Proposal #605

Good morning, I'm Sauro Gaudenzi, my observer code is GSAD, in support of the AAVSO alert nr 889 I ask for the use of a telescope to observe the subjects V1280 Sco and V5856 Sgr, I ask for a weekly observation for each subject, 30 photos of 30 seconds with filter B and 30 photos of 30 seconds with filter I for each subject, All until July 30, 2025. Dr. Frederick Walter (Stony Brook University) writes: We have identified two long-lived novae that remain bright more than a decade past their classical nova eruptions. These systems, V1280 Sco and V5856 Sgr, frequently fade from their "quiescent" levels, during which their optical spectra change from being dominated by cool emission lines to displaying spectral lines indicative of hot gas, most notably He II, C IV, and [Fe VII]. During TESS sectors 91-93 (April 9 - June 29 2025) we will observe these with in X-rays with SWIFT approximately weekly (simultaneously with the TESS photometry) to test the hypothesis that the fading is due to a thinning of a common envelope, permitting a view into a hot interior. We request BVRI CCD filter photometry during this time to look for color changes in the novae.
Justification:

We request nightly BVRI CCD filter photometry to look for color changes in the targets. While TESS provides a superb cadence, it is a only single-channel photometer. Color variations as the systems fade will help us assess the physical cause of the fadings, and provide insights into nature of the systems. Note that the campaign begins April 1 and TESS coverage begins April 9; nightly coverage is requested to begin immediately (see below for instructions).

Additional Observer Input:

Current V magnitudes are about 10 (V1280 Sco) and 13 (V5856 Sgr). These fade by about 1 mag during the dips. Dips last a few days to a week or so. One observation per color per observer per night is requested. BVRI is most useful; U is welcome. B and I bands are most important because they will give the best color change information. R is the least useful because of Halpha contamination. CMOS/DSLR and unfiltered (CV) will be used for timing and dip detection but not for quantitative analysis. V5856 Sgr will be observed 4/9/25 - 6/2/25 (TESS sectors 91 and 92) ; V1280 Sco will be observed 4/9/25 - 5/7/25 and 6/2/25 - 6/29/25 (TESS sector 91 and 93). Thank you very much for your cooperation and have a nice day