Ephemeris discrepancy

[Ron]

I'm confused again

I added 2012 EG5 to my SNPP and the ephemeris for 9:00pm EDT Tampa Fl does not agree with ephemeris from two other sites, JPL & CalSky.

Can someone check and see what ephemeris you get?

My SNPP is Ra 5h 27m 48.2s Dec 20 41m 47s

JPL is RA 09 13 53.04 Dec-04 09 06.2

CalSky is Ra 9:23:27.0 Dec-8:36:45

Thanks,

Ron

[drclay]

Ron....even though I am an NEO contributor to JPL and other NASA sites, you need to be using ONLY the Minor Planet Center ephemeris locator at:
http://www.minorplanetcenter.net/iau/MPEph/MPEph.html
Type in 2012 EG5
and then specify below what sky program you are using; for OBSERVATORY CODE, simply use one of ASO's: H45
Then click "Get Ephemeris" 

It will ask you if you want to OPEN it or save it.  Open it and get the values printed and then save if you like; this was updated this morning at 2:20 a.m. and my observations were used to generate it.

NOTE that 2012 EG5 will be at magnitude 15 tonight about 10 p.m. and south of overhead, moving very fast from north to south and a bit eastward now as well....it is really starting to fly and this may be the last night you will be able to "freeze it" via a 5-6 second exposure.

Doc

[drclay]

UPDATE:  Below is exactly what you need to copy and paste (or manually enter the numbers) into SNP"
**************
NOTE: If viewing this file and it appears confused, make the window very wide!

   The numbers are all in the proper format for easy use in Starry Night's
orbit editor. Just click on the word Sun in the planet floater and then
click on add. In the first window that appears select the comet as the type
of object you want to add. Please see the manual for more information.

   The orbital information should have the reference plane set at Ecliptic
 2000 and the Style should be near-circular.  Don't forget to use copy and
 paste to ease the input of the orbital data into Starry Night.

This file kindly prepared by the IAU Minor Planet Center & Central Bureau for Astronomical Telegrams.

Num   Name                Mag.       a          e        i       Node        w         L      Epoch

      2012 EG5           24.3     2.219834  0.555312   2.6186  193.1825   14.4041  350.7612  2456000.5

[Ron]

Thanks so much for your help.

I will use the information to input in my SN and hopefully we will have a clear evening to try and capture this fast moving rock.

Ron

[drclay]

Excellent....if necessary, simply enter the elements manually and make sure you have the right number for the particular parrameter needed for each space.
This should help a lot.

Good luck and let us know if you catch up with this rumbling rock.

Doc

[Ron]

No joy here in Tampa yesterday evening.

Total cloud cover, and tonight looks like a repeat

I hope someone got a chance.  Even though my chances look rather dim for tonight, I'm glad I started this discussion on the ephemeris.  Thanks to Dr. Clay, if we waited until April 1 & 2 we would have missed the opportunity.  According to his calculations, it looked like the best time would have been on March 30th and maybe tonight if anybody has a clear sky.

Thanks Dr. Clay for all of your help.

Ron

[drclay]

Here are details from our (ASO H45) photometry run (astrometry listed first followed by photometry/magnitude estimates to 0.01 mag accuracy).
Near perfect conditions with 0.8 arc second steady seeing:

COD H45
CON [drclay@tcworks.net]
OBS P.C. Sherrod
MEA P.C. Sherrod
ACK ASO Observations
AC2 drclay@tcworks.net
TEL 0.51-m f/4.3 astrograph + CCD
COM Reduction done using Charon
COM Series 2012 EG5 astrometric and photometric run
COM Report file created Sat Mar 31 01:28:22 2012
NET UCAC3

