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The observatory is principally dedicated to imaging the planets, including the Moon, but some work on comets and minor planets and some deep-sky imaging is also done. The light-polluted location means that imaging of faint objects is difficult, particularly in broad wavelength bands, but not impossible. Observing meetings of the West of London Astronomical Society are held at the Stag Lane Observatory regularly. Results are shared mainly through the observing sections of the British Astronomical Association, the principal organistion for amateur astronomy in the UK, and the websites of the Japanese Association of Lunar and Planetary Observers and the Oriental Astronomical Society Mars Section. Images of Jupiter are used in the international Jupiter feature-measuring programme JUPOS, through which the long term behaviour of Jupiter's atmospheric features are tracked. Images have featured in The Sky at Night TV programme, Astronomy Now, Practical Astronomer and The Sky at Night magazines, as well as the Journal of the BAA. The main telescopes are a Celestron C-14 Schmidt-Cassegrain and a Celestron C-11 Schmidt-Cassegrain. The C-14 is mounted on an Astro-Physics 1200GTO German equatorial mounting, the C-11 on an Astro-Physics 900GTO German equatorial mounting. Having tried a wide variety of astronomical equipment the past, I have found the Celestron optical tubes and Astro-Physics mountings to be the most reliable and high-quality pieces of equipment in the mass-market amateur range, of those I have tried, and the only ones I would have no hesitation recommending. There are also smaller telescopes attached to each mounting. With this set-up, one of the telescopes, normally the C-11 or or an attached refractor, can be used for deep-sky or cometary imaging for a long period without any interruption for planetary imaging, which can be performed independently with the another telescope, normally the C-14. Alternatively, deep-sky imaging and visualy observation can be performed simultaneously, or one object can just be monitored on camera while another is being imaged. A wide range of subjects can be coped with by the range of telescope focal lengths available, shortest 389mm (312mm with a 0.8x focal reducer) on a 66mm refractor, longest 3912mm (extendible to more than 20m with a 5x Powemate) on the C-14. Both telescope triplets are attached to the mountings using Andy Homeyer Scope Cradles. These cradles I have found to be the optimum system for SCT mounting. They are extremely well-machined, accurate, and rigid, and allow easy removal of the telescopes, effective balancing, and rigid attachment of subsidiary telescopes. With the AP mountings, they allow for extremely accurate, repeatable GOTO slewing. The
C-14 is mounted permanently with a Celestron 100EDR OTA (100mm f9 ED
refractor). A third telescope on the mount is attached using the Vixen dovetail and saddle system on the other side of the mount to balance the 100EDR. I can switch this telescope between a Celestron C-5, a Lunt LS60T hydrogen alpha telescope, a Skywatcher ED80 or a William Optics Zenithstar 66. The 100mm is
mounted using (slightly modified) Losmandy tube rings bolted directly
to the cradles, to the side of the main telescope. The third, switchable, telescope is attached using an ADM Vixen-type dovetail saddle, attached to a Losmandy
dovetail bar which is bolted to the Homeyer cradle base plate at the front of the mount. The C-14 is mostly used for planetary imaging and visual observation.The C100EDR is mostly used visually, but can also act as a guidescope for the C-14 in cases where guided imaging is required and the radial guiding method will not work, as it can be un-aligned from the main scope using the guide rings. The C-5 is mostly used for white-light solar observation, in conjunction with a Thousand Oaks Type 2+ filter, the Lunt is used for hydrogen alpha solar observation and imaging, and the Skywatcher ED80 and William Optics Zenithstar 66 are mostly used for widefield imaging. These telescopes are almost always kept and used on the east side of the mount. The eastern horizon is not good from this location, so they mostly look southwest: the C-14 and C-5 are accurately collimated for that direction and the collimation rarely needs to be readjusted. A major strength of the Astro-Physics mounts, unlike many other GOTO mounts, is that they allow the telescopes to look to the same side of the mount as they are located (by the mechanism of advancing or delaying the meridian reversal on the handset), so that normalisation can be completely avoided. This also helps preserve the collimation. C-14 on AP 1200 mount with 100ED and C-5 subsidiary telescopes mounted to Homeyer scope-cradle assembly. The
AP 1200 mount has been modified to the extent that it has had the
shorter 14.5 inch counterweight shaft substituted, which makes for more
room in the 2.3m square shed. The balance using this shaft is achieved
in part using a large mild steel counterweight made by Dave Tyler.In addition, the GTO control box has been shifted away from Astro-Physics' standard position on the polar axis to a safer position below the mount base (not shown here).
