SOHO-LASCO Comet Reports for 200201

Another informational notice:



Those good folks at LASCO have created more useful internet stuff

for you to use.  Running difference real-time movies are

available at http://lasco-www.nrl.navy.mil/rtmovies.html

These images are excellent for identifying comets as they maximize

the contrast.  It's the way I usually look at the data.



Doug

possible Kreutz comet in C2 images

b/w 512*512 from the lasco website

enlarged to 1024*1024

0,0 in upper left corner



time (Jan 05) x,y

1854  42, 748

1931  72, 712

1954  92, 690

2006 100, 678





Regards, Rainer

Don't consider my report Jan 05 2002 15:12:55

nothing visible in 1024*1024 at 1954



 Regards, Rainer

If you look carefully you can see 96P (Machholz) near the edge of

the C3 field of view a little below the oculting bar.  My guess is mag. 9 and it looks decidingly elongated.



Anyone else see it?



Terry Lovejoy 

Dear Terry, dear all.



Actually 96P/Machholz starts to be visible at the left side of

the pylon in 12:42 b/w. It is very bright, brighter than 

expected - estimation: ~ mag 3.5 (with pylon obstruction!)



Perhaps it is only visible in b/w due to the gif mask.



Positions (0,0) upper left, 512 x 512



12:42  81,420

13:42  84,416



Regards, Sebastian

I think 96P is just emerging from the oculting bar

in C3 1342 UTC 166,834 (0,0) upperleft corner

very bright!



 Regards Rainer

OK Sebastian, 96P is now really visible on two B&W images at 12:42

 and 14:42 UT. It's very bright and elongated.



Xavier Leprette

Greetings all;



It's great to see Periodic Comet Machholz 1 doing well

in these SOHO images.  I've been looking forward to its

passage through the C3 field for some time now.



P/96 is the periodic comet (comets with orbital periods

of under 200 yrs) with the 5th shortest period (5.24 yrs)

and goes closest to the sun (0.10AU) than any other known

periodic comet.  Because of it's closeness to the sun, and

because of the way it behaves, it gets brighter, on a con-

sistant basis, than any other periodic comet.  The problem

is that when it is at its brightest it is close to the sun

and not visible in dark sky.  In large instruments it is

also visible at aphelion (~5 AU).



The comet is known to outburst at times so let's keep an eye

on it.  One theory is that it is only a mile across, the other

theory is that it is large and mostly dormant.  Its last

passage through the SOHO field was on Oct. 15, 1996.



FYI, the comet was discovered on May 12, 1986 from the Santa

Cruz Mtns near San Jose in California.  I found it two degrees

south of M31.  It was mag. 10 and slowly dimming.



You SOHO comet guys are doing a hearty job of searching for

comets.  I'm pleased to join you for these next few days

as the comet crosses the field.



Don Machholz

 

As an addition here is a reference that might be useful for those

who have a further interest in this comet:



Zdenek Sekanina

"Periodic Comet Machholz and its idiosyncrasies"

Astronomical Journal, vol. 99, April 1990, p. 1268-1277, 1378



It is downloadable via the NASA Astrophysics Data System (ADS).



Regards, Maik

Possible comet in C2 image



positions 512x512 (0,0) top-left corner





2002/01/06



14:54 (6,438)

15:06 (7,434)

15:30 (13,419)

15:54 (19,408)

16:06 (23,402)



Object faint on a Kreutz orbit



Regards,



Toni Scarmato

20020107_2142_c3.gif (187,254)

20020107_2342_c3.gif (183,259)

20020108_0042_c3.gif (177,269)

20020107_2142_c3.gif (177,269)

20020107_2342_c3.gif (184,259)

20020108_0042_c3.gif (187,256)

96P/Machholz has entered C2 at 04:54 UT.



Regards, Sebastian

A question:



Why doesn't the tail look perpendicular 

to the sun/occulting disk? I thought 

a comet's tail would slowly rotate

counter clockwise pointing away as it 

neared the Sun.



 Mike B.

Wow! What a nice comet Don Machholz provided for us.  We're taking

lots of images that don't show up in the real-time images.  Primarily,

we're taking images with shorter exposure times toprevent saturation.

Unfortunately, even some of those are saturated.  Looks like the

comet reached at least magnitude -1.  About the tail.  I think

there are a few considerations.  First, we are seeing it in projection.

