Search Results for 'espin telescope'

[Robert Ian Henderson]

My list of inspiring astronomy books has something in common with Denis Buczyinski’s.
Also, like Graham Winstanley, I spent far too long in the Picton & Brown Libraries in Liverpool browsing the astronomy and science section!

The Starry Heavens                            Ellison Hawks    1950
Suns, Myths and Men                         Patrick Moore    1954
The Boy’s Book of Astronomy             Patrick Moore    1959
The Amateur Astronomer                    Patrick Moore    1959
Norton’s Star Atlas                              Norton & Inglis   1959
Larousse Encyclopedia of Astronomy    L Rudeaux & G de Vaulcouleurs    1962
Making & Using a Telescope              H P Wilkins & Patrick Moore    1956
The Sun and the Amateur Astronomer    W M Baxter    1963
Radio Astronomy for Amateurs           Frank Hyde        1963
Survey of the Moon                             Patrick Moore    1963
etc, etc…

Robert

[Denis Buczynski]

Hello all, Very interesting to read everyone’s selections. I am sure the same books will come up time and time again. Here is my rather long list ( not that I am well read)
Hutchinsons Splendour of the Heavens
The Larousse Encyclopedia of Astronomy
Celestial Objects for Common Telescopes(2 vols)
Amateur Telescope Making (3 vols)
100 years of Astronomy ( Waterfield)
The Amateur Astronomer (Moore)
Constellations (Rukl)
Nortons Star Atlas (1950 and 2000)
The Planet Saturn History of Observations etc( Alexander)
History of the Harvard College Observatory (Jones and Boyd)
Starlight Nights (Peltier)
History of the Telescope (King)
Analysis of Starlight (Hearnshaw)
Planet X and Pluto (Hoyt)
Cometography (Kronk 5 vols)
Burhams Celestial Handbooks ( 3 vols)
The Messier Album (Mallas and Kreimer)
Astronomical Scrapbook (Ashbrook)
Sorry it is so long, there are many more!
Denis Buczynski

[Gary Poyner]

John Glasby’s 1971 ‘Variable Star Observers Handbook’ was a treasure to me in the years between my first VS observations (1975) and joining the BAA and the BAAVSS (1978).  Lots of controversy about Glasby of course, but I found this book invaluable.

Sidgewick’s 1971 edition ‘Observational Astronomy for Amateurs’ rarely left my side in my early observing days too, along with his ‘Amateur Astronomers Handbook’ of the same year.  I still treasure those books.

My 1965 Ladybird book of Astronomy remains in pristine condition, and I guess this must have been the first book I used with my first telescope in 1965, closely followed by Nortons 1950 epoch star atlas.

Gone very nostalgic now…

Gary

[Bill Ward]

Hi,

I found a filter for 850nm (16nm fwhm) which happens to be very close to the emission wavelength of the Ca II IR triplet, however the image is much more bland at 850 due to less scattering and the fact that the telescope optics have less than half the resolution at this wavelength cf 390nm. (The Ca II IR triplet is used in spectrohelioscopes for photopolarimetry. The family of UV and IR transitions are quite interesting…)

Even a casual inspection reveals the limb just looks brighter, so doing the very same thing as before gave this graph…

Which indeed does have a slightly less steep gradient than the 350nm image. The edge has a brightness of around 56% of the centre.

This was all done with “auto everything” on, with the camera and software so I’m not sure how absolutely accurate the measurements are photometrically but it makes sense, which is kinda re-assuring… 😉 

On doing a bit more digging, this continues for some ways until the very shortest radio wave wavelengths are reached when there is a transition to limb brightening!

cheers,

Bill.

[Robin Leadbeater]

For anyone intersted in purchasing the ALPY 600 I thought I would pull out the limiting magnitude figures. These are Christian Buil’s calculated figures, which seem to be matched in practise.

Note that a spectrum with 10 signal/noise ratio is pretty noisy but still useful for identifying features for identification of transients for example. SNR is roughly proportional to sqrt of the signal (neglecting camera and sky noise) so a low noise spectrum at say 100 SNR, sufficient for quantitative measurements to a few percent precision would need ~100x more signal or 5 magnitudes

Cheers

Robin

From http://www.astrosurf.com/buil/alpy600/performances.htm

Magnitude V limit  reached is based on a star of spectral A0V type, a signal to noise ratio of 10 (by FWHM) and a 1 hour integration time divided into 6-up 600 seconds each. The seeing is assumed to be 3 arc seconds. The camera is an Atik460EX model used in 2×2 binning (pixel binned 9.08 microns). Guiding module with slot 23 microns. The star is at the zenith. The observatory is located at sea level, but with a dark sky (magnitude 6.0 visual boundary to the naked eye).

