The Occultation of a 13.1 Star by 2000 RX40

Wed eve Aug 28, 2025 at 9:02:09pm

OWc page

 

This event is bright enough to be quite do-able, and with a dark sky and 1.3s duration, should be all good.

Alt=37, Az=153 in Sagittarius, 10 deg above/left of the top of the "Teaspoon"

I will be teaching Astro 9ABC at this time, and have to take time off to try to get it. But Cabrillo Observatory is outside the path and unlikely to get an event. We'll have to see if I can even try it (no. Could not try it). I will have to count on Kirk, Karl and maybe Bernard to try it.

     

Kirk Bender

I got a 1.4 sec event for 2000 RX40, 8x at Scotts Valley Skypark. Predicted time for Skypark according to OWC was 4:02:08, midpoint for my event was 4:02:04.0776, so about 4 sec early, which confirms Karl's results of being earlier than predicted.


magDrop report: percentDrop: 94.6  magDrop: 3.161  +/- 1.789  (0.95 ci)

DNR: 3.93

D time: [04:02:03.3810]
D: 0.6800 containment intervals:  {+/- 0.0294} seconds
D: 0.9500 containment intervals:  {+/- 0.0756} seconds
D: 0.9973 containment intervals:  {+/- 0.1482} seconds

R time: [04:02:04.7743]
R: 0.6800 containment intervals:  {+/- 0.0294} seconds
R: 0.9500 containment intervals:  {+/- 0.0756} seconds
R: 0.9973 containment intervals:  {+/- 0.1482} seconds

Duration (R - D): 1.3933 seconds
Duration: 0.6800 containment intervals:  {+/- 0.0440} seconds
Duration: 0.9500 containment intervals:  {+/- 0.0981} seconds
Duration: 0.9973 containment intervals:  {+/- 0.1770} seconds

Karl von Ahnen

Aug 27 (28) 9:02:09 (62010) 2000 RX40 East of rock, clear dark v.thin moon behind trees, at 8X No obvious occ. Processing: had to use bright star for Ref1 saturated about 1/2 the time. Looks like a definite event earlier than expected.

magDrop report: percentDrop: 85.9  magDrop: 2.123  +/- 0.527  (0.95 ci)
 
DNR: 3.18
 
D time: [04:02:00.5424]
D: 0.6800 containment intervals:  {+/- 0.0335} seconds
D: 0.9500 containment intervals:  {+/- 0.0936} seconds
D: 0.9973 containment intervals:  {+/- 0.1870} seconds
 
R time: [04:02:02.2774]
R: 0.6800 containment intervals:  {+/- 0.0335} seconds
R: 0.9500 containment intervals:  {+/- 0.0936} seconds
R: 0.9973 containment intervals:  {+/- 0.1870} seconds
 
Duration (R - D): 1.7350 seconds
Duration: 0.6800 containment intervals:  {+/- 0.0503} seconds
Duration: 0.9500 containment intervals:  {+/- 0.1153} seconds
Duration: 0.9973 containment intervals:  {+/- 0.2210} seconds


         

 

RN: Interesting that both of you got events longer than the prediction. Another oblong asteroid perhaps? Or just low albedo.