     K12E05G  C2012 03 31.07581 09 17 05.83 -05 40 57.2          15.2 R      H45
     K12E05G  C2012 03 31.07609 09 17 06.09 -05 41 05.6          15.2 R      H45
     K12E05G  C2012 03 31.07669 09 17 06.64 -05 41 24.0          15.2 R      H45
     K12E05G  C2012 03 31.07729 09 17 07.24 -05 41 42.5          15.5 R      H45
     K12E05G  C2012 03 31.07823 09 17 08.13 -05 42 11.2          15.4 R      H45
     K12E05G  C2012 03 31.07916 09 17 09.00 -05 42 40.0          15.5 R      H45
     K12E05G  C2012 03 31.07991 09 17 09.70 -05 43 03.2          15.3 R      H45
     K12E05G  C2012 03 31.08062 09 17 10.40 -05 43 25.0          15.6 R      H45
     K12E05G  C2012 03 31.08130 09 17 11.03 -05 43 45.7          15.6 R      H45
     K12E05G  C2012 03 31.08199 09 17 11.68 -05 44 07.0          15.3 R      H45
     K12E05G  C2012 03 31.08269 09 17 12.35 -05 44 28.6          15.4 R      H45
     K12E05G  C2012 03 31.08338 09 17 13.01 -05 44 49.9          15.4 R      H45
     K12E05G  C2012 03 31.08407 09 17 13.68 -05 45 11.6          15.4 R      H45
     K12E05G  C2012 03 31.08478 09 17 14.33 -05 45 33.0          15.5 R      H45
     K12E05G  C2012 03 31.08546 09 17 14.99 -05 45 54.1          15.6 R      H45
     K12E05G  C2012 03 31.08616 09 17 15.65 -05 46 16.3          15.5 R      H45
     K12E05G  C2012 03 31.08685 09 17 16.31 -05 46 37.5          15.2 R      H45
     K12E05G  C2012 03 31.08755 09 17 16.99 -05 46 59.1          15.2 R      H45
     K12E05G  C2012 03 31.08824 09 17 17.64 -05 47 20.6          15.0 R      H45
     K12E05G  C2012 03 31.08894 09 17 18.31 -05 47 42.1          15.4 R      H45
     K12E05G  C2012 03 31.08963 09 17 18.95 -05 48 03.7          15.2 R      H45
     K12E05G  C2012 03 31.09032 09 17 19.63 -05 48 25.7          15.2 R      H45
     K12E05G  C2012 03 31.09102 09 17 20.29 -05 48 47.0          15.3 R      H45
     K12E05G  C2012 03 31.09171 09 17 20.94 -05 49 08.5          15.3 R      H45
     K12E05G  C2012 03 31.09241 09 17 21.62 -05 49 30.7          15.4 R      H45
     K12E05G  C2012 03 31.09310 09 17 22.29 -05 49 52.0          15.4 R      H45
     K12E05G  C2012 03 31.07581      2456017.575810              15.19R      H45
     K12E05G  C2012 03 31.07609      2456017.576088              15.17R      H45
     K12E05G  C2012 03 31.07669      2456017.576690              15.12R      H45
     K12E05G  C2012 03 31.07729      2456017.577292              15.42R      H45
     K12E05G  C2012 03 31.07823      2456017.578229              15.34R      H45
     K12E05G  C2012 03 31.07916      2456017.579155              15.44R      H45
     K12E05G  C2012 03 31.07991      2456017.579907              15.26R      H45
     K12E05G  C2012 03 31.08062      2456017.580625              15.54R      H45
     K12E05G  C2012 03 31.08130      2456017.581296              15.54R      H45
     K12E05G  C2012 03 31.08199      2456017.581991              15.27R      H45
     K12E05G  C2012 03 31.08269      2456017.582685              15.32R      H45
     K12E05G  C2012 03 31.08338      2456017.583380              15.35R      H45
     K12E05G  C2012 03 31.08407      2456017.584074              15.40R      H45
     K12E05G  C2012 03 31.08478      2456017.584780              15.50R      H45
     K12E05G  C2012 03 31.08546      2456017.585463              15.53R      H45
     K12E05G  C2012 03 31.08616      2456017.586157              15.42R      H45
     K12E05G  C2012 03 31.08685      2456017.586852              15.15R      H45
     K12E05G  C2012 03 31.08755      2456017.587546              15.19R      H45
     K12E05G  C2012 03 31.08824      2456017.588241              15.00R      H45
     K12E05G  C2012 03 31.08894      2456017.588935              15.31R      H45
     K12E05G  C2012 03 31.08963      2456017.589630              15.11R      H45
     K12E05G  C2012 03 31.09032      2456017.590324              15.19R      H45
     K12E05G  C2012 03 31.09102      2456017.591019              15.30R      H45
     K12E05G  C2012 03 31.09171      2456017.591713              15.22R      H45
     K12E05G  C2012 03 31.09241      2456017.592407              15.40R      H45
     K12E05G  C2012 03 31.09310      2456017.593102              15.40R      H45

