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2006 JF42 Southern Bright Rock
This large (1/3 mile) Aten Potentially Hazardous Asteroid from my location, does not get high enough to trip my wire. For those in the southern hemisphere, it gets high when close and bright (mid 13s). From Sydney, May 7 to 10, it will track through southern Scorpius, thru Norma and into Lupus moving just under 1/2°/hour while remaining in the mag 13s. It remains about 15LD out and just outside our orbit. Good hunting.
The close approach of this MP is nearly here (close  Wink). Here's the predicted path for Sydney, AU from May 5-12. As BMD said, this is primarily a southern hemisphere object. ST4v predicts a peak brightness of 13.5 magnitude from the evening of May 9 to the morning of May 11 when the MP will be 0.04 AU distant. 

Here's an Interactive Atlas chart showing the path from May 5-12 for Sydney, AU: [attachment=2350]

Maybe you'll catch a break in the weather.

Phil S.
Excellent chart Phil. Thanks for providing the track.

I may have a shot at this rock during the late days of its passage. It climbs to ~20° at 00:00CDT on the 12th. Problem is, my southern sky has the most light pollution from Conroe and Houston. Just a bit lower 24 hours prior (May 11). Total proper motion is ~20"/sec so fairly noticeable with magnitudes in the dim 13s. The 80% illuminated moon is 50° up and 50° away. I'm seeing the shot at this rock getting more difficult as I scan the specs Sad
At least CNEOS lists the Condition Code for this MP as '0' so the orbit is well defined & the predicted track should be very accurate. The minimum Re is 0.038 AU (14.9 LD). I don't know how much the approach will perturb the orbit. The osculating elements used to produce the IA chart were downloaded from the MPC on 2022 May 1 for the epoch 2022 May 1. I suppose you could query HORIZONS to see how quickly the elements are changing with time as the pass occurs. They certainly change a bit, but what effect that has on the trajectory, who knows. You'd need to use the trick of entering both sets of elements into ST4v simultaneously & comparing the resulting predicted trails. I don't want to risk messing up the MP DB to find out  Rolleyes.

Hopefully you'll be able to get a view of this one. It's rare that any of these MPs get this bright.

Phil S.
Phil, please. People will read this and it makes my software look bad.

Your database is already messed up. It happened from the heavy testing you have done, and your reluctance to follow my instructions to fix it have apparently kept it that way. There are currently no known issues with the SkyTools minor planet database!
Clear skies,
Head Dude at Skyhound
Hi Greg,

I didn't mean to imply any deficiency with SKyTools or its accuracy in predicting the positions of MPs. I was just relaying the high quality of the elements to BMD for this NEO. I have no plans to get any elements from HORIZONS.

I need to find your instructions for cleaning up the MP DB again. I flushed it a couple month ago, but apparently, it's gotten messed up again. I was referring to the 'trick' we used last summer to add several sets of elements for a single MP with slightly different epochs. Then using SkyTools charts to compare the differences in predicted positions. After those 'extra' entries are added, deleting them afterwards poses some risk to the MP DB, correct? Instead of deleting a single entry, I clicked on the 'Delete All' option by mistake & wiped out the whole MP DB. That's what I didn't want.

ST4v has been working fine. Sorry for the confusion,

Phil S.
Phil, This rock is large but the close pass is ~15LD out so little change in orbit. I get this for b4 and after elements:

.txt   2006 JF42 elements change.txt (Size: 632 bytes / Downloads: 1)

I think I ran it back a few weeks ago and the ephem did not vary from that of Horizons with just a simple download from either the MPC or Lowell. Don't recall which. I currently cannot even get this rock into my ST MPDB, no matter what I do. Post in support discussion.
Ha - I just had a look at this rock, and it is too bright for me, might burn out my CMOS Camera. Tongue 

On a more serious note, this La Nina weather cycle is playing havoc down under and folks are finding it difficult to get a clear night or two. Exclamation 


Hi Dennis,

Too bright! That's one you don't hear every day. What do you consider a convenient brightness for your system? I've been using the visual limit of my 13" scope as the minimum brightness for one of these events, but imagers can go much deeper. There have been many MPs in the 17 - 18.5 mag range that I haven't reported here, but certainly could if you're interested. If that's the case, what magnitude limit would you like me to use? Bear in mind that this will make your weather situation worse with more astro events to observe  Big Grin.

Have you considered masking the objective of your scope to stop it down & reduce the brightness at the sensor? Or maybe a ND filter?

Phil S.

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