Stewart John Bean

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  • in reply to: N 2024 Oph (V4370) #622245
    Stewart John Bean
    Participant

    ~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

    in reply to: N 2024 Oph (V4370) #622233
    Stewart John Bean
    Participant

    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

    in reply to: N 2024 Oph (V4370) #622232
    Stewart John Bean
    Participant

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

    in reply to: N 2024 Oph (V4370) #622227
    Stewart John Bean
    Participant

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

    in reply to: N 2024 Oph (V4370) #622221
    Stewart John Bean
    Participant

    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

    in reply to: OJ287 #622067
    Stewart John Bean
    Participant

    Ah yes. the two competing models. Thanks

    in reply to: OJ287 #622063
    Stewart John Bean
    Participant

    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

    in reply to: Preparing for the eruption of T CrB #622062
    Stewart John Bean
    Participant

    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

    in reply to: Preparing for the eruption of T CrB #619095
    Stewart John Bean
    Participant

    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

    in reply to: IX Dra: observations requested #613388
    Stewart John Bean
    Participant

    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

    in reply to: CG Dra: a VSS campaign #612179
    Stewart John Bean
    Participant

    With a screen shot

    Attachments:
    in reply to: CG Dra: a VSS campaign #612177
    Stewart John Bean
    Participant

    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

    in reply to: IX Dra: observations requested #611064
    Stewart John Bean
    Participant

    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

    in reply to: ER Uma and RZ Lmi: Observations requested. #610828
    Stewart John Bean
    Participant

    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

    in reply to: ER Uma and RZ Lmi: Observations requested. #610316
    Stewart John Bean
    Participant

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

    in reply to: ER Uma and RZ Lmi: Observations requested. #610302
    Stewart John Bean
    Participant

    Richard, Looks like you may have captured the start of the superoutburst. At the same time Steve Johnson made very similar observations reported to AAVSO.
    A little later (UTC 2022/05/12 03:36:29 JD 2459711.65 ), using AAVSOnet New Mexico, I got a V magnitude of 13.1 which is in superoutburst territory. So it will probably remain bright for the next 5-10 days. If the superoutburst has started, it is 50 days from the last start – which is typical.

    Regards

    Stewart

    in reply to: ER Uma and RZ Lmi: Observations requested. #610260
    Stewart John Bean
    Participant

    ER UMa is likely to go into superoutburst in the next few days. The last superoutburst started at 2459660. The superoutburst period varies between 45- 55 days. It is now 50 days since the last outburst.

    Further observations this week would be timely.

    Stewart

    in reply to: IX Dra: observations requested #609965
    Stewart John Bean
    Participant

    An update on IX Dra recent behaviour. Observations are been made by the AAVSOnet telescope in New Mexico, by BAA-VSS, and by AAVSO members.

    The most recent superoutburst was well recorded by AAVSOnet telescopes with a start around JD 2459688.

    TESS contributed a detailed record of the superoutburst at JD 2459633.

    The previous superoutburst was well recorded at JD 2459577.

    The next previous superoutburst was well recorded on JD 2459520.

    Graphing the most recent data gives the data in the attachment. This shows a declining trend from a peak around 60 days. The data point at JD 2459106 is almost certainly too high owing to limited observations. Observations were available only once the outburst had started so the start must be uncertain by a few days.

    It seems that for IX Dra the trend towards longer superoutburst periods has paused. It may be reversing.

    Thanks to all who have, and continue to, contribute to following this star.

    in reply to: IX Dra: observations requested #609547
    Stewart John Bean
    Participant

    The TESS satellite captured the most recent superoutburst completely. I estimate a start date of JD 2459633.

    The most recent estimated super outburst start dates are complied below. Sources are BAA database, AAVSO DB and TESS results.

    JD-2450000
    9162.5 56.5
    9224.2 61.7
    9283 58.8
    9344 61
    9403 59
    9463 60
    9519 56
    9577 58
    9633 56 TESS image below

    These give an average of 58.5 days.
    Thanks to all contributing to these measurements
    Stewart

    in reply to: Suggestions for CV stars in the Southern Hemisphere #585083
    Stewart John Bean
    Participant

    I have come across a paper by Kato et al “Photometric study of new southern SU UMa-type dwarf novae

    and candidates: V877 Ara, KK Tel and PU CMa”  

    So I am occasionally imaging PU CMa as it may be coming up for a superoutburst in January/February. The other two will be better placed in the spring. 

    In the meantime, I have joined G Poyner and IL Walton in following V1159 Ori.

Viewing 20 posts - 1 through 20 (of 111 total)