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.
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.
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.
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
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