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Cam,
Nice images. Definitely worth persisting with the cal frames though (flats, darks and biases). They will make a big difference when you get them right. For DSLR imaging I take my flats on a daytime sky and usually median combine 50-100 frames. I do darks and biases at night when the temperature is around the same as lights but again combine 50-100 frames to get the noise down.
BTW – Turn your scope on C/2014 Q2 (Lovejoy) and have a go at that.
Nick.
My first image of this comet from my garden in Chelmsford. Over Christmas I was away in Somerset and had seen it from down there. Tonight I rushed home from work to take advantage of the nice clear sky. I had a good view of the comet visually in 11x80bins as the Moon was rising in the east. It was quite a large fuzz-ball but with no sign of a tail. This comet is definitely worth a loook and should be fairly easy to find with a pair of bins using the chart here. The Moon is now moving out of the way and this comet will be at its best for us over the next couple of weeks.
Denis,
One in three nights, excluding the summer, is pretty good. Who was it who said “You’ll not see anything from there” when you moved up to NE Scotland?
I’ve had a look at my observing stats from Chelmsford but they are rather meaningless since I’m often not able to observe even if the weather is clear. Anyway, I obtained CCD images from Chelmsford on 107 nights in 2014 so rather worse than your one in three. I suspect it would be better if I was a gentleman of leisure…
Nick.
David,
Thanks for your UK image. Sounds like you had to do some considerable gardening to get it!
While we would prefer the time part of the filename to be the mid-time of the exposure this is not essential and we’re happy with start, middle or end. Ideally the caption on the figure should state which one is used, particularly where the total exposure time is long. The time part is actually optional so 2014q2_20141230_ndj.jpg and 2014q2_20141230_1452_ndj.jpg are both valid. I use the time to distinguish between multiple images taken on the same day, or even sometimes multiple ways of processing the same image.
All the pages of the comet archive are automatically generated by scripts which depend on the correct filename structure. At present we are receiving 30-40 images of 2014 Q2 each day. This will no doubt increase so it does help us greatly if the filename conforms to these rules.
Nick.
Denis,
Yes, 2014Q2 is developing nicely and should be a decent object from the UK when it climbs high enough above the southern horizon. It is currently around 40S but is coming north at over a degree a day. By the end of the year it will be around 15 deg up in the south from southern England at midnight. I obtained the attached image remotely from Siding Spring yesterday and there is a lot of detail in the tail. Let’s hope this keeps developing.
C/2012 Q2 (Lovejoy) – 2014-12-18, 16:44. 9x60s, iTelescope T12. FoV 2.4×2.6 deg
Nick.
Bill,
That’s a nice result. A direct measurement of the composition of a little piece of 3200 Phaethon!
Nick.
Here’s my image of that same meteor from Chelmsford. It was classified as a Geminid. I’ll send the details so you can add them to the groundtrack solution.
A good clear night with only a few periods of cloud here in Chelmsford last night. My two cameras picked up a total of 265 Geminids (with 33 sporadics in the same period). Here are some of the best taken from my December summary page:
There are lots more on the BAA live meteor page. If you are registered on the BAA website please go there and vote on the best ones. That helps to promote the best images to the top of the page so that visitors will see spectacular meteors rather than the Essex Police helicopter!
Nick.
Hi William,
Great pics. I was waiting for this in the garden, but although clearish to the north there was persistent cloud in the SE.
I gather that there have been a number of reports of a bright “comet” seen by people out observing at the time. It must have been quite spectacular. Just sorry I didn’t get to see it.
Nick.
William,
Thanks for posting this. I’ll be setting up a DSLR to cover the predicted area in case the launch goes ahead.
Nick.
Hi Cam,
I don’t have any experience of this scope either but I would certainly agree with Jeremy that small refractors are best for imaging at these scales. For visual deep sky though, you’re right that aperture is key, the more the better! You may notice that the really dedicated visual DS people now need to transport their scopes on trailers!
FYI, I’ll be showing a couple of your images during the Sky Notes session at next weekend’s BAA meeting. If you are going to be there please say hello.
Nick.
Hi Robin/Alex,
Yes this was caught on my Chelmsford NE camera too. Combining my data with that from Alex shows that the ground track runs from Just north of Peterborough to just north of Birmingham. We’ll have more details for you soon.