The
C-11 is mounted with a Skywatcher 100mm f9 ED refractor,
mounted in adjustable rings bolted to a steel bar bolted to the
cradles. An 8" Robin Casady
dovetail saddle is bolted to the front of the Homeyer cradle base plate, and this takes a Losmandy dovetail bar to the end of which is attached a saddle arrangement for a Vixen dovetail bar. This can carry any of the small telescopes referred to above (C-5, ED80, ZS66 or Lunt LS60), as they have all been fitted with a compatible bar, or it can just carry a counterweight to balance the the whole system properly. The reason for the system with the Robin Casidy dovetail saddle is that it allows the counterwighting "arm" on the mount to be collapsed into the mount for stowage. The run-off shed in which this system resides is of limited height and cannot close unless the Losmandy dovetail bar is slid along the Robin Casidy saddle so the counterweight is brought close to the C-11 OTA. It is easily slid out again for use. Telescopes on this mount are not often used visually. Any of them can be used for either long-exposure or fast-frame rate ("webcam") imaging under control from the computers in the warm shed, or for DSLR imaging. They are used on whichever side of the mount is needed.
 
Another view of the same system, showing the "collapsible" dovetail arrangement that can carry another telescope or counterweight. Both the C-14 and C-11 are equipped with Astrozap rigid aluminium dewshields and dewshield caps. I can thoroughly recommend these as a dewing solution for permanently-mounted SCTs, in preference to the thoroughly useless flexible dewshields offered by Celestron and other manufacturers. All the telescopes and finders are supplied in addition with Dew-Not dew heater bands, and I also use one of these to warm the nosepiece of the Artemis 285 CCD camera. Both the C-11 and C-14 have Meade motorised Crayford micro-focusers. The C-11 also has coarse electric focusing provided by a JMI motofocus unit. Coarse focusing of the C-14 has to be done by hand. The refractors all have motor focus adaptations either from JMI or Switched Systems. Both mountings are bolted to aluminium cap-plates on concrete piers with concrete foundations going 3-4 feet into the ground, and reinforced with iron pipes driven 1-2 feet further into the London clay subsoil. The pier for the AP1200/C-14 is about 16 inches diameter at the base and 14 inches diameter at the top. The pier for the AP 900/C-11 is about 12 inches diameter. Significant vibration problems are experienced from the traffic on Stag Lane, over 50m away, despite the apparent solidity of these constructions. The observatory has mains power, and most equipment runs off 13.8V, which is supplied from two 10A and one 4A power supplies. There are some exceptions to this, such as the USB hubs and CCD Peltier cooler, which have other power supplies. Cameras, filter wheels, guiding systems Cameras in use at the moment are a Canon EOS 350D DSLR for general and comet imaging, a Lumenera SkyNYX-2-0 monochrome camera for lunar and planetary imaging, an Artemis 285 cooled CCD camera for deep-sky and cometary imaging, and a DMK 21AF04.AS monochrome camera for auto-guiding. I have made extensive use in the past of colour and mono Philips ToUcan webcams, and the ATK 1HS-II camera, but these are now superceded.  Canon EOS 350D, Praktika LTL3 SLR (circa 1975, no longer used), Philips ToUcam (no longer used), Artemis 285. To create colour composites of the planets using the Lumenera camera, high-speed filter changing is essential. This is done with an Atik Instruments ATK-EFW electric filter wheel (I reviewed this in the July 2008 Astronomy Now.) I have modified the controller of this so it can be triggered remotely from a home-made secondary control box in the warm shed. For deep-sky imaging, which is slower, this is not really needed, and I use ATK, AE and Modern Astronomy (2") manual filter wheels containing LRGB, light-pollution or narrowband filters  The ATK-EFW electric filter wheel
Despite the high accuracy of the Astro-Physics mounts, and the fact that they have both been precisely polar-aligned using the drift method over a long period, active guiding is still necessary for very long-exposure imaging at moderate focal lengths, or long exposure imaging at long focal lengths, for various reasons. Having experimented with many combinations of guiding one telescope with another, I have come to the conclusion that this never works perfectly: there is always a long-term drift between the pointing of two telescopes, no matter how rigidly coupled together, that spoils the guiding. This is particularly true of SCTs, with their moveable primary mirrors, but it afflicts refractors too, which usually have some slop or flexure in the focuser and camera couplings. The solution is the use of one telescope for both guiding and imaging using a radial or off-axis guider. I use the Celestron Radial Guider for this purpose, with the Artemis or EOS camera as the imager and the DMK camera as the guiding camera, in conjunction with PHD Guiding software.
