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Hello Michael,
the requirement for a filter depends what type of variable star you are observing. I observe Cataclysmic Variables, in particular Dwarf Novae in outburst. I usually do unfiltered photometry to get the best signal-to-noise ratio. I’ll use a V-band comparison star sequence. Observing some eclipsing systems, where timing the eclipse is critical rather than the actual mag, can also been done unfiltered. For much other VS work a filter is highly desirable in order to be able to compare your photometry with other observers – and in the case of coloured variables (like Miras) a filter is essential. Whilst many amateurs use a V-band filter, some use a B, R or I filter. These are specific wavebands, based on the Johnson-Cousins system, which are designed for photometry and are thus different for standard coloured filters for tri-colour imaging (and different from UV or IR cut-off filters).
I am not sure where one can buy 2-inch V filters. The company Astrodon lists them, but they are unmounted. Maybe someone else can advise.
Best regards,
Jeremy
Wonderful image, James. Looks like you had good skies during your trip to North wales.
All the best,
Jeremy
Congratulations to everyone that observed this event – indeed an excellent result!
I enjoyed your Youtube video, Tim – thanks for posting. It looked to me that there were a couple of flashes towards the end of the occultation – was that due to the seeing?
Jeremy
Nice image with a huge amount of detail, Cam. You seem to be mastering narrow band imaging. Best of luck with your search for a larger format CCD.
Thanks for sharing.
All the best,
Jeremy
This is excellent news, Steve. Do keep us posted about your experiences with the new lights, and how they affect your views of the night sky, now that the nights are drawing in.
Jeremy
Excellent images, Cameron. Well done!
You must have superb negotiation skills to convince the other people to pack all that kit into their cases, but it was well worth the effort.
All the best,
Jeremy
Nice image, Paul. Yes, the sky was pretty decent this morning and I too had some good views in H_alpha.
Jeremy
My daughter and I spent last evening touring the Cheshire countryside looking for good views of the conjunction, which was absolutely beautiful. The attached pic has Beeston Castle in the foreground.
Jeremy
Indeed some pretty esciting data from Nick. Incredible to think we are looking at the secondary effects of a black hole.
Paul, I am not sure I know what is causing these variations. Much of the work on V404 Cyg has been whilst it was in quiescence, where large variations, or flares, are also seen. One idea is that the flares are caused by local magnetic reconnection events in or above the accretion disc. The theory goes that a dynamo mechanism, driven by the strong shear produced by differential rotation, operates in accretion discs, and regions of oppositely directed magnetic fields develop within the disc or between the disc and corona and reconnect explosively. There’s more discussion in the MNRAS paper: http://cdsbib.u-strasbg.fr/cgi-bin/cdsbib?2003MNRAS.346.1116S
However, maybe in outburst it’s something else? I am sure that the current outburst will reveal more – and much of the new data will be contributed by amateur astronomers!
I hope others will get a chance to see such a rare outburst of this peculiar system before it fades.
Go well!
Jeremy
Hello Donald,
A very warm welcome to the BAA! I am sure you will enjoy your membership experience and with the enthusiasm you clearly have, you will find all sorts of opportunities to get involved in observing.
It sounds like you are already well equipped with a telescope and binoculars. The BAA organises Back to Basics workshops, the next one being in North Wales, so not the most convenient location for you in Stonehaven. There are lots of observing sections where your observations would be most welcome. The first question to ask yourself is what do you enjoy observing? You mention you have done some variable star work in the past. This is clearly a field where your observations would be very valuable – and you have eminently suitable equipment to hand. One of the simplest places to start is observing binocular variables. The Variable Star Section’s web site has a page on Binocular Variables here: http://www.britastro.org/vss/chartcat_binoc.htm
The section also publishes a booklet on binocular observing, with instructions and which contains quite a few charts. This is available from Roger Pickard, the Section Director, or the BAA Office. There is a page for “absolute beginners” here: http://www.britastro.org/vss/absolute_beginners.htm
The Section also publishes an “Observing Guide to variable Stars”, available from the BAA Office.
The VSS also has mentors who are happy to help people starting out: http://www.britastro.org/vss/Mentoring.htm
Binoculars and small telescopes are also ideal for observing the brighter comets (drawings and magnitude estimates are always appreciated by the Comet Section) and deep sky objects (again send sketches and descriptions to the Deep Sky Section).
Living in Scotland (if I have the correct Stonehaven) means you are well placed to observe the aurora and noctilucent clouds – the season for the latter is upon us now.
