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2024

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

Thursday, December 19

Five comet hunting sessions were conducted so far, this month. There were many days when clouds tended to appear, and I satisfactorily searched only twice. Of those two days, on Wednesday December 4 with poor transparency, Night Vison (NV) was a powerful tool.

Wednesday, December 4
Sweeping was started from M104, a galaxy in Virgo, at 4:35am. There are many galaxies in this region, although not so many of them in comparison with near the boundary between Coma Berenices and Virgo. I moved down my telescope toward the horizon, ant the first galaxy came into the FOV was NGC4856 with the 10th magnitude. After once the FOV reached the horizon, I lifted the optical tube assembly up to the altitude of around 30°, and again I swept the FOV downward to the horizon. During the second sweeping, NGC4825, a 11th magnitude galaxy, appeared in the FOV. I confirmed this object using SkySafari 7 Pro, and noticed that NGC4820, mag. 14th, is 4’ SW of the galaxy. NGC4825 is shown as the mag. of 14.9 in SkySafari based on B band mag., but the mag. is 13.9 in Gude 9 in V band. I tried to spot NGC4820, however, could not recognize at a glance. I turned up the gain of NV and a stellar image of NGC4820 appeared. The altitude of the object was only 20°.

NGC4825 (center) and NGC4820 (lower right of NGC4825). The image is 30’ square.
The Digitized Sky Survey copyright © 1994

This is unique function only for NV. If I used optical eyepiece, I needed to change the eyepiece to confirm such a dark galaxy. When dark multiple stars that look like a nebula-like object, I need to change the eyepiece to separate them, while I can do it easily with NV by increasing the gain.

NGC4782, 4783 (center) and NGC4794 (left). The image is 30’ squre.
The Digitized Sky Survey copyright © 1994

At 4:47am two 11th magnitude galaxies, NGC4782 and 4783, shaped like a snowman and a 13th magnitude galaxy, NGC4794, came in the same FOV. The altitude of the objects at that time was 22°, and I felt that NGC4794 would not have been invisible if I had used a glass eyepiece. I thought I owed NV to identified 32 galaxies during one and half hour hunting session under a poor transparency.

Monday, December 9
Before the hunting session, I enjoyed observing three comets, C/2022 E2 ATLAS, 333P LINEAR and 29P Schwassmann-Wachmann. All of them looked better with Ethos 21 mm than with NV. The results were opposite when I observed them on Sunday, December 1. I think that the visibility of comets is dependent not only on characteristics of comets but also on sky conditions. NV has a drawback that some comets, e.g. C/2023 P1 Nishimura and C/2020 A2 Iwamoto, were invisible or difficult to see. Especially, in my experience, I am afraid NV is weak for comets discovered by Japanese. However, there are no best methods or tools for comet hunting. I try to use a glass eyepiece under a good sky condition and NV under a poor one.

Homemade filter adapter

One of my favorites is using NV to observe HII regions. Last week, I made a filter adaptor for NV at 1x. I applied Hα filter using it and trained at the constellation of Orion. Seagal Nebula (IC2177), Rose Nebula (NGC2237), Angelfish Nebula (Sh2-264) not to mention Barnard Loop were clearly and easily visible like a photo. The image from Aladin shown below quite similar what I saw then.

Image of Hα.
https://aladin.cds.unistra.fr/AladinLite/

I felt the power of NV, and at the same time I worry a bit about it actually leads to a discovery of new comet.

Sunday, November 24,

I went comet hunting 10 times this month.
I wrote on the glaucoma of my left eye in October last year. It did not get worse at least, but I do not have Western medical treatment. I have only examinations. Recently, I feel my eye sight has improved thanks to scalp massages, Chinese medicine and salt water treatment. I no longer use the tree of eye drop I did last year. To test my eye sight, I measured limiting magnitude of naked eye at the observing site where the altitude of 850 m above sea level. I have not conducted this kind of test for many years and it is regrettable not to compare the results with those of the past.

I tried to detect four stars in the vicinity of Castor and Pollux in the constellation of Gemini at around 4a.m. JST at predawn prior to the comet hunting session on November 6 and 7. They were dark nights and the altitude of stars were about 80°.