Telescope	S / N 10 @ 650 nm	S / N 10 @ 450 nm
Refractor 85 mm f / 5.3	12.9	14.3
Refractor 106 mm f / 5.0	13.4	14.8
Newton CN212 (D = 212 mm f / 3.9)	14.8	16.2
Schmidt-Cassegrain 8-inch f / 10	14.3	15.7
Schmidt-Cassegrain 8-inch f / 6.4	14.6	16.0
Schmidt-Cassegrain 11-inch f / 10	14.8	16.2
Schmidt-Cassegrain 11-inch f / 6.4	15.1	16.5
Schmidt-Cassegrain 14 inches f / 6.4	15.4	16.8
Newton D = 940 mm f / 4	17.0	18.4

[David Boyd]

The following is a copy of the article in the April BAA Journal about this initiative. It contains live links to save you typing in the links printed in the Journal.

Spectroscopy is now a practical possibility for amateur astronomers motivated to produce scientifically useful observations. The BAA is therefore launching an initiative aimed at helping members wishing to move into spectroscopy to acquire some of the necessary equipment. Spectrographs intended for amateur use are now available commercially and after considering those currently on the market we have decided to assist members to purchase a grism-based Alpy 600 spectrograph from the European company Shelyak. This is a mature product with several dozen already in the hands of amateurs in Europe and the US who are using it to produce spectra of real scientific value. The Alpy is compact, lightweight and relatively straightforward to use, and software to analyse the data it produces is freely available.

We are inviting BAA members of at least two years’ standing to apply for a BAA Ridley Grant of £400, which will cover 25% of the normal price of an Alpy 600 spectrograph fitted with calibration and guiding modules. The calibration and guiding modules are necessary for productive use of the spectrograph. Shelyak will offer a matching 25% discount on their list price to participants in this scheme so in effect the equipment will be available to BAA members at half price. As Shelyak are based in France their equipment is priced in Euros, so there may be small changes in the sterling price as exchange rates vary. At the time of writing the list price of the Alpy 600 with calibration and guiding modules is 2125 Euros.

Ridley Grant conditions can be found on the BAA webpage https://britastro.org/about-grants together with a link to download the application form. Please note that a description of the intended use of the equipment and the BAA Observing Section(s) to which results will be sent should be supplied with the completed form. We expect these spectrographs to be put to productive use.

For those wanting more technical information about the Alpy, there are links to User Guides for all three components on the User Documentation section of the Shelyak website at http://www.shelyak.com/dossier.php?id_dossier=40&lang=2. Some examples of what can be achieved with the Alpy 600 can be found on Christian Buil’s website at http://www.astrosurf.com/buil/alpy600/first_light.htm. Many of the spectra which have been submitted to the ARAS database at http://www.astrosurf.com/aras/Aras_DataBase/DataBase.htm have been acquired with Alpy spectrographs.

In addition to purchasing the spectrograph, participants in the scheme will need two CCD cameras, one for recording spectra and one for acquiring guiding images. You may already have suitable cameras but the two ranges most frequently used with this spectrograph are those from Starlight Xpress and Atik, so as part of this initiative we have also negotiated discounts for suitable CCD cameras from both suppliers. Details of these discounts are available in another post on this Forum. These discounts will only be available to those participating in the Alpy purchase scheme with the aid of a Ridley Grant.

I should stress that cameras from either supplier will work well with the Alpy. Depending on which cameras you use, you will need appropriate adapters to connect these to the spectrograph. Shelyak will advise you and can supply these.

Prospective users should have a telescope mounting capable of guiding on a star for several minutes. Spectra are normally recorded as a series of spectral images of several minutes each which are later combined in software. The Alpy will work with any telescope with a focal ratio between F/4 and F/10. Optimal transmission of light into the spectrograph occurs at F/5. If desired a focal reducer can be used in front of the spectrograph to reduce the telescope focal ratio but a high quality focal reducer should be used as poor chromatic correction will adversely affect the spectrum.

We intend to run a hands-on training course later in the year once the spectrographs have been delivered to help people get up to speed in using the equipment and in learning how to process their spectral images. This Spectroscopy area within the BAA Forum is for members to share information and ask questions about all aspects of spectroscopy.

Applications using the Ridley Grant application form should be sent to the Business Secretary, BAA, Burlington House, Piccadilly, London W1J 0DU. The closing date for applications under this initiative is 2016 June 30.

