Proposal #611

Proposer	(4603) Ray Tomlin (7tomlin@gmail.com) obscode: TRE
Assigned To	(3663) Dirk Terrell
Date Submitted	June 2, 2025
Status	Allocated
Priority	Normal
Proposal	Need 3xBVRI or as many JC filters as available and 3 to 4 nights weekly. ASASSN-25cd 4 lies in Sagittarius. 18 31 52.79 -28 48 26.7 (277.96996 -28.80742) The linear fading trend and the previous lack of variability suggest it might be a long period eclipsing binary. The star stayed constant in previous years of ASAS-SN data (2016-2025) and also in ASAS-3 data (2000-2009). It is a K-type giant so it might be an EA/GS. It seems to have reached a minimum magnitude of 15.0 g but we need more data to see if that is indeed the bottom of the “eclipse”. In EA/GS systems, amplitude varies strongly depending on passband, because a late type star is usually eclipsed by a hotter fainter object. We now only have ASAS-SN g data. It would be interesting to have multicolor photometry to see if the amplitudes are indeed that different.

Targets
Target	RA (H.HH)	Dec (D.DD)	Magnitude	Telescope	Observation Frequency	Expiration Date	Proprietary Term
ASASSN-25cd	18.531331	-28.80742	13.6–15.0	OC61	1	Dec. 2, 2025	No

(4726) Kenneth Menzies — June 5, 2025, 5:04 p.m.: Committed to OC61 and Berry with available filters and appropriate exposures. Should answer your question?
(4603) Ray Tomlin — June 30, 2025, 9:12 p.m.: No data arriving from this one recently? Is it on the menu?
(4603) Ray Tomlin — July 3, 2025, 4:49 a.m.: Data from 2460858. is not solved.
Some images have triple stars.
VPHOT will not work with them.
(4603) Ray Tomlin — July 28, 2025, 9:05 p.m.: I am monitoring 65 variables from the good images of BSM Berry5 on ASASSN-25cd.
One has nova'd. V1017 Sgr.
Can I get images from BSM Berry5 more often than once per month?
3x300 second BVI a couple times per week would be nice.
ASASSN-25cd data from OC61 is more or less unproductive so far.

Comments on this proposal are closed.