Paul,
Great to meet you and your fellow Mac Astro members too. A very enjoyable weekend although I agree that a couple of the talks needed quite a bit of concentration! Very enlightening though and I know a lot more about the Standard Model of particle physics and its connection to current cosmological ideas than I did before the weekend.
Nick.
PS – Thanks for posting the photos, even the one of me…
Hi Sheridan,
It is true that a ratty dark frame will add noise to the output image but you don’t use ratty dark frames. Since darks are much easier to obtain than light frames you can collect hundreds of them when it is cloudy and median stack them. You then use the clean dark in your calibration process. The same applies to flats and biases. With a DSLR flats are very easy to obtain since you can use short exposures on a bright sky, I even do them in daylight. It is true that if you median clip stack dithered images you can get away without darks but you still need to calibrate the light frame so that you can properly apply the flat. If you don’t you can get significant zero point errors, particularly if you are stacking a lot of short exposures. You can possibly get away without using a flat in dark locations but not where I live.
All of this may be too much for beginners, although programs such as Deep Sky Stacker make it easy to do, but my problem with Graham’s website is that he appears to dismiss calibration altogether and I think that is wrong.
Going back to the original subject I have read David’s review again and it seems perfectly reasonable to me. A book review will always involve some degree of personal opinion and the Journal would be a much worse place if we only ever published positive ones.
Doing anything generally lends to the risk of criticism. That is part of life and it is something that you get used to.
Nick.
Hi James,
The reason for the magnitude limit is that this is roughly the detection limit of my TV system (Watec 902H2 Ultimate + 3.8mm, f/0.8 lens) in individual video frames. Deeper limits are possible with TV systems using longer focal lengths but you then get smaller fields of view.
The frames are analysed using a program called UFO Analyser. This matches stars in the image with a catalogue (see the image below) and then uses this to estimate the magnitude of the meteor throughout its path. The magnitude quoted is the maximum magnitude but the advantage of a TV system is that you can get a magnitude profile sampled 25 times a second.
Nick.
Denis,
That’s a great video. Amazing what Bill managed with such simple equipment and a lot of dedication.
Nick.
Peter,
That is a classic observation but perhaps doesn’t conform to the Meteor Section’s rules!
Pete Lawrence also got it from Selsey and his excellent image is on the spaceweather.com front page today. This has allowed us to confirm that the track started at the Orwell Estuary and ended somewhere around Bradwell on the Dengie so it would have been to the north of you. From comparison with the Moon the terminal burst was brighter than mag -12 for around 80ms or so.
Nick.
Hi Sheridan,
I think there is certainly a debate to be had and you can make the case that mentioning the use of calibration frames can be offputting to beginners. As I said, I haven’t seen the book that was the subject of David’s review, but I have seen Graham’s website here and that appears to go much further in that it says: “This page explains why they are not important – unless you wish to do photometry” and “We have seen that bias frames are absolutely not needed for DSLR work”. I think that is plain wrong, particularly if you live in areas of the country, as many of us do, where the sky is reasonably bright.
By all means tell beginners that they don’t need to use cal frames when they start but don’t dismiss the process entirely. If those beginners are using high-end DSLRs they will ultimately want to get the best out of their equipment and good calibration is required to do that. It really isn’t that hard if explained clearly.
Whenever you publish anything on a subject where there are a range of opinions you need to be ready to take criticism and respond appropriately. Such is life!
Nick.
I met Dame K several times and she was a great character with an amazingly varied set of interests and many fascinating stories. She really hit it off with Patrick and they were very similar characters. Listening to a conversation between the two of them was great fun.
I visited her Coniston observatory but it was chucking it down at the time so it was rather hard to judge the potential sky conditions…
Nick.
Hi Sheridan,
One of the things that you quickly have to gain as an author is a thick skin. Bad reviews are par for the course and, if you think that the criticism is unwarranted, the appropriate action is to send a letter of rebuttal and hope to get it published. I would welcome the return of fiery debate in the letters column of the JBAA as authors (often Patrick) slugged it out with reviewers. Perhaps the modern equivalent is this forum.
In this case I have not read the book and so cannot comment directly but David is one of our best imagers and he is well placed to provide a review. I certainly think that some of his criticism is valid (Graham’s views on the non-use of calibration frames in particular) so there are questions to answer. Let’s have the debate!
Nick.
