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Alert Notice 564: 21 Cataclysmic variables to be observed by William Herschel Telescope

December 12, 2016: Roque Ruiz-Carmona (Ph.D. candidate, Institute of Mathematics, Astrophysics and Particle Physics, Radboud University Nijmegen, The Netherlands) has requested AAVSO assistance with his campaign to observe a set of 21 cataclysmic variables (CVs) with the William Herschel Telescope (WHT) at La Palma on 2016 December 16. This campaign is essentially identical in format to the ones successfully carried out by the AAVSO on his behalf in 2015 and in May 2016 (AAVSO Alert Notices 524, 527, 543).

Ruiz-Carmona writes: "As the end of my PhD is closer now, this is the second-to-last campaign monitoring CVs into outburst. As an update on my research, it seems that unexpectedly spiral density waves can only be detectable in high inclination systems and it seems that the luminosity of the disk in outburst outshines the spiral pattern for the rest of the system. This can also have deep implications: it can be that the spiral density waves are only an effect of the atmospheres of the disks and are therefore unrelated to transport of matter and angular momentum in the disks. In order to investigate this hypothesis, the sample of CVs I would like to monitor contains only eclipsing systems.

"[As before,] I just need to know if the targets are in outburst or not. Even non detection can be useful, because it means that the systems are in quiescence. I prefer R filter but anything will do (even no filter)..."

The PI has requested AAVSO observers to obtain one image of each target on each of TWO separate nights so he may analyze them to determine the final observing list for WHT.

One image of every target should be obtained:

 - between 14 December 15:00 UT and 15 December 15:00 UT
 - between 15 December 15:00 UT and 16 December 15:00 UT

***The images must be posted to the thread on the AAVSO Campaigns forum no later than December 16 16:00 UT.***

Observers should post their images to the thread ("21 PTF CVs campaign") in the AAVSO Campaigns & Observation Reports forum (https://www.aavso.org/content/21-ptf-cvs-campaign), and include the date/time, filter, and exposure in the posting. Raw or reduced images of each target may be posted on the forum. It is not necessary for observers to determine and submit a magnitude estimate of each target.

**Only one image per observer per target per night should be submitted. Please do not submit multiple images of any target obtained by you on the same night.**

An observer does not have to take images of the same targets on both nights (although that would be ideal); if conditions change between nights, whatever images can be obtained will be extremely helpful.

The table of targets is given below. Some of the targets are quite faint, and stacking of images may be necessary. The maximum size of an image file that can be uploaded to the Forum thread is 40 MB, so if any files are larger, please trim the image(s).

Observers should use the charts supplied by the PI. PDF images of PTF (Palomar Transient Factory) close-up finder charts and two AAVSO charts containing the targets and offset stars chosen by the PI may be downloaded here: (https://www.aavso.org/sites/default/files/publications_files/alerts/FindingCharts_rruizc4.pdf).

Please note that there are two versions of the finding chart for PTFS1507o (U Gem).

Please be sure that each image includes the offset stars, especially if you trim it so its size is less than 40MB.

Because the windows for observation by AAVSO observers are relatively short and the target list is quite long, it is recommended that observers coordinate their observing plans so that all of the targets are covered on both nights if at all possible. Please use the forum thread given above to post what targets you plan to observe; if you see that more difficult targets are not being covered and you can observe them, your doing so would be greatly appreciated.

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.

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