AAVSO Alert Notice 832 announces an observing campaign beginning immediately on FO Aqr. Please see the notice for details and observing instructions.
There are threads for this campaign under the following AAVSO forums:
Please subscribe to these threads if you are participating in the campaign so you can be updated. Join in the discussion or ask questions there!
Many thanks, and Good observing,
Elizabeth O. Waagen, AAVSO HQ
HST is scheduled to look at FO Aqr with the COS instrument starting at 00:40 UT on September 28 (the night of Wednesday, September 27). Because FO Aqr is fairly bright in the UV, the Space Telescope Safety Officer requires observations every night starting a week before the visit and within 24 hours of the visit to be sure COS does not exceed its count-rate limits.
There is a second visit scheduled to start at 22:30 UT on September 29, so observations should continue through Saturday, September 30.
The safety officer, Serge at STScI, looks directly at the AAVSO light curve of FO Aqr to be sure the star is staying within brightness limits. So if you take data, please calibrate it and load it up to the archive in a timely manner.
You may recall that we looked at FO Aqr last October with HST, but there was a failure to lock on the guide stars, so the data was compromised. This is a second try with different guide stars.
Let me know if you have questions.
Thanks to ATE, FRGA, MXD, DANF, HMB, and NROA for observing FO Aqr over the last few days. It is behaving fairly well, but we do need to keep an eye on it every night and observations within 24 hours of the two HST visits.
It has been cloudy here in Indiana for the past few nights. I hope to get some photometry on Friday if it clears off.
HST begins its observations of FO Aqr at 00:40 UT Wednesday night/Thursday morning. The safety rules require a magnitude estimate within 24 hours of the visit so that a review board can make the go/no-go decision at 9:00am eastern time Wednesday morning.
A calibrated photometric observation after 00:40 UT tonight and before 12:00 UT is required.
Pouring down rain here at Notre Dame right now, so not much chance of my getting an observation.
Time-series photometry during the HST visit (00:40 to 04:45 UT Sep 28) would also be very useful.
We do this again for the second visit scheduled for Sep 29 starting 22:30 UT.
David Messier has pointed out that the Moon is very close to FO Aqr tonight. It appears to be about 8 deg south of FO Aqr, with Saturn in between.
Given the need for an observation tonight, I am willing to accept the poor photometric accuracy that will come from a large amount of scattered Moon light. Even a point with a precision as large as 0.1 mag should be adequate for the safety decision. FO Aqr does vary by about 1 magnitude over its binary orbit, so we always see quite a variation.
I took a quick look at the first three orbits of HST spectra of FO Aqr. The guide stars appear to be good ones this time. The spectra are wonderfully complex with absorption and emission constantly moving around.
We need a confirmation magnitude tonight to allow the second visit to execute tomorrow. Still cloudy here in Indiana.
Safety at STScI has approved the second visit to FO Aqr scheduled for 22:30 UT tonight. Thanks to all that reported their observations from last night!
The last thing I will ask is that, if possible, is for time-series photometry during the HST observations. As fast a cadence as possible that still gives precisions of 0.05 mag is best. Looking at the UV data from visit 1, I do not see the typical optical variations of the white dwarf spin pulse and orbital modulation. We can certainly put together and average light curve from all the data, but having simultaneous optical would be reassuring.
It looks to clear up today, so I will try observing FO Aqr from Notre Dame tonight. But sunset is about 0 UT these days, so I am likely to just get the last piece of the HST visit.
Thank you all!
I've just uploaded a series of 60 frames at 40 seconds of exposure as part of a 1-hour patrol.
Unfortunately, the target is too low over the horizon and hiding behind the trees.
The moon is still very bright.
Uncertainty averages 0.034.
I hope this data is helpful to you.
I was able to monitor FO Aqr in V for 60 mins centred on Sept 30th 0415 hrs UT. The orbital period of approximately 20 minutes is easily seen.
I hope this helps.
I am looking at the HST data of FO Aqr from visit 2. So far it looks excellent. Far more variability in the UV than in the optical...and it is already pretty variable in the optical.
Thanks to Andrew Pearce and Nikola Antonov for attempting overlapping observations with the HST visit. I was able to get about 40 minutes of simultaneous data starting when the sky was still very bright.
That should do it for the HST observations. It appears that the guide stars locked on this time, so no do-overs. We have lots of data to analyze.
Thank you all for your help! It was critical in getting these observation done.
On the night of 02/29/2023 I made a time series of 150 images of the variable star FO AQR. These photometric measurements are without filter (CV) and were carried out remotely by the telescope dependent on the University of La Punta, San Luis Argentina. The observations made with reference to AAVSO charts have already been entered into said Site.
Prof. Daniel J. Mendicini.
Santa Fe, Argentina.