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MAS archive

  All meetings will be presented using ZOOM until further notice 

Photo: jpeg (meeting in progress)
This page lists our monthly meetings. For other events open to the general public, see our Events page

Dates are set well in advance but the 'content' of the meeting is only updated (from our 'meetings database') when details are entered, so 'blank' or 'TBA' may be shown when data has not yet been entered (please be assured that the meeting will take place and a talk on (some) Subject will be delivered by (some) Speaker ! )

Photo: MAS Meeting
During the COVID-19 restrictions, all meetings are being held on-line using ZOOM. Meetings are normally held at the Church Hall (aka 'The Soltau Center') of St James-the-Less, Stubbings, Maidenhead SL6 6QW, from 7.30 (for a ZOOM link, or map and directions, see the About MAS (Where we meet) page

The Main Topic is usually delivered by an invited guest speaker. We aim to provide a diverse range of subjects linked (in some way) to Astronomy - whilst the 'Second Session' is typically delivered by one of our members. If time allows, the evening concludes with a short 'What to see this month'.

Details of a typical evening (times are approximate) :-
7.30pm. The evening starts with the Chairman delivering any important Announcements and then introducing the main speaker.
7.45pm (latest). Main Topic Speaker gets up and the lights are turned off.
If you arrive after 7.45, please enter the Hall by the first door (on the right, after the entrance) and please be extra careful when finding a seat at the back of the Hall as members often setup telescopes there !
8.45-9pm +. Coffee break during which visitors often chat with members who have set-up their telescopes at the back of the hall. If the weather is good, sometimes members will nip out for a quick look at the sky.
Smoking is permitted outside the Hall, however smokers are asked to avoid any 'observers' (smoke particles always seem to get into optical equipment, no matter how well 'sealed' it may be)
9.15pm (at the latest). The 'Second Session' then runs for about 45 mins, typically ending with "What's Up !" (what to look out for in the sky this month)
10pm. We aim to clear the hall by 10pm.
Post meeting Observing. If the weather is good, the Observing Organiser then leads the way to our chosen observing site, or (if the weather looks even a slight bit 'iffy) members sneak off to the local Pub instead :-)

Next meeting :

(+)  2 Apr 2021 ZOOM on line meeting - (TBA)

(+)  7 May 2021 ZOOM on line meeting - (TBA)

(+)  4 Jun 2021 ZOOM on line meeting - (TBA)

  Meetings Archive  

The meetings archive gives an 'overview' of the Society activities over the past 10 years (see also the Events page).

Members have access to the full 'History of MAS' (including AGM minutes going back to 1957) along with full names and photos

The MAS 'year' runs from September of one year to June of the following. The end of year AGM in June elects the Committee for the following year (there are no meetings in July and August - although often members will meet informally at the local pub - which gives the new Committee time to 'get a grip' on running the Society)

The "short cuts" (in the 'title bar', at the very top of this page) will take you to the June AGM entry for the end of that MAS year

The Maidenhead Astronomical Society meetings archive (last 10 years only)

Missed a meeting, or can't remember when a topic was last covered ? Here is the archive of past MAS meetings.
Note that this list covers only our monthly meetings and AGM's. Reports on Observing and Other Events are separate pages

If notes were taken at the meeting, the date below is underlined and shown with a '(+)' = click to see the notes (if no '(+)' is shown, no notes were taken - or, more likely, the webmaster hasn't found them and posted them up yet :-) )

(+)  5 Mar 2021 Tour of the Universe - (Jane Green ZOOM on line meeting)

(+)  5 Feb 2021 Space Vehicles - (Graham Bryant ZOOM on line meeting)

(+)  8 Jan 2021 The Astronomer's Toolkit - (Dr Lee Anne Willson ZOOM on line meeting)

(+)  6 Nov 2020 The Monster in the Crab - (Gary Poyner)

(+)  2 Oct 2020 Is there anyone out there ? - (Bob Mizon)

(+)  4 Sep 2020 Two eyes are better than one - (Stephen Tokin)

