Here are confirmations for June 2021, which turned out to be a very busy month for SOHO comets!
Soho# Date/Time of Post Discoverer Tel Group Images of... ===================================================================== 4199 Jun03,21 02:19:44 R.Biros C2 Kreutz Jun03,21 4200 Jun03,21 04:56:57 W.Boonplod C2 Kreutz Jun02,21 4201 Jun04,21 01:09:03 R.Pickard C2 Kreutz Jun04,21 4202 Jun04,21 09:56:58 M.Uchina C2 Kreutz Jun03-04,21 4203 Jun04,21 10:29:27 M.Uchina C2 Kreutz Jun03,21 4204 Jun09,21 03:58:57 W.Boonplod C2 Kreutz Jun09,21 4205 Jun09,21 04:35:14 R.Pickard C2 Kreutz Jun09,21 4206 Jun10,21 03:48:41 R.Pickard C2 Kreutz Jun10,21 4207 Jun10,21 12:46:52 W.Boonplod C3,C2 Kreutz Jun10-11,21 4208 Jun14,21 11:50:05 M.Biesiada C2 Kreutz Jun12-13,21 4209 Jun14,21 11:52:07 M.Biesiada C3,C2 Kreutz Jun12-13,21 4210 Jun14,21 20:21:05 W.Boonplod C2 Kreutz Jun14,21 4211 Jun20,21 05:44:11 M.Uchina C2 Kreutz Jun18,21 4212 Jun20,21 06:29:00 M.Uchina C3,C2 Kreutz Jun20,21 4213* Jun20,21 03:21am W.Boonplod C3,C2 Kreutz Jun20,21 4214 Jun21,21 13:58:29 W.Boonplod C3,C2 Kreutz Jun21-22,21 4215 Jun21,21 19:59:50 R.Pickard C2 Kreutz Jun21-22,21 4216 Jun23,21 15:04:55 M.Uchina C2 Kreutz Jun23,21 4217 Jun25,21 02:30:21 R.Pickard C3,C2 Kreutz Jun25,21 4218 Jun25,21 09:14:12 M.Uchina C2 Kreutz Jun25,21 4219 Jun26,21 02:28:50 R.Biros C2 Kreutz Jun26,21 4220 Jun26,21 03:40:32 W.Boonplod C3,C2 Kreutz Jun26,21 4221 Jun26,21 15:56:08 M.Uchina C2 Kreutz Jun25,21 4222 Jun27,21 09:42:46 M.Biesiada C3,C2 Kreutz Jun27,21 4223 Jun27,21 10:04:00 M.Biesiada C3,C2 Kreutz Jun27,21 4224 Jun28,21 02:29:28 R.Biros C2 Kreutz Jun27,21 4225 Jun29,21 02:46:12 R.Pickard C2 Kreutz Jun29,21 4226 Jun29,21 04:02:19 R.Pickard C2 Kreutz Jun28,21 4227 Jun29,21 11:23:40 R.Biros C2 Kreutz Jun28,21 4228 Jun29,21 13:45:22 R.Biros C2 Kreutz Jun29,21 4229 Jun30,21 18:07:20 M.Biesiada C3,C2 Kreutz Jun30,21 4230* Jun19,21 06:23pm W.Boonplod C3 Kreutz Jun19,21
Couple of notes about these. First, Masanori's comet report from June 14 was the same as SOHO-4208. Second, Peter's report from June 27 was the same as SOHO-4222. Third, I forgot about Worachate's groups.io report on Jun19 06:23pm, so I had to add it to the end. It's kind of a pain to squeeze a new comet in, because the comet number gets added in to the astrometry data at time of creation, and I have to manually find/replace it in every file if I need to make corrections. So this way is just easier in most situations.
This was a very busy month with 32 new comets - the third highest monthly total on record! Still a long way behind the huge 40-comet tally we saw in December 2010, but an impressive total anyway. Congratulations to all of you, and especially to Rafal and Robert, who are both still very new to SOHO comet hunting, but still managed to find 12 of this month's comets!
I do not normally make these monthly confirmation posts "informative" but I thought you might all be interested in the following, inspired by Worachate's report. It's a small insight into my process of how I "confirm" comets.
At time of discovery, Worachate noted that he expected his comet to arrive in C2 around 08UT, and sure enough a Kreutz appeared in C2 around that time. So we could assume that they were the same comet. But Masanori then reported a C3 Kreutz the next day, and that report clearly corresponded to the comet in C2. So the natural assumption is that Worachate and Masanori were probably reporting the same comet, but a quick look at the positions tell you that was probably not the case:
2021-06-19 2006 603 680 [Worachate report] 2018 603 679 2030 603 678 2042 603 677 2118 603 673 2130 603 672 2142 603 671 2154 603 669 2206 603 668 ... 0601 599 609 [Masanori report] 0634 599 608 0642 600 606
So the question then becomes: "how do we know which report corresponds to the C2 comet?". The answer is a great example of how/why I need to use specialized (though not complicated) software for measuring comet positions.
When I measure your comets, not only do I record the x,y pixels, but my software also automatically calculates other parameters such as the "height" and "position angle" of the comets in the data. The "height" is the apparent height of the comet above the solar surface in units of solar radii (Rsun, or Rs). The "position angle" is the counter-clockwise angle of the object from solar north. See this terrible diagram for an example. This extra information allows me to make a number of different plots of data to determine if comets are obeying laws of physics and if they are following a consistent trajectory. In the example of Masanori and Worachate's comets, I can combine both sets of C3 observations and the C2 observations, and the result is below:
We can clearly see that Worachate's observations were on a very different trajectory than Masanori's, and do not line up at all with Masanori's C3s and the C2 observations. I do think Worachate's comet is real, but was either visible in C2 during the 3hour gap that day, or (more likely) just failed to survive that far, which does sometimes happen.
So this is how I inspect a lot of your comet reports -- by making various plots like this to ensure that C2 and C3 are consistent, and also to make sure that all your coordinates fall on a (roughly) straight line. It also helps me eliminate (most of) my own mistakes when making complete lists of x,y positions for the comets.
You might also be interested to know that at some point within the next year, we plan to release most of these python-based software tools publicly (probably via github), so that you will all have access to the same image processing, astrometry, and measurement tools that I do now! I will certainly let everyone know when that happens.
As always, email me with questions, corrections, etc. Oh and please note that I will be 'out-of-office' all next week, so your emails will go unanswered between July 18-26.