New comet C/2010 X1 Elenin

[Outbackmanyep]

Hi all,

C/2010 X1 Elenin has had it's orbit adjusted, it should reach mag 4 next year providing the prediction stay sound.
Perihelion is in September, and because of it's low solar elongation it will favour northern hemisphere observers, we will see it as a morning object in the dawn twilight then the Moon will interfere. The comet will follow the ecliptic, and it will cross the border from Virgo to Leo.

http://scully.cfa.harvard.edu/~cgi/R...d=c&o=CK10X010

The geometry is good with the comet passing between Earth and the Sun, a perihelion distance of 0.4 AU.

The comet was discovered by Leonid Elenin, an amateur astronomer in Russia last week which was announced on the 14th December.

I will post more details shortly!

[mithrandir (Andrew)]

From JPL Horizons for Stellarium:

[Elenin_C2010_X1]
# Data taken from JPL/HORIZONS
# correct for the specified time frame:
# Start Time : A.D. 2010-Dec-24 00:00:00.0000 CT 
# Stop Time  : A.D. 2010-Dec-24 00:00:00.0000 CT 
name                        = Comet Elenin (C/2010 X1)              
parent                      = Sun
coord_func                  = comet_orbit
radius                      = 10
oblateness                  = 0.0
albedo                      = 1
lighting                    = true
halo                        = true
color                       = 1.0,1.0,1.0
tex_halo                    = star16x16.png
tex_map                     = nomap.png
lighting                    = false
orbit_Epoch                 = 2455554.500000000
orbit_TimeAtPericenter      = 2455572.1216092836
orbit_PericenterDistance    = 5.754485624450996
orbit_Eccentricity          = 1.00003539933058
orbit_ArgOfPericenter       = 211.2547634005463
orbit_AscendingNode         = 322.0587099338747
orbit_Inclination           = 1.54681826747003

** WARNING **

The initial state available for this object was a Keplerian two-body
orbital element set, not osculating elements. This means the orbit is probably
very poorly determined. Predictions for times many months or years from the
epoch may not be suitable for high-accuracy applications or expectations.

Since the epoch is inside or within ~30 days of the relatively short data
arc, the elements (such as they are) were numerically propagated with
perturbations, just as if they were osculating elements.

[CometGuy]

Maik Meyer Just released a new orbit:

T = 2011 Sep 11.454713
q = 0.487002 AU
Arg Peri = 343.58500
Asc Node = 323.29387
i = 1.84273

In the southern hemisphere the comet is best seen before and at perihelion (mid-September), with post perihelion being better seen from the northern hemisphere when the comet makes a relatively close passage to earth in mid-October.

Based on current CCD magnitudes the comet appears intrinsically faint so there some question as to whether it will become bright. But we wont know until it is a lot closer to the sun.

Terry

[Outbackmanyep]

well Terry, i guess we'll just have to keep an eye on it and see what it does!

[mithrandir (Andrew)]

JPL's latest figures have it reaching mag ~3.5.

In the middle of the day in September and down to about 6 by the time it will be visible in the morning sky of early October.

[Outbackmanyep]

It's going to move rapidly post-peri, we should still get a good view!

[Liz]

Originally Posted by Outbackmanyep

It's going to move rapidly post-peri, we should still get a good view!

Woohoo ... great to hear OBMY!!

[astroron (Ron)]

Fingers and Toes crossed it is a good one and we get a chance to see it
Cheers

[ZeroID (Brent)]

Forgive my ignorance but I presume that some of the below data replaces the earlier posted script for Stellarium .ini file above. ( still learning this stuff ). If that is the case I figured where the last three lines go but T & q I can't see where they would fit. ( I just wanna track and see this comet !! )

Originally Posted by CometGuy

Maik Meyer Just released a new orbit:

T = 2011 Sep 11.454713
q = 0.487002 AU
Arg Peri = 343.58500
Asc Node = 323.29387
i = 1.84273

In the southern hemisphere the comet is best seen before and at perihelion (mid-September), with post perihelion being better seen from the northern hemisphere when the comet makes a relatively close passage to earth in mid-October.

Based on current CCD magnitudes the comet appears intrinsically faint so there some question as to whether it will become bright. But we wont know until it is a lot closer to the sun.

