBIG ST-8 CCD (unbinned, usually).

Phase-folded LC.


Belskaya, I. N. and V. G. Schevchenko, Icarus, 147, 94-105.

Related Links

    86279 observations web page for observations up to 2007
    Tips for amateurs observating faint asteroids 
    Master list of my web pages & Resume


WebMaster: B. GaryNothing on this web page is copyrighted. This site opened:  Oct 07, 2015 Last Update:  Oct 07, 2015