Proposal #633

Good morning, I'm Sauro Gaudenzi, my observer code is GSAD, in support of AAVSO alert nr 904 I ask for the use of a telescope to observe the nova DDE 155, I ask that 60 shots of 60 seconds with V filter and 60 shots of 60 seconds with R filter be taken, it would be sufficient in my opinion that these shots are taken in a row in one night, and on several nights per week from now until 15 October 2025. DDE 155 (ZTF18abmbdyk) is a dwarf nova with suspected orbital period bellow 1 hour. Its magnitude in filter g ranges between 16.6 and 21 due to outbursts and superoutbursts. We would like to obtain light curves from multiple nights, each covering about 2 hours or longer time span, to detect orbital variations. Ideally, we would like the observations to be taken during outbursts and superoutbursts, where we expect the variations in brightness to be the largest. Determining the orbital period of DDE 155 will help us to classify this target, which is suspected to have an orbital period below the period minimum of cataclysmic variables. Photometry cadence: 2 hours or more per run, as many nights as possible, exposure duration as necessary to give the best S/N obtainable with your equipment. Photometry filters in order of priority: CV, CR, V, R. Due to the low brightness of the target, unfiltered photometry is requested in order to achieve the best signal-to-noise ratio. In conditions which allow for filtered photometry, Johnson V or Cousins R would be the most suitable ones. Also, while outbursts and superoutbursts occur frequently, their precise occurrence can't be predicted. It is therefore necessary to check the brightness of the target at the start of observations to determine whether it is bright enough to obtain usable photometry.