AAVSO: American Association of Variable Star Observers

Proposal #270

Proposer (1546) Walter Cooney (waltc1111@gmail.com) obscode: CWT
Assigned To(3663) Dirk Terrell
Date SubmittedJune 22, 2022

V407 Lupi (Nova Lupi 2016) seems to be a close relative to V1674 Her in speed class and in its periodic signals soon after going nova according to Joe Patterson of the CBA. He has requested data for this system but it is faint and there are few southern CBA members who can work it. Gordon Myers has worked it recently from Siding Spring and finds it ranging from about 17.7 to 19 in CV. I would like to ask for several time series runs of this system on OC61. Since it is so faint and cadence and S/N are critical to seeing periodic signals well, I ask that we image it unfiltered or with a clear filter.

I am uncertain what exposure time to ask for since I have not used OC61 before. Maybe the best thing to do to minimize the impact of a time series on other targets would be to first run a short series of exposures at, say, 2 minute integration. I can reduce those images and recommend a reasonable optimum between cadence and S/N for a longer time series on other nights.

Once an optimized cadence is determined, I would ask for as long a time series and as frequent a time series as the AAVSOnet can allow understanding that the system is also working other targets. Would it be possible to run the star as long as possible on one night and then every fourth night of available clear skies? I would ask to run the system as available until July 31.

Thanks for your consideration.

Walt Cooney (cwt)

Target RA (H.HH) Dec (D.DD) Magnitude Telescope Observation Frequency Expiration Date Proprietary Term
V407 Lup 15.483828 -44.82772 19.0–17.0 OC61 Dec. 29, 2022 No


(3663) Dirk Terrell — June 23, 2022, 2:10 a.m.

This could be a tough target. Arne suggests SG for the filter (no clear filter on this system). Is there any periodic signal, and if so, what is the amplitude?

(4726) Kenneth Menzies — July 2, 2022, 12:14 a.m.

Committed test exposure of 300s.

(1546) Walter Cooney — July 2, 2022, 7:48 p.m.

Sorry, just seeing Dirk's question now. Yes, there are two known periods for this system. The orbital period is believed to 3.5 days with a WD spin period of 9.8 min. The amplitude of the spin period has been measured as 0.026 mag. I am hoping that OC61 can provide data with a S/N of app. 30 to 50 with a cadence of 2 to 3 minutes. If that is the case, we should be able to see the WD spin period in the Fourier analysis.

(1546) Walter Cooney — March 31, 2023, 5:13 p.m.

Thank you for the test data of March 26. The S/N is too low with the SG filter unfortunately. Since there isn't a clear filter available, no further work on this system is requested.


Comments on this proposal are closed.