I made the information on unconfirmed comet, 2024 April 19 04:33am JST, available via mailing list both domestic and international. Also, I asked several Japanese comet/nova searchers to confirm if the object is on their photos. Some of them scrutinized their images. After all, the comet was not confirmed both on SWAN and photo images. I am grateful those who spent time.
Presentation at the 52nd Annual Comet Conference in NAOJ
The result was presented using a poster at the 52nd Annual Comet Conference in NAOJ held through May 18 to 19, 2024. Actually, I myself attended online.
Poster
The identity was a satellite?
As described on the poster, Vladimir Bezugly (a discoverer of C/2012 E2 SWAN), Ukraine, pointed out that the comet-like object might be leaked or exploded liquid fuel from a satellite. After that, I received an email from Bezugly, and he presumed the comet-like object was a satellite launched by China gHongyan 1h. One can display positions of any satellites using the web site https://in-the-sky.org/satmap_planetarium.php The position of Hongyan 1 at 04:32:59 on April 19, 2024 JST at my observing site coincides with the position I observed. The satellite moved about 11º in one minute to the north northeast. The speed was some 1º per 5 seconds, which was faster than reported value of 1º per 10 to 15 seconds. However, the reported value was estimated from my memory, and 1º per 5seconds is within the error.
At 04:32:59 JST (+9:00 UT) on 19 April 2024. White arrow indicates Hongyan 1
At 04:33:59 JST (+9:00 UT) on 19 April 2024. Hongyan 1 moved NNE ~11º in one minute.
Hongyan 1
https://www.youtube.com/watch?v=1_-VlHkv20U
https://www.youtube.com/watch?v=V1Afg_JK4gc
It is not confirmed whether the satellite spewed fuel or exploded. Nevertheless, the fact that the position and motion of the satellite were the same with those of my observation is the strong basis that the object was Hongyon 1. I think some phenomenon related to Hongyon 1 was the comet-like object I observed.
Unconfirmed comet: Part 2
Posted on April 27, 2024
I spotted a possible new comet with the magnitude of 11 on 2024 April 18.8146 UT. At the time of the discovery, some 20 minutes had passed since the start of the twilight. I lost sight of the comet before measuring the precise position, because it moved toward the sun at a high speed. I emailed the discovery to CBAT and Syuichi Nakano at 16:48 April 19 JST (+9:00). Considering potential discoverers of this comet, I disclose the discovery on April 27, 2024, after more than one week has passed.
Sketch of the comet that I drew recalling the image at the time of discovery at home. The zenith is left.
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E-mail I sent to CBAT and Syuichi Nakano at 16:48 April 19 JST (+9:00) .
Dear Sir,
Cc: Mr. Syuichi Nakano
I am Shigeki Murakami, Japan, a comet discoverer of C/2002 E2 Snyder-Murakami and 332P Ikeya-Murakami.
I have spotted a possible new comet visually. Although it is very challenging to make confirming observation, I report the discovery because the comet may have been observed by someone or can be in the future.
Date: 2024 April 18.8146 UT
R.A. 21h54m
R.D. -01º30f
Magnitude: 11
Apparent diameter: 3f
Tail length: 3f
Motion: 1º per around 10 to 15 second to north-northeast (parallel to the horizon)
Telescope: 46 cm reflector, 37x, Night Vision PVS-14 (ACT PVS-14 Photonis 4G INTENS Autogate P45 WP), Field of view 1.1º.
The position is very rough; I prioritized to try to take photos of the object instead of taking notes of the position shown on the digital map. In the end, I failed to take photos. I consumed a few minutes to prepare my mobile phone to take photos and I lost sight of the comet I was tracking. When I spotted the possible comet, some 20 minutes have passed since the beginning of the twilight and the comet moved toward brighter side, i.e. the sun. As a result, I took note of the estimated position after I losing sight of the comet. To make the things worse, I moved my telescope a few degrees to search the lost comet that made the accuracy of the position worse. I think the position indicated above includes a few degrees of error.
When I spotted the object, I convinced myself it was not a deep sky object, because I knew there is no deep sky object like that in the area. At the next moment, I thought it was meteor train, because the object was elongated; I have ever observed meteor train in the field of view many times. If so, it must move and deform over time. Actually, it moved but, surprisingly, the shape never varied with time, and on closer inspection it consisted of a coma and a tail. Those were the basis that I judged it as a comet.
The comet had passed near the earth and must get darker rapidly. I believe there is little chance it is detected again. This discovery information will be posted on my web page in a week.
Regards,
Shigeki Murakami