www.caa-cya .org

CAMBRIDGE ASTRONOMICAL ASSOCIATION

Newsletter 173 Mar / Apr 2015Registered Charity No. 800782

Cover Comet Lovejoy 2014 Q2 .………………………....Chairman’s Comments ……………….………..………..Eclipse of the Sun 20/3/15 ………………………………...Open Afternoon IOA 21st March .…….………………....Super massive black holes - Michael Parker 20th Mar ...Cosmology in the 21c - Simon Mitton 17th April & AGMImages using a Canon DSLR by Paul Fellows ……………Capturing Comet Lovejoy David Davies ………………....

M46 & M47 D Davies & Chelyabinsk 2 yrs on J Whitehead …CAA news Cambridge Science festival and Public ObservingCYA Meetings 7-11 year olds …………..…..……….…Sat 28th March 2015 “Extrasolar Planets” ………………Sat 25th April 2015 “25yrs of Cambridge Young Astronomers”11+ Age group ……..……….…………….…..…………Mon 2nd March 2015 “The Solar Eclipse” .……………..Mon 6th April 2015 “Gravity” ………………………..….

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Contents this month

CAPELLACAPELLA

CAA & CYA Who’s who contact info. 8

Comet Loveday 2014 Q2LRGB image captured Friday evening 16 January 2015 around 23:45.

By David Davies

This image comprises 10 x 60 seconds each of luminance, red, green and blue subs.

David captured two versions of CometLovejoy on the evening of 16 January:a monochrome image at 21:40 and thiscolour version later, when the sky hadbecome less transparent.

Telescope: Skywatcher Equinox ED80with a X0.85 reducer/flattener.Field of view is approx 147 x 109 arcmin. Pixel scale is 2.62 arc sec/pixel.The image has been cropped veryslightly to remove the non overlappingedges.Camera: QSI 583 wsg with a Lodestaras off-axis guiderMount: Skywatcher EQ6Auto-focusing by Scopefocus workingwith Nebulosity for image capture

A high resolution version of thecoloured image is available at:

https://www.dropbox.com/s/518nd1q4a0wc2op/2014Q2_2015162345_DDavies.png?dl=0

A high resolution version of the monochrome image captured at 21:40 is available at:

https://www.dropbox.com/s/fv6ux6idvwu0glx/2014Q2_Lum20150116_2140_DDavies.png?dl=0

The colour data was extremely thin and has needed lots of careful processing to achieve this result. For anyoneinterested, there is a summary of processing of the image on page 5.

Comet Lovejoy - taken by David Davies

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Chairman’s Comments

Well, we are now well into 2015 and so far our observing sessions have been largely thwarted by the weather - surely itmust improve soon!

However, the rest of our activities continue unaffected. We have booked up the speaker meetings well into the year andare visiting the North Norfolk Railway for a day of steaming again for those of you who like that. Our loan telescopeprogramme has been extended again, and probably we now have more than enough 'scopes - thanks to those who havedonated them. We do have a pair of very large binoculars but have had to withdraw them because the tripod that we havefor them is not up to carrying the weight. Anyone who happens to have a sturdy and spare mount that might suit themplease let us know!

Paul

Cambridge Astronomical Association& Cambridge Young Astronomers

Eclipse of the sunSafe public viewing (weather permitting)

Friday 20th March 8.15 – 10.15amAt the Institute of Astronomy

IoA Open AfternoonSaturday 21st March 2015 from 2 - 6pm

∙           There'll be a series of half-hour talks in the lecture theatre;∙   There’ll be posters, displays, demonstrations and hands-on activities all around the site - for everyone to learn more about Astronomy, and the kind of research the IoA do;∙   IoA librarian Mark will showcase some of the rare and unique Astro-gems to be found in our historical library;∙   If you're a Dr Who fan, then come and meet our friends from the 15th Cyberlegion;∙   We'll have meteorites to examine and buy from our friends from Space Rocks UK;∙   The Cambridge Science Centre  will be bringing along some of their hands-on displays from their forthcoming Explore the Universe exhibition;∙   There will be an art exhibition from Livvy Fink in one of the telescope domes;∙   You can visit the historical telescopes on site and see what they look like in the daylight;∙   The IoA Starlite cafe will provide tea and snacks, a welcome chance to rest your feet;∙   The CAA will be offering family make-and-do activities, and will be showing a range of amateur telescopes;∙   However please note that this year there will not be observing in the evening.