HD63138 (magnitude of 6.65), HD61805 (6.17), HD61295 (6.17), HD60935 (6.84).
HD represents Henry Draper Catalogue.

Surprisingly, I could observe all those stars. The two stars with the magnitude of 6.17 could not be seen all the time due to scintillation, but I could identify them by direct vision for some time. The darker stars flashed when the scintillation was stable and were seen by averted vision.

The light pollution map showed that the value of SQM at my observing site is 21.81 mag./arc sec2. The limiting magnitude rises 0.5 up to 1, as the altitude increase every 900 m (“Deep Sky Companions: The Messier Objects” by O’Meara). Satoshi ISHIZAKA referred Schaefer (1990) and said that one can observe a star with the magnitude of 6.5 for SQM 22. Considering those factors, it is reasonable I observed the star of 6.8 magnitude.

I often identified 40 to 50 galaxies per comet hunting session this month, because I swept in the galaxy group in the constellation of Coma Berenices to Virgo. If I had used Night Vison instead of a glass eyepiece that I mainly employed at dark nights, I could have detected much more galaxies. NV has a shortcoming that it cannot identify blue colored comets. Such comets look star like objects. However, NV greatly improves visibility of a dust rich comet with a continuous spectrum. Additionally, NV works well under the moonlight, light polluted and hazy sky conditions. I use it under the conditions of moonlight, poor transparency.

This predawn, the moon that was the last quarter yesterday was shining in Leo. I compared a glass eyepiece (a combination of Planokular 30 mm and Paracorr) with NV before the hunting session by observing NGC4464 some 10’ north of M49. It was seen easily at a glance with NV, but not with the glass eyepiece. I convinced that NV is effective under the moonlight, and use it for the session.

There exists a comet that is detectable using a glass eyepiece but not using NV and vice versa. It is just a luck which one I encounter.

Wednesday, October 30

Six comet hunting sessions were made this month. However, above all, I spent a lot of time and effort to observe C/2023 A3 Tsuchinshan-ATLAS.


2024 Oct. 11.3868－11.3924 UT. Ethos 21 mm, 97x.	2024 Oct. 12.3806－12.4063 UT. Ethos 21 mm, 97x and NV, 37x.	2024 Oct. 16.3924－16.4028 UT. NV, 37x.

Sketches of C/2023 A3 Tsuchinshan-ATLAS using 46 cm reflector.

The first day when I observed C/2023 A3 that moved to the dusk sky was Friday, October 27. On that day, I took an expedition to Kameishi pass, Hita City, Oita, where there is a good view of the western sky. At that time, the solar elongation was only 9.5°. I set up Nexus DSC Pro that was attached to the 46 cm telescope using the moon and Venus as the reference stars, and introduced the comet at the center of the FOV at 18:07 20 min after the sunset. At first, the only feature visible using Ethos 21 mm 97x was the coma, but tails began to be recognized about 18:17. The comet was only 2.8° above the horizon at that time. Two tails were seen, one was the position angle of 0° and another 240°. The coma diameter and the length of each tail were both estimated to be 1’.

The sky was clear on the next day, Saturday, October 12, and again I went to Kameishi pass. The solar elongation increased to 14.1°, but the altitude of the comet was 8.7° when I introduced the object at the center of the FOV. I observed the comet using Ethos 21 mm and NV, 37x until it sank and disappeared below the horizon. With Ethos 21 mm only the upward tail on the sketch, i.e. anti-tail with the length of 3’, was visible, whereas with NV only downward tail with the length of 0.3°. The feature of tails was completely different from that of the previous day due to the change in the position between the earth and the comet.

2024 Oct. 15.4323 UT. Canon EOS 20Da, 24－105 mm, F4, 24 mm, F4, ISO 800, 4 sec.

Sunday Oct. 13 and Monday Oct. 14 were the days when the visibility of the comet was the best, however, I was clouded out at the observing site. At dusk on Tuesday, Oct. 15, suddenly, there appeared gaps of clouds. I went to Kumamoto Plain Viewing Point, 15 min from my house. I observed the comet from the gap of clouds using 110x15 Russian binocular. The nucleus was not visible to naked eyes because of the light pollution, but the tail of about 3°.

