11:03:59	 From Hugh Hudson : Laura and Jeff - when we get to Paulo and me, please have him go first. I just have an addendum.
11:04:16	 From Laura Hayes (she/her) : No problem
11:04:36	 From Jeffrey Reep : Sounds good!  We don’t have an explicit order for speakers beyond our sub-groupings, so if anyone needs to go early please let us know.
11:12:06	 From Iain Hannah : When does ASO-S launch? (sorry if missed this info in the slides)
11:13:01	 From Yang Su_PMO : expected in early 2022 or first half of 2022
11:22:07	 From Brian Dennis on gmail : Yang Su. What will be the data access [policy for ASO-S?
11:22:47	 From gan : open to everyone
11:25:03	 From Ivan Zimovets : Question to Frederic: is it expected to detect some optical solar flares using STIX SAS? And another naïve question: could the detected 3-min oscillations be related to the solar 3-min oscillations or is it a coincidence?
11:25:15	 From Iain Hannah : Very nice, but would caution calling them all flares - maybe jets, bright points in there.
11:27:22	 From Hugh Hudson : The XBP spatial distribution is definitely global, whereas flares concentrate very strongly in ARs
11:28:10	 From Pradeep Chitta : There are also bright point eruptions that could give rise to flare-like signatures. They are also globally distributed.
11:28:56	 From Iain Hannah : Has anyone done a statistical study of all the small brightenings/flares in AIA or XRT?
11:32:03	 From Pradeep Chitta : @Yang: Here is a paper we did on statistical properties of very small brightenings (nanoflares?) seen with AIA: https://ui.adsabs.harvard.edu/abs/2021A%26A...647A.159C/abstract
11:32:42	 From Iain Hannah : Of course, thanks for the link
11:39:43	 From Pradeep Chitta : @Paulo, have you looked into the magnetic field properties underlying these hot onsets?
11:40:41	 From Paulo Simões : @pradeed not yet, and that's an interesting point. We're trying first to understand how common this is
11:41:19	 From Yang Su_PMO : Thank you for the link, @Pradeep. Iain, you are right. Thank you! The idea was to get DEM for all the event peaks. Then we know the temperature change. Maybe they can be called AIA94 events, or
11:41:29	 From Pradeep Chitta : @Hugh, what is the interpretation of temperature level at 10 MK that is generally higher than typical AR temperature?
11:43:05	 From Pradeep Chitta : @Hugh, cont... shouldn't there be a phase where temperature rises from 3-4 MK to over 10 MK?
11:44:43	 From Pradeep Chitta : @Alexander, are these also white light flares?
11:45:09	 From Jeffrey Reep : @Alexander K, is the correlation of seismic activity to SXR derivative a form of the Neupert effect?
11:45:29	 From Laura Hayes (she/her) : @Alexander - is there a relationship between events that have a CME and those that do not?
11:45:34	 From Paulo Simões : @pradeed yes, one would expect to see the temperature rising as the flare starts; we know GOES is sensitive to 4MK and above, so why T starts at ~10 MK?
11:46:25	 From Alexander Kosovichev : Not all of them are real white-light flares but they show some enhancement in the HMI continuum.
11:46:37	 From Stephen Bradshaw : @Pradeep / Paulo - perhaps the temperature increase is so fast there simply isn't enough signal below ~ 10 MK?
11:46:48	 From Hugh Hudson : @Pradeep - the temperature increase has to be faster than the GOES sampling time, 2 sec. No idea why it happens at 10-15 MK every time
11:47:37	 From Pradeep Chitta : @Hugh, what is the role of general GOES background in obtaining hot onset information?
11:47:41	 From Alexander Kosovichev : We think that the correlation of sunquakes with the SXR derivative is due the Neupert effect.
11:48:39	 From Paulo Simões : @Stephen @Pradeed @Hugh yes, T rising very rapidly is probably the answer; but also then T seems to be regulated around 10-15MK before having the typical behaviour
11:49:18	 From Joel Allred : @Hugh and Paulo. Return current and deka keV ions can heat corona to 10 MK *very* quickly. Certainly less than 1 s. What is the time difference between the GOES signal and the nonthermal HXR signal?
11:49:21	 From Hugh Hudson : Probably that regulation effect should be the target of theoretical work.
11:49:38	 From Alexander Kosovichev : There is no relation of sunquakes to CMEs. Sunquakes often associated with compact impulsive flares without CMEs. Impulsiveness is an important feature of seismic flares.
