We are back at our normal venue from 3rd Sept. 2021 |
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 ! )
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 :
(+) 1 Nov 2024 Black Holes and exploding Stars - (Dr Chris Crowe)
(+) 6 Dec 2024 Christmas Quiz - (by members)
(+) 3 Jan 2025 Telescope Parade and Workshop - (by members)
(+) 7 Feb 2025 The Armchair Messier Marathon - (Lillian Hobbs)
(+) 7 Mar 2025 Admiral William Henry Smyth and the Bedford Catalogue - (Rob Peelings)
(+) 4 Apr 2025 TBA
(+) 2 May 2025 TBA
(+) 6 Jun 2025 MAS 68th AGM - (Annual General Meeting)
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 :-) )
(+) 4 Oct 2024 The Crendon Observatory - (Gordon Rogers)
(+) 6 Sep 2024 The Discovery of Neptune - (Barry Kellett)
(+) 7 Jun 2024 MAS 67th AGM - (Annual General Meeting)
(+) 3 May 2024 The Exploration of Venus - (Jim House)
(+) 5 Apr 2024 The Visible Universe - (Doctor Max Whitby)
(+) 1 Mar 2024 Water in the Universe - (Prof Jonathan Tennyson)
(+) 2 Feb 2024 The Mechanics of Eclipses - (Sheridan Williams FRAS)
(+) 5 Jan 2024 Telescope Parade - (and the Parker Solar Probe by Arthur White)
(+) 1 Dec 2023 SPECIAL FEATURE Herschels Lunatick Friends - (Andrew Lound)
(+) 3 Nov 2023 Binary Pulsars Einsteins Perfect Laboratories - (Barry Kellett)
(+) 6 Oct 2023 Solar Space Weather SOHO - (Dr Eric Dunford)
(+) 1 Sep 2023 The Changing Climate of Mars - (Peter Read)
(+) 2 Jun 2023 MAS 66th AGM - (Annual General Meeting)
(+) 5 May 2023 Two talks by members - (LATE CHANGE)
(+) 31 Mar 2023 Overview of telescopes and mounts - (Dave Hayes)
(+) 3 Mar 2023 Study of our Galaxy in the Era of Gaia - (James Binney)
(+) 3 Feb 2023 The Galaxy without a dark side - (Barry Kellett)
(+) 6 Jan 2023 Telescope Parade and Workshop - (by members)
(+) 2 Dec 2022 Xmas Social Photo Comp and Quiz - (set by members)
(+) 4 Nov 2022 Exploration of Jupiter - (Dr Mike Legett)
(+) 7 Oct 2022 The Lunar 100 - (Dr Lilian Hobbs)
(+) 2 Sep 2022 InfraRed Astronomy - (Dr Eric Dunford)
(+) 10 Jun 2022 MAS 65th AGM - (NOTE 2nd Friday)
(+) 6 May 2022 Gravitational Waves - (Joshua Pooley)
(+) 1 Apr 2022 Saturn - (Michael Foulkes)
(+) 4 Mar 2022 Update on the Exploration of Mars - (Jim House)
(+) 4 Feb 2022 What Astronomy Tells Us About The Origins of Life On Earth ? - (James Hough)
(+) 7 Jan 2022 Telescope Parade and Workshop - (by Members)
(+) 3 Dec 2021 Christmas Quiz set by members - (followed by Social Evening)
(+) 5 Nov 2021 CANCELLED - (Hall closed)
(+) 1 Oct 2021 Dark Nebulae - (Owen Brazell)
(+) 3 Sep 2021 How we reached the Moon - (Jerry Stone)
(+) 4 Jun 2021 63rd AGM (ZOOM on line meeting)
(+) 7 May 2021 Milestones in Astronomy - (Rod Hine (ZOOM on line meeting))
(+) 2 Apr 2021 The Red Sun - (Lyn Smith (ZOOM on line meeting))
(+) 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))
(+) 4 Dec 2020 Xmas Quiz - (set by members (ZOOM on line meeting))
(+) 6 Nov 2020 The Monster in the Crab - (Gary Poyner (ZOOM on line meeting))
(+) 2 Oct 2020 Is there anyone out there ? - (Bob Mizon (ZOOM on line meeting))
(+) 4 Sep 2020 Two eyes are better than one - (Stephen Tonkin (ZOOM on line meeting))
(+) 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)
(+) 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)
Starting Astro-Photography - short talks by Members
(note - there will be a practical session next year at the 8th January 2016 meeting)
report by: Steve B
Tim H.
