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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!
JeremyI had my first naked eye view of the comet last night and it was seen well in 8 x 40 binos.
It’s not often we get to see a bright comet, so I hope others will have an opportunity to look at it.
Go well!
Jeremy
Hello Cam,
those are great images: a nice range of star colours in the Double Cluster and a wealth of detail in M42. I always think M42 is one of the toughest objects to image, given the range of contrast – but you have done a very job job.
You seemed to have tamed your HEQ5 – it’s certainly giving you good results.
Keep up the imaging.
Go well!
Jeremy
I have begun the analysis of the CSS photometry data from the campaign, so I thought a quick update might be helpful. We have 6552 data points from the BAA VSS, AAVSO and CRTS databases, covering the 2013 and the 2014 observing seasons. You can view the 100-day plots for the recent season (data up to 2015 Jan 2) here: http://www.britastro.org/vss/CSS%20plots%202014.pdf
The red dashes are “fainter than” measurements. The blue data are CV or V.
You can see that coverage got better as the campaign took off. The light curve is typical of an SU Uma system (not an ER UMa as once postulated) with frequent outbursts and in my mind is quite beautiful. There are 4 superoutbursts visible, plus many normal outbursts. Analysing the superoutburst times gives a fairly consistent ephemeris, with a period of 66.4 days, taking into account the 4 supers in 2014 and an additional 2 in 2013; or 68.7 days if I only include the 2014 supers. Of course, superoutbursts are only quasi-periodic and it is a mug’s game to try and predict the next. But for a bit of New Year fun I’ll have a go anyway: sometime between Jan 18 and Jan 25, depending on several assumptions – most likely around Jan 23 if I were a betting man. You heard it here first, as they say….
However, given the field is slipping into the west, it will be a challenge to spot the next superoutburst, but it would be fun to try – and would help to update the ephemeris before the seasonal gap. So single shot imaging of the field would be helpful (as would short photometry to look for confirmatory superhumps). The supers last about 13 days.
Of course, this analysis makes use of the hard-won data submitted by many observers – hats off to them! I have used data kindly contributed by: David Boyd, James Boardman, Juan-Luis Gonzalez Carballo, Ian Miller, Ken Menzies, Roger Pickard, Gary Poyner, Richard Sabo, Pavol Dubovsky, Richard Sargent and Denis Buczynski. If you have observed this star and your name is not listed, please contact me as it probably means I have not seen your data.
Good luck and go well! Jeremy
Great work, Bill. Fascinating to see the results you are obtaining. Hopefully we’ll soon get some multi-station captures of the same event, to tie in with your spectroscopy.
Go well!
JeremyThat’s an interesting project, Mike. And nice images. Hope you will continue to extend the gallery.
Go well!
Jeremy
Hello Cam,
good to hear from you. I am afraid that I do not have experience of that telescope, but perhaps somebody else does.
Personally I have always found small refractors to be good for wide field imaging, given their compactness, no need for collimation and ability to use relatively small mounts. I recall from your previous postings that you have used an ED80, which was giving you excellent results.
Anyway, I hope to see some further results from you with whatever telecope you use.
Go well!
JeremyTime for a brief update. In my previous note I mentioned there was a long outburst from Sept 7 to 19. The star was then in quiescence until earlier this week, when it was found on Oct 8 at mag 16.3C. This was one of its brief outbursts, lasting no more than 2 days. Last night (Oct 9) it was back at quiescence again. I still expect a long outburst in early November, but this is by no means certain. Further monitoring is still requested to see if this materialises “on time” and how many brief outbursts there are in the meantime. We need dense coverage (preferably nightly) to be able to discern the brief outbursts and to spot the beginning of a long outburst – an event which would prompt time-resolved photometry. I would like to thank the people who have contributed data so far. I review data in both the BAA VSS and AAVSO databases regularly, which include observations by Ian Miller, Roger Pickard, Kenneth Menzies, Juan-Luis Gonzalez Carballo, David Boyd, Richard Sargent and Richard Sabo. Apologies if I have missed anybody. Go well! Jeremy
It’s time for an update on this target – a little overdue as I have been on hols for the last couple of weeks.
In the previous update I reported that at the end of August we had a short outburst. During the first week of September the star was in quiescence. Then a long outburst started on 7 September, lasting at least 12 days. Ian Miller valiantly carried out time-series photometry on several nights during the outburst. This again revealed hump-like features, with a period near 0.0807d, although there was a significant alternative around 0.0881d. Observations during the previous long outburst, in July, suggested a period near 0.0882d, with a significant alternative around 0.0810d. In each case the runs were rather short, introducing the uncertainty in the period. The upshot of all this is that further observations are needed!
So far we have observed long (>10 day) outbursts in late April/early May, early July and mid September, which might point to a ~2 month supercycle. Will we see the next one in early November? Of course there are short (~3 day) between the long outburst that we need to track too.
Many thanks to everyone who has contributed to the campaign so far.
Go well!
Jeremy
In my previous note, I mentioned the brief outburst of CSS from Aug 2 to 5. Since then the star has been languishing at minimum of about ~19 or lower. That is until last night (Aug 22), when it was again in bright outburst. Ian Miller conducted a 2 h time series photometry run in the early hours of today (Aug 23) which showed the star at ~16.0, with a pretty flat light curve. What will tonight bring? A fade or the start of a long outburst? Only further observations will tell!
These notes are based on observations in the BAA VSS Database and the AAVSO International Database by Juan-Luis Gonzalez Carballo, Kenneth Menzies, Ian Miller, Roger Pickard, Richard Sabo and myself. Further observers are welcome.
Go well!
JeremyHah! The old “to calibrate or not to calibrate” debate! My view: calibration is needed on scientific images, where one intends to extract data, such as photometry. But if it’s purely for images, then the choice is yours. The proof of pudding is in the eye of the beholder (to mix two sayings). I have seen many wonderful images which were not calibrated, which also convey the beauty of the night sky. I also think that for beginners, who may be keen to get their first results, then there is no real issue in not calibrating – they can move onto that later.
A similar debate has run in CCD photometry on the use of photometric filters (he ventures, not really wishing to trigger another subject of debate). There is certainly a place for using these, depending on the objective of the work. But I have noticed that some beginners have been put off even starting CCD photometry because they are worried about getting V filters etc. I say: have a go unfiltered to start with and select you targets with that in mind. If you find you like the work, then by all means invest in filters later.
Go well!
Jeremy
