Abstract: 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.
Justification: 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.
Hi, doing a light curve, what time resolution is required. 21mag might need some exposure time. Or are we just have to look for some variations in brightness with a period of about 1h regards at which brightness level and better focus on the bright phases?
It appears the “thing” just came down from an outburst… way too faint for me. Maybe if we get another outburst before solar conjuction… Anyone got an idea what the average outburst interval is?
I would suspect you should get a decent SNR, of greater than 10, more would be better. Basically it is a trade-off between exposure (sampling time) and photometry errors. The amplitude of the variation is important as well; large amplutudes are easier, low-amplitude variation is harder. At minimum this is a job for big scopes. During an outburst medium sized telscopes can play.
It would be a good idea if anyone catches this in outburst to announce it here.
Hello everyone and thank you for showing interest in observing DDE 155!
The best time to observe the target is during outbursts and superoutbursts, when we expect the orbital variations to be the largest. However, we have no estimation of the amplitude of these variations. I would suggest checking the brightness of the target at the start of observations and continuing with observations only when it appears to be in its bright state. The exposure times can be up to about 3 minutes.
The recurrence time of outbursts is about 10 days, so it should be possible to catch the star in its bright state in the coming nights. Here is a link to a plot of ZTF light curve of this target:
Due to the still-bright moon, I was only able to make one estimate in V and Rc, averaged from four individual measurements. Unfortunately, the object’s season is passing, the star is already descending in the west, and I will hardly have the opportunity to observe it for much longer from my latitude. I will try to do what I can, hoping the data is useful to you.
Hello everyone,
I just uploaded two measurements from August 24th, one in V and one unfiltered CV, each obtained from a stack of five FITS. The magnitude obtained is about 19, SNR is 16. I had to discard a measurement taken in R because the SNR was too low, even after stacking. I hope you find the data useful.
