Confirmations for June 2021

Hi All,

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 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:

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.