Terry

[mithrandir (Andrew)]

Originally Posted by ZeroID

Forgive my ignorance but I presume that some of the below data replaces the earlier posted script for Stellarium .ini file above. ( still learning this stuff ). If that is the case I figured where the last three lines go but T & q I can't see where they would fit. ( I just wanna track and see this comet !! )

It will take more observations to get a reliable set of figures to produce predictions more than a few days ahead. So far JPL only has 8 days of data with 62 observations. This is why the warning accompanies the data:

The initial state available for this object was a Keplerian two-body orbital element set, not osculating elements. This means the orbit is probably very poorly determined. Predictions for times many months or years from the epoch may not be suitable for high-accuracy applications or expectations.

Based on the latest JPL data:

[Elenin_C2010_X1]
# Data taken from JPL/HORIZONS
# correct for the specified time frame:
# Start Time : A.D. 2010-Dec-29 00:00:00.0000 CT 
# Stop Time  : A.D. 2010-Dec-29 00:00:00.0000 CT 
name                        = Comet Elenin (C/2010 X1)              
parent                      = Sun
coord_func                  = comet_orbit
radius                      = 10
oblateness                  = 0.0
albedo                      = 1
lighting                    = true
halo                        = true
color                       = 1.0,1.0,1.0
tex_halo                    = star16x16.png
tex_map                     = nomap.png
lighting                    = false
orbit_Epoch                 = 2455559.500000000
orbit_TimeAtPericenter      = 2455344.8351876955
orbit_PericenterDistance    = 5.383678459548473
orbit_Eccentricity          = 1.000050824373353
orbit_ArgOfPericenter       = 187.2421383600018
orbit_AscendingNode         = 321.2292862441847
orbit_Inclination           = 1.521556790548213

This differs from the figures in MPEC 2010-Y24 so neither can be considered really accurate.

[CometGuy]

Not sure if this link will help, but has updated orbital elements for different programs:

http://www.minorplanetcenter.org/iau...ftwareEls.html

As for the JPL orbit it appears to be similiar to the original orbit published in MPEC 2010-X101 on December 12. However, the latest orbit on MPEC 2010-Y24 is based on 12 days of observation. I believe the perihelion distance and general orbit is pretty close to correct in Y24, however I believe the Perihelion date may change a couple of days.

For stellarium it seems that

q = orbit_PericenterDistance
T = orbit_TimeAtPericenter (but you have to convert to Julian Date).

So the try these:

[Elenin_C2010_X1]
# Data taken from JPL/HORIZONS
# correct for the specified time frame:
# Start Time : A.D. 2010-Dec-29 00:00:00.0000 CT
# Stop Time : A.D. 2010-Dec-29 00:00:00.0000 CT
name = Comet Elenin (C/2010 X1)
parent = Sun
coord_func = comet_orbit
radius = 10
oblateness = 0.0
albedo = 1
lighting = true
halo = true
color = 1.0,1.0,1.0
tex_halo = star16x16.png
tex_map = nomap.png
lighting = false
orbit_Epoch = 2455808.50000
orbit_TimeAtPericenter = 2455808.92662
orbit_PericenterDistance = 0.4420298
orbit_Eccentricity = 1.000000
orbit_ArgOfPericenter = 345.23890
orbit_AscendingNode = 323.24604
orbit_Inclination = 1.84963

Terry

[mithrandir (Andrew)]

Originally Posted by CometGuy

Not sure if this link will help, but has updated orbital elements for different programs:

http://www.minorplanetcenter.org/iau...ftwareEls.html

As for the JPL orbit it appears to be similiar to the original orbit published in MPEC 2010-X101 on December 12. However, the latest orbit on MPEC 2010-Y24 is based on 12 days of observation. I believe the perihelion distance and general orbit is pretty close to correct in Y24, however I believe the Perihelion date may change a couple of days.

For stellarium it seems that

q = orbit_PericenterDistance
T = orbit_TimeAtPericenter (but you have to convert to Julian Date).

Stellarium 0.10.6.1 can use the MPC data directly with the "Solar System Editor" plugin - you only have to enable it, restart and run through the panels to import the data.

