|Proposer||(43151) Stewart Bean (firstname.lastname@example.org) obscode: BENS|
|Assigned To||(3663) Dirk Terrell|
|Date Submitted||Feb. 3, 2021|
Multi color photometry of VW HYI through a superoutburst.
The last three superoutbursts have been separated by 163 days judged by folding the TESS lightcurves. This then predicts the next
In "Testing the disk instability model of cataclysmic variables" Guillaume Dubus et al A&A 617, A26 (2018) modelled a generic Dwarf Nova in superoutburst in the filters UBVRI in their Figure 1. Although this is not directly for VW HYI the model could be applied to VW HYI if required.
I have used the itel T30 scope to obtain the magnitudes for the BVRI filters recently - now in the AAVSO database.
VW HYI has a quiescence value of 14 mag for the V filter rising to 8 or 9 mag at the peak of outburst. This means a factor of 100 in brightness change though the superoutburst.
Stewart Bean (BENS)
|Target||RA (H.HH)||Dec (D.DD)||Magnitude||Telescope||Observation Frequency||Expiration Date||Proprietary Term|
|VW Hyi||4.153133||-71.29483||14.0–8.0||BSM_Berry||—||Aug. 4, 2021||No|
Committed to Berry
VW Hyi now in outburst at V mag 9.3. on 8 Feb 2021 using itel T30.
Based upon results from itel T30 the exposure ratios for the various filters are approx:
Ken, Is all OK with Berry?
Hi, I have images now from BSM Berry 2. Thanks.
Point 1. 30 s exposure seems to be fine for even the quiescent stae so: No need for 60 s, 120 s or 180 s images for all filters.
Point 2. Vphot does not seem to recognise the filter "SR". Is this the Rc filter? If so how do I get Vphot to process it.
Thanks again ,
I have analysed the data so far and have noticed that the 30 second exposures are nearing saturation during a normal outburst. They will saturate when in superoutburst.
Request: Can the all the short exposures (30 s for I, SR, V and 60 s for B) be all reduced to 10 sec please.
All of the 120 s and 180 s exposures can remain as they are fine for the quiescent state.
Short exposures reduced.
You can rename SR filter to R. The transform coefficients take the SR filter into account and report magnitude as Cousins R (assuming you transform this data?).
I have renamed one set to R. Running Vphot I do get a reasonable looking result, but I have not "transformed" the data.
Can you explain the transform step please?
You should really ONLY report the SR filter mag IF you transform the SR filter image WITH a second or more filters. Do you see either the two color transform link or transformapplier link in VPhot? Try the two color transform first because it should be quite obvious what to do? TransformApplier takes a little more effort to explain. We should talk by email (email@example.com) if necessary. There is some guidance in the VPhot forum.
The SR image gives a reasonable R magnitude only because the SR bandpass is similar (not identical) to the R bandpass.
The most recent images from Berry did not include the long exposure set. These give good S/N when VW Hyi is in quiescence.
Both short and long exposures are need for VW Hyi owing to its large dynamic range.
Today I did receive both long and short exposures . So all OK.
VW Hyi is now in outburst at magnitude 9. The strategy of having both short and long exposures has worked. The short exposures avoid saturation in outburst. The longer exposures record the quiescent state well enough. However, I note that the total time allocated to this project is about one hour. I think that stacked 10 s exposures, for all filters, would be more efficient and work fine:
V 15x 300s in total including ~10s download from camera.
B 15x 300s "
I 15 x 300s
SR 15x 300s.
So the total time used for this project would be approx 1200 s which is about 3x less than at present.
Comments on this proposal are closed.