Общие вопросы астрономии > Новости наблюдательной астрономии
СИЛЬНЕЙШАЯ ВСПЫШКА 17P/HOLMES – до 2.5m !!!
ctac:
Снимки от Garik'а из Воронежа:
ctac:
Интересное сравнение изменения размеров кометы
Иван Сергей:
И мои снимки с разными выдержками. При 2,8 с комета получается передержанной. Прямой фокус 200 мм SW ссd. Визуально, яркость кометы 24/25 10 07 около 2,7-2,8. При 300 кратном увеличении видно желтое продолговатое ядро. Заметна ассиметрия ядра - его центр не совпадает с центром головы.
Выдержки 1, 0,5 0,7 0,17 сек
ched:
IAUC 8886
--- Цитата: IAUC 8886 ---COMET 17P/HOLMES
This comet (currently near opposition) has been observed to be
undergoing a very large outburst in brightness; based on normal
behavior in recent apparitions, it was predicted to be near total
mag 16 for most of 2007 (H_15 approximately 9.5, from 2007 Comet
Handbook) -- and, indeed, observers have consistently reported it
around mag 16 +/- 1 since last May, L. Buzzi (Varese, Italy, 0.60-m
reflector) reporting the comet at mag 17.8 on Oct. 20.9 UT and G.
Muler (Lanzarate, Spain, 0.20-m reflector) measuring mag 16.8-17.3
on Oct. 23.0. The first known detection of the current outburst
was communicated by M. Kidger (Herschel Science Centre, European
Space Astronomy Centre, Madrid), who writes that observations by J.
A. Henriquez Santana (Tenerife) on Oct. 24.067 show the comet at
``nuclear" mag 8.4 ("some 9 mag brighter than previously" seen)
with a 0.2-m reflector, and that the comet was brightening by 0.5
mag/hr "over the course of 6 hr"; the outburst was confirmed during
Oct. 24.07-24.09 by Muler and by R. Naves and M. Campas (Barcelona)
with a bright, almost-stellar inner coma (mag R = 7.3 in a 10"
square aperture on Oct. 24.136). F. Kugel (Banon, France) reports
that unfiltered astrometric CCD images taken by C. Rinner and
himself on Oct. 24.21 with a 0.5-m reflector shows an object of
stellar appearance of mag 7.4 at the predicted position of 17P.
Following a discussion-group e-mail alert of the outburst,
several other observers have confirmed the outburst. E. Guido and
G. Sostero (Castellammare di Stabia, Italy, 0.25-m f/3.4 reflector)
write that ten co-added 5-s B-band CCD exposures taken remotely on
Oct. 24.34 with a 0.25-m reflector near Mayhill, NM, show the comet
as a bright, featureless, starlike object of total mag about 4.6.
A. Hale (Cloudcroft, NM) reports viewing the comet as an easy
naked-eye starlike object of mag 4.0 on Oct. 24.50. S. Yoshida
(Yokohama City, Kanagawa, Japan) reports the comet to be visible
via naked eye even in a large city, at mag 3.5 on Oct. 24.55; with
a 6.6-cm refractor, it looked completely stellar. Within two hours,
Yoshida adds that the comet had brightened an additional half a
magnitude, to mag 3.0 on Oct. 24.63 as seen via naked eye. K.
Kadota (Ageo, Saitama-ken, Japan, 0.25-m f/5 reflector) notes that
his CCD image from Oct. 24.61 yields total mag 3.6 and coma
diameter 1'.7 (though starlike with no tail).
Comet 17P also underwent a large outburst in brightness when
it was first discovered in Nov. 1892 near total visual mag 4 (which
was also about 12 mag over the "normal" brightness); at that time,
it faded by about 3 mag over the following week (e.g., Kronk 2003,
Cometography 2, 694).
2007 October 24 (8886) Daniel W. E. Green
--- Конец цитаты ---
ched:
IAUC 8887: спектр кометы
--- Цитата: IAUC 8887 ---COMET 17P/HOLMES
H. Kobayashi, H. Kawakita, and A. Nishikoji, Kyoto Sangyo
University, report that they have obtained low-dispersion spectra
of comet 17P on Oct. 24.58 and 25.46 UT with a 28-cm telescope (+
F2SPEC spectrograph; range 380-750 nm, resolution 900 at 600 nm).
The comet's spectrum on Oct. 24.58 was dominated by reflected
sunlight, and there were no significant emission bands and lines
visible. The Oct. 25.46 spectrum was still dominated by reflected
sunlight, but emission bands and lines (CN and C_2 bands, as well
as [O I] emission lines) appeared in the spectrum. The authors
speculate that this delay in the visibility of emission might be at
least partly caused by sublimation from icy grains ejected at the
outburst.
R. M. Wagner, LBT Observatory; S. Starrfield, Arizona State
University; G. Schwarz, West Chester University; S. Larson, Lunar
and Planetary Laboratory; and R. Kaitchuck, J. Childers, and G.
Turner, Ball State University, write that they obtained several
long-slit spectra (slit length 3'.7 in p.a. 90 deg; range 340-640
nm; resolution 0.6 nm) of comet 17P on Oct. 25.181 and 25.465 UT
with the Bok 2.3-m telescope on Kitt Peak. The spectra exhibit a
strong reflected continuum arising from dust. The spatial
continuum profile along the slit is strongly peaked in the inner
0'.5 but extends out to a diameter of about 1'.5; the profile also
appears asymmetric to the east and becomes more pronounced and
wider in the later spectrum, suggesting that dynamical effects
arising from the outburst are visible in the inner coma. Molecular
emission bands of CN, C_3, C_2, and NH_2 -- typical of other
gaseous comets -- are detected, as well, and are prominent away
from the bright optocenter. Emission from CN (0-0) can be traced
out to at least 2'.4 from the optocenter in each direction.
Further reductions and analyses are underway. Additional
spectroscopy to study the evolution of the dust and gas is
encouraged.
A. Fitzsimmons, Queen's University, Belfast; C. Snodgrass,
European Southern Observatory; and J. Southworth, University of
Warwick, report that spectra of comet 17P, centered on the central
condensation, were obtained on Oct. 26.05 UT using the 2.5-m Nordic
Optical Telescope (+ FIES echelle spectrograph; range 370-730 nm,
resolution 48000) on La Palma. The spectra are dominated by a
reflected solar spectrum from dust grains. Molecular emission bands
due to CN at 388 nm, C_3 at 405 nm, and C_2 at 516 nm are also
visible.
Further naked-eye magnitude estimates (cf. IAUC 8886): Oct.
25.29 UT, 2.8 (C. W. Hergenrother, Tucson, AZ, U.S.A.); 26.07, 2.6
(A. Pereira, Carnaxide, Portugal); 26.90, 2.4 (J. Carvajal, Madrid,
Spain).
2007 October 26 (8887) Daniel W. E. Green
--- Конец цитаты ---
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