Asteroid 2004 BL86

[OffGrid (Steve)]

G'day folks,
Just joined this forum and would appreciate any useful info for viewing Asteroid 2004 BL86 that is supposedly due for a scope visible flyby around 26-27 Jan this year.
1st heard about it from son in law to be and confirmed through Earthsky.org.

Seems it will be in Cancer just after dark but wondering how long viewable as Cancer is vey low in the east at that time.

Steve

[Dennis]

Originally Posted by OffGrid

G'day folks,
Just joined this forum and would appreciate any useful info for viewing Asteroid 2004 BL86 that is supposedly due for a scope visible flyby around 26-27 Jan this year.
1st heard about it from son in law to be and confirmed through Earthsky.org.

Seems it will be in Cancer just after dark but wondering how long viewable as Cancer is vey low in the east at that time.

Steve

Here is a screen capture from The Sky X Pro showing the position and details for Brisbane on 26th Jan 2014 at 23:25.

Rises: 16:45
Transits: 23:29 at an altitude of 80º
Cheers

Dennis

[OzEclipse (Joe Cali)]

Are you sure that Sky X calculates topocentric rather than geocentric coordinates? Makes a huge difference to the position for a NEO.

At its brightest, before dawn on Jan 27, the objects apparent position in the sky differs by some 2 degrees between Brisbane and Melbourne. It may only just be visible in 7x50 binoculars at its brightest to a keen experienced observer.

It will be visible over several nights but brightest on Jan 26. That night, it will move at approximately 1 degree per hour or to put it another way, through the diameter of the Moon ~ every 30 minutes. Its motion is perpendicular to the motion of the background stars.
Best policy is to generate coordinates for your specific location using the ephemeris service at :
http://www.minorplanetcenter.net

cheers
Joe

[Dennis]

Originally Posted by OzEclipse

Are you sure that Sky X calculates topocentric rather than geocentric coordinates? Makes a huge difference to the position for a NEO.
>snip
cheers
Joe

Hi Joe

I have been lucky enough to capture a few of these NEO’s from my back garden in Brisbane using The Sky X Pro (and previously The Sky 6 Pro).

I usually refresh the orbital elements from within The Sky via the SB website on the day I plan to capture the event. I understand that the positional calculations for the “Find” and “GoTo” operations are based on my saved/selected Location (Lat & Long entered using GPS).

So far The Sky has managed to place the object on the chip (FOV approx. 25x18 arc min) as predicted by the on-screen representation.

Here are a few examples when I have been lucky enough with the somewhat fickle SE Qld weather…

Cheers

Dennis

[OzEclipse (Joe Cali)]

Dennis
Great. You're obviously on top of it. I'm not familiar with Sky X and so my question / caution was only of a general nature.

Some of these programs don't do topocentric calcs.

For example, different programs when plotting the path of 2012 DA 14 in early 2013 which was a closer approach gave 10 degree variations in apparent position.

Cheers

Joe

[Blue Skies (Jacquie)]

Thanks for the reminder that I needed to input my location (be topocentric!).

I've used the JPL HORIZONS web interface to generate an ephemeris for myself for this event. The night of the 26th is indeed looking to be the best night.

I think I used a different online source for 2012 DA14 but can't remember exactly where to find it.

[pdthomas23 (Peter)]

Hello All,

Here are some charts I made in Cartes du Ciel for seeing 2004 BL86 from my location in suburban Melbourne.
I used a topocentric ephemeris from JPL's HORIZONS system as of about a week ago.
http://ssd.jpl.nasa.gov/?horizons
It included the recent observations from the iTelescope (Q62) but not those from the LCOGT (W87) in the last few days. Uncertainty was down to only about 30 arc-seconds so shouldn't be too bad. However there will be a parallax difference for other locations.
For those using Cartes du Ciel there is a How-To for close asteroid passes that was written for the pass of 2012 DA14 in 2013.
http://www.ap-i.net/skychart/en/docu...isplay_of_neos
2004 BL86 is 3 lunar distances (1.2 million km) so nowhere near as close, much more like (4179) Toutatis in 2004 or 2006 VV2 in 2007.
If you just use CdC's regular asteroid display it will be off by about 1 degree. It just takes the Keplerian elements at a reference epoch from the Minor Planet Center and propagates them to the observation epoch using 2-body methods.
The asteroid will be around mag 10 during the night of 26-27 Jan and will be visible the whole night.

