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Hello Mike,
It’s tricky to give precise advice without knowing a bit more about your observing ‘site’. Any kind of fixed pillar in a lawn, or backyard, can be a huge advantage, even if a crude observatory is not possible. Setting up each night is a huge hassle, even for someone without a bad back! Before the planets sank so low I used to do quite a bit of planetary imaging with a 12-inch Newt. on wheels.
See: http://martinmobberley.co.uk/images/Orion12inch_f5p3_mpm.JPGThe entire telescope just rolls out on a carpet from a wooden shelter attached to the house wall. After the telescope was polar aligned for the first time I knew by looking at the angle the base/wheels made with the lawn/paving slabs when the base was correctly aligned. In fact, under the carpet I made crude marks on the slabs indicating where the wheels should sit. This only guarantees polar alignment within a few degrees, but for 2 minute imaging runs on, say, Jupiter, it is more than good enough. Yes, you will get declination drift and a small amount of field rotation, BUT, compared to the problems of atmospheric seeing it will be negligible when the images are stacked with, say, AutoStackert! Deep Sky imaging is more of a problem (especially if you want to use accurate Go To) but, as Grant says, even with Alt-Az systems you can do very short exposures before field rotation trails the stars.
On a few occasions I used a small, fast, system on wheels to image big Deep Sky objects or comets like 17P/Holmes. This was a160mm f/3.6 Takahashi E160 on a Vixen Sphinx mount. See attached image…..
Occasionally this wheeled out on plastic rails, but on other occasions I just wheeled it around the lawn and literally ‘guessed’ the polar alignment by aiming the tube along the polar axis and getting Polaris centred. This was more than good enough for multiple 30 second exposures! If I was planning several sessions over a week I’d just leave the system outdoors covered with a tarpaulin!
Martin
I last imaged the field, after a false alarm, back in 2015, with the 24-inch itel T24 in California. 3 mins unfiltered.
http://martinmobberley.co.uk/images/AL_Com_20151114_1301_mpm.jpg
Martin
I agonised about renewing my S&T sub when it was due to expire a few months ago. I was very close to letting it lapse.
As others have said, it simply is NOT the quality publication it used to be.
This was not helped by having the same experience as Jimmy: renewing online did seem to be impossible from the UK.
I e-mailed the publishers and got an acknowledgement from a robot, but nothing from a human.
Eventually, my unbroken paper mag collection since 1981 swayed me to renew using the renewal card.BTW, on the subject of The Astronomer magazine I recently informed Guy Hurst that there is a public house named ‘The Astronomer’ near Liverpool Street!
See https://www.theastronomerpub.co.uk/
Guy was amused by this ‘rival’ organisation, fittingly part of the Fuller’s chain!
Martin
Hello James,
There’s no simple answer to the question of how to process comet images as every comet is different. Some move fast, some move slowly, some have very little tail detail and some have loads of complex ion tail detail. Also, individual equipment, and skies, and detectors vary considerably. My own recent 46P images have all been remote, via Siding Spring. The comet has been almost overhead there, in a very dark sky. In addition the system I’ve been using has a sensitive FLI 16803 cooled detector. I take LRGB images because the L image goes deep and produces a very smooth background, so the noise in the RGB images is not obvious. With the system you are using it would be best to take as many frames as possible to improve signal-to-noise. Even exposing for 1 hour (eg 60 x 60s) is not excessive providing you are happy with long star trails.
Modern CMOS (eg ZWO ASI) devices have sensitive low noise detectors which would outperform your Canon 6D. The Sony A7s cameras have remarkable sensitivity too. Your images look very dark. What’s needed is some sort of log stretch to brighten up the outer coma without burning out the comet’s core. A straight histogram stretch won’t work. All modern astro packages have a variety of stretches which can be experimented with for best results.
I used to use AIP4Win but now (as AIP V2 doesn’t like Windows 10) use AstroArt 6. Weeks of endless experiments with various stretching routines and tweaks will deliver the results. For final labelling and jpeg production I use an old copy of Paintshop Pro!
I could go on, but it’s an endless subject!
Some experts use k-sigma type routines to separately stack on the stars and stack on the comet resulting in an image with stars and comet stationary, but that is VERY complex and labour intensive. Some even image the stellar background separately when the comet has departed so the comet doesn’t mess up the starfield! Obviously at some point science drifts into art if you take that approach too far!!As a first step I’d simply stack as many short exposures as possible with the comet as high up as possible, in as dark a sky as possible, and then experiment with every non-linear stretch routine you have at your disposal to see which works best!
Email me direct, off-forum, if you want any detailed info!
Martin
Hello Ron,
Firstly, I don’t have any experience with PHD, sorry!