So, the bulk of the tail may very well be pointing at least roughly

radially.  But also, comets at 1 AU and beyond are trudging along.

This comet is smoking, on the order of 100 km/s.  Thus, the motion

of the comet significantly affects the tail direction, as radiation

pressure is a relatively weak force and takes time to push

the tail out.



I have not been able to find anything at the locations of the

Jan 6 object claimed by T. Scarmato.



The positions reported by Zheng Yin are positions for 96P/Machholz.



Doug

The tail's bending behind the comet is an effect of

differential orbital angular momentum, caused by

radiation pressure.  Eventually the comet will have

two tails, one to the north (new ejecta) and the one

to the southeast (old ejecta).  The sector in between

will also be filled with material, which will only

faintly be seen.

Possible not Kreutz comet in c3



positions 512x512(0,0) top-left corner





2002/01/10



15:42 (6,231)

16:42 (9,227)

17:42 (12,223)





I am waiting other images to confirm





oni Scarmato

Not consider my last report.



No object visible at 18:18





Toni Scarmato

Possible comet in C2 realtime images 

(1024 x 1024 format, 0,0 in upper left corner)



20020111_0230  63,772

20020111_0206  35,787

20020111_0154  25,797

20020111_0131  14,816 



Tony Hoffman

Wow!  Wasn't that a great comet?  I want to thank Don Machholz for

providing us with what is definitely the best comet seen with LASCO

thus far.  Many of you may have noticed an apparent reduction in

the number of C3 pictures.  That's because the real-time movies

only show the standard 19sec exposures.  In fact, in between each

of those 19sec exposures we took a 5sec exposure.  Thus, preventing

saturation and enabling us to do photometry.  However, even these

exposures saturated slightly right at perihelion.  Due to this,

there is some uncertainty in the magnitude estimates.  However,

it appears to have reached at least -0.6 and it may have peaked

at just about -1.  And wasn't that tail fantastic?



One of many sites to feature this comet in LASCO:

http://antwrp.gsfc.nasa.gov/apod/ap020111.html



Now back to those `boring' old sungrazers.



Doug

I do not believe that the claim of T. Hoffman for an object in

C2 on Jan 11 is anything other that cosmic rays.  One of the

reasons is the apparent shape of the points indicated.  Any 

astronomical object imaged with the telescope must of course

have the light pass through the telescope.  This light, due to

a variety of effects, is not focused perfectly.  The resulting

image is always slightly spread out.  Cosmic rays interacting

in the CCD, do not exhibit this spreading.



Doug

Sorry for the late noteice.  Last week, it was determined that

spacecraft momentum management and station-keeping maneuvers were

necessary.  These will take place tomorrow.  Thus, the LASCO doors

will be closing at about 22 UT today and we expect to re-open them

at about 16 UT on Thursday (Jan 17).  Take a welcome break everyone.



Doug

Well, it took a long time, but we have finally acted on a

couple of old reports.  First, we have accepted the report

of X. Zhou of a comet on 18 Dec 2001 in C2.  The rough

position measurements are given below.  Second, we were

considering a claim by T. Scarmato for a comet on 25 Apr

2001 also in C2.  For that object, we believe it likely

to be a real comet, but it doesn't meet our minimum

criteria, thus, we are adding it to our 'denied' list.

This is a list we keep only for comets where there is

doubt remaining.  These are comets that don't meet

our criteria but which also show some compelling evidence.



Doug



SOHO-387

# HEIGHT   DATE     TIME   ANGLE  TEL  FC    COL     ROW

  7.88 2001/12/18 05:54:05 138.7   C2  10    77.0     8.0

  7.79 2001/12/18 06:06:05 138.3   C2  10    79.0    17.0

  7.60 2001/12/18 06:30:06 137.5   C2  10    83.0    35.0

  7.41 2001/12/18 06:54:05 136.6   C2  10    87.0    54.0

  7.10 2001/12/18 07:32:17 135.4   C2  10    96.0    82.0

  6.91 2001/12/18 07:54:34 134.5   C2  10   101.0   100.0

  6.60 2001/12/18 08:30:05 132.9   C2  11   110.0   130.0

  6.39 2001/12/18 08:54:06 131.9   C2  10   116.0   149.0

  6.28 2001/12/18 09:06:05 131.3   C2  10   120.0   159.0

  6.07 2001/12/18 09:30:05 130.1   C2  10   126.0   179.0

 

 20020114_2147_c3          (502,212)

  c3  20020114_2147_c3          (502,212)

Possible comet in C3 realtime images

(512x512 format  0,0 upper left corner



20020120_1618    131,415

20020120_1542    106,428

20020120_1518     85,454



Alex Roca

Possible comet in C3 realtime images

(512x512 format 0,0 upper left corner)

fourth frame

20020120_1642    145,392

Alex Roca

I am unable to confirm the report of A. Roca.  The first 3 points

appear to be just random cosmic rays and the fourth point is a

star.  Note, the chaotic motion of the points indicated are not

what one would expect for a physical object.



