Asteroid 1999 NC43 (86039)
B. Gary, 2014.05.05
This web page summarizes observations of the above NEO (suggested as the "parent" for the Chelyabinsk meteorite) using a Celestron 11-inch telescope at the Hereford Arizona Observatory in 2014.

Links Internal to this Web Page

     Data downloads 
     2014 Apr28-May01 Tan LCs  
     2014 April/May Gary LCs
     2014 March Gary LCs
     Error analysis  

Data Download File:   
        Gary data:   Data for 2014 March & Apr/May by B Gary   
        Tan data:     Data for 2014 Apr28-May01 by TG Tan

2014 April/May Gary Observations 

Observations for Apr/May, 2014 are complete. Here's a light curve for Apr/May showing Gary & Tan observations.

r'-mag vs date for observations beginning Apr 28.

First observation with Meade 14-inch since the mount failed a year ago.

Last LC using Celestron 11-inch telescope.

Just a quick 15-minute observation.

With care it's possible for a 11-inch aperture telescope to obtain LC mag's for an asteroid with r'-mag ~ 18.5 (V-mag ~ 18.7).

Apr 28 observation with Cb filter and calibrated against reference stars using their r'-mag's.

2014 March Gary Observations

The asteroid was observed on 9 dates in early March, 2014. Below is a 3 sinusoid fit (in which periods for 2 sinusoids were fixed to be 1/2 and 1/3 of the free parameter period; all amplitudes and phases were free to vary).  The largest amplitude periodicity was 63 hours, implying a rotation period of 126 hours.

Error Analysis

Uncertainties are of four types:

    1) Target asteroid stochastic
    2) Reference stars stochastic
    3) Reference stars systematic
    4) Target asteroid systematics due to background stars

In each light curve I report the stochastic components for (1) and (2). These should be orthogonally added, along with ~ 0.020 mag which I assume is a reasonable SE for component (3), the set of APASS star mag's within a FOV. Finally, component (4) should be orthogonally added, but it is difficult to estimate because it depends on the density of background stars and the brightness of the asteroid. I recommend estimating component (4) by eyeballing the variation of average values in a LC with respect to the model fit trace. Every LC has the most obvious background star interference images removed from consideration, but there will be a residual variation due to those i didn't identify.

For example, in the LC for 2014.04.29, above, I estimate the SE variation of the averages to be 0.025 mag. The two stochastic components are 0.018 and 0.009 mag. All components to be orthogonally added are 0.018 (asteroid stochastic), 0.009 (reference stars stochastic), 0.020 (APASS systematics) and 0.025 (background star systematics) mag. Their orthogonal sum is 0.038 mag.

This web page created 2014.04.29 by webmaster Bruce Gary