July 7, 2017: Roque Ruiz-Carmona (Ph.D. candidate, Institute of Mathematics, Astrophysics and Particle Physics, Radboud University Nijmegen, The Netherlands) has requested AAVSO assistance in determining the status of 20 eclipsing cataclysmic variables (CVs) in order to select one system in outburst for observation with the William Herschel Telescope (WHT) at La Palma, to detect and study spiral density waves in the system. The WHT observations will begin on 2017 July 11 UT.
It is essential to know whether the potential targets are in outburst or quiescence. To this end, the PI has requested that our observers obtain one image of each target on each of TWO separate nights so he may analyze them to determine the system he will observe with WHT.
One image of each target should be obtained on each of the following nights:
- between 9 July 15:00 UT and 10 July 15:00 UT
- between 10 July 15:00 UT and 11 July 15:00 UT
***The images must be posted to the thread no later than 11 July 16:00 UT.***
Observers should post their images to the thread ("2017 20 PTF CVs campaign") in the AAVSO Campaigns & Observation Reports forum (https://www.aavso.org/2017-20-ptf-cvs-campaign), and include the date/time, filter, and exposure in the posting.
It is not necessary to determine and submit a magnitude estimate of each target, just to obtain the images and place them where the PI can access them. Any filter may be used, and raw or reduced images of each target should be posted in the forum. If a star is not visible, an image of the field that shows an upper limit reasonably below the outburst magnitude is fine.
**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 the 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).
|PTF ID||Primary Name (VSX)||RA (2000)||DEC (2000)||PTF Ref Mag||Outburst Mag||
|AAVSO Min||AAVSO Max||Priority|
|PTFS1716bd||CSS 090419 J162620-125557||16:26:19.9||-12:55:56.1||20.31||19.80||CV||20.40||16.80||Medium|
|V416 Dra||V416 Dra||18:57:20.4||+71:31:19.1||----||----||V||17.30||12.70||High|
|EM Cyg||EM Cyg||19:38:40.1||+30:30:28.1||----||----||p||14.40||11.90||Medium|
Observers should use the charts supplied by the PI. PDF images of PTF (Palomar Transient Factory) close-up finder charts containing the targets and offset stars chosen by the PI, and some AAVSO charts prepared by the PI, may be downloaded here.
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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