Offers of help to assist with the children’s activities would be very welcome (even for a short while to give someoneelse a break), let Brian know on 01223 420954 or email btl21@cam.ac.uk

The Institute of Astronomy and the CAA will be running safe eclipse viewing for the partial Solar eclipse observable(weather permitting!) from Cambridge. The eclipse begins at 08:26am, with the maximum coverage of the Sun's disc(85% obscured) happening at 9:33am.

We'll provide short talks about solar eclipses in the lecture theatre, and hope to relay a live feed with expert commentaryfrom locations where the event will appear as a total eclipse. If the weather is clear, we'll also open up the telescopes atthe Observatory for safe viewing of the eclipse.

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Friday 17th April 2015Speaker : Simon Mitton

"Cosmology in the 20th Century"

These speaker meetings will be in the Hoyle building of the Institute of Astronomy, Madingley Road, Cambridge.Doors will open at 7.30 pm. and the talks will begin at 8:00 p.m. For security reasons, entry will not be possibleafter 8:10pm. As usual, the library will be open before and after the lecture and refreshments will be available after thelecture. These meeting are free to members. Non-members are charged £1

Speaker MeetingsFriday 20th March 2015

Speaker : Michael Parker"Supermassive Black Holes"

This lecture is the 24th annual Michael Penston Lecture : Michael was based hereat the Institute of Astronomy. In 1990 he was due to give a talk to the CAA, but had tocancel because of illness. Sadly, Michael died soon afterwards. In March 1991 theCAA held a lecture in memory of Michael, and a collection was made for CancerResearch. By the following year a fund had been set up in his name, administered bythe Royal Astronomical Society, to help up-and-coming astronomers establishthemselves in their chosen profession. Each year, at the end of the lecture we haveasked CAA members to make a donation to this fund.

Tonight, Michael Parker will talk on the subject of Super-massive black holes.

Michael is a member of the Cambridge X-ray group, NuSTAR science team. His is based aroundunderstanding the X-ray emission from the innermost regions around black holes. His work on reflectionspectra has contributed to several different research projects, most noticably expanding reflection modelsto new areas of parameter space to cope with the increased energy range and sensitivity of NuSTAR.

The AGM will start at 7:30pm (doors open 7.00pm) before the speaker meeting getsgoing at 8pm. These are not lengthy affairs as we strive to keep the formalities to aminimum

The agenda 1. Apologies for absence 2. Minutes of the 2014 AGM 3. Matters arising 4. Chairman's report (see page 2 of the next issue) 5. Treasurer's report (in the next edition of Capella) 6. Election of Officers 7. Election of Committee 8. AOB

Following the AGM at 8pm will be our speaker lecture.

Simon Mitton will be discussing the history of cosmology in the 20th Century - a period when our ideas ofspace and time underwent a series of revolutions

Simon is an astronomer and writer based at St.Edmund's College Cambridge. He has written manyastronomical works including a biography of fellow Cambridge Astronomer Fred Hoyle.

4 Members ContributionsPictures taken with a DSLR Canon EOS Camera.

Submitted by Paul Fellows

The Rosette Nebula - taken with the canon EOS 600 camera and300mm lens - piggy back on the main telescope for tracking purposes.

This object is hard to see with the eye - all that shows up is the centralgroup of bright young stars which have "blown" the hole in thecentre of this giant bubble.

The camera, which has been modified with theremoval of its internal infra-red-blocking filter, isexcellent at picking up the light from glowingHydrogen gas - The red colour of the nebula beingthis light which is at 656.28 nan0-meter wavelength.

The nebula covers such a large area of the sky thatit is many times the size of the full moon, and so thewide field of view of the camera is excellent forpicture.

The Orion Nebula taken at 300mm with the Canon EOS 600 - again shows howyou don't need a massive or expensive telescope to be able to get some reallypleasing results.

Here is an image Paul took of Orion from the dark skies of Jamaica withjust his canon DSLR on a tripod with no tracking. This time using the55mm lens to frame the constellation nicely. It shows the colours of thestars very nicely, especially the red of Betelgeuse and the blue-white ofthe belt stars. The Nebula shows up beautifully too.