2024 Oct. 16.4167 UT. Canon EOS 20Da, 24－105 mm, F4, 24 mm, F4, ISO 800, 10 sec.
The bright light in the upper center is an airplane.

I traveled to Uto City, one hour from my house on Wednesday, Oct. 16. Finally, I could observe the nucleus of the comet and a tail with 10° in length by naked eyes. It was impressive to see the tail of nearly 20° long using NV! Again, I went to Uto City on Friday, Oct. 18. The sky was clear at first, however, after a whole, clouds spread and I could not sketch the comet. On Sunday, Oct. 20, I went to Kameishi Pass, but clouded out. On Monday, Oct. 21 and Tuesday, 22, I enjoyed observing the comet using NV with a long pass filter. The length was 20° on Monday and 10° on Tuesday. I failed to observe C/2020 F3 NEOWISE while it was bright due to nasty weather during rainy season. This time, it was disappointing that I could not see the comet at its best on Saturday, Oct. 12 and Sunday, 13, but I was impressed to see the tail of 20°.

I expect bright comets to appear in the future.

Friday, September 27

The only comet hunting session this month. There were some clear sky, Monday, September 9 and Friday September 13, however, I could not because I had been in Tokyo to attend scientific conference as a professional hydrologist. This day, besides the comet hunting session, I aimed to observe C/2024 A3 Tsuchinshan-ATLAS that was as bright as the 3rd magnitude, which would just pass the perihelion on the day.

At the usual observation site with the altitude of 850 m a.s.l., the air temperature was 18º with breeze. I felt chilly because the maximum air temperature in Kumamoto City have been 32 to 37ºC this month. I wore light down clothing and polar shoes, additionally, turned the heather-installed vest on. After setting up my 46 cm telescope, I tried to aim my telescope at a referring star of Nexus DSC Pro, LED in the Telrad finder did not light up. The battery seemed to have run down, because it had not been renewed for more than some five years. I replaced it with the new one, and completed the reference star setting. Then, however, I failed to connect Nexus DSC Pro with SkySafari 7Pro, a digital star atlas, installed in iPad mini via WiFi. First and foremost, I recognized that iPad mini did not receive WiFi emitted from Nexus DSC Pro. I have experienced the same trouble several timed, and I had confirmed if the devices worked the previous dusk. They were normal at that time. I restarted Nexus DSC Pro and iPad mini and so on, but they did not. Finally, I stopped to connect them (surprisingly, they connected on the next day at home!).

C/2023 A3 Tsuchinshan-ATLS. 46 cm 37x Night Vison. 2024 Sep. 27.844 UT.

I wasted as much as 20 min due to the trouble. I got myself together, I started the comet hunting session from Procyon. Under the moonlight of the crescent moon, I dared to use Ethos 21 mm not NV. At 4:45am the twilight began. I lasted the hunting until 4:50am when the comet rose above the horizon to prepare the observation. Just at the start of the twilight, clouds appeared in the very low sky in the direction from the east to the east-southeast where the comet located. The clouds moved upward at almost the same speed with the diurnal motion. At that time, in the south Canopus with the altitude of 3º was clearly seen. At 5:10am when I was about to give up to observe the comet, it appeared above the clouds. The tail length was only 0.1º with Ethos 21 mm, and I replaced it with NV, 37. The comet was magnificent with the tail length of > 1º, and I began to draw the sketch. The tail was extremely straight, I have never observed such a comet with straight tail so far as I remember.

At around 5:20am, I searched the comet using 5cm 7x binocular, but I could not. I managed to see it with 5 cm finder of my 46 cm. I could not with NV 1x, either. If I had observed earlier, I could have. At the same time on the same day, one of my pals saw the comet using 4 cm binocular.

I am interested in the forecast that the comet will brighter after the passage of the perihelion. John Drummond in New Zealand reported that the comet was 3rd magnitude using a 3-cm binocular at Sep. 28.7 UT with the tail of 3º. So far, the comet did not get brighter. I wonder what happens the comet in the next month when it moves to the evening sky. Let’s wait without expecting to become brighter.

