Forum Replies Created
-
Posts
-
Posted by Richard Miles at 17:47 on 2014 Jan 05
Alex – The lightcurve amplitude of Vesta is small, like you say, at between 0.08-0.19 mag depending on its heliocentric longitude for the present apparition. That of Ceres ranges from 0.02-0.06 mag.By doing colour difference magnitudes, such as (B-R) for Vesta MINUS (B-R) for Ceres, any variation in general brightness of the two objects cancels out and we are left with colour changes only. Since DSLRs do 3 colours at a time, and these asteroids are both brighter than magnitude 8.5 (Vesta reaches mag 5.7 in April), these cameras are pretty ideal tools for the job. The only thing to watch will be to use a short enough exposure time to avoid saturating pixels in the image of Vesta.I’ll look to write a short ‘How To’ crib sheet for folk planning on having a go. If several people tried it then the combination of all would be better than an effort by one person only.There might be a spin-off too in that it could kick start more use of DSLRs for variable star observations as well as those of asteroids!
Posted by Martin Mobberley at 15:39 on 2014 Jan 05
I will only be contributing one post to this thread, simply because the forum is not a place for advertising my book, and there is no such thing as bad publicity, as any author will tell you! All discussion on a publicly visible forum simply increases the book’s Google presence and therefore its sales!First, I’d like to thank those people who have sent me e-mails saying how much they have enjoyed reading the book since its publication in August. These e-mails now exceed 100 in number and originate mostly from BAA members of long standing, mainly those born in the 1950s, and those who knew Patrick well. The general response has been very similar in tone to the JBAA review by Dr Mitton and the Cloudy Nights thread on the subject.Writing a book about such a popular figure was never going to be easy, but I had plenty of advice. Most of it, from experienced authors, warned me that I would be very tempted to write a hagiography (simply hero worship) and leave out the negative stuff. But this was never my plan. Having spent more than ten years unearthing everything about Patrick there was no way I would be shoving the bad stuff under the carpet. It would be a waste of a decade of work and others would soon reveal the information anyway. I knew that others were planning biographies of Patrick too, so mine had to be released promptly. No-one would spend a decade on a project just to sit back and see less comprehensive ones be published first! Even in Patrick’s lifetime a few (such as Richard Baum and Ewen Whitaker) had dared disclose flaws in Patrick’s stories, such as the murky Mare Orientale business…..After their paper was published in the JBAA Patrick issued an apology of sorts on TV and in a JBAA letter….To omit everything negative of this type would make the biography of little historical value.Patrick will always be a hero figure to me and a man who shaped my life, but to deny he had serious flaws would make my book no more than a fan-worship book, with no real substance. It is clear from Dr Simon Mitton’s review of ‘RAF Blazer’ that he feared it might be just that…..a hagiography, but clearly he was very pleased to see that it was, instead, a comprehensive account and I had not chickened out from writing the truth, whoever it annoyed. As we all know, Patrick always spoke his mind, and I have done the same with the ‘RAF Blazer’ book.One term that keeps occurring in e-mails I have received is that this must have been a horrendous task to get the mixture right, but that ‘you have got that tricky balance dead right’. It was not easy, and the 330,000 wordswere read and re-read several dozen times before I was happy. Even so, a few other authors did tell me: "If you say anything negative about Patrick, anything at all, there will be a witch hunt and you will be lynched by the baying mob, who will have no interest in the facts….." One astronomy author told me he would never write anything negative about Patrick as "I would surely be beheaded with a meat cleaver…" Fair enough, but the baying mob has not appeared, just a daily influx of ‘thankyou’ e-mails. If a few people would prefer a book that was 100% positive about Patrick, and omitted almost everything prior to the late 1950s, then Patrick’s own book, in ’80 not out’ and ‘The autobiography’ format, is still available. The reader has a choice! Indeed, there isanother option too….the critics can write their own biography of Patrick if they prefer. I have already had half a dozen e-mails (and some letters) insisting I must write a follow-up book! Perhaps I can quote from a personal letter received from Dr Allan Chapman last week, who was a good friend of Patrick’s over many years:’Dear Martin, I really must let you know how very much I am enjoying your RAF Blazer biography of our dear late friend Sir Patrick. I think that you have struck exactly the right balance: how to write a sharp and penetratingbiography while still displaying a deep affection for the man and his fables: I did so laugh at "Tut, Tut, Naughty Patrick" regarding the RAF.’ Allan goes on to note that some of Patrick’s negative points weresimilar to those of Galileo, so he was ‘in good company’.If such a close personal friend of Patrick’s, and such a noted historian, thinks I have got the balance exactly right then I am more than happy…..Patrick’s closest friends all agree that he had some major faults, but he was such an entertainer and raconteur that it was almost impossible to dislike him, whatever he said or did!!As I say, this will be my final forum posting on this subject, but I am happy to answer (even more!) e-mails via martin.mobberley@btinternet.com, even if I am currently spending about six hours a day answering queriesabout telescope problems and Patrick…..Martin
Posted by Grant Privett at 15:09 on 2014 Jan 05
I’ve not read it and have no particular opinion about Dr Moore as we never met.Surely the purpose of any book like this is to convey a true impression of what the person was like. He was a man, and like the most of us presumably had his own loves and hates. Personally, I prefer a warts and all approach from which a balanced comprehension may be drawn.