[Ron]

Another miss for me, I really didn't have much hope because of the weather and Moon light.

This was my second try for a fast moving Asteroid.  The first one was back in Nov of 2011, Asteroid 2005 YU55.  After reviewing the images from that try, I wasn't even sure that I had the location right.

This time with 2012 EG5 I'm pretty sure I had the location right, but the skies were really crummy; clouds, haze, moon light, city light, and low to the horizon

After reviewing the images I shot, it looks like my limiting magnitude was around 13 mag.  I matched one star in my Image that looked to be a mag 13.85 according to my SNPP.

Doesn't look like I'm going to be much of a rock hound

I guess I'll have to wait on the next one, whenever that is

 
Ron

[lindendave]

Ron,

There are a couple really good websites that have tables of close approach asteroids. On those pages there is also more links to sites with useful information on observing them.

http://neo.jpl.nasa.gov/ca/ NASA site

http://www.minorplanetcenter.net/iau/lists/PHACloseApp.html Minor Planet Center close approaches

http://www.minorplanetcenter.org/iau/lists/Dangerous.html Minor Planet Center potentially hazardous

http://www.rasnz.org.nz/Asteroids2012.htm#tble Royal Astronomical Society of New Zealand

[Ron]

Thanks Dave,

On the JPL site, what does the H stand for in the magnitude list?

Most of those mags scare me.  I think my limiting mag in Tampa is around 16 mag under good condition.  I'll have to check some of my past images to make sure.


Ron

[lindendave]

Ron,

Since " (mag) " is below the H in that column my assumption is that it's magnitude.

Many of the asteroids are rather faint, I don't even try and image anything over 19th magnitude with my setup.

[Ron]

I guess I would have to look for ones probably up to mag 16.  I'll have to check and make sure exactly what my limiting mag is.

I'm just mainly interested in making Asteroid trail images, like the nice one for 2012 EG5 on Spaceweather http://spaceweather.com/archive.php?view=1&day=01&month=04&year=2012

Thanks,

Ron

[lindendave]

I am not sure what sort of exposure times one would use for those type of images. My exposure times are based on magnitudes of the NEO's I do photometry on, from a couple seconds to 60 seconds. Doc would most likely have a better handle on what you are looking for.....I will shake the bushes and see what falls out! 

[Ron]

Doc entered into the discussion we had on 2005 YU55 back in Nov of 2011, and gave some real good information on how to capture the Asteroid's trail.  I think the mag of that one at the time was around 12, I'll  have to check back and see.

Ron

[drclay]

NOTE first that "H" indicates the absolute magnitude based on a set distance from Earth; it is the determining factor for predicting magnitude changes as the asteroid approachs to and recedes from Earth.  It is NOT the actual magnitude of the object on any given date....the mag. changes based on that number in concert with Earth disttance.

Now as to asteroid trails....very fast ones leave easy trails.  A mag. 15 asteroid like 2012 EG5 would leave a trail in a 20 second exposure, plenty of time to capture both stars and asteroid.  The very slow ones (like most numbered asteroids i.e., EROS, APOLLO, etc.) move so little over time that you would like not be able to guide long enough (or at least make it worth your while) to get a true trail of the target.

So...the trail is going to depend on the speed at which it moves across the sky is the quick answer....most do not move all that fast.

Doc