It would be helpful if members interested in purchasing a spectrograph through this initiative could email me using the Send Email button (to the left of the post) at an early stage so we have an indication of the likely take-up. At the moment we are not imposing a limit on the number of purchases which we will support, but we reserve the right to introduce a limit if the number of applicants is very high. Any questions about the operation of the scheme should also be addressed to me.

David Boyd

[David Graham]

It’s a while ago now, but I did some pre-Messenger research for a two part paper that was published in the Journal in the 1990’s. I found that it was possible to correlate some of the albedo features seen through the telescope on Mercury with the images teturned from the Mariner mission to the planet. Bright spots seen at the eyepiece do agree with the more prominant rayed craters on the planet.

[Grant Privett]

Sorry Martin. Just for once I reckon you are wrong. I reckon I have a book out that sells slower than yours.

Was impressed by the fact it was on a russian free download site and on one of the US rent-telescope time type sites as a pdf before I even had a hard copy in my hand.

I’m amazed anyone ever writes any books anymore.

[Martin Mobberley]

Thanks Gary,

The graphic in question was actually Figure 5.10a from my book ‘Cataclysmic Cosmic Events and How to Observe Them’, probably the world’s slowest selling book! Figure 5.11 was the BAA lightcurve produced by yourself. I just looked back at our 2007 e-mails and in fact there was another similar diagram in circulation at that time. We both asked OJ 287 expert Dr Mauri Valtonen if the image was his, and he said it was drawn by Sky & Telescope. I think we both asked S&T for permission to use it,  but never received a reply! So, in the end, I drew the diagram in question myself, based on Mauri’s data…. The OJ 287 disc is actually a blurred image of mine, of M81, tinted blue!

Martin

[Callum Potter]

Hi Nick,

I am not an expert on the technique, though I have some understanding of how it should work… What sort of telescope were you using to do the observation?

Thanks, Callum

[Nick White]

Hi, last night I attempted to observe visually the double star 78 Ursa Major using a two-slit interference mask. The intent was to use separation of the slits to determine the sub-arc second separation of the double. The image through the eyepiece was as expected, the usual diffraction pattern had the broad undulations with sub-undulations in accordance with the ratio of the slit separation to slit length. The separation of the two slits was such that for a suitable rotation of the mask the interference pattern for the double should have minimised (slits perpendicular to the axis of the binary). However, when on axis, the diffraction pattern wouldn’t minimise no matter the rotation of the mask. In other words, the diffraction pattern fine structure remained visible. However, I noted that the star disappeared from view completely when the star was off axis by about 2/3 of the way out to the edge of the fov but would re-appear further out and closer in (like there was a blind spot in the telescope). Can anyone help me understand this observation of its disappearance? For instance, could it be the experiment was working but that the lack of correct collimation meant the pattern disappearance happened off axis? (if you see what I mean). Thanks.

[Roger Dymock]

I am finding it difficult to focus properly across the whole image with the subject set-up (scope is a William Optics 71mm refractor). Using Live view on my Canon 550D camera to focus at the centre of the image I found that stars in the corners were out of focus.

Bench testing using pinholes in a black card at approx 8m from the telescope showed that focusing at the corners of the image gave a slightly better but not perfect result.

Chip to FF distance and length of FF plus T ring appear correct according to the WO Flattener 6A Usage Chart.

Any suggestions as to how to achieve a good focus would be much appreciated.

Regards

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[James Screech]

Is there any reason why a Alt – Az goto mount cannot be used for DSLR photometry? I know there will be field rotation but for short exposures (30sec) I don’t think it should have a detrimental effect on the photometry.

The reason I ask is that I have just ungraded to a CCD camera on my telescope / EQ mount and was thinking about using both this and my DSLR (with telephoto lens) at the same time, to take time series of eclipsing binaries. I can get a new alt – az goto mount for about £220 much cheaper and smaller than a second goto EQ mount.

James

[Nick James]

As forecast the sky cleared around 2am after rain and the transparency was very good this morning at 5. The Moon is getting closer to the comet but it is now only a thick crescent so is becoming less of a problem. Since the comet is still too low for my main telescope I drove to a dark site east of Chelmsford and set up there.

At around 5:30 I had set up my imaging equipment (Canon EOS550D + 200mm, f/2.8L lens on a Vixen Sphinx mount) and so started searching with 10×50 bins. The comet was definitely easier to see in the bins than my last chance a week ago but the conditions were a lot better.

This image is a stack of 22 x 30s exposures from 05:41 – 05:54 not tracked on the comet. The dust trail and gas tail show up nicely.

