[vsnet-alert 21196] Re: CTCV J1940-4724 outburst and a bonus

[Peter Nelson]

I’m getting about 13.90  937.07068 (13:41 UT)

Peter

> On 2 Jul 2017, at 10:43 pm, Josch Hambsch <hambsch at telenet.be> wrote:
> 
> I can confirm the outburst.
> 
> 2457936.93139, mag 13.946.
> 
> Josch
> 
> -----Original Message-----
> From: vsnet-alert [mailto:vsnet-alert-bounces at ooruri.kusastro.kyoto-u.ac.jp] On Behalf Of Rod Stubbings
> Sent: Sonntag, 2. Juli 2017 12:22
> To: Denis Denisenko; vsnet-alert at ooruri.kusastro.kyoto-u.ac.jp
> Subject: [vsnet-alert 21191] Re: CTCV J1940-4724 outburst and a bonus
> 
> An observation tonight on CTCV J1940-4724 shows it to be in full outburst!
> 
> CTCV J1940-4724   170702.417   136  Stu.RASNZ
> 
> Regards,
> Rod.
> 
> 
> Rod Stubbings
> Tetoora Road Observatory
> Victoria, Australia
> Telescope: "Infinity" 22" f/3.8
> stubbo at sympac.com.au
> http://rodstubbingsobservatory.wordpress.com/
> 
> On 2/07/2017 12:08 PM, Rod Stubbings wrote:
>> Hi Denis,
>> 
>> I have also been keeping tabs on this star after your request and
>> noticed a brightening. Expecting the star to brighten further I
>> checked the field 7 hours later and it had faded.
>> 
>> Regards,
>> Rod.
>> 
>> CTCV J1940-4724           170630.574   170  Stu.RASNZ
>> CTCV J1940-4724           170701.392   154  Stu.RASNZ
>> CTCV J1940-4724           170701.689  <165  Stu.RASNZ
>> 
>> Rod Stubbings
>> Tetoora Road Observatory
>> Victoria, Australia
>> Telescope: "Infinity" 22" f/3.8
>> stubbo at sympac.com.au
>> http://rodstubbingsobservatory.wordpress.com/
>> 
>> 
>> On 2/07/2017 5:33 AM, Denis Denisenko wrote:
>>> The neglected dwarf nova in Telescopium CTCV J1940-4724 is going into
>>> outburst on the images from iTelescope.Net T32 in Siding Spring.
>>> 
>>> CTCV J1940-4724
>>>   20170630.6832  17.065CV  T32
>>>   20170630.6857  17.184CV  T32
>>>   20170701.6072  14.801CV  T32  Outburst!
>>>   20170701.6097  14.774CV  T32  Outburst!
>>> 
>>> VSX entry:
>>> https://www.aavso.org/vsx/index.php?view=detail.top&oid=477956
>>> Range from Siding Spring Survey data: 13.2-17.5 CV Approximate
>>> orbital period: 0.0809 d from spectroscopic observations covering
>>> 0.11 d (less than 1.5 period!)
>>> 
>>> With a period like that CTCV J1940-4724 must be nothing but a UGSU
>>> dwarf nova. Time-resolved photometry is requested. Recommended
>>> Comparison and Check stars are 135 (V=13.479) and 152 from AAVSO
>>> sequence marked on the color-combined DSS finder chart
>>> http://scan.sai.msu.ru/~denis/J1940-4724-comp_stars.jpg (10'x10' FOV).
>>> 
>>> Bonus: there's another hot star 15' from CTCV J1940-4724 named
>>> SSS_J194140.2-473502. SSS catalog (Drake et al., 2017, MNRAS) lists
>>> it as a Delta Scuti variable with P=0.142769 d and range 17.7-18.0 CV.
>>> However, it is impossibly hot in the ultraviolet to be the HADS star.
>>> FUV=16.378, NUV=16.714 in GALEX DR5. (FUV-NUV)=-0.34 is too hot even
>>> for CVs, rather typical of sdB stars. Hot subdwarf varying by 0.3m at
>>> P=0.14277 d is even more interesting than the dwarf nova in outburst.
>>> 
>>> Chart showing the position of both stars:
>>> http://scan.sai.msu.ru/~denis/J1941-4730.jpg
>>> 
>>> Please take the opportunity to investigate two poorly studied hot
>>> variables in one field!
>>> 
>>> Denis Denisenko
>>> Sternberg Astronomical Institute of Moscow State University
>>> 
>>> 
>> 
>> 
> 
> 
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