Tim started his talk, entitled 'Digital Basics', with a quick review of the 'good old days' of film astro-photography (Ed. of which the less said the better = when the first digital photos of the planets, taken with a WebCam (about .3 Mpixels), were published readers assumed that had been taken by professionals at mountain-top observatories).
The sensitivity of digital camera's (at least 6400 ISO - some now even reach 256,000 ISO ) beats that of film (which is limited to about 800 ISO or so) to such an extent that exposure times are seconds (rather than minutes) or minutes (rather than hours). Further, the ability check a digital image immediately after it's been taken means anyone can achieve good results (especially focus) more or less by 'trial and error'.
Equipment needed: Any digital camera (for photos of the Moon) that can be set to 'under expose' by up to 3 stops (the Moon is so bright against a black sky that almost every camera with 'auto-exposure' will massively over-expose the Moon). To photograph the stars, you need a camera with a 'manual' mode, since you must be able to set the focus and exposure time 'by hand'.
Technique:
To p[hotograph the Moon, you really need a long (zoom) lens - 300mm is about the smallest that will give a decent result. For the stars, use a wide angle lens (50mm or less) and just point the camera at the sky. You don't need any sort of 'star tracking' so long as you keep exposures short.
Focus can be difficult to achieve - if the Moon is out, most camera's will focus on the Moon, if not you will need to focus on some far away object whilst it's still light. To stop the camera 'hunting' in the dark (the stars provide too little light to allow auto-focus), you will need to switch off the auto-focus and 'lock' the lens (eg. with some sticky tape). With modern cameras that have a 'live view' mode, if your can 'aim' at a bright star (eg Sirius), often you can manually adjust the focus (with Live View set to x10).
For star photos, set the lens 'aperture' at it's maximum (lowest F number), or perhaps 1 stop before (if your focus is 'less than perfect', a slightly higher F number will be 'more forgiving').
Keep the exposure short (otherwise you will get 'star trails' i.e. 'tracks', rather than 'points') - typical max. times are :-
18mm lens, 20s
25mm lens, 15s
50mm lens, 8s
Adjust the ISO to get a good photo - for a typical 18mm lens at F/4, 3200 ISO means a 10s exposure will give you a decent photo of the sky with most bright stars. If you want the fainter stars of the Milky Way (only really possible in very dark skys), you need to double the exposure (to 20s) or double the ISO (to 6400) - or halve the F (to F/2). Be aware that, in general, the higher the ISO the more 'noise' you will get.
If your camera supports RAW mode, use it. Many DSLR's (eg Canon) offer a 'long exposure compensation' mode - this reduces the 'noise' by 'subtracting' a 'dark frame' (a second exposure with the shutter closed, so it records just the 'thermal noise' generated by the sensor, which it then subtracts from the actual image) which you can also give a try.
If you take multiple exposures of the same area of sky in Canon RAW .CR2 (or any of .NEF (Nikon), .CRW (old Canon), .DNG (from Adobe 'Camera Raw' converter), or any other raw format supported by the 'DCRaw' component) you can use Deep Sky Stacker (free) to reduce noise (each 'double' expose count reduces noise by half - so 2 exposures halves the noise, 4 halves it again, another half requires 8, then 16 and so on).
Tim H. showed us an example of a single JPG exposure v's 4 'stacked' RAW exposures.
Ed. Thermal noise is 'random', so subtrating a 'dark frame' or 'stacking' multiple images only reduces your 'average' noise = it's far bettter to avoid the noise in the first place, by keeping the camera as cool as possible (this is why 'real' astro-cameras come with cooling systems).
The graph (right) shows that for a typical DSLR (a Canon 500D), thermal noise is virtually linear from about 5 degrees C upwards. Reducing the temp from 20 degrees to 10 degress more than halves the noise. So make sure your camera is allowed to cool down on a cold winder night before taking your photos (and keep it powered down as much as possible)Those on a budget can check eBay for a second hand, old film camera 'manual' wide-angle lens (so long as it can be fitted to your camera with an adapter) which will be significantly cheaper than the auto-focus / auto-aperture 'branded' version. Ed. Note that old Canon camera lens (and most 'generic' makes) will default to 'wide open' when 'off camera', whilst some vendors (Nikon) old film camera lens will become 'closed' (although it should be possible to get an adapter that will 'force them open').
