Skip to main content

V745 Sco

skiyota's picture
skiyota
Offline
Joined: 2010-07-24

I checked V745 Sco with Light Curve generator.

It has very long plateu abound 13 in Ic.

Is it correct?

Identification of V745 Sco would be checked.

 

Seiichiro Kiyota

V745 Sco
ocn's picture
ocn
Offline
Joined: 2010-07-25

Hi Seiichiro,

Please see my V,Rc,Ic observations from March 20.7UT. My Ic estimate was about 0.6 mag fainter than observations from other observers. I noted the immediate field around V745 Sco is very crowded in all filters. Great care should be taken with identification. I also observed in V,Rc and Ic on April 13 but have not posted the observations yet. I will do this tomorrow. I suspect the star is continuing to fade. Do you have any observations more recent than mine ?

kind regards,

Steve O'Connor

 

 

 

V745 Sco
skiyota's picture
skiyota
Offline
Joined: 2010-07-24

Hi, Steve O'Connor

 

>V745 Sco is very crowded in all filters

Yes. I agree.

My last observation was Mar. 22.

My observations will be available in VSnet-obs.

 

I will take another images with iTelwscope.NET in a few days.

V745 Sco brightness
hambsch's picture
hambsch
Offline
Joined: 2010-07-23

Hi guys,

indeed there are lots of stars in the field.

If I use an aperture of 2 pixel I get about 0.7 mag less for V745 Sco.

I generally use a standard aperture of 4 pixel for my analysis as I get every night about 600-1000 images, so no chance to look at all the images.

So I guess I need to reanalyse those data for V745 Sco with a smaller aperture as now also other stars pop up inside the inner aperture and are counted in addition to the variable.

Thanks for pointing this out.

Since my data are the most abundant for this variable (as for many others), a direct contact would have been appreciated.

Josch

All my data are removed from the database
hambsch's picture
hambsch
Offline
Joined: 2010-07-23

Hi,

 

all my data are removed for this star and I am goiung to reanalyse them again.

Please share your measurements with me so that in the end we get similar results.

 

Josch

V745 Sco in I
skiyota's picture
skiyota
Offline
Joined: 2010-07-24

Dear all,

Josch kindly sent me his image of V745 Sco. I confirmed that his identification was correct.

Sorry, I was shomewhat confused about brigtness of V745 Sco in I band.

My recent photometry also steady around 13 in I band.
I also checked my past observations of V745 Sco. V745 Sco was around 13 in I band at quiescence in 2010. V745 Sco (might) already reached nearly quiescence maginude around 13.
V745 Sco is much brigher in I than V and it mihgt be due to secondary star of V745 Sco.

Sorry again for my confused post to Josch and all.

 

 

The secondary of V745 Sco is
PJOC's picture
PJOC
Offline
Joined: 2012-12-01

The secondary of V745 Sco is a red giant - it's one of those unusual CV's
with a long orbital period and a very large companion.  So the increasing
value of V-R and V-I as it fades is quite explicable.

I don't see Josch's data any longer.  I do hope you put it back up!  I'm
using Josch's data as a gold standard of accurate photometry in  his
current observations of V745 Sco, Nova Sgr 2014, and the new dwarf nova in
Oph.

If it weren 't for Josch's VI data on Nova Sgr, I'd be doubting my own
measurements.  The thing's leaping about like a mad thing.  Fascinating
object, yet V1369 Cen is getting all the Southern glory.

I might have a crack at timeseries on V745 Sco tonight.  I was thinking
about using I filter, but on reflection the short-period accretion disk
phenomena would be better captured in B/V.  So I'll go without filter and
as short a cadence as possible.

Cheers

Jonathan

V754 Sco data are back
hambsch's picture
hambsch
Offline
Joined: 2010-07-23

Hi Jonathan,

thank you for your comment on my data of other stars.

I have had an e-mail exchange with Seiichiro Kiyotaand used his comp star. Nevertheless we have still an offset between our data of about 0.2 mag, maybe due to the different systems (mainly CCD cameras) used. I have re-submitted all my data both in I and V I took during the recent plateau phase.

Regards,

Josch

AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484