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Help Locating Apophis?

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#1 OtisJackson

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Posted 05 March 2021 - 01:19 AM

Went out to try to image Apophis this evening in advance of the close approach tomorrow night. I used Stellarium to identify coordinates and then to verify the image, but depending on whether I used the desktop or mobile version, I was getting slightly different locations of the asteroid. I took a 20 minute exposure, and captured what might (?) be the trail of the asteroid, but it was in a different place than where it should have been at that time according to either version of Stellarium. This is (as you probably can tell :) my first time trying to capture a minor planetary object, so would appreciate any pointers on how to narrow down the precise coordinates/location for tomorrow evening. (Also is the trail in the image below the asteroid or something completely different?) Thanks!

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  • Apophis.jpg


#2 Tapio

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Posted 05 March 2021 - 01:29 AM

I tried it too last night but have trouble too locating it.
I took 3 min exposures so that movement would show.
I am going to blink my images later.
It's about mag 16 so it should show.

What is your imaging equipment?

#3 OtisJackson

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Posted 05 March 2021 - 01:39 AM

So, I went back and looked at the two previous exposures (5m and 10m) and see clearly the progression of this object, which I assume given the general vicinity is Apophis. I can't confirm the location w/ Stellarium which has it in a slightly different position, but close (w/in a few arc minutes). (I bumped the scope on the second frame and guiding wasn't perfect over the 20m integration but you can still make out the trail of the object).

 

I'm using an Esprit100mm refractor and an ASI1600MM. I know it's pushing the limits of the scope, but I can usually capture up to mag19 from my location with this gear. 

Attached Thumbnails

  • Screen Shot 2021-03-05 at 1.33.53 AM.jpg

Edited by OtisJackson, 05 March 2021 - 01:40 AM.


#4 BinaryField

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Posted 05 March 2021 - 02:27 AM

Regarding Stellarium, have you updated the object using the Solar System Editor? The orbits of these small objects tend to be perturbed by other bodies, so the elements need to be updated every so often. I tried to take a screenshot but the windows fade out if not in focus. It's in Configuration Window > Plugins > Solar System Editor > Solar System > Import Orbital Elements in MPC Format.

 

You may also try using JPL HORIZONS. Make sure to specify your exact location so that they can give you the appropriate topocentric coordinates. https://ssd.jpl.nasa.gov/horizons.cgi

 

Have fun!

Attached Thumbnails

  • post-362199-0-80376500-1614929363.jpg

Edited by BinaryField, 05 March 2021 - 11:50 AM.

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#5 ButterFly

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Posted 05 March 2021 - 03:21 AM

(99942) Apophis on NeoDys-2.

 

There is a link on the left to generate an ephemeris.  Use the observatory code closest to where you will observe.  You can also generate a mag 18 chart of desired field as well.

 

NeoDys is the only site I have found that lets one search by apparent magnitude of close approaches.  I have grown to like it.


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#6 MikeK314

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Posted 05 March 2021 - 04:22 AM

Yes, that's Apophis in your image.  I visually checked against the field shown by the charting program Guide 9.0, and it's in the right place and moving at the right angle in the correct direction.

 

As others have said, use one of the ephemeris tools online to get the position for tomorrow night.  I usually use the one at minorplanetcenter.net.  It's under the OBSERVERS tab at the top, first item ("Ephemeris Service").  Type "apophis" in the big blank box then hit the "Get Ephemeris/HTML page" button.  Then you might want to hit 'back' and do it again with the exact date and time you want, and maybe an observatory code or your longitude/latitude.  I'm not sure there's enough parallax (in this instance) to make your location important, but it doesn't hurt to be more precise.

 

- Mike


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#7 beggarly

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Posted 05 March 2021 - 04:34 AM

These are orbital elements for 44492 Apophis:

asteroid orbit,"Apophis MPC ",99942,0.922617,0.19150640,3.336820,204.059570,126.687310,2458000.500000,215.856280,19.20,0.15 MPC today (https://minorplanetc...t00Unusual.txt)
asteroid orbit,"Apophis 2020",99942,0.922617,0.19150640,3.336820,204.059570,126.687310,2458000.500000,215.856280,19.20,0.15 MPC April 2020
asteroid orbit,"Apophis Lowell",99942,0.922492,0.19156499,3.339547,203.979441,126.648384,2459300.500000,221.964683,18.91,0.15 LMPS today (https://asteroid.low...du/main/astorb)

As you can see, data from MPC hasn't been updated since April 2020.

