[Stewart John Bean]

TMO61 (AAVSOnet) just sent their first, if slightly streaky, image. I thought they had forgotten about CG Dra. Hopefully the first of many.

16.7 CV – so mid range.

[Stewart John Bean]

I get 16.74 CV at
2024/06/29 04:14:01
Slooh Canary 2

[Stewart John Bean]

Got Slooh Canary 2 booked for this evening.

[Stewart John Bean]

I have tried to answer my own question without particular success. Certainly gamma ray bursts (GRB) are detected about once per day by satellites. Close supernovae may have caused extinction events and ground based radio astronomy may have a chance. I think it is possible that at a dark site and with a whole sky detector sensitive to green light (from excited N2) you may detect something. I am not going out in a deck chair waiting for a few seconds flash!

The largest GRB so far was GRB 221009A ( on 2022 October 9) which was associated with a supernovae 2 billion light years away. . Search “A Significant Sudden Ionospheric Disturbance Associated with Gamma-Ray Burst GRB 221009A” . https://iopscience.iop.org/article/10.3847/2515-5172/ac9d2f/meta
The event was detected with a very low frequency radio SuperSID monitor.

Are the radio section aware?

Now a recurrent nova is not a supernovae and the radiation is not focussed in our direction, but it is a million times closer so who knows.

Stewart

[Stewart John Bean]

I listened to Brad’s enthusiastic delivery.
~Interesting to think about detecting a neutrino flash. Now I do not have a suitable detector in my back yard, but it triggered the thought:

Will the X ray/gamma ray flash be sufficient to be detected as a blue/green scintillation flash from the upper atmosphere?

Stewart

[Stewart John Bean]

~I checked that saturation effects are not relevant by using a short exposure of 10 s instead of 45s. The V magnitude is in line with the trend.
So no further to understand why Slooh Chile 2 V produces much lower magnitude values.
Stewart

[Stewart John Bean]

Andrew Pearce has kindly provided me with the three sequences used on each of the telescopes he uses.

I have applied each sequence to the Mar 15 Slooh V image in question and found that all sequences, plus AAVSO, give a Magnitude of 12 or there about. Min is 11.86; max is 11.99.

I will now reply to Andrew with fuller details and share the Mar 15 image with him via Vphot.

Stewart

[Stewart John Bean]

thanks Robin. Redness is probably at the centre of this topic.

[Stewart John Bean]

I have emailed Andrew Pearce to ask for the sequence he is using.

[Stewart John Bean]

Jeremy,
The image has a JD of …384.896.
Gary Poyner has, I think, taken the ultra wide field ( Y Slooh in his nomenclature) scope image from the same run and obtained Mag 11.6 (V) so that is reassuring. He has done the same the following night and obtained 12.3 .

Mazin has marked star 113 as the nova and given different coordinates to VSX. VSX gives 17 39 57.08 -26 27 41.9.
The nova is close by and very red towards 10 o clock.

Direct measure of the brightest pixels in my image gives

V4370 113 128
11,000 21,000 4000

So I think around Mag 12 is about right for Mar 15.9 but means that there is a two mag difference in V between these results and those from some experienced observers. This is a situation that is unsettling and probably has to do with the redness of the nova. I have not reported my results to AAVSO.
Stewart

[Stewart John Bean]

Ah yes. the two competing models. Thanks

[Stewart John Bean]

Gary, Do you know when the next big flare ( smaller black hole punches through the accretion disc) is supposed to be? I cannot work it out from the papers. Stewart

[Stewart John Bean]

Got the binoculars out last night – it was clear in Gloucestershire – for the first time. Easy target now in the south at 3am.
Had a look in the TESS archive but only 4 recorded LCs and not currently pointing in the right direction. The LCs are noisy with a slow drift in amplitude reflecting the orbital period.
Stewart Bean

[Stewart John Bean]

I also watched the webinar last night. I had a look at the TESS data for T CrB later but not too interesting: You see the orbital period and the flickering ( on all timescales). There are only 3 28 day periods that TESS has observed it.

I found the lack of understanding of the “high state” and “secondary brightening” after 100 days post eruption and interesting.

Stewart

[Stewart John Bean]

The most recent two superoutbursts (JD24598001 and JD2459853) were observed by the TESS satellite giving a very short supercycle period of only 53 days. Analysis of the last 800 days of AAVSO light curve suggests a gradual shortening of the cycle period. I’ll try to write this up in time for the next VSSC.

If the current super outburst cycle is 52 days, we can expect the next superoutburst to start on JD2459905 or about November 20. Again thanks to the, at least, nine BAA members who are following this star.

Stewart

[Stewart John Bean]

With a screen shot

Attachments:

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   CG-Dra.jpg
   

[Stewart John Bean]

I had a look at the AAVSO curve, dominated by Max’s data of course (impressive). The last period 2459700 to present reminds me of an ER UMa star in that there are two bright outbursts with a series of smaller ones between. The brighter outbursts seem to be 70 days apart.

There are no TESS observations unfortunately.

Ive added it to my SLOOH watch list for Canary.

Stewart

[Stewart John Bean]

IX Dra is now in outburst (probably superoutburst) based upon two nights observations by AAVSOnet New Mexico and three by R Sargent.

The previous superoutburst started 57-58 days ago. Hopefully more data from other observers, TESS and Lasair will refine the start date. This value (57-58 d) is unremarkable compared to the previous 10 superoutburst periods and suggests some stability.

Thanks to those making observations.

Stewart

[Stewart John Bean]

ER UMa has been observed through May by R Sargent, G Poyner, PB Withers, S Johnston, ND James yielding good coverage of the May 12 superoutburst. So far in this observing season, the superoutburst period has an average value of 45 days. This is fairly low compared to the graph presented in VSSC 188 one year ago ( see attachment).
Maybe the super-cycle period has a minimum value of about 40-45 days with occasional excursions to higher values? Only long term observations can illuminate this topic. The next superoutburst will be at the end of June if 45 days remains a reliable estimate.

RZ Lmi continues to show 26-27 days super-cycle periods consistent with a steadily increasing period length. The rate of change appears to be about 0.2 days per year as presented in VSSC190. Fewer observers follow RZ Lmi probably because it is a magnitude less bright than ER UMa but it compensates by always changing state. The next superoutburst may be on June 14.

My own observations are all via AAVSOnet or SLOOH. My thanks to those two organisations.

Stewart Bean

Attachments:

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   Updated-Zemko-graph-to-present.png
   

[Stewart John Bean]

Definitely in superoutburst now. V mag is brighter than 13.0 last night.

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