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Asteroid Florence (3122)


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About this observation
Mike Olason
Time of observation
26/08/2017 - 09:01
Asteroid Florence (3122)
Observing location
Denver Colorado
11" SCT f/6.4
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djswan2002's picture

I have just been reading about the upcoming fly-by of Florence! I will aim to start imaging this from Aug 30, ~2230 BST - at that time it will be >20deg alt where I am. The rapid movement through Aquarius, Equuleus/Delphinus, Vulpecula and then Cygnus - over the course of a single week - should be something. Hopefully the weather will be good.


Nice to hear from you. The good thing about Florence is that it will be about magnitude 9 and it will only be moving about 1/2 degree per hour at close approach. "If " I have my information correct then with an 8" SCT one can take 5 to 10 second images depending on your FOV with whatever camera you use without smearing of the asteroid and show a nice step pattern in an image with an average of images. I may try it with a 1" f/4 refractor FOV 3.9*x2.6* with ST-402, although it may be dim and averaging a number of images the asteroid may eventually get washed out due to my wonderful light pollution. I will have to run a test in the next few nights. I did get a nice image of the asteroid last night that I just put online. Have you tried animations of comets yet? This asteroid should be an ideal way to test such a setup and show a nice animation as it moves across the night sky.

Clear Skies, Mike

djswan2002's picture

The new image is nice. No, I haven't tried the animation yet - there hasn't really been a suitable starter object (bright and rapidly moving) until now. This is a good target. My camera's FOV is a bit small: 20.0 x 13.4 arcmin. I should be OK though if I retrieve up to date ephemerides from the MPC and output some star charts.


The current MPC and JPL ephemeris for Asteroid Florence  (3122) are good. I used the MPC ephemeris to find the asteroid and verified that JPL ephemeris agreed. On my images it was 30 arc seconds SW of where it was suppose to be and since it won't be moving that fast across our night skies there should not be much more of a delta at close approach. The asteroid will be moving at about 24'/hour at it's fastest across our night skies, so with your FOV you should be able to easily get a 1/2 hours worth of data regardless of how your camera is oriented with respect to the asteroid's track before having to reposition your FOV. The good thing is the asteroid is bright and moving relatively slow so that you will have several good nights to image it and work out any problems that you may encounter. You don't need any sleep before going to work do you?

Good luck, look forward to hearing how it goes,



I did some investigating into the MPC ephemeris that I had loaded into Guide 8 to try to figure out how an asteroid that has become so popular could have ephemeris that was 30" off from the asteroid positions that I had observed. I reloaded the ephemeris for Florence (3122) from the MPC site and what I found was that the new ephemeris showed the asteroid to be almost exactly where I had observed it in my images and there was also an old ephemeris in the Guide 8 database which showed the error that I had observed. About 3 weeks ago I had trouble with Guide 8 and had to do a Restore Point to get it working again. I guess that I had updated the Florence ephemeris in Guide 8 before I had the problem but after the date of the Restore Point that I used, so when I went searching for Florence several nights ago I was using ephemeris from quite some time ago. Bottom line, the MPC ephemeris is good and shows the asteroid exactly where it should be. I apologize for my mistake.

I am heading out right now to see what I can do with the 1" Refractor and it's wide FOV, the wind is blowing really hard so the 1" Refractor is about the only thing that I can use anyway I hope. Looks like the Moon will grace our skies when the asteroid makes it's close approach.


djswan2002's picture

Thanks for letting me know. The weather forecast for here is cloud today, but improving through to the end of the week. Hopefully clear skies at some point! David

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