 Guided imaging system on C-11, showing, from the left, telescope, Meade electric micro-focuser, Celestron radial guider with DMK camera in the radial position, spacer, Astro-Engineering filter wheel, and Artemis camera with heater band. To the left of the blue DMK can be seen the JMI motofocus on the C-11's focusing knob.
The observatory, with others, is described in detail in my book Setting-up a Small Observatory
(Patrick Moore's Practical Astronomy series, Springer, 2008). It
occupies land at the end of a suburban garden about 30m from the
nearest heated buildings. The observatory with both telescope sheds opened It
consists of three buildings: a run-off roof shed 2.3m square, which
houses the AP1200/C-14 configuration, a run-off shed 1.5m square, which
houses the AP 900/C-11 configuration, and a warm-room shed. The latter
also doubles as a summertime composing studio (see my music pages). Inside
the warm room. The laptop on the left is a modern one with USB 2.0 and FireWire, and is used for imaging, and for guiding and control of one mount and focuser. The laptop on the right is an older one having a serial connction, used for control of the other mount and another focuser. Star and Moon charts adorn the walls. Operations
in the observatory can generally be controlled from two computers in the
warm room. USB 2.0, FireWire, Serial
(RS-232), and DC focuser connections, plus wiring that allows remote-control of the electric filter wheel, are installed between the warm room and both telescope piers. The mountings can be remote-controlled from the warm room
via USB or serial connections. Images can also be received here from
the cameras via USB or FireWire. All the telescopes are focusable
electrically from here. Three focusers can be operated at any one time (two via USB/RS-232, and one via the DC line), and one telescope can have filters remotely changed. It is
possible to use three cameras simultaneously, the Lumenera and the Artemis or EOS over USB, and the DMK via FireWire, and hence it is possible to do autoguided long-exposure imaging using the AP 900
set-up simultaneously with short-exposure planetary imaging
using the AP 1200 set-up, or vice-versa, all controlled from here. Since the shed is close to the telescopes, it is easy to get back to them to diagnose one of the many problems that can arise in remote-controlled imaging. Run-off shed covering C-11 in closed position, with camouflaging tomato-growing trellis I
built my first observatory at my father's house in Christchurch,
Dorset, in 1980. This was a 5 foot square shed with a roof which folded
back in two halves. It housed a 6.25 inch f8 Fullerscopes Newtonian on
a Fullerscopes Mk III German equatorial mounting (manually-driven).
This observatory was dismantled about 1985, and the telescope put into
storage. My
next observatory-building project was the current run-off roof shed at
Stag Lane, Edgware, Middlesex. This was completed in early 2004, and
initially housed the 6.25 inch Newtonian. Drawing
of Jupiter made in 2004 using the 6.25 inch Newtonian, seen, right, in
the newly-built run-off roof shed. The telescope pier initially was
brick.(The 6.25 inch, made in 1980, is still in use, now on loan to another local astronomer.) A
250mm Orion Optics Europa Newtonian was aquired in 2004 and fixed to
the Fullerscopes mounting, but this was not a very successful
configuration, and it was soon replaced with an almost unique 10-inch AE Dall-Kirkham-Dall Cassegrain on an AE C-type mounting telescope, loaned by Robert Katz.