[Mr Michael Alan Frost]

At 8 PM last night (Wednesday 4 November) Channel 4 showed episode 4 of “Restoring Britain’s Landmarks”, entitled “Telescopes, Stargazing and a Copper Mine”. Don’t worry if you missed it; it’s repeated at 7 PM this Sunday (November 8th)

My TV guide summarised the contents as “John Evetts hunts for the perfect antique telescope, Anna Keay digs for story behind the mysterious Victorian star-gazer Dr Bangay. And there’s a refurb at a copper mine”

https://twitter.com/dgs99/status/593472439809617920 is a tweet from David Strange showing Allan Chapman at the Norman Lockyer Observatory, Sidmouth, during the filming of the program.

The observatory is at Belmont House, Lyme Regis, which was the home of Dr. Richard Bangay, a BAA member in the first half of the twentieth century (proposed 1905 June 28, elected 1905 July 18, died 1931).

Caroline Kennett, the SHA county co-ordinator for Dorset, has asked me if anyone in the BAA knows any more about Dr Bangay. All we can find in the Journal on him are his nomination and election, and a list of books donated to the BAA by his daughter after Bangay’s death. Please contact me if you know anything about his BAA career.

Mike Frost

Historical Section Director

[Roger Dymock]

Looking to spend max of £500 on the subject telescope. Suggestions appreciated.

Regards

[Andy Wilson]

With only a few days to go until the BAA spectroscopy workshop at the Norman Lockyer observatory this Saturday, I thought I’d post a few of my latest spectra.

Here are 4 high resolution spectra of the hydrogen alpha emission line from the B1I star Kappa Cassiopeia. This emission line comes from a high velocity stellar wind which can reach around 1000 km/s.

These spectra were taken on 4 nights in late September. I used them to refine the setup of my LHIRES III spectrograph. The first spectrum on 22nd looks quite noisy, while by the final one on 30th the signal is strong with low noise. I was adjusting the main mirror position, telescope focus and guide focus to improve the light thoughput which increased the signal.

Though the early spectra are more noisy there does appear to be a change in the profile over a few days. A star I’ll be watching closely!

Cheers,

Andy

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[Richard Miles]

Got back from France at 10pm last night and woke at 4am. Sky here suffered from high misty cloud with one or two clearer patches. The cloud made the sky very bright within 10-15 degrees of the Moon. Since the main observatory is ‘hors de combat encore’, I would have had to use a tripod-mounted 4″ short-focus refractor to observe, but from experience I was convinced I would never have found the star in question. With a telescope of 10″ aperture or more, it might have been possible. Looking at the track of the shadow, the location here in Dorset would have been very close to that of Tim Haymes and David Arditti so not a great deal lost in the event. Congratulations to those two folk and to Peter Carson for their positives. Not easy!

Richard

[Robin Leadbeater]

Hi Steve, Andy,

Provided you have good lines to work with it is fairly straightforward to measure radial velocities to a precision 1/10 of the resolution or better. (As I plan to show at the workshop in a couple of weeks) so an ALPY with say 10A resolution could measure a 1A shift or 50km/s at 6000A as a reasonable target.

You can go much, much more precise than this though if you use an off telescope fibre fed spectrograph and correlation techniques as is done for exoplanets. eg Buil measured to 50m/s (yes metres!) using a 0.6A resolution echelle spectrograph which I think works out at   ~1/500 of the resolution

Cheers

Robin

[R.A. Marriott]

The Instruments and Imaging Section has always included spectroscopy within its remit, and my approach as Director is to support all the Observing Sections and to have close ties with them, but not to impinge directly on their work. Like astrophotography and imaging, spectroscopy is a discipline that can be applied to the work of almost all the Sections, and historical precedent demonstrates why there is no need for a new Section. The original BAA Sections included a Spectroscopy Section and a Solar Spectroscopy Section (in addition to the Solar Section), but eventually these were discontinued, as it was considered that spectroscopy had become an applied discipline rather than an activity in its own right. There was also a Photography Section, but in the 1930s this was also discontinued, for the same reason. Fifty years later, in the early 1980s, the Astrophotography Section was inaugurated, but, together with the Telescope Technology Section, was, in 1995, superseded by the Instruments and Imaging Section, dealing with all aspects of practical astronomy. Therefore, I would be pleased to receive enquiries, and would welcome articles on spectroscopy for inclusion in I&I News. As with articles on imaging, these would mostly pertain to instrumentation, techniques, and results, while specific observational results would, of course, be submitted to the appropriate Observing Section or Sections. If you would like to discuss this with me, or if you would like to contribute, please contact me at ram@hamal.demon.co.uk.

Bob Marriott
Director, Instruments and Imaging Section