11:50:20	 From Hugh Hudson : The GOES signal in the hot onsets starts well before the hard X-rays, always. It is not “coronal” heating, I think this is chromospheric material.
11:51:19	 From Yang Su_PMO : @Brian, As explained by Dr. Gan, ASO-S data will be released for everyone after data processing, software will be provided, like most of the solar missions.
11:51:37	 From Paulo Simões : @Pradeed re: GOES background, we're investigating that more in depth now, but it is now "game changing", see fig 2 in https://arxiv.org/pdf/2007.05310.pdf
11:51:44	 From Paulo Simões : not*
11:53:54	 From Paulo Simões : @Joel complementing Hugh's answer, maybe there are electrons doing the heating but not enough to create detectable HXR? that needs investigating!
11:54:07	 From Hugh Hudson : @Pradeep. re background.  It is in principle irrelevant since we subtract it. But of course there are subtleties. This is explained in the paper.
11:54:20	 From Meriem Alaoui : @ Paulo and Hugh, do you observe any brightening in the corona before or after the brightening at the footpoints?
11:54:49	 From Jeffrey Reep : @Jonas, Paulo, Hugh — your results appear to be in disagreement.  Perhaps the background subtraction is playing a role?
11:55:03	 From Paulo Simões : @Meriem no coronal compact sources; diffuse coronal loops might appear tho
11:55:48	 From Hugh Hudson : @Jeff  - no disagreement
11:57:13	 From Ryan Milligan : @Hugh, @Paulo, have you looked for any high-temperature (~10MK) emission line signatures at the times of your hot onset from EIS, IRIS, or EVE?
11:57:43	 From Paulo Simões : @Ryan not yet!
11:57:49	 From Ivan Zimovets : @Hugh, I would like to mention our old work where one example is shown when 'GOES' temperature grows from 10 to 15 MK in parallel with HXR emission (>150 keV) detected by ACS/INTEGRAL 10 min before the flare impulsive phase (https://ui.adsabs.harvard.edu/abs/2010AstL...36..430S/abstract)
11:58:52	 From Paulo Simões : re: hot onsets, we're in touch with Kathy Reeves to look at XRT data about this too. there's lots to do!
11:59:40	 From Ryan Milligan : Definitely! If it shows up in GOES data, then I imagine it should be seen in EVE data too.
11:59:43	 From Paulo Simões : re: hot onsets, anyone interested in taking part on this, get in touch! :-)
12:00:22	 From Paulo Simões : @Ryan very likely, yes!
12:01:10	 From Paulo Simões : @Ivan thanks for the link to your paper! will have a look!
12:01:34	 From Hugh Hudson : @Ivan - Thanks, will check. There are lots of examples of this in the literature because it always happens!
12:02:16	 From Hugh Hudson : @Ivan - yes, thanks, will send an email after reading about the ACS observations, nice
12:03:16	 From Yang Su_PMO : GOES' full disk X-ray flux could not reveal early signals. Most of the events I detected can't be seen in the light curves of full corona.
12:04:38	 From Ivan Zimovets : @Hugh, ok, good. Maybe sometimes HXRs cannot be seen in the "flare onset" due to the signal-to-noise ratio problem. (by the way, let me know if you don't have access to this paper published in the Russian journal)
12:06:15	 From Hugh Hudson : @Ivan - no problem with the journal. Is it a new form of the venerable Solnechnye Dannye?
12:08:04	 From Ivan Zimovets : @Hugh - it is Astronomy Letters, actually an old Russian journal started from USSR times. Prof Rashid Syunyaev is the chief-editor
12:17:41	 From Ryan Milligan : Or GOES/SXI..?
12:19:26	 From Stephen Bradshaw : A quick back-of-the-envelope calculation yields an estimate of ~ 4 x 10^13 cm^-3 for the chromospheric density for radiation to equilibrate with energy input in ~ 1 second (less than GOES cadence) at a temperature of 10 MK. Is this reasonable for the chromospheric density in such a scenario?
12:20:29	 From Hugh Hudson : That’s interesting. My hunch is that it is a wave-like disturbance, so we are seeing a composite effect.
12:21:27	 From Stephen Bradshaw : If so... We might just be seeing equilibration between heating and radiation, before the main energization kicks in and drives the system way out of equilibrium.
