my recent diary
otherwise noted I use the following materials since the end of October,
Telescope: D: 45.5cm f: 2037mm
Dobsomian (Newtonian reflector)
Eyepiece: and magnification: Lavendura
63mm, apparent FOV 45 deg. with Paracorr
x37, actual FOV 1.2 deg.
Night Vison: ACT
PVS-14 Photonis 4G INTENS 1800 Auto gate P45 WP
Saturday, January 21 to Sunday, January, 22
Drawing a sketch of C/2022 E3 ZTF
Although air temperature was as low as -6ºC, the condition was
favorable without wind and clear sky. C/2022 E3 brightened up to 6th
magnitude and worth observing. I have observed the lengths of the ion and
the dust tails of the comet as 1.5º and 0.5º, respectively, on Tuesday,
Jan. 17 using my 46 cm reflector, and I was curious about the present
situation of the tails. The appearance of the tails observed by Night
Vision, 37x was equivalent with that seen by Ethos 21 mm + Paracorr, 112x.
I confirmed the length of the dust tail was 0.5º using a 7x50 mm binocular
at this predawn after 4a.m. local time. I tried to detect the comet by
naked eye but could not do by any means.
Sketch of C/2022 E3 ZTT Part 1. 46 cm NV 37x.
I had a plan to draw a sketch of this comet this predawn using my 46 cm
telescope with NV 37x prior to the comet hunting session. The first
impression when I aimed my telescope at the comet was that weirdness of
the short tail as short as 40f (refer to the sketch). I wondered if the
cause was slightly poor transparency of the sky, but it is unlikely
because NV has a tolerance for hazy sky condition due to the extended
sensitivity up to infrared area. Anyway, the length had become shorter
without doubt. Later, I have learned there was a hypothesis on the
reduction of the length via comets-ml. That said the cause was cut-down of
the tail due to solar plasma polarity reversal originated from recent
solar flare. Comets have a magical power to transform!
Observation by Nick James: C/2022 E3 (ZTF) tail disconnection
Todayfs hunting session
After making a sketch, I started one-and-a-half-hour hunting session
from Zubenelgenubi, Ώ Librae. There are many galaxies are with 11th
magnitude or darker in the constellation of Libera, but few of them are
detectable during the session if the sky condition is not good. Thanks to
the aid of NV I could identified seven galaxies in total: NGC5898, 5893,
5796, 5878, 5861, 5915 and 5916. Among them the darkest one was NGC5916
with the magnitude of 13.5. Those galaxies along with a diffused globular
cluster NGC5916 came into the FOV within 30 minutes from the beginning of
the session. In the latter half of the session, I observed 10 globular
clusters in the constellation of Scopius and Ophiuchus. One of them,
NGC6144, is close to Antares, Ώ Scorpii, and one may overlook it dazzled
by the brightness of Antares even if the 46 cm telescope is used. Twenty
five minutes after the start of the twilight, I identified the last
globular cluster during the session, M107, in Ophiuchus.
Although air temperature was -3ºC, I felt it was very cold due to weak
wind. Continuing yesterday, I drew a sketch of C/2022 E3. This time I
prepared printed map and sketched on it. I noticed the length and the
shape of the tails varied in comparison with those of the previous day at
a glance. The ion tail extended to 1º in length with a branch downwards.
The dust tail also had a branch that looked like a part of an anti tail.
Sketch of C/2022 E3 ZTF Part 2. 46 cm NV 37x.
I began to sketch at 4:20a.m., however, the comet was disappeared because
of clouds at 4:35a.m. I resumed to draw the sketch at 4:45a.m. as clouds
parted; I noticed the distribution of the brightness in the ion tail was
apparently different from that at the beginning of drawing. The movie
taken by Nick James showed variation in the ion tail during one hour, and
I have confirmed similar temporal variation visually. If I had not been
interrupted by the clouds and forced to stop drawing, I would not have
noticed the change. Though I could not draw the change, I was amazed and
impressed by the fact that I detected the short time variation in the tail
At 4:47a.m. when I completed sketching, clouds increased. At 5a.m.the sky
got completely cloudy. I had been waited for clear sky until 6a.m. just
after the start of the twilight, but after all the clouds did not break
and I could not sweep the sky. The duration of the clear sky was spent
only for drawing, but I think I have felt the joy of receiving the comet's
living light directly with my own eyes since the time of the discovery of
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