(+)  5 Jun 2020 COVID19 Postponed MAS 62nd AGM

(+)  1 May 2020 COVID19 Postponed The Monster in the Crab - (Gary Poyner)

(+)  3 Apr 2020 COVID19 meeting CANCELLED

(+)  6 Mar 2020 Recent Developments in Gravity Wave Research - (Martin Dyer)

(+)  7 Feb 2020 Ask an expert Q and A panel - (By Members)

(+)  3 Jan 2020 Equipment Parade - (By members)

(+)  6 Dec 2019 Xmas Quiz and social - (By members)

(+)  1 Nov 2019 The Origin of the Solar System - (James Fradgley)

(+)  4 Oct 2019 Kew Observatory and the origins of modern solar physics - (Dr Lee Macdonald)

(+)  6 Sep 2019 History of Mars Exploration - (Jim House)

(+) Aug 2019 Summer break - (no meeting)

(+) Jul 2019 Summer break - (no meeting)

(+)  7 Jun 2019 MAS 61st AGM - (and Photo Competition prizes)

(+)  3 May 2019 13 Journeys in Space and Time - (Colin Stuart)

(+)  5 Apr 2019 Space Weather - (Dr Colin Forsyth)

(+)  1 Mar 2019 The Extremely Large Telescope (ELT) - (Dr Aprajita Verma)

(-)  1 Feb 2019 Ask the Expert - (members panel)