However, from 1997 to 2003 I did regularly battle with my own LX200 and faced the same dilemmas as yourself, except that I also had huge non-Go To Newtonians at my disposal.I initially used an SBIG ST7 with a built in autoguiding chip with my LX200. The arrangement worked, BUT, was always a hassle to set up. It was far less stressful to simply take multiple 60 second (or less) exposures, especially as I mainly imaged comets that moved in longer exposures anyway. Mind you, I was never a mega-long exposure Deep Sky imager anyway. As well as comets I imaged novae, supernovae, and other objects for which a set of 60 second exposures was good enough.
My biggest problem though was with the LX200 itself. On the 2nd night of use the RA motor/gearbox failed. This was soul destroying on a brand new £5K instrument. Eventually the dealer replaced the entire telescope, but the problems continued. Once or twice a year the telescope had to be dismounted and sent back to the dealer for new motors to be fitted….. This went on for 6 years. I examined the motor/gearbox assembly and was horrified to find a (literally) Scalextric toy car motor providing the drive to the gearbox chain; the gearbox consisting of tiny plastic wheels, glued onto shafts before the final worm stage. It was this gearbox/encoder system that always failed. On full slew the motor spun at 14,400 rpm (gulp!)
After I found this out I never slewed the telescope again, just synced on a star and crawled to the right RA and Dec, or unlocked the axes and pointed the LX200 manually. Eventually I gave up and simply used the LX200 for planetary work. But I dreaded even going outdoors at night for fear of the drives failing yet again. I bit the bullet and acquired a Paramount ME & C14 at this point (2003) which has never let me down. I temporarily remounted the LX200 tube on an EQ6 but this was not a brilliant solution as the 12″ tube was a bit too heavy (your 10″ will be considerably lighter though).
I’ve gone off topic here and not really answered your questions Ron, but, suffice to say, with my own LX200 the only way I could use it without loads of night-time hassle was using multiple short exposures and never slewing at high speed. There was not enough time between breakdowns to enjoy using the system and to perfect autoguiding. Eventually I grew to really hate the telescope with a passion!
I guess what I’m saying is, a decent modern mount really is the best solution. Even a humble NEQ6 Pro is in a totally different reliability and stability league to a vintage LX200. It’s like the difference between a BMW 5 series and a Morris Marina!
Hopefully someone else can answer your PHD query.
Good luck!
Martin
Hello Bill,
Pasted straight from my Hepburn files, with no attempt to sort out the line length etc….Hepburn said the following at the
October 26th 1921 BAA AGM (JBAA Vol 32, 1, pages 4 – 5) re. the imminent 1922 Handbook.
Regards,
MartinVery many of us must have felt that we had lost a friend
when we learnt that the Editors of that excellent magazine
The Observatory found themselves unable to continue publication
of their annual Companion. Perhaps the best compliment
I ever heard paid to it was that of a somewhat lukewarm
admirer, who said he had but little use for it, since there was
not much of its contents that he could not find either in the
Nautical Almanac, Whitaker’s Almanac, or the English Mechanic.
It has been felt that something ought to be produced to
take its place, and the Council has decided that this Association
should publish an annual ” Observer’s Handbook ” on somewhat
similar lines. The work has been very ably carried out under
the direction of Mr. Comrie, with the assistance of the Computing
Section and other Members of the Association, and I hope that
the number for the ensuing year will be in your hands before
the end of next month. Besides the ” almanac ” matter, it
will be found to possess features of great interest. There is,
for instance, a comprehensive list of Astronomical Constants
from authoritative sources, such as is published in some foreign
national Ephemerides, but is conspicuously lacking in our own
Nautical Almanac. There is also an instalment of a glossary
of astronomical terms, the need for which was pointed out by
my predecessor in this Chair at the last annual meeting. In
place of tables of the times of rising and setting of the planets
is an ingenious diagram which enables one to see at a glance
what planets are at an observable distance above the horizon
at any hour of any night in the year, as well as the exact times
when they become observable in the evening either by rising
or by the Sun’s setting, and, conversely, when they cease to be
observable by setting or with the dawn.
The expense of this publication has to be closely considered,
and it has been decided to provide for it at present by dropping
the number of the Journal following the Conversation Meeting.
There will, however, be some saving of space which will be
available for other matter, by relegation to this annual Handbook
of detail which would otherwise appear in the Journal,
as, for instance, tables of phenomena of Saturn’s satellites,
and cometary search ephemerides. It is hoped that many
Members will make a point of ordering an extra copy of the
Handbook for knockabout daily use, so as to preserve a clean
copy for binding. This will be well worth while, as it contains
much matter which is not ephemeral and which will not
necessarily be repeated from year to year. If a considerable
proportion of Members will do this the Handbook may soon
become nearly self-supporting.Hello James,
>If anyone can recommend another telescope <
A Sky-Watcher Explorer 130P-DS OTA might be worth considering. They get good reviews and at £169 (FLO price) it’s not a financial disaster if things don’t work out…..