Posted by Phillip Hudson at 12:43 on 2014 Jan 05
I have been reading and for the most part enjoying this book but do wonder why it has to go and somehow (in my opinion ) spoil the impression of the man that I (and maybe many others) have grown up with.
Posted by A R Pratt at 09:53 on 2014 Jan 05
Hi Richard,That’s an interesting project.What do you think would be the amplitude of Vesta during the 6 hours? About 0.1 mag in the visual?Clear skies, Alex.
Posted by Richard Miles at 16:42 on 2014 Jan 04
Thanks for this Graham.I must mention that back in 2012 October, Jean Meeus added the following comment to an e-mail note about the opposition brightnesses of Ceres and Vesta:"There is something else that is interesting about Ceres and Vesta.In April 2014, these two asteroids will reach opposition with theSun at a time inteval of less than 48 hours. During almost eightmonths they will stay less than 5 degrees from each other in thesky, and during almost two months at less than 2 degrees.On 2014 July 5 their angular separation will be only 10 arcminutes,their least angular distance since at least the year 1800."Jean MeeusSince we know that Vesta changes colour slightly as it rotates, whereas Ceres does not, it would be useful to verify whether these changes can be detected photometrically. Maybe the easiest way of doing this is to do a time-series of images using a DSLR camera with enough FOV that both objects are on the same frame and then to extract the Red, Green and Blue FITS files and measure the relative B-V, V-R and B-R magnitude of Vesta relative to Ceres vs. time. Vesta rotates in just 5.34 hours so a 6-hr run should follow more than an entire rotation.
Posted by M C Butcher at 13:47 on 2014 Jan 04
I had thought that 2012 was not a good year but then 2013 came along and it was much worse!During the year I observed on 9 nights only (for a total of 16 hours 35 minutes). On all other occasions it was either cloudy or too windy or both. My best months were August (2 nights 4 hours 50 minutes) and October (3 nights 8 hours 25 minutes).A very windy year, 2013 saw 2 days with Violent Storm Force 11 winds, 5 days with Storm Force 10 winds, 13 days with Severe Gale Force 9 winds and 43 days with Gale Force winds. Since mid-October it has been too windy to set up a telescope.I missed 14 nights through being absent.Here’s hoping for a better 2014.Martin ButcherIsle of Colonsay
Posted by Terry Byatt at 19:17 on 2014 Jan 01
I think it’s appalling that the existence of Laura (Patrick’s girlfriend) has been "debunked" by this book. Whether it’s true or not is irrelevant. Patrick wanted us to believe his story and to publicise this barely a year after his death is to my mind unforgivable. I always thought that Martin was one of Patrick’s friends!For this reason alone I will not buy or recommend the book.
Posted by Gary Poyner at 13:04 on 2014 Jan 01
Slightly better for me in 2013. I had 93 observable nights in 2013 compared to 84 in 2012. I also had a good run on Nova Del where I made 63 observations in the first 100 days, although these were mainly brief holes in cloud where I could use bins or the small 22cm.These 93 nights equate to 191.18 hours of eyepiece time in 2013. 59 of these nights were completely clear, whilst 34 were partially clear (more than 50% cloud and good breaks). Best month was April with 12 nights, and the worst was January with just 3. Of the 93 nights, 37 were under strong Moonlit conditions. I made 6,651 visual observations (my lowest number of observations in a single year by far since 1992) as I was unable to observe on all of the 93 nights due to various reasons. I also accumulated 1,952 CCD observations from BRT and AAVSOnet remote telescopes. All CV’s of course :-)As usual I keep a track on how the weather guys do in their predictions for cloud cover. In 2013 they made incorrect cloud/clear forecasts on 60 occasions.Looking forward to seeing other observers stats.Happy New year!Gary
Posted by Grant Privett at 21:37 on 2013 Dec 23
Managed to get some time away from wrapping presents and had a look at the talk. Well worth the effort. An astounding bit of kit.Note for others: after clicking download it took about 2-3 minutes before the first slide appeared on the screen and the presentation began.