Friday, 1st February 2019 - Members’ evening – “Ask an Expert” It was noticeable that the number of members attending was less than half the normal count. This was, no doubt, due to the weather, a sort of slushy snow Announcements 1) Matt is our new volunteer Chairman. He will be assisted by Andy.
Under the Constitution, the (only) volunteer can be co-opted to the position by the Committee. A formal vote by the Members is not required until the AGM
2) Members are asked to take part in the BAA Start Count 2019 (Deep Sky darkness survey). Running this month (February ) from Saturday 2nd to Saturday 23rd, all you need to do is count the number of stars you can see within Orion.
Ask the Experts Tim 'chaired' the evening as Andy was unable to attend. The panel consisted of Dave H, Jim H. and Dave M. Fortunately, a number of Questions had been submitted in advance giving the team a chance to do some research !
Q1. How do you make an Occulting Bar ?
(asked by Peter H., answered by Tim H.)
As it's name suggests, and Occulting Bar is for blocking things out - specifically, for blocking out bright objects - such a star or planet, for example Sirius or Mars - so you can see much dimmer objects close by - such as The Pup or the Martian moons. The goal is to block unwanted light before it enters the eyepiece. Whatever is being used - a piece of black tape or foil - it must have a sharp edge and has to be placed at the focal plane of the eyepiece. For a Plossl (and most other) eyepiece this is at the 'field stop', just in front of the first element of the lens assembly. To observe the Martian moons, you will need to be using a sub-10mm eyepiece with a x2.5 or x5 Barlow. To access the field stop, unscrew the silver barrel end of the eyepiece. A good explanation, along with photos, can be found here NOTE that, if the tape etc. is at the correct position, it should appear as a sharp edge - if you see a fuzzy or out-of-focus edge means you are out of position. What if you want to image the view ? The problem is that the typical camera connects directly to the focusing draw-tube and the focal plane is thus at the camera sensor. One solution is to use 'eye piece projection', which means you can place the Occulting Bar inside the lens as mentioned above. For more on eye piece projection, see here Tim mentioned using the Lens Formula, 1/F = 1/V + 1/U to calculate the Focus position. Another approach would be to enable Live View on your camera and then adjusting the Bar position until the best focus position is found. One final point from the audience was that an eyepiece with built-in cross hairs might be disassembled and the cross hairs replaced - or added to - with an Occulting Bar. Ed. Tip for the home-builder = the focal plane is where the 'hairs' in a cross-hair eyepiece go
Q2. Does Jupiter have  solid core ?
(asked by William W, answered by Jim H.)
Yes, although it rather depends on your definition of solid. Prior to the Juno mission a solid core Jupiter was predicted by one theory of how it formed. Juno suggests that below the top layers Jupiter's gravity has compressed hydrogen until it has reached a liquid form in which the electrons have been freed from the nucleus. This highly conductive mass extends from about 20% to 95% of the planet. In the center, under a pressure of 45 million Bar or more, a rocky core is believed to exist at a temperature between 16,000 and over 30,000 °C. This contrasts with the Earth's core, which is iron at a pressure of about 3.5 million bars and a temperature of 6,300 °C.
Q3. When was the Keiper Belt discovered ? (answered by David M.) After the discovery of Pluto in 1930, it was postulated by more than one individual that other such trans-Neptunian Objects (TNO's) must exist. In 1951, Gerard Kuiper published a paper speculating that a disc of objects similar to the asteroid belt formed early in the Solar System's evolution, but he did not think that such a belt still existed today. If Pluto had indeed been the size of the Earth, as was commonalty believed at the time, it would indeed have scattered any such bodies out toward the Oort cloud or out of the Solar System altogether. Lucky for Kuiper, this was not the case. Conformation of the existence of other TNO's came in 1992, when Albion was discovered, the first Kuiper belt object (KBO) since Pluto. As of January 2018, over 2,400 further objects have been found beyond Neptune's orbit. Most of the objects in the Kuiper Belt are best described as 'dirty snowballs', a mix of rock and water / methane ice. This is not surprising, since the Kuiper Belt is the source of the short period (less than 200 years) comets. The Kuiper Belt is a torus shaped area 30 to 50 AU from the Sun. Long period comets originate from the Oort cloud, thought to be spherical area from 1,000 to 10,000 AU. On January 1, 2019, the New Horizons flew past 2014 MU69 "Ultima Thule", the subject of an Earth based occultation study mentioned in a previous MAS meeting.
Q4.  In Deep Sky Stacker, with 3 dark frames 2 flat frames and 5 (jpeg) images, why is the result 'whited out' ?(posed by Matt, answered by David M) Dave considered two possibility - one was the the software was treating the Flats as images, the other that the entire 16bit TIFF was being compressed into the 8bit jpeg output. He suggested stacking without the Darks and Flats first, then adding these in. During output, the histogram of the TIFF should be examined and only the section containing the image data used to generate the jpeg. Input from meeting also questioned the use of Jpeg images, ideally RAW should be used.  The Color temperature setting should be set to Manual, Daylight or Tungsten and not Auto. Ed. In Deep Sky Stacker, a "light frame" is your actual picture image. A Flat Frame is your 50% white flat response compensation and a Dark Frame is the thermal noise compensation. As a rule, you need one Dark for each normal image. If you don't have enough Darks, hopefully DSS will 'match up' the nearest one (in time) to each image. If you only have 3 darks, and 5 images, then it's possible DSS is not 're-using' two of the darks = this would result in an over bright result. Flats and Bias Frames are icing on the cake. A tutorial of DSS can be found here, however it's explanation of Darks, Flats and Bias frames is lacking (as is it's suggested approach to generating each). Note that :- Flats compensate for unequal light gathering through your telescopes' optical system (which is why you put the T shirt over the end of the telescope), including the cameras' sensor. So long as you don't rotate the camera in it's mounting, you can get away with a single Flat for the entire session = it's not as if your telescope is suddenly going to re-balance it's light gathering capability. NOTE that a Flat is specific to the telescope+camera setup. If you take the camera off, redo the Flat just before you start imaging again. Darks compensate for thermal noise generated during imaging. It's very time and temperature dependent, so you really should take a Dark after each image, and this MUST be using the same time exposure. DSS will subtract the (nearest) matching Dark from each of your images. DON'T dismount your camera to 'put the lens cap on'. Take the Dark with the telescope cap on (if nothing else it will help you discover any light leakage in your system). The longer the exposure the more vital it is to have a matching Dark. It's quite possible to re-use Darks of the same exposure time - so if you are doing 10 * 30s, you can get away with one 30s Dark at the start and one 30s Dark at the end (or even just a single one some-when in the middle). {Some cameras (eg Canon) have an automatic Dark exposure and subtraction option (you can tell since a 30 second exposure will turn into a 60 second one) - however the Canon won't allow access to the Dark, not even in RAW mode, so you can't re-use it.} The Offset/bias compensates for un-equal response in the camera imaging pixels, more specifically for 'hot' pixels (those 'stuck on') or 'offset' pixels (those that don't start at 'zero'). The Bias can change with temperature but not by much so you can usually get away with one for the session. Of course they are so fast to do that you might as well run one off at the same time as the Dark (DON'T dismount your camera to 'put the lens cap on' - just take the Bias frame with the telescope cap on). For DSLR's, Offset Frames are really just the frosting on the icing on the cake - I doubt you will see any difference unless you are using RAW images from older DSLR's that don't have built in Bias compensation and 'hot' pixel substitution.
Q5.  What are the Lagrangian points and where can I find them ? (answered by Dave H) These positions are named after Joseph-Louis Lagrange, an 18th-century mathematician who, in 1772, discovered 5 solutions to the three-body problem at which the gravitational forces balanced out in such a way that no additional force is needed by a 3rd body to maintain it's position at that point, relative to the other 2 bodies. At other positions, a 3rd body would drift away due to the unbalanced gravitational attraction of the other two bodies.

