Asteroid 52768 and light curve

[lukebl]

I've been watching the close approach of Asteroid (52768) 1998 OR2, and have captured an interesting light curve. It's a 2km Amor asteroid, which swings right out nearly as far as Jupiter and passes within 16 lunar distances of Earth on 29th April. It's normally pretty faint, but I measured it at around mag 13 last night and it's predicted to get to around 10.8 next week, although by then it'll only be visible for southern viewers. It was in Cancer last night, moving at around 8 arc seconds per minute and speeding up rapidly.

I took 30 second exposures with an Atik428ex and 200mm f/5 Newtonian. Using Miniwin software, I generated this interesting varied light curve over a period of three hours, suggesting that it's quite irregular in shape. Wiki suggests that the rotation period is 3-4 hours, so I guess I've nearly captured a complete rotation. My measurement with Astrometrica indicated that its magnitude ranged from 12.7 at 20:40 to 13.1 at 23:00. Quite a significant range over a short time.

Here's a composite image showing its position at 5 minute intervals:

This is an image stacked on the asteroid using Astrometrica, showing its movement over 10 minutes

This is a straightforward stack with DSS, of 199 exposures. No darks or flats.

Finally, here's an animation of it at 5 minute intervals:

 

 

Edited April 21, 2020 by lukebl

[andrew s]

Very nice work, I like the various ways of displaying your data especially the light curve.

Regards Andrew 

[lukebl]

Many thanks Andrew.

Here's a somewhat better presentation of the light curve. I've averaged out every 10 measurements (i.e. 10 x 30 sec exposures) and inverted the scale so that it reads better. I have noticed that asteroids often have a dip or peak in mid-rotation, so a rotation period of about 3½ hours seems about right.

Edited April 21, 2020 by lukebl