Lovejoy : taken with a 75mm lens on a Canon EOS DSLR fromCambridgeshire, on a tracking mount.

5 Members ContributionsThe technicalities of capturing the cover image of Comet Lovejoy

By David Davies

Warning: If you are not into deep sky image processing this will most likely read like gibberish!

The colour data was extremely thin and has needed lots of careful processing to achieve the result on the cover of thisCapella Newsletter. For anyone interested, here is a summary of processing of the image.

Each set of LRGB subs were separately calibrated, registered relative to the stars and median integrated with darks andflats in Pixinsight to produce a set of LRGB images of fixed stars with a blurred comet.

The calibrated subs were then aligned with respect to the comet using Pixinsight's Comet Alignment tool. These imageswere then average integrated a second time but with respect to the comet. The integration tool was set to reject thetrailing star images (using Winsorized Sigma Clipping) , thus producing a set of comet images with smudges in placeof the stars. Each of these images was then cleaned up using the Clone tool (about an hour).

The images had their black and white points calibrated using the Linear Fit tool.

A star mask was constructed from the luminance star image using the Star Mask tool. This took some time to getapproximately right (another hour) as the mask needed to capture the small stars but yet not have too big holes thatwould produce halos around stars shinning through the comet.

The images were given approximately the same stretch in Pixinsight.

The RGB star images were aligned and combined to give an RGB image of the stars with a multi-coloured, blurredsplodge were the comet was. I had a slight background gradient which I removed with the DBE tool.

The RGB star image and the separate LRGB images of the comet were exported to Photoshop. The RGB comet imageswere assigned to red, green and blue channels of a new image and the channels were aligned on the comet head toproduce an RGB image of the comet.

The black level was set in in the comet RGB image.

Some noise reduction was applied to the comet tail using a mask and the Topaz noise reduction tool. The mask wasinitially black but then painted with various shades of grey to allow different strengths of noise smoothing through tothe image.

The luminance image of the comet was cleaned and black level set in the same way and applied to the RGB image toproduce an LRGB image of the comet.

The LRGB image of the comet was imported back into Pixinsight and the background gradient removed using the DBEtool. The cleaned image was then sent back to Photoshop.

The black level in the RGB image of the stars was made the same as that in the comet image. The stars were overlaid onthe comet image using the star mask made in Pixinsight to allow only the stars through to be added to the comet. Themask wasn't very satisfactory and I ended up editing it by hand (star by star - it took over an hour).

I now made a mask from the comet image and inverted it - making the sky background white. This mask was used toapply noise smoothing to the sky background using the Topaz noise reducer tool but protecting the stars and brighterareas of the comet.

Finally some time was spent inspecting and cleaning the image and applying a small contrast enhancement using Leveland Curves to bring out more of the tail.

I hope that helps some of the questions on how to take a challenging fast moving image.

I told you it was gibberish!David Davies

6 Members Contributions

Date 15th February 2015 2nd yr anniversary of themomentous event over Russia.

It is stated that the initial mass of this meteor was of theorder of 10,000 tons when it first entered the earth`satmosphere at a speed of about 20 kilometres per second,and that actually only about 5 or 6 tons fell to the ground.Imagine the terrible destruction if the trajectory had notbeen tangential to the Earth but at a more acute angle.

There seems to be some argument as to what the initialmass of the meteor was composed of? If it was water ice,the large trail which I believe was 90 kilometres long andabout two or three kilometres in diameter would accountfor the change of this mass of ice into a trail volume ofsteam and water vapour, at a steam pressure equating toan altitude of 28 kilometres, but why so bright? The heattransfer rate within the meteor must have been very great!

When you consider the enormous amount of absorbedlatent heat energy which is needed to convert 10,000 tonsof ice into superheated steam, I think it is amazing that thebrightness of the head of the trail appeared so great, whenall this ice (if it was ice) was converted into superheatedsteam and later vapour, in a very short space of time. Mostother metals or rock would oxidise and would appear verybright, but it is difficult to imagine why ice or watershould oxidise in a similar manner.