Photo: ../Meetings/photos/Lagrangianpointsanimated.gif
Here is a diagram of 2 bodies, one rotating about the other eg Sun (Yellow) + Earth (Blue), or it could be Earth (Yellow) + Moon (Blue). The 5 Lagrangian points, where the 3rd, pale blue body can rest without needing to be under power to stay in position, are conventionally numbered as shown, L1 - L5

L4 and L5 are stable, in that a body that drifts slightly away from that point would tend to drift back again. The other points are unstable in that a body drifting away would tend to drift further away. The L2 point in the Earth Moon system is where the Chinese positioned Queqiao, a relay satellite launched on 21 May 2018, for their Chang'e-4 'dark side' lunar explorer. Launched on 7 December 2018, Chang'e-4 landed on Jan 3, 2019 and communicates with the Earth via Queqiao, which is in orbit around the L2 point in a vertical plane so that it can beam back Chang'e-4's images past the Moon to the Earth.
Q6. What is Escape Velocity ?  (answered by Dave H) For any body (eg Earth) Escape Velocity is the speed at which you will escape that bodies gravitational influence, assuming, of course, that you are not slowed down by other things (like, air resistance). If you start with the exact Escape Velocity you will eventually come to a (relative) stop but not be pulled back, any less than this and you will be pulled back. This speed varies depending on how close to that body you are. If you are in orbit around the body, then your Escape Velocity is always root2 times your orbital speed. This Velocity applies in any direction (it's not a vector). This means that if a body, such as the asteroid 'Oumuamua, is passing the Earths orbit at a speed of greater than 42.42 m/s (the Escape Velocity from the Sun at the orbit position of the Earth), then that body is an interstellar object. When first detected, 'Oumuamua was already past the Earths orbit on it's way out of the Solar System and was going at 44 km/sec. The Sun will slow it down to it's final (and start) interstellar space speed of over 25 km/sec. Ed. In contrast, Voyager 1s' speed is about 17 km/s and Voyager 2s', 15 km/s. In about 300 years, both Voyagers should reach the inner edge of the Oort Cloud. They will exit the Cloud some 30,000 years later.
Q7. Why does Saturn have rings ?  (answered by Dave H) Essentially, because the dust and ice particles making up the rings are within the Roche Limit. This means that the tidal forces due to Saturn's' gravity are stronger than the self-gravitational forces that could bring the particles together. In fact, all the gas giants have (much fainter) rings = see here for more. Ed. a good example is Shoemaker-Levy 9, which disintegrated into a 20+ fragments after passing within the Roche Limit of Jupiter. Many Comets also pass well within the Roche Limit of the Sun and some totally break up. The more visible Comets tail is out-gassing caused by the Suns heating The Shepherd Moons survive because the Roche Limit not only depends on the density of the moon but it's also composition (how it is held together). Ed. The Roche limit for the Earth is about 20,000 km above the surface. Many satellites are within this limit but don’t break up because they are held together by something stronger than their own gravity :-)
Q8. Why do meteors burn up ?  (answered by Dave H) Atmospheric friction plays a part, however even more significant is the compression of the air in front of the meteor. As it's compressed, air heats up - so much so, that it will ignite the fuel in a diesel engine ! For a YouTube clip demonstration, see the "Fire Syringe".
Q9. Can you have fun with sugar ? (answered by Dave H) Yes, see here. Get some sugar cubes and a pair of pliers in a dark room. Wait for your eyes to adjust, then crush the cubes with the pliers. You will see the some blue light flashes that are known as Triboluminescence. Many crystals exhibit Triboluminescence and generate other colours. Explanations of Triboluminescence in sugar suggest it is an ionisation effect, however an interesting observation is that the light appears very similar to the characteristic blue/violet Cherenkov radiation given off by particles exceeding the speed of light in a medium. Whilst you can't exceed the speed of light in a vacuum, the speed in a non-vacuum is often significantly less than c. For example, the speed of light in water is only 0.75c. Cherenkov radiation is analogous to the shock wave caused by exceeding the speed of sound in air, although this seems an unlikely explanation for Triboluminescence in sugar !
All our indoor Meetings are open to the public, however non-members are asked to make a contribution of £2 toward the hall hire costs (this may be collected by Fred, our Membership Secretary, at the door on arrival, or left at the 'Tea hatch' at half time).
This note last modified: 11th Jun 2019 10:37.