Posted by Nick James at 22:10 on 2013 Dec 22
Dave,Are you stacking images to offset at Gaia’s sky motion? At present it is 2.86"/min in PA300 but this changes quite quickly. The best way to get this info is to use the MPC space junk page here although I expect ESA would object to Gaia being called space junk!Given that Gaia is now fainter than mag 18 it is important to stack at the correct rate and offset so that it is not smeared out. This is very good practice for imaging faint asteroids so it is worth persevering.Nick.
Posted by Dave Eagle at 22:03 on 2013 Dec 22
That area was towards the edge of my field of view, so I guess my 190 Mac-Newt and MDK camera just cannot pick it up. I would like to know how low in magnitude I can get with my setup. Here’s a single image: http://www.eagleseye.me.uk/Sky/Images/Gaia-0049_21-01-05.bmp
Posted by Nick James at 21:41 on 2013 Dec 22
Dave,It is a little off the predicted position. I’ve just measured it at mag 17.8:2013 12 22.89666 06 02 53.78 +14 12 44.8 17.8 R 970This is around 5 arcmin SW of the position given for my location in http://gaiainthesky.obspm.fr/fov/.Update at 21:45 – With a longer stack and higher SNR it is actually 18.1R using UCAC-4. Here are the images (all stacks of 10x60s, 13′ square, N up):image from 21:34UTCimage from 21:44UTCimage from 21:55UTCimage from 22:06UTCYoutube timelapse movieNick.
Posted by Dave Eagle at 20:12 on 2013 Dec 22
I have got the calculated field of view, but can see no sign of anything moving in the field. I will persevere for a bit longer.
Posted by Nick James at 10:57 on 2013 Dec 22
Dave,That would be great. The GBOT team are keen to get magnitudes at the current aspect angle so any observations you can get would be useful. Assume that it will be around mag 18 tonight and it may be a little off the predicted position.Nick.
Posted by Dave Eagle at 09:54 on 2013 Dec 22
Thanks for the update on the solar shade angle. I will definitely revisit Gaia given clear skies. Hopefully tonight.
Posted by Nick James at 00:28 on 2013 Dec 22
I managed to observe Gaia again tonight between rain and gales but it is dramatically fainter than a couple of nights ago at around mag 17.6. It is also about three arcmins SW of the position predicted. I assume that the magnitude change is due to a change in the spacecraft attitude so that the sunshade is now offset but I need to confirm this.At present it is around 400,000km away so it will be around 3 mags fainter at L2.Nick.Update at 08:37, Dec 22 – The Gaia optical tracking team have confirmed that the reason for the dramatic fade (a factor of a around 100) is a change of spacecraft aspect angle. The large reflective sunshade is now angled at about 45 deg to our line of sight. There’s an interesting paper on this here. This is the final aspect angle that the spacecraft will have at L2.
Posted by Dave Eagle at 20:39 on 2013 Dec 20
I managed to capture it last night. It was much brighter than I was expecting it to be. http://wp.me/p2y7OF-N5
Posted by Nick James at 19:54 on 2013 Dec 20
The guys involved with the Gaia Ground Based Optical Tracking project have been using these images to calibrate their brightness model for the spacecraft. They are keen to get more optical observations since Gaia is now near the phase angle that it will have at L2. This will allow them to predict the final magnitude more accurately. For us, the spacecraft is well placed in the northern part of Orion, on the border with Taurus. It’s about twice as far away tonight so I would guess that it would be around mag 12 based on last night’s observation.The weather doesn’t look good for me tonight. If anyone does manage to get some mag estimates tonight then please post them here and I’ll forward them on.Nick.
Posted by Richard Miles at 11:53 on 2013 Dec 20
Nick, I was watching the weather last night and hoping the clear sky would reach you in Chelmsford. Excellent that you managed to capture an excellent video of GAIA and also that the video is now on ESA’s blog at:http://blogs.esa.int/gaia/Richard