Saturday, August 10 and Sunday, August 11

Saturday, 10
I could not conduct a comet hunting session since Tuesday, June 4, because of bad weather.
Finally, we had a clear sky at dusk on Saturday, August 10. I headed for the observation site at the north outer rim of Volcano Aso, in Aso city, instead of usual site in Takamori town, to observe 13P Olbers, which had brightened to 7th magnitude.
The end of the twilight was 20:26JST, but there occurred the lunar occultation of Spica 22 minutes before it. I observed the occultation prior to the observation of 13P. At 20:00 I recognized Spica close to the moon by eyes, though bright moon made it difficult. At the predicted time, Spica in the field of view of my telescope was hidden behind the moon in a moment.

13P Olbers. 46 cm reflector, Night Vision 37x. 2024 Aug. 11 20:50JST.

Let’s get back to 13P. I compared Ethos 21 mm 97x to NV 37x in terms of visibility of the comet. The result was obvious; NV looked better. The tail of the comet was seen using Ethos 21 mm, but the structure of the tail was not. The structure was clear with NV and I could not help but say, “Aha!”. The tail length looked longer using NV than Ethos 21 mm. I observed this comet last at dusk on Monday, April 1, and the site was the same with this time: the north outer rim of Volcano Aso. At that time, the comet was 11th magnitude with an apparent diameter of 1’ without a tail. It became a fine comet of 7th magnitude with the tail length of 10’ in two months.

On April 1, in addition to 13P I observed 12P Pons-Brooks that was as bright as 5th magnitude. I was deeply moved to knew that both comets were discovered at the beginning of the 19th century, and that they are the third return. In the 21st century, many comets do not have human names attached to them. If 12P and 13P had not been named after persons, I would have observed those comets with more uninteresting feeling.

12P Pons-Brooks. 46 cm, Night Vision 37x. 2024 April 1 19:45JST.

Sunday, August 11
I slept in my car, and got up at 2:40am. I enjoyed observing Mars, Jupiter and Saturn before the comet searching session. Surface features on Mars was clearly visible thanks to good seeing. However, contrary to usual observing site, it was very humid and condensation was likely to form on the secondary mirror without a heater. I set up the power cable and turned the heater on.

I used Ethos 21 mm not NV, because the sky condition was rather good. I remembered that 185P Petriew was discovered visually (11th mag.) and C/2023 P1 Nishimura photographically (10th mag.) in August, which made me nervous.

While watching some bright meteors of Perseids, I started hunting session from M1. After a while, several open clusters came into the field of view: M35 shining powerfully, NGC2158 beautifully dissolved into faint stars and seen in the same field of view with M35, NGC2266 and M37. Condensation was formed on the eyepiece due to carelessness. I should have wrapped a heater around the eyepiece. I removed condensation by blowing warm air starting a car engine to continue the session. I finished the session at 4:27am 27 min. after the beginning of the twilight. It has been nasty weather since June. Probably, this was the last comet hunting session this month.

Sunday, July 21

We had no clear sky after the hunting sessions of last month. It is a matter off course because of rainy season in Japan. We cannot expect stable clear sky this month.

Concerning unconfirmed comet discovery on April 19 JST this year, the situation has progressed thanks to Vladimir Bezugly (a discoverer of C/2021 E2), Ukraine. The article was posted “Unconfirmed comet: Part 2 Sequel” page. Please have a look at. I appreciate his great effort.

Sunday, June 16,

I conducted comet hunting sessions twice this month. The first one, on Saturday, June 1, I dared to sweep the sky near the moon past waning phase, and did not identify any comet like object. The next session, on Tuesday, June 4, seven galaxies past through the field of view. Among them, NGC63 was the most impressive. From my memory I have never identified any NGC objects with double digits.

I cleaned mirrors today in two years, because dust on the primary mirror stood out. “The Dobsonian Telescope” (1997 David Kriege, Richrd Berry, ‎ Willmann-Bell) reads the reason for mirror cleaning is not to remove dust but to harmful pollutants to the mirror coatings like acidic contaminants. A small amount of dust on the mirror little affects the visibility of the telescope. The book reads over cleaning deteriorates mirror coatings. However, one wants to clean the mirror that stands out the dust.