12:24:10	 From Paulo Simões : @Stephen yes!! I hope so! :-)
12:24:44	 From Hugh Hudson : @Stephen - sounds good!
12:25:06	 From Stephen Bradshaw : @Paulo - It'll be interesting to get some chromospheric density measurements to confirm or refute.
12:26:00	 From Paulo Simões : @Stephen definitely!
12:30:06	 From Hugh Hudson : @jonas  - can you provide event times, and I’ll double-check? Thanks
12:32:40	 From Paulo Simões : anyone interested in chat more about hot onsets (ideas, suggestions, collaborations, etc), feel free to drop an email to Hugh or myself paulo@craam.mackenzie.br
12:33:01	 From Jonas Saqri : yes I will do that
12:39:35	 From Pradeep Chitta : @Jeff. Did you also test with different locations of heat deposition?
12:40:37	 From Jeffrey Reep : @Pradeep, no, the heating functions in these were electron beams with the same parameters.  Different heating parameters will affect the cooling time of course as well.
12:56:04	 From Phillip Chamberlin (CU/LASP) : Here are some results from MinXSS on abundance factors, as it seems there was a lot of discussion and interest in this.  https://ui.adsabs.harvard.edu/link_gateway/2017ApJ...835..122W/doi:10.3847/1538-4357/835/2/122
12:56:54	 From Phillip Chamberlin (CU/LASP) : And another one with MinXSS abundances: https://ui.adsabs.harvard.edu/abs/2018SoPh..293...21M/abstract
12:58:27	 From Ryan Milligan : @Pradeep In relation to your first talk, we published a similar paper in 2010 in which we also saw increased HXR emission in the current sheet using RHESSI during an occulted event. The emission came from the merging of plasmoids with the looptops. {2010ApJ...713.1292M}
13:01:09	 From Jeffrey Reep : @Hugh, Paulo, Pradeep, this chromospheric flare might be interesting to check for the pre-flare behavior.
13:02:25	 From Bin Chen : @Pradeep, for your 2nd talk, except that the coronal flare emission is probably “blocked” by the cool (chromospheric temperature) spray, could you elaborate why this flare is “unusual”?
13:02:40	 From Jeffrey Reep : @Graham, if this dimming is from non-thermal collisions with helium, could dimming in e.g. Fe IX 171 be similar?
13:03:03	 From Paulo Simões : @Jeff most definitely! nice to see such a clear view of a footpoint
13:03:34	 From Pradeep Chitta : @Ryan, many thanks for the paper. I will go through it.
13:05:42	 From Pradeep Chitta : @Bin, I found it unusual because of the interesting footpoint appearances in EUV channels and how RHESSI identified only one footpoint. Another aspects is the lack of Fe XII and Fe XXI line emission (more interestingly, we detected some pseudo FeXII line whose thermal width is very narrow). There are no other known lines at this wavelength.
13:07:00	 From Pradeep Chitta : @Bin this is also interesting in terms of energy injection from low-lying magnetic reconnection that could heat plasma to well over 10 MK. This also follows my other work of footpoint heating of coronal loops.
13:07:34	 From Ivan Zimovets : @Pradeep: very nice work on 'current sheet' observations. But what exactly proves that it is really a current sheet? Probably it is (in total, all observations are consistent with this hypothesis), but could it be something else, e.g. a heated flux rope leg? (I will look your paper, the answer is probably there)
13:09:06	 From Pradeep Chitta : @Ivan, the plasma sheet, its location, its formation all match with the description of a current sheet. We did discuss those in the paper and in particular why it is different from flux rope leg.
13:10:23	 From Ivan Zimovets : @Pradeep, ok, thank you. I will read your paper carefully.
13:11:19	 From Bin Chen : @Pradeep, would the lack of Fe XII and Fe XII lines consistent with absorption by the cool spray as well? I agree that the reconnection could be at low (coronal?) altitudes, but from what you have shown in the few minutes, I am not sure if this is a chromospheric flare. It is likely that I may be missing something - look forward to seeing your full paper!
13:13:08	 From Graham Kerr : @Jeff, I’m not sure but my guess is ‘no’. The Fe 171 dimming occurs later in the flare, after we expect beams to no longer be present, right? I also don’t know the non-thermal collisional cross sections are for Fe XI but probably pretty small.