This is an interesting telescope which has a full explanation here.
The author in 2006 with the 10-inch Dall-Kirkham-Dall telescope on strengthened brick pier, also showing webcamming equipment
The Dall-Kirkham-Dall was used for webcam imaging of the Moon and
planets with some success, but the optical design was found not to be
well-enough corrected for aberrations over the full wavelength range of
sensitivity of CCDs to be optimal for this purpose. It was also an
extremely heavy, bulky and tricky instrument to use, not
well-compatible with modern accessories. For these reasons it was
relaced in mid-2006 with a Celestron C-11 SCT. This was a far more
compact and lightweight instrument of superior optical performance and
greater versatility. The Dall-Kirkham-Dall is still at Stag Lane
Observatory, not in use, but could be revived at some point. The
C-11 was initially used with the AE mounting, but this had poor tracking accuracy
and no computer control, and it was replaced with an Astro-Physics
900GTO mounting at the beginning of 2007. The brick pier had
been demolished in mid-2006 and replaced with an improved
cylindrical concrete and stainless steel one. As
a parallel project, in 2006 work started on a second permanent
telescope set-up. The optics of the Orion Optics Newtonian had been
rearranged in a new tube, and this was mounted on a modified
Fullerscopes Mk III mount, which was used for a time on a tripod, sited
on the patio by the run-off roof shed, and covered-over when not in use
by a car-cover. This arrangement was made more permanent firstly by the
construction of a concrete pier, then by a wooden deck around this, and
then by a run-off shed running on the wooden deck, in between the rail
supports for the run-off roof shed. The fact that this new construction
had to work together with the run-off roof shed determined its size and
design. So that both set-ups can be used together, the run-off roof
shed can slide underneath the opened run-off roof. The 245mm Newtonian telescope on Fullerscope mounting and concrete pier, 2006 The
warm room was developed for control of the C-11/AP 900 set-up. This
shed was actually a pre-existing summer house located a few metres from
the telescope sheds. The Newtonian could only be used visually, as the
mounting was inadequate for imaging, and not computer-controllable. A
Celestron CG5GT computerised mount was substituted for a time, but this
was also found to be inadequate for the purpose. In
mid-2007 the decision was taken to move to a C-14 as the main
observtory telescope, and to mount this on an Astro-Physics 1200GTO
mount. The AP 900 mount and C-11 were moved from the run-off roof shed
pier to the run-off shed pier to make way for this. The 245mm Newtonian
OTA is still at the observatory and may be put to use again, but it is not currently mounted. These changes have given the observatory
two separately remote-controllable telescope systems of virtually equal slewing
and tracking accuracy.
The three semi-apochromatic
refractors were added to the equipment in the course of 2007. The Celestron 100EDR replaced an old Helios 90mm achromat that had been used with the Dall-Kirkham and the C-11 in the run-off roof shed, and the Skywatcher 80ED and 100ED replaced a Skywatcher ST80 that had ben used with the 245mm Newtonian in the run-off shed. The C-5 was added alongside the C-14 in 2008. It is also used as a portable telescope on a Vixen Altaz Porta mount.
In mid-2008 I was involved with re-homing the remains of the famous English telescope-making business of H. N. Irving, following the death of Ron Irving in 2005, before the property, 258 Kingston Road, Teddington, was sold and the workshop demolished. Out of bits and pieces from Irvings I constructed a rather classic-looking 3-inch portable equatorial refractor.
The Irving 3-inch refractor
Finally, I have a long-focus (at least f10) 6-inch mirror, bought for a small donation to the Campaign for Dark Skies which I have an unfinished project to construct a planetary/double-star Newtonian around, using the Fullerscopes Mk III mount that was used with the 245mm Newtonian (but was inadequate for that telescope).
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