The book includes Section 11.4 Cleaning the Optics, which explains how to clean the optics with the telescope assembled. I used to clean the optics using the method. It is true that the method is simple because one need not to recollimate the secondary mirror. However, the azimuth encoder should be removed and it is a hassle and physically hard to crawl between truss tubes.

Washing out dust on the primary mirror using tap water in the bathroom.

Washing the surface of the primary mirror using dish detergent dissolved in water and sterile cotton.

For the reasons, at least the primary mirror was brought into the bathroom and washed. On top of that, I concerned trouble of the dew removal heater installed on the flip side of the secondary mirror due to water. Considering those, both primary and secondary mirrors were removed to clean.

The Dobsonian Telescope states to use distilled water throughout the process, but I use tap water except for the last rinse after using the detergent. Firstly, I remove dust on the mirror by pouring over tap water. Secondary, dish detergent dissolved tap water is poured on the mirror. Using the sterile cotton wads, wash the surface with a circular motion from the center to the outer part of the mirror without pressure.

The book describes to dissolve one drop of the detergent for one quart of water, because two drops or more of detergent makes it difficult to remove soap film from the mirror. After washing with the detergent and the cotton, I rinse off the detergent components with tap water, and finally, the mirror is rinsed using distilled water (purified water) to avoid water droplet marks.

The secondary mirror cell was disassembled and the mirror was removed. The dew removal heater was installed on the flip side of the mirror.

It is quite troublesome to remove the secondary mirror from the cell, however, it is secure to do so to avoid getting the heater wet. The collimation shifts largely with disassembling and reassembling the cell. It is desirable to collimate the secondary mirror by setting up the telescope before the next observation. I collimated the optics today during daytime, and it was difficult to recognize the ray of the laser collimator. However, it avoids to consume extra time for the collimation in the dark at the next observation.

This year, the start of the rainy season delayed, but finally, it will come on the next week. From the next session, I will observe with fresh mind using the clean mirrors.

Tuesday, May 28

I gave a poster presentation on Unconfirmed Comet on April 18 UT, 2024, at the 52nd Annual Comet Conference at NAOJ, Tokyo, held on May 18 and 19, 2024 (participated online). I had been busy for preparing the presentation and I took a break “From Diary” last month.

I conducted comet hunting sessions six times this month. The first one was on May 4. It was foggy at the time of the arrival at the site. I waited for the recovery in my car, and there appeared breaks of clouds after 20 minutes. I set up my telescope and was waiting for the clear sky until 10 minutes after the beginning of the twilight for a half and one hour in total. As the result, it had been cloudy and I broke down the telescope and got back to home. On Wednesday May 15, the forecast was clear sky, however, I did not go comet hunting because it was overcast at home when I looked at the sky. I identified a smaller number of deep sky objects in each night during the hunting session. I overlooked some brighter objects while spotted darker ones, although it is true that the area I swept includes many darker galaxies in many cases. I think one of the reasons is that heterogenous distribution of air glow. Tsutomu Seki wrote in his book that psychological factors at the time is the cause. It is difficult to know how those factors affect observations. All I can say is effort × luck.

Below I describe those six hunting sessions.

Thursday, May 9
Night Vision (NV) was used. I started to sweep from M2. At an altitude of 18º, I identified 10th magnitude galaxy, NGC7606. It was the only galaxy I spotted during the session.

Friday, May 10
I used NV because transparency was poor like the previous night. I began with M15. The air temperature rose from 8ºC to 10ºC during the session. Mars passed through the field of view, but no comet-like object was identified.

Saturday, May 11
I started to sweep from NGC7331 using NV. It was easy to spot Stephan's Quintet located near this galaxy. I identified NGC404, Mirach’s Ghost, followed by NGC7426 that rose as high as 33º with the magnitude of 13.5. After 30 minutes of the start of the twilight, M32, 31 and M110 entered the field of view. Thanks to the power of NV, dark lane of M31 was clearly seen.

PGC68743. The image is 60’ wide.
The Digitized Sky Survey copyright © 1994

Tuesday, May 14
I began to sweep the sky from α Aquarii using a glass eyepiece 78x, as the transparency was good. The only galaxy I spotted the night was PGC68743 with the magnitude of 13.8 (the altitude was 18º). As shown in the DSS image, the galaxy is well concentrated and it made the object easy to identify. However, there are brighter galaxies in the area I swept and it is very strange I did not spot those galaxies.