I question why was the temperature raised so high. Was itconceivable that water was being split into hydrogen andoxygen and burning on the surface of the meteor due tofriction with the atmosphere, raising temperatures evenhigher, and hence the brightness? The relatively smallamount which did fall to the ground was chrondrite (a typeof rock), but if the whole meteor was of this material,surely a much larger amount would have fallen to theground? I bought a piece of this Meteorite (from DavidBryant our guest speaker at last months meeting) whichgot me thinking!

Note from the Capella Editor: If you would like to contributeto this interesting topic, please send your response tojohngwhitehead@talktalk.net in word format and copymyself at richard@rwhitestudios.co.uk.

Interesting sites will give you more information.

http://news.discovery.com/space/astronomy/surprisingly-bright-comet-lovejoy-dazzles-skywatchers-150108.htm

http://livecometdata.com

www.abc.net.au

http://www.asteroidday.org/interactive

Chelyabinsk Meteor

Discussion topic by John Whitehead

The region of M46 and M47

Article by David DaviesI have returned to using my Equinox ED80 scope to trythe Skywatcher x.85 reducer/flattener giving a field ofview of 147 x 109 arc minutes.

The attached image is my first exploration of the regionaround M46 and M47 in Puppis where we find a lovelygroup of open clusters plus two planetary nebulae. Thelocation is a bit low in the sky from my location and aguiding challenge in poor seeing. I get some light pollutionspilling into the sky from the village of Barrington on theother side of the hill. I don’t use a light pollution filter butrely on the gap between green and red colours of myAstrodon filters to eliminate any pollution. I dealt with theresidual background gradient in Pixinsight using theDynamic Background Extraction tool.The image astonished me. Looking along the outer spiralarms of the Milky Way, the image is full of stars. Wehave some lovely open clusters:

NGC 2437, M46, is at the lower left centre;NGC 2478, M47 is at the right centre;NGC 2423 is at the top, right of centreand lovely NGC 2425, a tiny cluster of golden stars about a quarter of the wayup from bottom in the centre.

I discovered the two planetary nebulae as I processed the image:

NGC 2438 is a magnitude 11 planetary nebula in the foreground of M46

Minkowski 1-18 is a magnitude 14 planetary nebula a little way above M46.

Continued in the next edition.

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Capella Editors notes to members.Come on please don’t be shy!!

Remember you are all invited to contribute anything as asuitable article with photos for Capella. It is carefullytypeset, abridged if necessary and published everyalternative month. Not every item can be published in themonth that you submit it but we will always try toincorporate your articles where possible. So it could beyours in the next one.

Please try to submit at least 4 weeks in advance ofpublication.

I would ask that any information you wish to includemust be in standard text or preferably formatted as aWord document. If you embed any pictures for your story,please also sent separate good quality JPG files smallerthan 10mb. You can contact me by email on any contentor publication issue at richard@rwhitestudios.co.uk

Loan Telescopes.Now is a good time to book a telescope especially as theinstruments have been augmented thanks to the IoA.We have a pool of nine telescopes and one set of giantbinoculars in our loan programme and all are designed tobe extremely easy to use, but of course we will be happyto show you exactly what to do. Please remember thattwo of the telescope will not fit in a standard sized car -the long focus planetary telescope and the Behemoth. TheBehemoth especially is not a one person telescope! Aswell as being big it is also heavy, and really does needtwo people to shift it.

The other telescopes will fit across the back seats of mostcars, and are recommended for first time users of our loantelescopes.

Visit our website (www.caa-cya.org) and click to book aninstrument, or alternatively please ring Mickey Pallett on01480 493045.

CAA News

Public Observing Sessions.

The last public observing session is on March 25th at the the Institute of Astronomy. These sessions on a Wednesdayevening are run jointly by the IoA and CAA. The evening kicks off at 7.15pm (it is advisable to arrive early as thesesessions are proving very popular and there's only limited space in the lecture theatre) with a lecture from somebodyfrom the Institute or visiting speaker followed by observing with the historic Northumberland and Thurrowgoodrefractors with the help of the other modern telescopes -some run by the CAA to project live images onto large screens.If however it is cloudy after the talk, there's a consolation cuppa and biscuits followed by a couple more short talks.

Cambridge Science Festival9th to 22nd March 2015

Here’s some events that may be of interest to CAA members. For full details see the Cambridge Science Festival website;www.sciencefestival.cam.ac.uk or pick up a booklet.

