From my recent diary

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Mainly, I use the following materials since the end of October, 2018.
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

Tuesday, February 27

I comet searched four times this month. I pick up impressive observation out of them.

Thursday, February 8
Moonless night with air temperature of |2ºC. It was very cold when the wind blew. The Milky Way rising above the eastern horizon was bright enough to take it for clouds.

I observed 62P Tsuchinshan 1 prior to the comet hunting session. I estimated the comet as the magnitude of 9th, the diameter of 5f, the degree of concentration (DC) = 4, and the tail length of 5f using a glass eyepiece, 78x, while the comet looked mag. 11th, dia. 4f, DC = 3, tail length 2f using Night Vision (NV). It was reconfirmed that this comet is exception of my empirical rule that short-periodic comets look brighter with NV. C/2021 S3 PanSTARRS was observed as follows: mag. 10th, dia. 2f, DC = 5, tail length 2f using glass eyepiece, while mag. 9th, dia. 2f, DC = 7, tail length 2f using NV. Regarding this comet, NV had a better visibility in comparison with the glass eyepiece.

The southeastern sky at the end of the hunting session. A comet at the center slightly right is C/2021 S3 PanSTARRS. SkySafari 7 Pro.

Moon rose up to 1º above the southeastern horizon at 6:00 local time.
SkySafari 7 Pro.

I searched the sky using the glass eyepiece with 78x. I started to sweep the sky from M10, a globular cluster in the constellation of Ophiuchus at 4:44am local time, and ended at 6am when M11, an open cluster in Scutum, entered the field of view (FOV). When I finished the session, I was impressed by a beautiful scenery: a thin moon and Venus shinning in the low southeastern sky.

Monday, February 13
Moonless night with good transparency. The air was warm with the temperature of 1ºC. I could spot M13 rose as high as 55º above the horizon with naked eyes in direct vision. Before starting the comet hunting session, I observed Omega Centauri. The cluster looked bright and powerful using NV as usual, but tonight it was fine and beautiful using the glass eyepiece.

I began sweeping the sky from Scorpii using the glass eyepiece with 78x. I identified 18 globular clusters in total including M4, M 80, and NGC6144, and several open clusters. During the session, C/2021 S3 PanSTRRS came into the FOV. M9 was seen in the same FOV. Rising to the altitude of 27º, the comet had a fine tail. I estimated it as 9th mag. dia. 6f, and the tail length of 6f.

Saturday, February 17
Moonless night, air temperature of 0ºC with light breeze. I enjoyed observing C/2023 A3 Tsuchinshan-ATLAS before starting the comet hunting session. The comet was well concentrated and easy to observe. The magnitude was 13th with the diameter of 0.5f, and DC = 3. I am looking forward to seeing what the appearance will be in the future.
I tried observing the antennae of the Antennae Galaxies using NV, but it was unsuccessful. It is said that the 60 cm telescope is required to observe.

I began to searching from C/2021 S3 PanSTARRS located near the center of the Milky Way using the glass eyepiece 97x. The summer showpieces, M8, M20, M22, M16 and M17 came into the FOV, which are scattered in gorgeous and countless stars, i.e. Large Sagittarius Star Cloud. The three parts of the Trifid Nebula, M20, was clearly seen in spite of the low altitude of only 14º above the horizon.

M23. The image is 1º wide.
The Digitized Sky Survey copyright © 1994

Usually, less impressive star cluster, M23, popped into the FOV with stars shining powerfully like fireworks today!

As seeing was rather good, I could enjoy clear star image without swelling regardless of the magnification of 97x. It was a comfortable session.

Monday, January 22

I have comet hunted 5 times this year. I described some impressive observations among them.

Friday, January 5
I searched under the moonlight; the moon had just passed the last quarter. I noticed Venus rose above the horizon at 4:37am local time. The altitude was only 0.4º that meant the observation site has a good visibility to a very low altitude.

I started comet hunting using Night Vision (NV) 37x from Librae. The first deep sky object I identified was NGC5634, a globular cluster in the constellation of Virgo, and the second was NGC5812, a galaxy in Libera. When I confirmed the galaxy with a digital map, SkySafari 7 Pro, it displayed a comet in the same field of view (FOV). The comet turned out to be C/2023 A3 Tsuchinshan-ATLAS! The comet is expected to become a great comet in this fall. Even though it was under the moonlight, I thought I could confirm the comet visually, because I knew Alan Hale, a discoverer of C/1995 O1 Hale-Bopp, succeeded to observe it visually using a 41 cm reflector on December 18, 2023, via comets-ml: . I increased the gain of NV and I was sure to see the comet. It was 14th magnitude with an apparent diameter of 0.2f that looked like a planetary nebula. I changed the eyepiece to the glass one, i.e. Ethos 17 mm, and the image was the same as that of NV. I lasted the searching session hoping that the comet would become great.

SkySafari 7 Pro displayed that C/2023 A3 Tsuchinshan-ATLS and NGC5812 were in the same field of view. The circle represents the field of 1.1º.

Thursday, January 11
As always, I enjoyed observing some objects prior to the comet searching session. I thought I would enjoy because both transparency and seeing were rather good.
I could spot C/2021 S3 PanSTARRS that was condensed easily at 4:41am, although the comet was only 4º above the horizon. I felt it was firmly discoverable during a hunting session. On the contrary, the comet was difficult to observe using Ethos 21 mm 97x, as it was diffused, and it was challenging to spot it during sweeping. The comet looked 11th magnitude through both eyepieces, but there was significant difference in visibility between the two.

Omega Centauri, a globular cluster that is the most beautiful in the sky, rose as high as 6º in altitude. When I observe M13, the most beautiful globular cluster in the northern hemisphere, I feel use of a glass eyepiece is better than that of NV. The glass one allows a greater number of stars visible in the cluster. In contrast, NV is always better for Centauri. This time, Centauri looked dynamic with Ethos 21 mm, 97x. However, using NV the cluster looked brighter and all the stars, which must have consisted of hundreds, were on and off due to scintillation! I have ever observed this object many times, but it appeared the most impressive this time.
I spotted a couple of wonderful double stars during the session. One was Scorpii and another wasScorpii. Those companions looked green and light blue, respectively, and impressive. One can enjoy double stars only when glass eyepieces were applied, because NV cannot reveal the color of stars.

Tuesday, January 16
I used NV as it was hazy at low altitude. I began to search from C2021 S3 PanSTARRS located at the constellation of Lupus. Between the comet and the globular cluster M4 in Scorpius, there is no particular bright deep sky objects except for NGC5897, a globular cluster in Libra. Contrary, there are numerous globular clusters beyond M4, i.e. the east at the horizontal coordinates. I encountered one of those globular clusters named 1636-283 (ESO 452-SC11) for the first time. The visual magnitude in SkySafari 7 Pro is 12.0. The appearance using NV was a globular cluster without doubt and I felt the magnitude indicated in SkySafari was appropriate. Nonetheless, in the photo of DSS the object does not look like a globular cluster, and there is no description in Guide 9. A scientific paper on the cluster said, gone of the faintest and least studied stellar clusters of the Milky Wayh .
Most globular clusters around the region beautifully resolve into stars using NV. Among them I always feel M19 wonderful. Stars with pinpoint image appeared tightly packed in spite of the low altitude of only 11º.

ESO 452-SC11. The image is 15f in width.
The Digitized Sky Survey copyright © 1994

Both the glass eyepiece and NV have their features, and I can enjoy observing each of them. I must say it is hard to decide which is better on the potential of the comet discovery.

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