Friday, May 17
NV was used as transparency was poor. The session was started fromα Pegasi. NGC7332, a 11th magnitude galaxy, and NGC7339, a 12th one, were identified in the same field of view.

Monday, May 20
I trained my telescope at Saturn and started comet hunting. At an altitude of 18º, 13th magnitude galaxy, NGC7537, and 11th one, NGC7341, were observed.

Sunday, March 17

Among 3 times of comet hunting sessions this month, I reflect sessions on Sunday, March 10 and Friday, March 15.

Sunday, March 10
It was very cold due to wind with air temperature of -4ºC. The transparency was poor because of cedar pollen, which is common in this season in Japan. Under such bad condition, Night Vision (NV) is a powerful tool. Before the start of the comet hunting session, I observed C/2021 S3 PanSTARRS. The appearance of the comet was almost the same using a glass eyepiece and NV, because the altitude of the comet was rather high, 32º above the horizon. If the comet was at lower altitude, it is presumed the visibility of NV is better.

I began searching from an open cluster in the constellation of Scutum, M11 at 4:17am local time using NV. After 10 minutes, at 4:27am I identified a planetary nebula in Sagittarius, NGC6818. The nebula is bright with the magnitude of 9.3, but the apparent diameter of only some 20”. I did not recall ever identifying this object during the session. I noticed the nebula with the magnification of only 37x, thanks to producing sharp pinpoint image even with poor seeing. Looking at SkySafari 7 Pro, there is an irregular galaxy, NGC6822, also known as Bernard Galaxy 40’ south-southeast of the galaxy. I have identified this galaxy several times during the hunting session. This time, I could not recognize the galaxy, because the altitude was only 10º with poor transparency and using NV that is difficult to observe extremely faint objects.

The next deep sky object came into the field of view was an open cluster in Aquila, NGC6749 with the magnitude of 12.4. Although the altitude was as high as 33º, the object was rather challenging to detect eve with NV. I wondered if I have ever identified it during the searching session. After identifying two bright globular clusters, NGC6740 in Aquila and M74 in Aquarius, I completed the session.

Friday, March 15
Temperature was 1ºC with light wind, and much warmer than on Sunday. I started the comet hunting session from M22, a globular cluster in Sagittarius. After Omega nebula, M17, and a globular cluster, NGC6517, came into the field of view, a nebula like object appeared in the field. The object was not shown on SkySafari 7 Pro. An open cluster, NGC6604 was in the same field of view. I remember that I had ever identified the object, which is H II region, and is not visible using a glass eyepiece. However, I did not want to rely on ambiguous memory without solid confirmation. I turned pages of Uranometria 2000, a printed sky atlas, and found Sh 2-54 (Sharpless 2-54) was at the position with the size of as large as 1.5ºx2º. I used Aladin Sky Atlas on line, and I found the same shape of nebula on the display as that in the field of view of the telescope to confirm the object. At home, I looked into the nebula, and it is named as Simeis 3-123.

Sh 2-54 and NGC6604 are shown in Uranometria 2000, but Simeis 3-123 is not.

Sometimes, it is time consuming to identify object when I use NV, because I can see some objects with NV that are not visible using a glass eyepiece. However, from the opposite point of view, it is enjoyable I can observe invisible objects using conventional glass eyepiece, like NGC6334, Cat’s Paw Nebula, easily using NV.

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 5’, the degree of concentration (DC) = 4, and the tail length of 5’ using a glass eyepiece, 78x, while the comet looked mag. 11th, dia. 4’, DC = 3, tail length 2’ 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. 2’, DC = 5, tail length 2’ using glass eyepiece, while mag. 9th, dia. 2’, DC = 7, tail length 2’ 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 fromπ 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. 6’, and the tail length of 6’.

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 0.5’, 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 α 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: https://groups.io/g/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 0.2’ 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 ω Centauri. This time, ω 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 β Scorpii and another wasνScorpii. 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, “one of the faintest and least studied stellar clusters of the Milky Way” https://doi.org/10.1093/mnras/stx2174 .
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 15’ 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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