(+)  4 Jan 2019 Equipment exhibition - (and EGM)

(+)  7 Dec 2018 Christmas Quiz and Social

(+)  2 Nov 2018 Short talks - (by members)

(+)  5 Oct 2018 The Future is out of this World - ( Dr Stuart Eves FRAS)

(+)  7 Sep 2018 13 Journeys through space and Time - (Postponed new date TBA)

(+) Aug 2018 Summer break - (no meeting)

(+) Jul 2018 Summer break - (no meeting)

(+)  1 Jun 2018 MAS 61st AGM - (and Photo Competition prizes)

(+)  4 May 2018 Using Video and an Aurora Encounter - (by members)

(+)  6 Apr 2018 Berkshire Astronomers - (Kenelm England FRAS)

(+) 16 Mar 2018 NEW DATE Jupiter and the Juno Mission - (Dr John Rogers)

(+)  2 Feb 2018 Talks by Members

(+)  5 Jan 2018 Telescope and Equipment workshop - (Q and A with members)

(+)  1 Dec 2017 Xmas Quiz and Social - (Quiz Master Tim H)

(+)  3 Nov 2017 Wonders of the Deep Sky - (Callum Potter)

(+)  6 Oct 2017 Observing the Sun - (by MAS members)

(+)  1 Sep 2017 Gravity Waves - (a recap by Martin Dyer)

(+)  2 Jun 2017 MAS 60th AGM - (and Photo Competition prizes)

(+)  5 May 2017 Novae - (Jim H)

(+)  7 Apr 2017 Comets - (Kenelm England)

(+)  3 Mar 2017 Pseudoastronomy - (Stephen Tonkin)

(+)  3 Feb 2017 Members short stories

(+)  6 Jan 2017 Telescope Parade - (exhibition by members)

(+)  9 Dec 2016 (note 2nd Friday) Christmas Quiz - (and members shorts)

(+)  4 Nov 2016 Observing Planetary Nebulae - (Owen Brazell)

(+)  7 Oct 2016 Astro tourism - (David Phillips)

(+)  2 Sep 2016 Rosetta Space Mission - (Andrew Morse)

(+)  3 Jun 2016 MAS 59th AGM - (and Photo competition results)

(+)  6 May 2016 Build a recording spectrometer John Paraskeva - (2nd half Spectrometer results Alun Halsey)

(+)  1 Apr 2016 The Universe in multiple wavelengths - (2nd half Gravity Waves)

(+)  4 Mar 2016 Astronomy and the Weather - (Robin Oldman)

(+)  5 Feb 2016 Sungrazing Comets - (Kenelm England FRAS)