[Edit]
Forgot to say that the asteroid is marked with open diamonds on my charts.
The 10 pm (AEDT) field is near Ksi Puppis and M93.

Peter Thomas
Oakleigh

[Dennis]

Originally Posted by OzEclipse

Dennis
Great. You're obviously on top of it. I'm not familiar with Sky X and so my question / caution was only of a general nature.

Some of these programs don't do topocentric calcs.

For example, different programs when plotting the path of 2012 DA 14 in early 2013 which was a closer approach gave 10 degree variations in apparent position.

Cheers

Joe

Hi Joe

These are excellent and very relevant points you raise and are real traps for the unwary with these close fly-by NEOs.

In The Sky X Pro “Object Information Report” Panel both Topocentric and J2000 values for RA and Dec are provided. You can see these in the left hand text panel of the screen capture that I posted, although it might take some digging out as it is a busy graphic!

The only times I have noted large discrepancies are when I download the orbital elements several weeks before a scheduled NEO fly-by and I then forget to update or refresh them on the day.

Thank goodness for Wi-Fi and Internet Servers making this data accessible from my back garden at all hours of the late night or early morning!

Hopefully the OP Steve (OffGrid) will find these discussions helpful and contribute to a successful observation of this close fly-by.

Cheers

Dennis

[OffGrid (Steve)]

Cheers Dennis, Joe and Peter,

Being a newbi the info provided will be challenging to decipher, although probly first language for the regulars like yourselves.

I will take your responses up to the pony club at Mangrove Mountain tonight and ask the team to help me with the data.

Much appreciated.

Steve

[OzEclipse (Joe Cali)]

Steve,

You possibly saw an American article. It won't be in Cancer until much later - around midday on the 27th our time. The Cancer just after dark reference must be relating to the USA. We'll see it in the constellations of Hydra and Puppis during the night of the 26th. It travels from just north of M48 in Puppis towards M93 in Hydra during our dark hours.

Topocentric coordinates are the position of the asteroid against background stars as seen from your position on the Earths surface.

Geocentric coordinates are are the position of the asteroid against background stars as seen from the centre of the Earth.

For distant asteroids like those in the asteroid belts between Mars and Jupiter, there is no practical difference. For Near Earth Objects (NEO's) parallax error causes differences in the apparent position even between cities along the east coast.

The attached diagram illustrates the effect. Position C is the centre of the Earth (Geocentric) Pos A and D show very different apparent positions because of their different locations. Pos B lies on the geocentric line and experiences no parallax shift from the geocentric position but only for an instant. During the night, the Earth's rotation moves it off this line and the position once again experiences parallax shift.

DA14 was very close to Earth so this difference was particularly large. This asteroid is a little further out so that differences along the coast are not so extreme.

Hope this clears it up a little.

Joe

[pdthomas23 (Peter)]

Originally Posted by OzEclipse

Steve,

You possibly saw an American article. It won't be in Cancer until much later - around midday on the 27th our time. The Cancer just after dark reference must be relating to the USA. We'll see it in the constellations of Hydra and Puppis during the night of the 26th. It travels from just north of M48 in Puppis towards M93 in Hydra during our dark hours.

Joe

Actually Joe has mixed up his Messier references.
The asteroid starts the night near Ksi Puppis and M93 and finishes near M48 in Hydra in the morning.

Peter Thomas
Oakleigh

[Dennis]

I used The Sky X Pro to draw the path of 2014 BL86 as viewed from our back garden in Brisbane (note Joe’s post re parallax and need for Topocentric coordinates for other locations).

The plot stars at 7:00PM AEST and is labelled every 1 hour, ending at 12:00pm (midnight) by which time is has already transited the Meridian.

Cheers

Dennis

[julianh72 (Julian)]

According to this report http://www.jpl.nasa.gov/news/news.php?feature=4441 , 2004 BL86 is expected to be observable to amateur astronomers with small telescopes and strong binoculars.

