Affiliation
American Association of Variable Star Observers (AAVSO)
Wed, 07/13/2016 - 19:55
AAVSO Alert Notice 545 announces an observing campaign from Dr. Colin Littlefield and colleagues on the intermediate polar FO Aqr; time-series observations are requested. Please see the notice for details and instructions.
Many thanks and good observing!
Elizabeth Waagen, AAVSO HQ
seems clear will try and do tonight, 1 minute cadences as requested.
Mario Motta
Here's one I've never seen before... "Unfiltered photometry reduced with a V zeropoint"... What does that mean?
Brad Vietje, VBPA
Newbury, VT
Pretty simple. It means
a) take images without a filter in place
b) when reporting magnitudes, pretend that you used a V filter
In other words, suppose you take some images without a filter. You see the target star and one nearby reference star. In your images, the target star is exactly 1.10 mag fainter than the reference star. You look up the properties of the reference star, and find that it has V=14.35. So, you report
I measured the target star to be mag (14.35) + (1.10) = 15.45
That's an unfiltered measurement, but using a V-band zeropoint.
Just an added comment. While I mostly do BVI photometry, there are some projects which the color information is not needed. I have a multi telescope project going where we use the 24 inch to do the B and V, while the 12 inchers are used unfiltered with V zeropoint to capture as much detail with as high signal to noise as possbile. In this case, both are useful.
WGR, Gary
On behalf of my collaborators, I'd like to thank everyone who has observed FO Aqr in response to our request for observations. Keep up the fantastic work!
Just to give a heads-up, our group will be obtaining X-ray observations with Chandra on July 25. I'll post specific details as the date approaches, as we'd love to have simultaneous optical data to accompany the X-ray observations. But in the meantime, nightly time series are very useful.
(Also, just to clarify the Alert Notice, I don't hold a PhD yet.)
Best Wishes,
Colin
I have over 569 transformed BVI (mostly V) mags for this object over the last few nights; 17Jul-24Jul16. Will continue shooting until about 05Aug16...then off to Mt. Pinos for pretty picture shooting new moon weekend!
James
My group's X-ray observing run with Chandra starts in just a few hours (7:26-12:26 UT) . Time series photometry during that span would be particularly helpful!
Best Wishes,
Colin
To: Dr. Colin,
Did a FO Aqr time series last night and doing one right now! Unfortunately clouds came in and limited this moring's run. 278 BVI (272 Vs) transformed and submitted from today and last night.
James
Hi James,
Great work! Your observations overlap with the Chandra data, so we're able to correlate the X-ray behavior with the optical behavior. This is really helpful.
Colin
My colleagues and I thank everyone who has contributed photometry of FO Aqr. During the past week or so, FO Aqr's light curve has started to show noticeable changes compared to its light curve from the start of July. We suspect that the 20.9-min modulation from the rotation of the white dwarf is becoming stronger as the system continues to brighten. Please continue your excellent coverage of FO Aqr. Also, I would like to encourage the use of relatively fast cadences (faster than ~60 seconds per image). FO Aqr can vary appreciably on timescales of much less than one minute, and fast cadences will capture more of the rapid variations.
Best Wishes,
Colin
I am going to reduce to 20 s exposure times.
Josch
AAVSO Special Notice #425 announces the schedule (November 13-14) for XMM-Newton observations of the intermediate polar FO Aqr, the target of the campaign announced in AAVSO Alert Notice 545. Time series photometry is needed for simultaneous coverage during the XMM-Newton observations and after. Please see the Special Notice for details and instructions.
Many thanks and Good observing,
Elizabeth Waagen, AAVSO HQ