Limitations:
All retail cameras incorporate IR (far red) 'blocking' filters. This cuts the red light (emission spectra) from faint diffuse nebulae (eg Orion Nebula etc). To get a decent photo of Orion is quite hard = long exposures are required which (above the time limits suggested above) result in 'star trailing'.
One way to avoid 'star trailing' (without the need for a full EQ telescope mount) is to use a tripod mounted Star Tracker 'mini-guider' - examples inlcude the Sightron Nano (small cameras) and Vixen Polarie. Tim also showed us a manual driven 'Haig mount'), but even so, getting an image of Barnard's Loop (in Orion) is almost impossible
An alternative (to improve sensitivity) is to remove the IR blocking filter. Canon sell a camera without the blocking filter (the 60Da, about £1k), although number of vendors offer modified retail cameras (eg ..) or, for the very brave, it's even possible to 'do it yourself'. Note, removing the IR filter means the camera will need to be used with some sort of filter at night to cut down light pollution (Tim uses an Astronomik CLS filter) which typically means the 'standard' lens (eg EFS on Canon) won't 'fit' anymore.
Tim showed us many examples of photos taken with a simple 'pointing up' camera and wide-angle lens, as well as the sky taken with his modified (IR filter removed) Canon 20D together with as 12" Newtonian reflector.
Alun H.
Alun followed up after Tim with a talk entitled 'Deep Sky imaging'.
Imaging (typically very faint) 'deep sky objects' (DSO's) is all about long exposures and thus the stability of the telescope mount. So you can expect to pay 2 or 3 times more for the mount than you do for the OTA (Optical Tube Assembly i.e. the telescope). A typical mount suitable for Deep Sky imaging - such as the EQ6 Pro - will set you back about £1k.
Next you will need to 'auto-guide' the mount. This means a second 'guide' telescope (almost any old 'short tube' refractor will do), co-mounted with your imaging OTA, along with a guide camera.
Alun uses the Starlight Express Lodestar (which has a cable that plugs straight into the EQ6 'guider' socket), however for those on a budget (the Lodestar is about £300) 'any' USB camera ('WebCam') can be used, so long as the lens can be removed and a 1.25" (telescope eyepiece) adapted fitted. To use 'any' camera you will need a computer (laptop) running suitable 'guiding' software (such as PHD) along with 'comms' software (such as ASCOM / EQ-MOD) that 'links' to your mounts 'autoguide' port (typically a serial link).
For the 'imaging' camera, you can use a DSLR (in which case you need suitable 'control' software (such as 'Backyard EOS' (for Canon) / 'Backyard Nikon' (available on 30day free trial, $50 to buy - or Astro Photography Tool with an unlimited Free Trial version and only 12.70 EURO for the full version) or a 'purpose built' astronomical CCD camera - which are are more sensitive (so lower exposure times required) and (because they also incorporate heat sinks and cooling fans) will give you a much better** (low noise) result. The resolution of an astronomical CCD camera, especially mono-CCDs, is better than a DSLR (because it has smaller pixels), however (at a given price point) the pixel counts are lower (a high pixel count CCD - such as the Celestron Nightscape 8300 at 8.3 megaPixels - is more than double the cost of a similar DSLR (the Nightscape 8300 will cost you about $1400)).
Note that astronomical CCD cameras are usually 'Black and White' (althogh colour ones can be had), and designed to be used with filters (R G & B if you want a coloured image or Narrowband (eg Hydrogen alpha) for nebula work (a motorised filter wheel + RGB filter set will set you back at least another £100).
** The performance of a DSLR can be much improved by removing the IR blocking filter. For the 'ultimate' astronomical DSLR conversion you also need to remove the Bayer Matrix (the lens and coloured filters that 'sit on top' of each individual pixel) - which gives you a B&W camera with a pixel count that rivals that of 'professional' astronomical cameras (a modified Nikon D800 delivers 36 mega-Pixels, whilst the Hubble Space Telescope Wide Field camera has 16 mega-Pixels !).
Alun recounted his attempts to "de-Bayer" a Canon 350D (failed, twice) and a Canon 450D - the first appeared to fail (after which he ruined it for sure by attempting to 'dig deeper'), however the second (purchased cheaply on eBay) was successful - and he showed us a stunning image of the 'black eye nebula' taken with the modified camera. To process a 'de-bayered' DSLR RAW file you can use Pixinsight or IRIS software.