Is this asteroid in the SkySafari catalog? I haven't been able to find it using the catalog search facility, so I'm wondering whether it has another designation? I would LOVE to be able to catch a look in my telescope or 15x70 binoculars, if only I knew where to look!

[astroron (Ron)]

Originally Posted by OzEclipse

Are you sure that Sky X calculates topocentric rather than geocentric coordinates? Makes a huge difference to the position for a NEO.

At its brightest, before dawn on Jan 27, the objects apparent position in the sky differs by some 2 degrees between Brisbane and Melbourne. It may only just be visible in 7x50 binoculars at its brightest to a keen experienced observer.

It will be visible over several nights but brightest on Jan 26. That night, it will move at approximately 1 degree per hour or to put it another way, through the diameter of the Moon ~ every 30 minutes. Its motion is perpendicular to the motion of the background stars.
Best policy is to generate coordinates for your specific location using the ephemeris service at :
http://www.minorplanetcenter.net

cheers
Joe

I have been through the MPC link above and trolled through all their planetarium sites and cannot find a listing for 2004BL86.
Cheers
PS I use the site all the time to down load my comet update's so am no stranger to it.

[Dennis]

Originally Posted by julianh72

According to this report http://www.jpl.nasa.gov/news/news.php?feature=4441 , 2004 BL86 is expected to be observable to amateur astronomers with small telescopes and strong binoculars.

Is this asteroid in the SkySafari catalog? I haven't been able to find it using the catalog search facility, so I'm wondering whether it has another designation? I would LOVE to be able to catch a look in my telescope or 15x70 binoculars, if only I knew where to look!

Hi Julian

I have Sky Safari Pro 4 running on my iPad and just updated the minor bodies list (Settings - Solar System - Update Minor Bodies) and I was able to find and centre 2004 BL86 via the Search screen.

Not sure if you have the Pro version? If so, be sure to update your minor bodies.

Cheers

Dennis

[Dennis]

Originally Posted by astroron

I have been through the MPC link above and trolled through all their planetarium sites and cannot find a listing for 2004BL86.
Cheers
PS I use the site all the time to down load my comet update's so am no stranger to it.

Hi Ron

I clicked the link and it took me to the MPC website.

At top right of the Home Page in "Search MPC" I typed 2004 BL86 and it found the object and displayed a page full of data.

I had a space between 2004 and BL86.

Cheers

Dennis

[julianh72 (Julian)]

Originally Posted by Dennis

Not sure if you have the Pro version? If so, be sure to update your minor bodies.

Thanks!

I'm running SkySafari 4.3.5 Plus. I updated the Minor Bodies database, but it doesn't recognise "2004 BL86" as an object name. However, I was able to find it using its other designation "357439". http://en.wikipedia.org/wiki/%28357439%29_2004_BL86

Best time to view looks to be about 9:00 pm - 2:00 am (Brisbane time) on the night of Sunday 26 / Monday 27 January, when it should reach magnitude 9 - 10 (so probably going to need a telescope rather than binoculars to spot it), in the general vicinity of Sirius.

[Dennis]

Originally Posted by julianh72

Thanks!
I'm running SkySafari 4.3.5 Plus. I updated the Minor Bodies database, but it doesn't recognise "2004 BL86" as an object name. However, I was able to find it using its other designation "357439". http://en.wikipedia.org/wiki/%28357439%29_2004_BL86
>snip

That’s odd – I did a search for "2004 BL86" via the Search screen and it recognised and found the NEO object okay – see attached screen capture.

I have also included the Object Info and Sky Display screen captures showing 2004 BL86.

Cheers

Dennis

[astroron (Ron)]

This data from MPC bears no resemblance to your data.
Putting the data into the sky program has it no where near
the positions on your program.
What am I doing wrong.
Note the position for the 26 Jan?
Orbital elements:
2004 BL86 PHA 0.004A
Epoch 2004 Jan. 16.0 TT = JDT 2453020.5 MPC
M 24.06569 (2000.0) P Q
n 0.53764402 Peri. 309.77739 +0.17125920 -0.92924834
a 1.4978656 Node 127.19921 +0.98185576 +0.13351605
e 0.4043040 Incl. 24.26670 +0.08142210 +0.34448656
P 1.83 H 18.8 G 0.15
From 10 observations 2004 Jan. 30-31.