 

Planetarium program C2A ( http://www.astrosurf...glish/index.htm )can import current data from the Lowell site.

capture_001_05032021_102058.jpg

 

Ephemeris generated by C2A (geocentric coordinates):

(99942) Apophis Lowell
UT Date & Time         Right Asc.    Declination    Mag.   Phase Size   Rise    Meri. Time  Set
--------------------------------------------------------------------------------------------------
2021-03-05 / 00:00:00  09h31m16s     -08°25'25"     +15,5  -      -      16h58m  22h19m48s  03h48m
2021-03-05 / 02:00:00  09h30m53s     -08°21'32"     +15,5  -      -      16h58m  22h19m48s  03h48m
2021-03-05 / 04:00:00  09h30m31s     -08°17'40"     +15,5  -      -      16h58m  22h19m48s  03h48m
2021-03-05 / 06:00:00  09h30m09s     -08°13'47"     +15,5  -      -      16h58m  22h19m48s  03h48m
2021-03-05 / 08:00:00  09h29m46s     -08°09'54"     +15,5  -      -      16h58m  22h19m48s  03h48m
2021-03-05 / 10:00:00  09h29m24s     -08°06'00"     +15,5  -      -      16h58m  22h19m48s  03h48m
2021-03-05 / 12:00:00  09h29m02s     -08°02'07"     +15,5  -      -      16h58m  22h19m48s  03h48m
2021-03-05 / 14:00:00  09h28m40s     -07°58'12"     +15,5  -      -      16h58m  22h19m48s  03h48m
2021-03-05 / 16:00:00  09h28m17s     -07°54'18"     +15,5  -      -      16h58m  22h19m48s  03h48m
2021-03-05 / 18:00:00  09h27m55s     -07°50'23"     +15,5  -      -      16h58m  22h19m48s  03h48m
2021-03-05 / 20:00:00  09h27m33s     -07°46'28"     +15,5  -      -      16h58m  22h19m48s  03h48m
2021-03-05 / 22:00:00  09h27m11s     -07°42'33"     +15,5  -      -      16h58m  22h19m48s  03h48m
2021-03-06 / 00:00:00  09h26m49s     -07°38'37"     +15,5  -      -      16h45m  22h11m31s  03h44m
2021-03-06 / 02:00:00  09h26m27s     -07°34'41"     +15,5  -      -      16h45m  22h11m31s  03h44m
2021-03-06 / 04:00:00  09h26m05s     -07°30'45"     +15,5  -      -      16h45m  22h11m31s  03h44m
2021-03-06 / 06:00:00  09h25m43s     -07°26'48"     +15,5  -      -      16h45m  22h11m31s  03h44m
2021-03-06 / 08:00:00  09h25m21s     -07°22'51"     +15,5  -      -      16h45m  22h11m31s  03h44m
2021-03-06 / 10:00:00  09h24m59s     -07°18'54"     +15,5  -      -      16h45m  22h11m31s  03h44m
2021-03-06 / 12:00:00  09h24m37s     -07°14'57"     +15,5  -      -      16h45m  22h11m31s  03h44m
2021-03-06 / 14:00:00  09h24m15s     -07°10'59"     +15,5  -      -      16h45m  22h11m31s  03h44m
2021-03-06 / 16:00:00  09h23m53s     -07°07'01"     +15,5  -      -      16h45m  22h11m31s  03h44m
2021-03-06 / 18:00:00  09h23m32s     -07°03'03"     +15,5  -      -      16h45m  22h11m31s  03h44m
2021-03-06 / 20:00:00  09h23m10s     -06°59'05"     +15,5  -      -      16h45m  22h11m31s  03h44m
2021-03-06 / 22:00:00  09h22m48s     -06°55'06"     +15,5  -      -      16h45m  22h11m31s  03h44m

 

Cartes du Ciel ( https://www.ap-i.net...php?id=en/start ) has a useful feature for calculating positions of near earth objects at the time of close approach: https://www.ap-i.net...display_of_neos


Edited by beggarly, 05 March 2021 - 06:57 AM.

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#8 beggarly

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Posted 05 March 2021 - 04:49 AM

Difference in positions using orbital elements from MPC and LMPS:

 

capture_001_05032021_104742.jpg


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#9 OtisJackson

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Posted 05 March 2021 - 08:11 AM

Wow, thanks all for the very helpful advice! Will dig into these resources before this evening.