Doug

Hi all,

	Just a note that I neglected to include the planet Neptune

on the C3 transits list.  It is currently visible in LASCO C3.  It

entered the FOV on Jan 20th.  Rough position measurements are given

below.  It appears to the left of the brightish star Upsilon

Capricorn (m=5.2) (SAO# 163779 and HD# 196777) and just to the

right of an m=7.3 star designated as SAO# 163811 and HD# 197187.



Doug



# HEIGHT   DATE     TIME   ANGLE  TEL  FC    COL     ROW

 29.20 2002/01/20 12:42:05  83.8   C3  10    10.0   586.0

 28.54 2002/01/20 17:18:05  83.8   C3  10    21.0   585.0

 27.83 2002/01/20 21:42:05  83.8   C3  10    33.0   584.0

 26.94 2002/01/21 02:42:05  83.8   C3  10    48.0   582.0

 26.35 2002/01/21 06:42:06  83.8   C3  10    58.0   581.0

 25.70 2002/01/21 11:18:05  83.8   C3  10    69.0   580.0

 24.88 2002/01/21 15:42:05  83.7   C3  10    83.0   579.0

 24.11 2002/01/21 20:42:06  83.8   C3  10    96.0   577.0

 23.29 2002/01/22 01:42:16  83.7   C3  10   110.0   576.0

 22.71 2002/01/22 05:42:05  83.7   C3  10   120.0   575.0

 22.01 2002/01/22 10:20:37  83.6   C3  10   132.0   574.0

 21.37 2002/01/22 14:42:05  83.6   C3  10   143.0   573.0

 20.63 2002/01/22 18:42:05  83.4   C3  10   156.0   573.0

 19.92 2002/01/22 23:42:05  83.5   C3  10   168.0   571.0

 19.17 2002/01/23 04:18:05  83.6   C3  10   181.0   569.0

Possible sungrazer comet in a real-time B&W C3 images now.



The object is fairly bright, small, and it's visible in 3 consecutive images

on 2002/01/24 from 14:42 to 15:42 UT on the left of the pylone. 

The object is moving towards the sun.



Approximate positions measured from the top-left corner

of a 512x512 frames : 

           col, row

14:42 UT  77,384

15:18 UT  80,381



Xavier Leprette

Ignore my previous report, it's not real.

Sorry



Xavier

Possible comet or minor planet on c3 field of view.

I did not find it on the debris list.



A fearly bright spotlike object is moving from left to

right horizontally above the Sun on C3 images.

Entering at 2002. jan 24. 2:42 UT, and still visible

at 2002 jan 26 6:16 UT.

Its brighness was at maximum when entered, and becoming

more and more dimmer since then.



Positions on C3 512x512 images:



         UT          (x,y)



2002 jan 24  2:42:   (5,136)

         24  5:42:  (13,136)

         24 11:18:  (30,136)

         24 21:56:  (61,136)

         25  5:18:  (83,136)

         25 18:18: (121,135)

         26  6:18: (157,135)



Jozsef Gyurusi

Please ignore my previous alarm.

The object seems to be the Mercury.

Jozsef

In SOHO Lasco c3 images, an object passes thru the field from L to R starting somewhat before 1/25 and exiting to the right side on 1/31 (today).  Object is above the sun, about halfway up the picture, moving from left to right.  If this is an identified comet, which one is it?

That would likely be the good comet Neptune? See C3 Transits for greater certainty.

Just to clarify the situation.  For the past week, 3 planets were

visible in the LASCO images.  Venus is the very bright one moving

from right to left, below the Sun.  Mercury was the fast moving

one above the Sun, moving left to right.  Neptune is moving at

about the same speed as the stars, from left to right.  It's

pretty much at the same height in the images as the Sun.



Doug