Ephemeris:
2004 BL86 a,e,i = 1.50, 0.40, 24 q = 0.8923
Date TT R. A. (2000) Decl. Delta r Elong. Phase V
2004 01 26 14 13.36 +09 38.5 0.334 1.078 97.2 64.9 18.9
2004 02 05 14 28.98 +20 32.5 0.363 1.137 105.3 56.7 18.9
2004 02 15 14 37.32 +29 52.5 0.400 1.198 112.4 49.7 19.1
2004 02 25 14 37.37 +37 33.8 0.444 1.260 117.9 43.9 19.2
2004 03 06 14 28.82 +43 27.6 0.495 1.322 121.9 39.6 19.4
2004 03 16 14 12.74 +47 26.9 0.553 1.383 124.1 36.5 19.7
2004 03 26 13 51.89 +49 28.8 0.619 1.443 124.7 34.7 20.0
2004 04 05 13 30.60 +49 41.3 0.693 1.500 123.7 33.7 20.3
2004 04 15 13 12.62 +48 25.0 0.775 1.556 121.6 33.3 20.6
2004 04 25 12 59.90 +46 04.5 0.864 1.609 118.6 33.3 20.9
2004 05 05 12 52.76 +43 02.9 0.960 1.660 114.9 33.4 21.2
2004 05 15 12 50.46 +39 38.3 1.063 1.708 110.9 33.6 21.5
2004 05 25 12 52.08 +36 02.3 1.172 1.753 106.5 33.6 21.8
2004 06 04 12 56.78 +32 23.0 1.286 1.796 102.0 33.5 22.0

[Dennis]

Originally Posted by astroron

This data from MPC bears no resemblance to your data.
Putting the data into the sky program has it no where near
the positions on your program.
What am I doing wrong.
Note the position for the 26 Jan?
Orbital elements:
2004 BL86 PHA 0.004A
Epoch 2004 Jan. 16.0 TT = JDT 2453020.5 MPC
M 24.06569 (2000.0) P Q
n 0.53764402 Peri. 309.77739 +0.17125920 -0.92924834
a 1.4978656 Node 127.19921 +0.98185576 +0.13351605
e 0.4043040 Incl. 24.26670 +0.08142210 +0.34448656
P 1.83 H 18.8 G 0.15
From 10 observations 2004 Jan. 30-31.

Ephemeris:
2004 BL86 a,e,i = 1.50, 0.40, 24 q = 0.8923
Date TT R. A. (2000) Decl. Delta r Elong. Phase V
2004 01 26 14 13.36 +09 38.5 0.334 1.078 97.2 64.9 18.9
2004 02 05 14 28.98 +20 32.5 0.363 1.137 105.3 56.7 18.9
2004 02 15 14 37.32 +29 52.5 0.400 1.198 112.4 49.7 19.1
2004 02 25 14 37.37 +37 33.8 0.444 1.260 117.9 43.9 19.2
2004 03 06 14 28.82 +43 27.6 0.495 1.322 121.9 39.6 19.4
2004 03 16 14 12.74 +47 26.9 0.553 1.383 124.1 36.5 19.7
2004 03 26 13 51.89 +49 28.8 0.619 1.443 124.7 34.7 20.0
2004 04 05 13 30.60 +49 41.3 0.693 1.500 123.7 33.7 20.3
2004 04 15 13 12.62 +48 25.0 0.775 1.556 121.6 33.3 20.6
2004 04 25 12 59.90 +46 04.5 0.864 1.609 118.6 33.3 20.9
2004 05 05 12 52.76 +43 02.9 0.960 1.660 114.9 33.4 21.2
2004 05 15 12 50.46 +39 38.3 1.063 1.708 110.9 33.6 21.5
2004 05 25 12 52.08 +36 02.3 1.172 1.753 106.5 33.6 21.8
2004 06 04 12 56.78 +32 23.0 1.286 1.796 102.0 33.5 22.0

Hi Ron

The MPC data you have copied/pasted looks like it shows the positional information in the date range of 2004 01 26 to 2004 06 04.

The Sky X Pro and Sky Safari data is for 2014 Jan 26th, some 10 years later.

Or, am I missing something?

Cheers

Dennis