Ed. For those with deep pockets, a dedicated B&W camera can also be found = the Leica M Monocrom, 18 megaPixels, at about $6k from Amazon USA (not available from Amazon UK)
Alum then showed us many of his amazing DSO images.
Davis M.
Finally it was David's turn, with a talk on using Registax and processing planetary images.
Compared to DSO's, the Moon and planets are very bright - so exposure times are short (in fact, almost all planetary imaging is done as a 'movie') and thus mount stability / star tracking almost irrelevant. Since imaging at 25-50 frames per second generates thousands of frames (or 'subs' as they are usually called) the 'bad' frames (distorted by mount wobble, atmospherics or passing aircraft etc) can be 'dropped' and only best 'stacked' to generate the final photo.
However, unlike most DSO's, for the planets you want the maximum magnification to 'bring out' surface details. This means the 'field of view' is very small, so the big DSLR sensor is a waste (the planet will appear in the very center of the sensor, leaving most of the pixels unused). Instead you need a much more 'compact' sensor - such as those used in Web-Cams or purpose built astronomical cameras - with pixel sizes (and pixel counts) much smaller than a DSLR. Further, the image 'stream' needs to be 'un-compressed' (.avi) rather than the more normal .mpg compressed format.
Ed. For those on a budget, one source of non-astronomically priced high sensitivity (IR sensitive) AVI generating cameras suitable for planetary imaging is from the CCTV vendors advertising on eBay. Of course these are not as good as the typical (cooled) astro-camera, however they do perform better than the typical Web-Cam and come it at a price below that of the typical (un-modified) Canon DSLR. Many come with 'industry standard' lens fittings (so a 1.25" adapter can be found)
David uses a 2.5x PowerMate Barlow to maximise the magnification of his telescope for planetary imaging (the camera is then fitted in place of the eyepiece - 'eyepiece projection' adapters can be found (that position the camera over a standard eyepiece) Ed. however these can be difficult to 'line up' (and even harder to focus))
The Moon is essentially 'grey', so can be imaged with a B&W camera, however the planets are not. This means generating 3 'movies', one with each R, G and B filter. When imaging Jupiter, because of it's fast rotation you need to 'take' the entire 'set' within 3 minutes (a minute of .avi at 50 fps would give you 3,000 subs in each colour, however you need to swap filter and (almost always) refocus between each set).
Atmospheric conditions - especially the absence of the jet-stream overhead - is key to getting usable (i.e. 'minimal distortion') .avi data. David showed us a movie of the Moon's surface 'swimming' in the jetsteam -- and compared that to one taken in better conditions that was 'almost' static.
He also demonstrated the use of Autostakkert, as well as the more often used Registax, to choose the 'best' fames, stack them and then apply 'sharpening' using the built-in 'wavelet' filtering controls.
To combat light pollution, a Hydrogen alpha filter can work wonders for the Moon and planets (for the Moon only, an IR (pass) filter can also work - the planets don't put out enough IR).
Note that, because you are imaging 'single' wavelength at a time (and refocusing between each), a fancy (expensive) Apochromatic (APO = a 3 (or more) element lens that eliminates colour fringing) OTA is not required - the (typically half price) ED is 'good enough'.
David now went into a practical demo of processing a set of 3 .avi (r g b) 'movies' he had taken of the planet Jupiter. Once all 3 '.avi's have been stacked, they are imported into PhotoShop as separate 'layers', contrast and brightness adjusted and then combined to create a full colour image.
The final 'tweak' he showed us in PhotoShop, was to take the 'most detailed' of the colour channels, apply 'extreme' sharpening and then add it as a 'transparency layer' to the final image. By adjusting the transparency (merge %), this extra layer was used to add surface detail to the final image.
In conclusion, David mentioned that PhotoShop CS2 can perform all the above tasks and can be found 'for free' if you search magazine covers etc. or even downloaded from Adobe itself
Ed. I was able to download CS2 (a 340Mb package) from the Adobe link without having to create an 'account', so didn't need to give Adobe my eMail address (and, no doubt, avoided mountains of 'your product is out of date, pay here to upgrade' spam). Adobe have 'turned off' the PhotoShop CS2 'Licence Registration' system, so you can just enter Adobe provided 'generic' Licence code for Windows, Serial number: 1045-1412-5685-1654-6343-1431 (or Mac OS X (power PC) Serial number: 1045-0410-5403-3188-5429-0639) and away you go.
This note last modified: 11th Jun 2019 09:21.