#10 Mike Phillips

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Posted 05 March 2021 - 12:11 PM

Yes, that's Apophis in your image.  I visually checked against the field shown by the charting program Guide 9.0, and it's in the right place and moving at the right angle in the correct direction.

 

As others have said, use one of the ephemeris tools online to get the position for tomorrow night.  I usually use the one at minorplanetcenter.net.  It's under the OBSERVERS tab at the top, first item ("Ephemeris Service").  Type "apophis" in the big blank box then hit the "Get Ephemeris/HTML page" button.  Then you might want to hit 'back' and do it again with the exact date and time you want, and maybe an observatory code or your longitude/latitude.  I'm not sure there's enough parallax (in this instance) to make your location important, but it doesn't hurt to be more precise.

 

- Mike

I second the use of minorplanetcenter.net!  Try Typically you can use the defaults.

 

I'm motivated to hit this now too!  Thanks!

 

HTH,

 

Mike



#11 ButterFly

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Posted 05 March 2021 - 01:46 PM

These are orbital elements for 44492 Apophis:

asteroid orbit,"Apophis MPC ",99942,0.922617,0.19150640,3.336820,204.059570,126.687310,2458000.500000,215.856280,19.20,0.15 MPC today (https://minorplanetc...t00Unusual.txt)
asteroid orbit,"Apophis 2020",99942,0.922617,0.19150640,3.336820,204.059570,126.687310,2458000.500000,215.856280,19.20,0.15 MPC April 2020
asteroid orbit,"Apophis

It's important to use the correct list.  NEAs' osculating elements can change a lot as they approach.

 

MPC's "NEAs today" is much more appropriate under the circumstances of a close approach.  Always check whether your intended target is on this list.  Here is the Apophis line from that file.  Despite the different order, you can tell which number corresponds to which.

 

99942   18.9   0.15 K2135 197.45754  126.66128  203.99211    3.33846  0.1916172  1.11252265   0.9224230  0 E2021-D54  5095  14 2004-2021 0.34 M-v 3Eh Veres      8802  (99942) Apophis            20210217

 

 


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#12 airscottdenning

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Posted 05 March 2021 - 02:14 PM

It's important to use the correct list.  NEAs' osculating elements can change a lot as they approach.

 

MPC's "NEAs today" is much more appropriate under the circumstances of a close approach.  Always check whether your intended target is on this list.  Here is the Apophis line from that file.  Despite the different order, you can tell which number corresponds to which.

 

99942   18.9   0.15 K2135 197.45754  126.66128  203.99211    3.33846  0.1916172  1.11252265   0.9224230  0 E2021-D54  5095  14 2004-2021 0.34 M-v 3Eh Veres      8802  (99942) Apophis            20210217

ButterFly, can you explain how to turn this line of text into coordinates (RA, DEC, UT)?

I'd love to catch this interesting event, but I don't know how to extract a time-dependent sky position from these data.



#13 ButterFly

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Posted 05 March 2021 - 03:44 PM

ButterFly, can you explain how to turn this line of text into coordinates (RA, DEC, UT)?

I'd love to catch this interesting event, but I don't know how to extract a time-dependent sky position from these data.

Not the math, no.  That's way too much typing.  Not just typing typing, but math typing.  Your goal is to understand what all of this means: Gauss planetary equations.  That can take years or a simple read through, depending on where you are.  Bookmark that and brush up on your vector calculus.  No need to do all that anymore, really.

 

Stellarium is what I use to watch the path of some candidate NEA that I may see.  When I plan to go out, I search the NeoDys site based on limiting apparent magnitude, declination, solar elongation, and motion per day (~2 deg/day is something I can watch in the eyepiece and not get bored).  1999 RM45 was such a candidate a few days ago.  I watched it get as bright as 14th mag, even catching it in bare eyepiece without an intensifier on my 15".  It was moving well over one arsecond per second.  That was fantastic.

 

Aside: X [deg/day] = 2.5 * X [arcminutes / hour], [arcseconds / minute] = X / 24 [arcminutes/minute], [arcseconds/second]

 

In Stellarium, I have my target name (Apophis), and I know it's an NEA.  So I update (or inject for the first time), it's current orbit into Stellarium.

