AAVSO: American Association of Variable Star Observers

Proposal #235

Proposer (1750) Shawn Dvorak (sdvorak@cfl.rr.com) obscode: DKS
Assigned To(3663) Dirk Terrell
Date SubmittedNov. 8, 2021

These targets are probably already being monitored, but just in case...

RS Oph is returning to quiescence. During the 2006 outburst, the typical flickering seen, particularly in U and B, disappeared for <= 240 days after outburst (https://www.astronomerstelegram.org/?read=14974), presumably due to disruption of the disk. These flickers occur on minute to hour timescales with amplitudes of a few tenths of a magnitude in B and occasional (once every 7-10 days) time series of a few hours would detect the reappearance and subsequent development of these flickers

T CrB is due for an outburst, with estimates ranging from 2023 (Schaefer) to 2026+/-3 (2020ApJ...902L..14L, et.al.). The 1946 outburst exhibited a high state a few years before outburst followed by a sudden dip in brightness about 1 year before outburst. T CrB is currently again in a brighter state and regular monitoring to watch for a recurrence of the pre-outburst dip could improve estimates for the time of outburst. Collecting 3-5 BVRI images every 5-7 days would provide good coverage.

Target RA (H.HH) Dec (D.DD) Magnitude Telescope Observation Frequency Expiration Date Proprietary Term
RS Oph 17.836944 -6.70778 11.1 BSM_NH2 June 1, 2022 No


(1750) Shawn Dvorak — Nov. 8, 2021, 10:13 p.m.

The second target, T CrB, didn't get added to the request for some reason:
T CrB, 15:59:30, +25:55:12, 10.2, proprietary = No

(3663) Dirk Terrell — Nov. 8, 2021, 10:18 p.m.

I know RS Oph was being observed recently, but I'm not sure if it is still in the queue. Maybe Ken can comment on that. I don't recall that T CrB was a target recently.

(3663) Dirk Terrell — Nov. 12, 2021, 5:51 p.m.

From Arne:
T CrB is being observed by RBCA (Proposal 223). This is in support of Alert Notice 750, and was to last until the HST observations were made. I don't think that has happened yet (HST is currently in safe mode). In any case, it is at solar conjunction and not observable right now. I think it would be reasonable to end Brian's project and approve Shawn's continuing long-term monitoring of this target.

RS Oph is also being observed by RBCA (Proposal 224) in support of Alert Notice 752, to monitor during its current outburst. That outburst is ending, and the target is also at solar conjunction and not observable right now, especially for time series. So I think that part of the proposal is probably not doable now. If Shawn thinks time series after solar conjunction would be useful, I'd approve.
So, Shawn let us know what you would like to do.

(4726) Kenneth Menzies — Dec. 3, 2021, 2:45 p.m.

Since RBCA has a plan for both of these, I think Shawn should discuss with him privately and decide who wants to continue AAVSONet observation and analysis?

Comments on this proposal are closed.