Regards,
Martin
Hello Gary,
I think I can identify the Cornish fisherman!
Sir Frank Dyson mentioned a letter received from W.F. Denning about the nova. Denning wrote:
‘It appears that the Nova was seen by Captain Piper, Fowey, on June 7, 12.45 G.M.T. He was watching for meteors, and saw a ‘pretty bright slow one shoot to just under Altair from a bright strange star on the right’. Though familiar with the constellations, he failed to identify it, and saw it again June 8, 9h 18m G.M.T. He thought it some phenomenon with which astronomers must be well acquainted. His observations have been investigated by an amateur astronomer, Mr. Τ.H.L. Hony, Manager of the Fowey Branch of Lloyd’s Bank, and he regards them as absolutely reliable. I must say that I incline to the same view. Captain Piper has been sending me reliable and interesting meteor notes for a long time’.This is mentioned in JBAA Vol 28 no 8 p237.
Martin
It’s certainly been a very grim 12 months indeed for the BAA, with the loss of so many fine observers, telescope makers and others. If I recall correctly Maurice was the first UK observer (around 1989/1990) to seriously use SBIG’s tiny ST4 autoguider CCD for imaging, despite its microscopic dimensions. This was in the era when a hard disk stored 30 Megabytes! How Maurice positioned the target onto the chip was a mystery! Pic attached of Tom, Guy, Nick H., me and Maurice at the Winchester Weekend on April 3rd 2004. Taken with my camera. Button pressed by Pete Seiden.
Martin
Nice! First time I’ve seen the whole interview. I’ve certainly never seen Steavenson speaking to Hay.
Martin
Hello Ian,
An 8-inch aperture will certainly outperform a 5-inch, on the planets or anything else. However, aperture is only one consideration. When I first started observing I could not see much fine detail on the planets, even with 8.5-inch and larger apertures. When I moved up to a 14-inch I still could not see the kind of details sketched by Paul Doherty et. al. So, I switched to photography. After a few more years experience I realised that the eye and brain become trained to see finer detail the more you observe. Then I realised how crucial accurate
collimation was. I also realised that the planets rarely look really good unless you observe a lot and catch the good seeing. Observing planets on a laptop screen, when imaging, is a revelation. The details distort every sixtieth of a second with the limb jittering by arcseconds! Then, on maybe 1 night in 20, planets look like a Damian Peach image, when the jetstream is absent and the weather is misty, or even foggy! However, unless the telescope has cooled to the night air and is precisely collimated you still won’t get great views. Moving up from a 5-inch to an 8-inch will not automatically give you good planetary views. So much depends on the state of our atmosphere and how often you observe. On this latter point some sort of user-friendly observatory, that can be set up in minutes, will make you observe 10 times more often, because you can just ‘nip out’ and check the seeing. For planets you do not need a computer control. Despite the hype, low-cost computer controlled telescopes can be more hassle than you need. Planets are easy to find, so a low-hassle Dobsonian is all that is needed… No need for star-alignment, cables and pressing buttons…just push the Dob and look through the finder….Deep Sky objects are obviously easier to find with ‘Go To’, but star-hopping is simple for the brightest objects.
So, to summarise, moving up to an 8-inch will not give you spectacular planetary views unless you observe a lot, train your eyes and brain, and keep the telescope collimated and cooled to the night air. The bigger the better though, so it may be worth thinking about a Dob. You can get a 12-inch Skywatcher Go To Dob for the same price as a Celestron 8SE, but you’d want to build a small run-off shed to house it, or put it on wheels. Deep Sky objects would look far brighter in a 12-inch! One final thought….Mars, Jupiter and Saturn are horribly low down at the moment so whatever telescope you get you have a long wait until they are nice and high again.
And the best views are usually obtained when planets are high up.
Martin
Seems like yesterday that I was in a battered old Hawaii jeep (an exotic vehicle apparently) on cloudy Hawaii with Nick James and Richard Fleet…… We were clouded out (unfortunately our tour guide was NOT John Mason…so we used a Jeep to give ourselves a chance…..) Distinctly remember sitting in the Jeep with the local radio playing Cat Stevens ‘Moonshadow’.
Martin
Just found some fascinating stuff that John sent me many years ago. If time allows I’ll try and dig out some more. This was John’s unique solution to making a Newtonian tube rotate, his sketch and the reflector he built. The mirror end rests on a ball and socket which takes the load when the tube clamp is slackened off……Martin
Grant,
My plastic roll off shed, described here: https://britastro.org/node/11048
is pretty much condensation free; the plastic walls stay dry, although the plinth gets very damp due to its sheer thermal mass.