“Animals in Time and Space” Prof Arthur WallaceMonday 9th March 6 -7pm Mill Lane Lecture RoomsPrebooking essential

“Space on Earth” Dr Monica GradyTuesday 10th March 6.30 – 7.30pm Mill Lane Lecture RoomsPrebooking essential

“Spacecraft and Solar Panels” Hands – on and talk 8 + ageSaturday 14th March 9.30am – 3.45pmPrebooking essential

“Seeing further than others: Isaac Newton’s world of colour and light”Prof Rob Lliffe Sat 14th March 11am – 12.30pm Milstein Seminar rooms

“Shaping the darkness: how light helped build the Universe”Dr Judith Croston Sun 15th March 4.15 – 5.15pm Madingley HallPrebooking essential

“Primary Rocket Launchpad” Hands – on. 9 – 11 ageDept of Engineering Prebooking essential

Light and Colour: experiments and theory” Prof Malcolm LongairWednesday 18th March 6 – 7pm Pippard Lecture theatrePrebooking essential

“Einstein’s Lagacy:100 years of general relativity”Prof John Barrow and Prof Michael KramerThursday 19th March 7.45 – 9pmPrebooking essential

“Longitude Found” Dr Rebekah HiggittSaturday 21st March 11am – 12noonIsaac Newton Institute for Mathematical SciencesPrebooking essential

“The Large Hadron Collider and the dark  matter mystery”Prof Ben AllanachSaturday 21st March 2 – 3pmCentre for Mathematical Sciences

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Meetings for the 11+ yr Group are held in the Hoyle Building at the Institute of Astronomy, Madingley Roadfrom 7.15pm to 8.45pm. Free to CYA members; for non-members there is a £1.00 fee.

If leaving a CYA member unaccompanied a contact telephone number of a responsible person MUST be left.No children aged 7 or under can be left unaccompanied.

President: Jim HysomVice President: Carolin CrawfordVice Chairman: Brian ListerCambridge Young Astronomers (both groups): Brian Lister Tel: (evenings)01223 420954 or email btl21@cam.ac.ukTelescopes for hire to members: Mickey Pallett Tel: 01480 493045 orbook on -line.Loan Telescope maintenance: Dave Allen, email day.vid@hotmail.co.ukLibrary: Kevin Black Tel: 01223 473121

Website: www.caa-cya.org

Chairman: Paul FellowsTreasurer & Membership Secretary: Mickey PallettSecretary: Michael JenkinsCommittee: Dave Allen, Kevin Black, Paul Drake, Clive Gilchrist,Clive Holt, Barry Warman, Christopher Wright and Brenda Field.Capella Editor and DTP Setter: Richard White richard@rwhitestudios.co.ukMembers should send stories for inclusion where possible by email to Richard.Alternatively send them to Brian Lister Tel: 01223 420954 (evenings) oremail btl@cam.ac.uk

7-11 Year GroupCYA Meetings

11+ group meetings

With the solar eclipse in which 85% of the sun will be covered on the 20th March at 9.33am, we’ll be covering what can be seen andwhat to expect during the unusual event (the next big one  will be in 2026). We shall also be looking at historical eclipses over thelast 2600 years.

The first planet called 51 Pegasi was discovered orbiting another star 20 years ago. Since 1995 after a slow start extrasolar planetsor exoplanets are now found on a regular basis, so that nearly 2000 have discovered.  We’ll be looking at these new worlds to seewhat they’re like, and the prospects of life forming on them.

"Extrasolar Planets."Saturday 28th March 2015 at 10:00am

It’s party time, CYA is 25. So there’ll be cake, candles, fun and games, we might even squish some astronomy into the morning. Ofcourse there’ll be a group photograph that will appear in our newsletter and on our webpage. Things have change dramatically sinceour first CYA meeting 25 years ago when only two children turned up!

Saturday 25th April 2015 at 10:00am"25 Years of Cambridge Young Astronomers."

Monday 2nd March 2015 at 10:00am"Solar Eclipse 2015"

Monday 6th April 2015 at 10:00am"Gravity"

Gravity is one of the controlling forces of the Universe, and a force that we take for granted, but it effects everything from galaxiesto keeping our feet on the ground!