13:14:58	 From Jeffrey Reep : @Graham, I’m not sure where it occurs relative to the HXR burst, but the dimming begins early.  It’s usually explained as CME dimming, but I was wondering if there might be something more to it.  There are other lines that dim similarly, but maybe the cross-sections are small as you say.
13:15:28	 From Paulo Simões : @Pradeep @Bin what I find interesting is the high T RHESSI emission coming from the footpoint! the emission shouldn't be blocked by the cool spray, so the high T plasma is likely in a compact region
13:16:06	 From Ivan Zimovets : @Pradeep, did I understand correctly, that each HXR peak is related (in time) with some dynamical feature in the plasma sheet?
13:16:35	 From Pradeep Chitta : @Bin, there is a clear RHESSI +GOES signal associated with that flare. So there is some hot plasma that clearly cut through the cool material. But yes, I will give more details in the paper.
13:17:26	 From Pradeep Chitta : @Iva, that is what we tried to outline in the paper, but due to lack of spatial information of HXR bursts, we could confirm this one-to-one association of plasma sheet dynamics and HXR bursts.
13:18:25	 From Graham Kerr : @Jeff ctd… it is also because of the formation properties of He I 10830, which is difficult to populate via thermal excitations unless T > 20kK n_e > 10^12 cm^-3. The beam ionises He I -> He II, and it is because there can be recombinations through excited states that orthohelium can be overpopulated compared to the quiet Sun case. So the excess population present to absorb background photons is relatively big compared to what would be there without that population route. Atomic levels (both in helium and in other species) that can be populated easily by thermal collisional excitation probably wouldn’t be affected much by what would be a relatively small overpopulation. For example I looked at how Mg II would be affected by non-thermal collisions and the effect was very minor (albeit it was a rough calc that I need to revisit).
13:19:45	 From Ivan Zimovets : @Pradeep, ok, I see
13:21:51	 From Bin Chen : @Pradeep @Paulo, interesting! Free-free absorption coefficient scales with wavelength^2, so it is easier for the X-rays to “leak out.”
13:22:31	 From Hugh Hudson : Jeff and Laura, could you save the chat please? Otherwise I think it goes away
13:22:36	 From Arun Awasthi : @Alexander Can you comment on the physical  nature of additional heating mechanism, since the "trend" of non-thermal energetics does not seem to be sufficient for microflares thermal energetics.
13:22:58	 From Pradeep Chitta : @Bin, yes, that is correct.
13:22:59	 From Jeffrey Reep : @Hugh, I’m recording this session.
13:23:33	 From Paulo Simões : infrared flare emission for the sept 2017 flare that Jana analysed https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2018SW001969
13:23:46	 From Pradeep Chitta : @Jeff, but chat is not saved right?
13:23:56	 From Jeffrey Reep : Good point.  I’ll save it.
13:24:04	 From Laura Hayes (she/her) : We’ll make sure to save the chat :)
13:24:37	 From Alexander Warmuth : @Arun: possibilities: 1. ions (probably the same problem as with electrons - why should there be more ions in smaller events?) 2. thermal conduction (may be suppressed in flares). 3. waves
13:27:16	 From Jana Kasparova : Hugh: f-f emission will probably come from different layer than f-b continua we assumed
13:28:45	 From Paulo Simões : @Jana @Hugh I imagine that f-f in the optical range is too weak compared to f-b
13:28:58	 From Graham Kerr : @jana, and @hugh — in my sims the f-f emission comes from the higher-lying layers of the loop. The footpoints are dominated by f-b (at T ~8-15kK, with high electron densities). This is quite a lot bigger than the f-f contribution
13:29:45	 From Jana Kasparova : @graham yes, we see that from our sims as well, see Heinzel + (201*) paper
13:30:02	 From Jana Kasparova : @graham yes, we see that from our sims as well, see Heinzel + (2017) paper
13:30:38	 From Jana Kasparova : @paolo, thanks a lot for the paper, I'll look at it!
13:30:50	 From pheinzel : Yes. I agree
13:34:08	 From Graham Kerr : @jana, I might have missed it — where you able to estimate the electron density from those obs?
13:35:28	 From pheinzel : we can get EM
13:36:56	 From Laura Hayes (she/her) : @meriem - is the software available in ospex to include return currents?