(+)  8 Jan 2016 (note 8th as 1st is New Year) Practical Astrophotography - (and Telescope Parade)

(+) 11 Dec 2015 Xmas Quiz and members shorts - (NOTE DATE CHANGE)

(+)  6 Nov 2015 The Big Bang Theory - (Kevin Pretorius)

(+)  2 Oct 2015 Starting Astrophotography - (short talks by members)

(+)  4 Sep 2015 Basketballs and Beyond - (Jane Green)

(+)  5 Jun 2015 agm

(+)  8 May 2015 (NOTE 2nd Friday) Talks by Members

(+) 10 Apr 2015 (2nd Friday) planned meeting replaced by - (talks from members)

(+)  6 Mar 2015 Astronomy in Namibia - (Scott Marley)

(+)  6 Feb 2015 Did the Moon sink the Titanic ? - (Dr Barry Kellett)

(+)  7 Nov 2014 Guest stars ancient and modern - (Guy Hurst)

(+)  3 Oct 2014 Measuring the Universe - (Kevin Pretorius)

(+)  5 Sep 2014 UKMON - (Richard Kacerek)

(+)  6 Jun 2014 agm

(+)  2 May 2014 Asteroids and Comets - (Jerry Workman)

(+)  7 Mar 2014 Talks by members

(+)  7 Feb 2014 History of Radio Astronomy - (Paul Hyde)

(+)  3 Jan 2014 Members telescope workshop evening

(+)  4 Oct 2013 Project Alcock - (Roger Dymock)

(+)  6 Sep 2013 Zooniverse - (Brooke Simmons)

(+)  7 Jun 2013 agm

(+)  3 May 2013 Members Photographic Compitition

(+)  1 Mar 2013 Exploring the Solar System by Satellite - (Dr Stuart Eves)

(+)  1 Feb 2013 Mars revisited - (Gerry Workman)

(+)  2 Nov 2012 (place holder)

(+)  5 Oct 2012 The History of Dark Nebula - (Owen Brazell)

(+)  7 Sep 2012 Photographing the Night Sky - (Nik Szymanek)

(+)  1 Jun 2012 agm

(+)  4 May 2012 Origins of time keeping

(+) 12 Apr 2012 The Faulkes Telescope Project - (Dr Paul Roche and Sarah Roberts)

(+)  2 Mar 2012 Astronomy for new members - (various)

(+)  2 Dec 2011 Xmas social and Reprocessing old data using new Registax - (Bruce Kingsley)

(+)  3 Jun 2011 agm

(+)  6 May 2011 Occultations Ancient and Modern - (Tim Haymes)

(+)  1 Apr 2011 Active Galactic Nuclei - (Dr Nick Hewitt)

(+)  4 Mar 2011 Astro Imaging Overseas - (Damian Peach)

(+)  4 Feb 2011 Dark Energy and the Accelerating Universe - (Dr Mark Sullivan)

(+)  7 Jan 2011 Social evening and Quiz - (Tim & Robin)

(+)  5 Nov 2010 Big Bangs - (Jim & Tim)

(+)  1 Oct 2010 Astronomy in Space - (David & Jim)

(+)  3 Sep 2010 The Sun Kings - (Dr Stuart Clark)

(+)  2 Jul 2010 Telescope and Camera workshop - (members)

(+)  4 Jun 2010 agm

(+)  9 Apr 2010 Meteorites - (David Bryant)

(+)  5 Mar 2010 Bits and Pieces - (Greg Smye Rumsby)

(+)  8 Jan 2010 (cancelled due to snow)

(+)  4 Dec 2009 Xmas Social and Quiz

(+)  6 Nov 2009 Planetary Nebulae - (Owen Brazell)

(+)  2 Oct 2009 A beginners guide to the night sky - (Tim H)

(+)  4 Sep 2009 Short talks - (members)

(+)  5 Jun 2009 agm

(+)  6 Jun 2008 agm

(+)  1 Jun 2007 agm

(+)  7 Jun 2006 agm

(+)  3 Jun 2005 agm

(+)  4 Jun 2004 agm