Comet C/2019 Y4 (ATLAS)
years, amateur astronomers have been waiting for a bright, naked-eye
comet to pass by Earth — and finally, such an object may have arrived.
possible celestial showpiece is known as Comet ATLAS, or C/2019 Y4.
When it was discovered on Dec. 28, 2019, it was quite faint, but since
then, it has been brightening so rapidly that astronomers have high
hopes for the spectacle it could put on.
But given the tricky nature of
comets, skywatchers are also being cautious not to get their hopes up,
knowing that the comet may fizzle out.
been awhile since a comet gave skywatchers a good show, particularly in
the Northern Hemisphere.
In March 2013, Comet PanSTARRS was visible
right after sunset, albeit low in the western sky.
But although it
briefly attained first magnitude with a short, bright tail, its low
altitude and a bright,
twilight sky detracted from what otherwise would
have been a much more prominent object.
Below is a stack of 66 30 second subs at 1600
ISO. Orion EON ED80 & Canon 60Da. Stacked in Astro Pixel Processor
Comat Atlas, C/2019 Y4 no longer has a round coma. It elongated now and brightness is down dramatically.
Here's my shot from tonight. second is a crop.
I thought my stacking program was messed up.....
Possible Disintegration of Comet C/2019 Y4 (ATLAS)
ATel #13620; Quanzhi Ye (U. Maryland), Qicheng Zhang (Caltech)
on 6 Apr 2020; 17:12 UT
Distributed as an Instant Email Notice Comets
Credential Certification: Quanzhi Ye (firstname.lastname@example.org)
Referred to by ATel #: 13622
report the possible disintegration of comet C/2019 Y4 (ATLAS), revealed
by the public monitoring program
carried out by the 0.6-m Ningbo
Education Xinjiang Telescope (NEXT).
Images taken on UT 2020 April
5.6-5.9 showed an elongated pseudo-nucleus measuring about 3 arcsec in
length and aligned with the axis of the tail,
a morphology consistent
with a sudden decline or cessation of dust production, as would be
expected from a major disruption of the nucleus.
The elongation is
grossly consistent with the roughly +5" in RA, -1" in Dec astrometric
residuals currently (as of MPEC 2020-G65) being reported relative to
JPL orbit solution #5,
implying a relative projected motion of order
5-10 m/s from the original nucleus' orbit.
A disruption event could
also potentially explain the large non-gravitational forces acting on
the comet, as reported in CBET 4744.
Composite stacks of 10 x 30-s
r-filtered frames illustrating the change in morphology from April 2 to
5 can be found at https://near.earth/shared/2020/04/next_20200405.png
(The images from both days were obtained without comet-rate tracking,
but the exposure was sufficiently short that the trailing of the comet
due to its non-sidereal motion is only 1.3 pixel,
much shorter than the
elongation of the pseudo-nucleus. The direction of the trailing is also
at a ~30 deg angle to the long-axis of the elongated pseudo-nucleus.)
C/2019 Y4. I think this is only the second time in my life I've seen a comet's tail without seeing a nucleus...
first time was Comet McNaught. It was so bright you could see the tail
on the horizon at dusk, even though the coma was below the horizon