All my wooden sheds attracted gigantic spiders, some the size of small dogs………. (OK, a slight exaggeration, maybe)
The plastic shed attracts snails….they even scale the plinth and sit on the C14 dovetail sometimes! But the spiders stay well away from the plastic….. Of course, my sheds are complete roll-off systems, not run-off roof systems.
Martin
Just found these old pics of John on my PC. Taken by someone at Crayford if I recall……
I think they say it all…John with his 32″ and 42″.
What a character!
Martin
This is very sad and shocking news Denis. Hard to take it in. Glyn would do anything to help anyone and seemed to have boundless energy for telescope and observatory construction projects. Frustrated by my experience with commercial gas-hypered film (and my own attempts at hypering) in the early 1990s I’d almost given up, but then Glyn offered to hyper all my Kodak 2415 reels for free with his own home-made facility. His stuff was far better than the commercial stuff…..and free! Just one example of his generosity……. Very hard to believe he has gone.
Martin
Hello David,
I can’t claim to be an expert on this subject but I did take quite a few Saturn images from the 1990s up to about 2011. These were, typically, at a scale of about 6 pixels per arcsecond and 10 – 15 frames per second, using 10 and 12 inch Newts. I don’t ever recall recording Mimas, but I did sometimes just get Enceladus, which is about a magnitude brighter. Like everything in planetary work, it largely boils down to the seeing. In perfect seeing I’m sure Mimas could be recorded without resorting to long exposures of a second or so. In fact I’m sure it must have been recorded on quite a few of Damian’s excellent images.
Expert visual observers (like David Gray, using a 415mm Dall-Kirkham) have seen Mimas when the rings are edge-on and there is less dazzle.
Regards,
MartinHello Eric,
>Is the spider and mirror mounting centrally placed and the mirror offset applied when gluing the secondary mirror to the flat?<
Yes. See the pic of the front end of Mike Sidonio’s Orion Optics AG12 which clearly shows the arrangement. This is roughly f/4, so an extreme case:
http://www.pbase.com/strongmanmike2002/image/132998032
To be honest, at f/6 you won’t notice a lot of difference, assuming the secondary is big enough, especially on such a modest imaging circle. Minor vignetting can be flat-fielded out.
Place your eye at the distance where your CCD sensor will be. Does the secondary show you the whole of the primary with a bit to spare? If so, fine.
For planets, assuming the telescope is collimated and cooled down, seeing conditions are the biggest factor by far. Everything else is pretty trivial!
Martin
I was just watching my downloaded video of Richard Miles’ presentation and, around 35 minutes in, I was surprised to hear Richard asking me a question, if I was watching the video…..! The question relates to Roy Panther’s comet discovery of Xmas Day 1980 and my activity that night. That was indeed the night that I first used my 14-inch AE reflector in Newtonian mode,
having acquired it a few weeks earlier. I had used it in Cassegrain mode prior to that and, just 2 evenings earlier, took a photo of the Mare Crisium which (somehow!) won the Lunar Section photographic competition 6 months later. But Xmas Day 1980 was the first time I used the 14-inch at f/5. It was the first ever night that I attempted sweeping for comets too (I continued for 4 years). I decided that I would start sweeping near epsilon Lyrae and so swung the telescope to that part of the sky, getting the star in the finder. However, being a big equatorial Newt on a high plinth, the eyepiece position, on a ladder, was too uncomfortable, and so I started elsewhere. Little did I know that at the same time Roy Panther was discovering his comet just a degree or two away! In fact, I did not hear about Roy’s discovery until a few days later when I bumped into my former Physics Teacher, Don Woodhouse, in W.H. Smiths in Bury St Edmunds. He told me that he had heard about it on the radio. I’d not seen Don for more than 4 years! It was only months later that it hit me that Roy had found his comet so close to where I had intended starting sweeping on Xmas Day, on my first ever comet sweep. It sent shivers up my spine…literally!That is spooky enough, but there is another twist. While watching the video of Richard’s talk, as soon as he asked if I was listening we had a MASSIVE isolated lightning strike here (4.10pm) and the power went off.
Are the astronomy Gods trying to send me a message……….?
Martin
Hello Lars,
I’ve not heard of it being recovered. It would be a major comet news item if it was, because it has been lost for a very long time. Guide 9 gives a perihelion date of 2017 Feb 27 but it’s pretty meaningless!
I mentioned the 2017 ‘Defunct Comets’ at the end of this piece:
https://www.britastro.org/node/8602
Regards,
Martin
