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Paul, I shall be seeking photometry that has the best possible SNR with a suitable time resolution (mutually exclusive!) to refine the ca 3.2 h period. To do, this I will be combining your data with other observers to get as long a baseline as possible. So please process your photometry with this in mind. If this is not suitable for the database (bearing in mind Andy’s guidance), then please send the data to me directly.
The upshot of all this is that 30 sec exposures are not really long enough, so stacking will help. But the real answer is to get your autoguider on line; I wish you luck with that. I have used 120 sec integrations with a C11, but which are not really long enough. Another observer is using 240 sec integrations.
A new BAA VSS visual chart for Betelgeuse has been prepared by John Toone and is available in the original article on the fading of this star. Unusually, this is an 80 degree chart, which includes many of the bright stars in the winter sky. You can also download the chart directly from the VSS website.
The latest observation in the BAA VSS database has the star a mag 1.6 (Gary Poyner, Jan 28, visual).
Further observations are encouraged to see whether the fade is actually bottoming out.
Good to hear you are getting CV data on U Leo, Paul. Hopefully you will be able to continue to get some runs during Feb.
Jeremy
Indeed, David. Variable stars are of course fascinating and I am hoping the Beeb will now make a New Year’s Resolution to make this a weekly event…..
I enjoy hearing about what other’s make of star patterns. There is a lovely chapter in Skylight Nights where the young Leslie Peltier gets up in the small hours to view an unfamiliar region of the night sky. He makes up his own constellations, but none coincide with the “standard” ones.
I tried to find Orion’s Arrow the other night, but even knowing what to look for, I struggled. Clearly I lack Mrs Basey’s imagination! Or perhaps it was that I was distracted by Betelgeuse’s faintness and that it might go supernova.
…I had it at CV = 16.0 last evening (Dec 23).
It’s getting harder for me to observe: if I don’t get it shortly after dusk it’s slipped below my local obstructions. I hope others will be able to follow into Jan so we can keep track on the recovery.
This paper by Arne Henden outlines how you can determine the faint limit of a CCD image (see page 75 for Arne’s paper). As Arne points out: “the devil is in the detail”.
This is for special projects. In other cases one should stick with the sequence for the reasons Gary gives.
Gary Poyner reports that HR Lyr was very faint last night (Dec 13.799, V = 16.63). He notes this is the faintest in V since 2016 Sep.
The light curve shows that HR Lyr has faded rapidly since the beginning of the month: just over 1 mag in 6 days.
How faint will it get? Let’s keep watching to find out…..
Jeremy
Thanks to everybody for arranging a superb meeting yesterday. Three brilliant talks; really good Sky Notes, Nick!
Really interesting, Robin.
Congratulations on receiving your gong at yesterday’s BAA meeting in London. Well deserved!
Hello Kevin,
I generally eyeball my data to see if there are any strange data points. Looking at the measured errors can also give a clue as to what might be happening- as can having a look at what is happening to the Check star at the same time. I’d be vary wary of any automated process for cleaning data.
But be careful about being too enthusiastic about deleting data as the results might be real!
Jeremy
I enjoyed seeing your light curve, Kevin.
You can submit the data as “Clear” filter (abbreviated to C).
For some purposes (like time series photometry of cataclysmic variables), C is perfectly acceptable (when you use a filter, you lose some of the light, so your signal to noise deteriorates). However, for many applications a filter is much preferred as it’s easier to compare data from different observers.
Many thanks everyone for your replies – also some I received offline.
I’ve ordered the Celestron NexYZ
Go well!
Jeremy
Thanks Paul. The behaviour looks different on the two nights (I realise the second run was quite a bit longer than the first)
An updated light curve covering the campaign up to Aug 9 is shown on the VSS website.
In the last month it’s faded by about a magnitude. Please do keep up nightly observations of the star and if anyone is able to do long CCD photometry runs (a few hours), it would be greatly appreciated.
There will be a more detailed update on the campaign in the next Variable Star Section Circular which is due to appear on Sept 1.
The Circular is emailed free to anyone that requests it – if you are not already on the distribution list please contact me using the “Send Email” button to the left of this message.
The NAM session was an excellent opportunity to meet up with some of the professionals we work with. Many thanks to Callum and Dirk Froebrich for proposing to the RAS that a pro-am session be held and for subsequently organising it.
A report will appear in a future Journal.
Very interesting results, Bill. Certainly an impressively faint detection limit.
I realise that you are mainly doing this for spectroscopy, but are you able to analyse the videos by UFO Analyser?
I hope you have some clear skies for the Perseids!
We are now 3 months into the HR Lyr campaign and we have a nice light curve of this old nova developing. This can be seen on the VSS website. It has been brightening steadily over the last 3 weeks and is now as bright has it has been for a very long while. It will be interesting to see just how bright it becomes.
Time-resolved photometry continues to show various humps and bumps in the light curve with an amplitude of ~0.15 mag. These appear to be fairly regular for a few cycles (~1.5 h), but they do not appear to be consistent. Moreover the shape of the bumps is quite variable.
A couple of requests:
1. Please keep the once-or twice per night snapshot photometry going. New observers are always welcome, of course.
2. Some really long photometry runs (several hours) over a few nights would help us to understand the short term variations and see whether a coherent signal emerges. Late July onwards would be a good time for this as the nights are becoming longer.
Many thanks to all the observers who have supply visual and CCD photometry:
David Boyd, Walter Cooney, Pavol Dubovsky, Sjoerd Dufoer, Carlo Gualdoni, Kevin Hills, Steve Johnston, Mel Joslin, Paul Leyland, JH Mallett, Ian Miller, Ken Menzies, Martin Mobberley, Roger Pickard, Gary Poyner, Jeremy Shears, Dave Smith, Richard Sabo, Tonny Vanmunster, Ivan Walton
Jeremy Shears
