[vsnet-alert 21191] Re: CTCV J1940-4724 outburst and a bonus

[Rod Stubbings]

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
>>
>>
> 
>