These are only a few ideas and I am sure others can provide info about further sections. And do contact the section directors. They’d be delighted to advise and to receive your observations. Whatever you do – keep asking! The BAA is here to help you further your interest in astronomy.
Go well!
Jeremy
Very interesting, David. What do you intend to do with the gratings?
Thomas Thorp was a BAA member, joining in 1892, and a leading light in the North-Western Branch, in Manchester, where he served as Vice President. A brief JBAA obituary appears in JBAA, vol 24 (10), page 503, October 1914:
We regret to record the death of Mr. T. Thorp which occurred on 13th June last at his home, Whitefield, near Manchester. He was educated at the Manchester Grammar School, and resided in Manchester all his life. He devoted much of his time and attention to the improvement of astronomical instruments. His replica gratings, invented several years ago, brought him into prominence as a pioneer in this department of instrumental mechanism. Many of our members have reason to be grateful to Mr. Thorp for supplying them with prism gratings, applicable to binoculars, which have proved so serviceable in the observation of total solar eclipses. Ho joined this Association in 1892, became a member of the Manchester Literary and Philosophical Society in 1896, and was elected a Fellow of the Royal Astronomical Society in 1902.
All the best,
Jeremy
Hello Alex,
Good to hear about your VS observations.
The VSS spreadshseet automatically converts UT to JD, as Gary says, which is absolutely painless.
If you need to convert UT to JD (or vice versa) at any other time, there is a great Applet on the BAA Computing Section web site:
http://britastro.org/computing/applets_jd.html
This is also linked from the front page of the VSS web site.
Jeremy
A couple of people have kindly asked if I wish to continue receiving data on this star.
My request is that observations are submitted directly into the BAA VSS Online Database. That’s the safest place for them and will ensure they are available to all researchers in the future.
Jeremy
Hello James,
nice to hear from you. There isn’t an online directory. I recall the BAA published a membership list (actually a booklet) in the late 80s or early 90s (I have mine around somewhere). There are all sorts of data protection issues now which I suspect would preclude publishing anything meaningful online.
All the best,
Jeremy
Last year a campaign was organised by the BAA Variable Star Section to monitor this dwarf nova.
A paper summarising the results has been accepted for publication by JBAA and a pre-print is available here: http://arxiv.org/abs/1505.07709
Many thanks to all those who contributed to, and supported, the campaign, which shows just what is possible via cooperation and pooling of observations.
Whilst the official campaign finished in January, observers are still welcome to monitor the star, which shows frequent outbursts and superoutbursts. The supercycle is one of the shortest of SU UMa’s on record, at 67 days.
Jeremy Shears
This is an amazing result, Robin. Having tuned your system to achieve such a faint LM, many objects will now be within your grasp.
Go well!
JeremyHello Mike,
Good to hear about your interest in CCD photometry of variable stars. Indeed there is quite a bit that the modestly equipped observer can do in this field – especially when they combine data with other observers. The objects you mention are popular, partly because these they often have short periods which means you can get interesting data in a few nights. RR Lyrae stars, delta Scu stars and their cousins HADS (High Amplitude delta Scutids) fall into this category. I haven’t done much on these stars as I mainly concentrate on cataclysmic variables, which also have short periods (a few hours). A few of us looked at a delta Scu in Cas a while ago: http://adsabs.harvard.edu/abs/2007OEJV…76….1S. I have to admit the target happened to fall in the same field as a dwarf nova which was our main target!
I would be happy to chat a bit more with you about this topic – if you are attending the Meteor Section meeting in Birmingham on Saturday, that would be an opportunity (whilst talking about meteors as well, of course!).
Go well!
Jeremy
Thanks for highlighting this, Martin. Just listened to it on iPlayer:
http://www.bbc.co.uk/programmes/b05qdw88
In spite of it being only a short piece, 15 mins, it contains a pretty though analysis of Hay’s achievements, by Simon Heffer. And his interest in astronomy is mentioned – along with his white spot on Saturn.
Go well!
JeremyGood to hear that you met with success, Nick. Nice images and well done for posting them so promptly.
I stayed at home in Cheshire and hosted some children from the local Primary school along with their parents. The BAA Solar Viewers went down well. It was clear throughout and everyone had good views through my H-alpha and white light telescopes. A bit warmer than Svalbard, I suspect, but we only got a 90% eclipse – impressive nonetheless.
Go well!
Jeremy