 

From Configuration, select Plugins, then Solar System Editor.  Press the configure button for the Solar System Editor, then select the Solar System tab.  Here's the screen you want:

 

Stellarium Minor.jpg

 

 

I want to update an Asteroid orbit, so I use that radio button, then click the button to get the MPC format elements.  I also know that it's an NEA and I want fresh elements for today.  That file is already on the prepopulated drop down:

 

Stellarium Minor NEA.jpg

 

 

 

It will take a few seconds to get the file and process it for display.  Gigantic files take logner.  It lets you choose which ones to add:

 

Stellarium Minor NEA all.jpg

 

 

Search by name just a little so you don't have to scroll through a huge list.  Check the box for whichever ones you like.  If you have more than one to add, just search something else and check it too - now's the time:

 

Stellarium Minor NEA selected.jpg

 

 

Now you can search for it like anything else in Stellarium, using the search box.

 

Happy hunting!

 

Note that SkySafari Pro cannot do this.  It has set files it gets from MPC and it imports everything in them.  The NEAs for today is NOT one of those files.  It can be way off for the closer ones, and not even have the more recently discovered ones at all.  By the time the new ones get into the files SkySafari gets, the asteroid is already at 21+ mag, so it's gone.  I need to use the NeoDys charts in the field for most of the objects I hunt to know where they are and see their paths.  I use SkySafari only for the star chart of the area that the ArgoNavis pointed at, and where NeoDys says it is.

 

 


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#14 Tapio

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Posted 06 March 2021 - 07:49 AM

Imaged Apophis last night.

Was difficult with just 80mm refractor and 2 minute exposure.

Measured it to be mag 15.4.

 

Also notable was the numerous Starlink satellites that were in every image (5 in worst frame).

 

 

Attached Thumbnails

  • 99942-Apophis_2021-03-05_2305_2min_L.jpg


#15 OtisJackson

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Posted 06 March 2021 - 08:50 AM

Thanks all for the help! I got a nice timelapse of the asteroid before some high-level clouds came in. Can’t post the video here, but you can see it at:

https://www.instagra...id=xwgnpdwhrj13

60x60s with 100mm refractor and ASI1600MM (Lum filter).

Edited by OtisJackson, 06 March 2021 - 08:51 AM.

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#16 wesastro

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Posted 06 March 2021 - 10:13 AM

Very nice animation Sputnik. I managed to capture Apophis last night too. 120 x 60" exposures with my 8" SCT. My images must have started about an hour before yours because I recognize the stars your animation is passing through. My images start with Apophis on the other side of the bright star, and passing it by to match with your animation path. I still need to edit the images and turn them into an animation. Strangely enough, the most accurate positions I had last night were from Sky Safari Pro. I tried using the positions from JPL, but had to use a city about 15 miles from my location because I couldn't get the Lat Long coordinates I entered to be recognized. Maybe I had the time conversion wrong, maybe I was using out of date elements from the JPL site.


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#17 OtisJackson

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Posted 06 March 2021 - 12:25 PM

Very nice animation Sputnik. I managed to capture Apophis last night too. 120 x 60" exposures with my 8" SCT. My images must have started about an hour before yours because I recognize the stars your animation is passing through. My images start with Apophis on the other side of the bright star, and passing it by to match with your animation path. I still need to edit the images and turn them into an animation. Strangely enough, the most accurate positions I had last night were from Sky Safari Pro. I tried using the positions from JPL, but had to use a city about 15 miles from my location because I couldn't get the Lat Long coordinates I entered to be recognized. Maybe I had the time conversion wrong, maybe I was using out of date elements from the JPL site.

Oh nice! Yes I updated my Stellarium per the above and also used Neo-Dys2 and minorplanetcenter.net. Never got exact agreement between the sources but definitely close enough to center on a coordinate and take a 600s exposure to identify the trail. Seeing was terrible here last night so between that and a 4” scope I’m pretty psyched to get anything at all. I took a pretty lazy route to do the timelapse and just registered all the images and then blinked them in PI. 


Edited by OtisJackson, 06 March 2021 - 12:28 PM.


#18 airscottdenning

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Posted 06 March 2021 - 01:31 PM

Thanks for the technical help!!

 

Here's a link to a tiny video of Apophis missing us by 10 million miles:



#19 wesastro

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Posted 06 March 2021 - 02:23 PM

8FEEEE06-176A-4E34-9EFC-CFE33C51FD2A.jpeg

 

I haven’t had a chance to make an animation of the images from last night, but here is a cropped snapshot of the stacked live view of the images. The image is pretty rough because it doesn’t have much editing.


Edited by wesastro, 06 March 2021 - 02:24 PM.



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