The way Stellarium uses the radius and albedo to calculate the size and brightness leads me to suggest these with Terry's figures:

radius = 86.1944596468567
albedo = 0.15

except in 0.10.6 and beyond which allows for H and G to be retained and so:

radius = 5 # fictitious as documented in the source code
albedo = 1 # also fictitious 
absolute_magnitude = 8
slope_parameter = 4

However an albedo of 0.15 is supposed to be a reasonable average value for comets, and give that the formula (Perl syntax):

$radius=1329/sqrt($albedo)*10**(-0.2*$mag);

is accepted as valid by several references, the radius comes out at around 86.

Barry, if you see this, can you get that formula given some consideration instead of the hard coded values in the source? The same formula applies to asteroids using albedo 0.04

[Greg Bryant]

The latest orbit determination from the Minor Planet Centre is given at the bottom of the below link.

http://www.minorplanetcenter.org/mpec/K11/K11A08.html

There's a chance that if the comet turns out to be very long period (which won't be known for a while longer), a very, very close approach to Earth in October is on the cards.

Watch this space.

Greg

[h0ughy (David)]

thats great news looking forward to this

[mithrandir (Andrew)]

Originally Posted by Greg Bryant

The latest orbit determination from the Minor Planet Centre is given at the bottom of the below link.

http://www.minorplanetcenter.org/mpec/K11/K11A08.html

There's a chance that if the comet turns out to be very long period (which won't be known for a while longer), a very, very close approach to Earth in October is on the cards.

Those numbers match JPL. New values for Stellarium:

[Elenin_C2010_X1]
# Data taken from JPL/HORIZONS
# correct for the specified time frame:
# Start Time : A.D. 2011-Jan-05 00:00:00.0000 CT 
# Stop Time  : A.D. 2011-Jan-05 00:00:00.0000 CT 
name                        = Comet Elenin (C/2010 X1)              
parent                      = Sun
coord_func                  = comet_orbit
oblateness                  = 0.0
lighting                    = true
halo                        = true
color                       = 1.0,1.0,1.0
tex_halo                    = star16x16.png
tex_map                     = nomap.png
lighting                    = false
orbit_Epoch                 = 2455566.500000000
orbit_TimeAtPericenter      = 2455815.5800386025
orbit_PericenterDistance    = 0.4845932028112245
orbit_Eccentricity          = 0.9999975116715066
orbit_ArgOfPericenter       = 343.762694978635
orbit_AscendingNode         = 323.1999299462579
orbit_Inclination           = 1.836414212487844
radius                      = 34
albedo                      = 0.15
absolute_magnitude          = 10
slope_parameter             = 13.6
type                        = comet

The last 3 lines are only to be used with 0.10.6.1 or later

[Blue Skies (Jacquie)]

Originally Posted by Greg Bryant

There's a chance that if the comet turns out to be very long period (which won't be known for a while longer), a very, very close approach to Earth in October is on the cards.

Watch this space.

Greg

Now I'm interested - I'll be watching! Although I'm wondering how much "very, very close" is. 0.1 AU? Or even less than that?

[mithrandir (Andrew)]

Someone might want to double check CdC's calculations on some other software, but it seems that by the time Elenin reaches the predicted mag 3.8 at a distance of 0.6 AU in Sep 2011 it will be setting at about sunset.

The first couple of weeks of Sep appear to have the best viewing.

[Greg Bryant]

Jacqui,

If the comet's orbit turned out to be long period (~400 years, e=0.99), we might have seen a close approach to Earth of 0.03 au in October (date of perihelion shifted by about 8 days). However, according to Maik Meyer, who has been analysing the reported observations thus far, at this stage it's looking less likely now.

Greg

[Liz]

Sounds good, but so far away still ..... next October!!
New data from Maik Meyer is certainly sounding more positive, bringing it nice and close to Earth.

[Blue Skies (Jacquie)]

Originally Posted by Greg Bryant

Jacqui,

If the comet's orbit turned out to be long period (~400 years, e=0.99), we might have seen a close approach to Earth of 0.03 au in October (date of perihelion shifted by about 8 days). However, according to Maik Meyer, who has been analysing the reported observations thus far, at this stage it's looking less likely now.

Greg

Thanks, Greg. That would be very close! I'll keep an eye on this one, anyway.