13:37:00	 From Jana Kasparova : @graham: as Petr says, only EM time evolution
13:37:11	 From Paulo Simões : @Petr @Jana we could estimate EM from the IR emission too; it would be interesting to compare the results from HMI and IR
13:38:20	 From Jana Kasparova : @Paolo: Yes! and we can compute IR emission (assuming f-b continuum) and compare it with your observations.
13:39:22	 From pheinzel : IR at which wavelength ?
13:39:28	 From Paulo Simões : @Jana we should chat more about this!
13:39:39	 From Paulo Simões : @Petr 10 microns
13:40:18	 From Jana Kasparova : @Paolo: let me first read the paper, I'll send you an e-mail.
13:40:38	 From Paulo Simões : @Jana perfect!
13:40:56	 From Hugh Hudson : We need more IR flare observations! 10 microns or even 20 microns
13:41:40	 From Bin Chen : @Paulo @Pradeep Is high T (some 20 MK) X-ray emission from near the footpoint uncommon (sorry for my ignorance here, but I am not a black-belt X-ray person :-)? Could it be associated with a compact loop that people often report at the base of X-ray jets?
13:41:42	 From Paulo Simões : @Hugh more IR flares coming soon! we have a paper about to be submitted
13:41:50	 From Jeffrey Reep : @Ivan, is this published?
13:42:33	 From Jana Kasparova : @Paolo, can you observe between 7-13 UT in end of July and beg of Aug? we'll have flare campaing with GREGOR, SST at Canary Islands
13:42:47	 From Ivan Zimovets : @Jeff, no, we are still working on it and are planning to prepare the article till the end of July
13:43:11	 From Jeffrey Reep : I look forward to reading it!
13:43:37	 From Ivan Zimovets : @Jeff, ok, I will send it to you when ready
13:43:40	 From Paulo Simões : @Bin 20MK I think it is uncommon, even rare, or unique I'd say! around 10MK, not so uncommon, see https://ui.adsabs.harvard.edu/abs/2015SoPh..290.3573S/abstract and references!
13:45:02	 From Paulo Simões : @Jana I'll have to check. there are 2 IR telescopes, one in Sao Paulo and one in the Argentinean Andes. I'm not too close to the daily operations, but I'll check with my colleagues here
13:45:26	 From Pradeep Chitta : Thanks @Paulo. @Bin, it is also in terms of general energy release and its location. For jets, people generally invoke coronal reconnection. But this chromospheric event shows that there could be a low-lying energetic aspect as well.
13:45:35	 From Bin Chen : @Paulo much appreciated! Will read it carefully.
13:46:05	 From Paulo Simões : @Bin no prob!! :-)
13:46:08	 From Meriem Alaoui : @Laura, yes the software is available under thick2_rc and another one using FP. It’s a little tricky to interpret but if people are interested, I can help them with that.
13:46:49	 From Pradeep Chitta : @Bin, then the question is about the relevance of these kind of (unobscured) events in major flares. Could some of the HXR footpoint emission come from compact low-lying reconnection events at  the feet of flare arcade? I ended my presentation (pdf) with this question.
13:47:59	 From Jeffrey Reep : @Yingjie, I missed — what does ECME stand for?
13:49:08	 From Paulo Simões : @Meriem would you say that thick2_rc and the FP one should be the "industry standards" from now on? From the discussion, I feel that a re-analysis of RHESSI spectra should be done...
13:51:43	 From Bin Chen : @Pradeep, thanks for the additional info. Interesting event. Not sure about your question on footpoint X-ray sources in major flares. A second reconnection/energy release near the footpoint would imply some complex temporal/spectral features.
13:52:02	 From Yingjie Luo : @Jeff, ECME is short for 'Electron Cyclotron Maser Emission'.
13:52:30	 From Jeffrey Reep : Thanks
13:54:31	 From Meriem Alaoui : @Paulo I already used thick2_rc in Alaoui & Holman 2017 and was able to rule out a few scenarios. I would say they should be used specifically to rule things out.
13:55:07	 From Alexander Warmuth : @Meriem: I agree that we should at least try to do a spectral analysis for a few RHESSI events with thick_rc in order to get a feeling of the magnitude of the impact. Since you say that interpretation is difficult, I guess any such effort should involve you.
13:56:50	 From Paulo Simões : @Meriem thanks!
14:04:09	 From Meriem Alaoui : @Alexander I’ll be happy to show you what has already been done and how to adjust the parameters, as we use the information about the beam and expected heating.