This page gives a few morsels of information to enable visitors to place Ravenshead Observatory on the world map and what is needed to make astronomical imaging a practical proposition. To start with - for non-UK visitors to the site - this is the only map I could find quickly that places Nottinghamshire on the map of England. I will be expanding the About This Site page as my astronomocal imaging experience develops so there will be times when I speak in the present tense and others in the past tense.
Due to the extremely poor and continually degenerating weather conditions and light pollution at the Ravenshead site I decided to re-locate my imaging system in November 2008. Now I have two observatories. One is in my back garden in the small town of Ravenshead, Nottinghamshire, England. One imaging camera is installed on the telescope that you can see in the pictures below. The other observatory is at the Sacramento Mountains Astronomy Park (SMAP), just south of Mayhill, New Mexico mounted on a new telescope and mount. The details of each observatory are set out below.
The observatory site is located 20 km North of the City of Nottingham, England and it is 6 km South of the town of Mansfield. Ravenshead is near the left centre of the green area shown on the map. The observatory is set in the back yard of our property and is within the area that was once part of the great Sherwood Forest. For avid film-goers, it is only partly true that the men around here still wear tights - and these tend to be football players (soccer to US viewers) !! The village of Ravenshead is quite rural but it is increasingly threatened with in-fill developments. As a result there are fewer trees every year and there is a moderate but increasing level of light pollution from all directions, but most heavy from SE - SW and NE - NW. If I had been around in the 16th century the site would have looked very different. This is Nottingham Castle at that time - I assume taken with the very first Kodak Brownie CCD Camera (??). I would have put the observatory at the top of the tower on the left of centre! Not much else around in those days..........
The area is very different now. At 20 km North of Nottingham Castle (which is now mainly re-built and restored) there have been many smaller towns developed - many of them grew to support the lace and mining industries until the late 20th century. At the site of Ravenshead Observatory now the least light pollution is through the directions NE to SE and the sky typically gives around magnitude 3.5-4.5 star visibility. Very occasionally the Milky Way is visible but with variable seeing (air stability). Due to nearby tree heights and the light pollution there is little opportunity to view the sky below 45° altitude and few images taken from this site have been taken when the target has passed the meridian (ie gone past South to the West).
As a concession to the semi-rural nature of the area around Ravenshead, in 2004 I built this private observatory to simulate a garden summer house and to blend in with the garden setting - in other words I painted it green. The second view is taken from the South East, looking North West. The equipment in view is currently being used for visual observing and is described in the Equipment section of the web site. Since this site was created the mount has been replaced with a Paramount ME German equatorial mount with full robotic control capability.
The wall supporting the roof rail track of the observatory was built high to shield the telescope from local lights in the house and neighbouring property security lights. The instruments I use can all "see" from about 35° altitude to the zenith - enough to keep above the heaviest light pollution.
The telescope shown here is an Astro-Physics AP155 refractor ie 155mm diameter object glass or 6.1" in old money. The focal ratio is f/7. The AP155 also has a Takahashi FSQ106N astrograph refractor mounted on its back. This has a 106mm object glass and has a focal ratio of f/5.0. This is used when I want to take very wide field images such as the Pleiades image in the Gallery page. The steel pillar supporting the telescope assembly is bolted down to a concrete base about 1 metre deep and 1.5 metres square. The base of the observatory itself is 3.1 x 2.6 metres. Mounted on the telescope (only just visible in this picture) is the digital imaging camera:- an 11 Megapixel Santa Barbara Instrument Group ST-11000M with an integrated ST-237H self-guider guider chip and an 8-position filter wheel for taking RGB colour and narrowband images. I also have the option to use a remote guide camera on the FSQ106 when imaging with the AP155.
On top of the pier and the workhorse of the entire setup is shown an Astro-Physics 1200GTO electronic drive mount. This was subequently replaced by a Paramount ME German equatorial mount which was more suited to remote controlled operation. This mount is aligned to within 40 arc seconds of the true north celestial pole to allow precise tracking of most celestial objects. This has recently been replaced by a Paramount ME
In the observatory I use a laptop computer that controls all the aspects of astronomical imaging. This computer is in turn controlled by a computer from inside the house using an ethernet power socket link and RADMIN PC control software. In a normal nights imaging, the only reason to be at the observatory is to roll off the roof and to connect the laptop. Typically this would take 5 minutes. From that point image target finding, framing on the camera CCD, focusing and imaging sequences are all performed using Windows XP on the observatory PC but then RADMIN controlled by computer inside the house. To avoid laptop damage through damp and cold it is never left in the observatory when not in use.
After only 12 months, the light pollution surrounding the observatory became so intrusive that I decided to find a dark sky site with reliably frequent clear and remote enough to be safe from similar problems. Whilst attending an amateur astronomy imaging conference in San Jose, California in 2006 I found a real opportunity to be the first user of a new telescope hosting site through contact with their English co-owner. We met in the bar of the conference hotel. This chance meeting was to change my aspirations and plans dramatically over the next 5 years. I made a committment there and then to be the first user and to have a completely new, large telesccope and camera system installed on the site.
SECOND OBSERVATORY - SMAP , WEED, NEW MEXICO (Sacramento Mountains Astronomy Park)
This site is a very dark site at an elevation of over 7,200 ft. It has been developed to support more than 100 individual amateur astronomer observatories, each with dedicated power and telecomms for internet control of the whole observatory. The site was purchased by two English amateur astronomers, Chris Traher and Phillip Stone - both of whom live in the UK. They have invested their own funds to make this facility available to amateurs anywhere in the world. In my own case, the roll-off roof observatory structure, the power, telecomms and insurance are all rolled into a single monthly rental sum. A resident on-site support astronomer provides the physical and technical support that is essential to installing and operating a remote observatory. Without this support and investment by the SMAP team I would not have been able to achieve my objectives and I am delighted to have been the first user of their astronomy park facility.
The equipment in the SMAP observatory is owned and operated by myself. This includes the UPS power supply, a weather monitoring device and a fairly powerful desktop PC. This PC has all the control programs to enable me to open and close the roof, monitor the local weather, switch the power on and off to any individual device in my telescope set-up and of course to operate and control the mount, telescope and cameras to facilitate digital imaging. The telescope that I installed is a 400 mm aperture f/8.26 Ritchey-Chretien supplied by Officina Stellare of Italy. The mount is a Software Bisque Paramount ME and the CCD camera I currently use is an SBIG ST-11000M (11 Mpixel monochrome) with a self guiding second CCD chip integrated into the optical path.
all the new equipment to site in November 2007, I returned to the site in February
2008 to install all the imaging systems and to build the controlling PC. The
PC was set up to operate as a RADMIN Server to enable me to use RADMIN Viewer
on my home PC in the UK to take full control of the observatory and all imaging
related functions. To avoid damage due to cold and damp this PC is only switched off when under maintenance. After numerous difficulties and a great deal of frustration,
the first light image was achieved in November 2008. The first light image is shown on the centre right below. The picture on the left below shows
the type of roll-off roof observatory that I use at SMAP as well as one of the
local inhabitants. The picture on the right is the 400 mm diameter Richey-Chretien telescope that I used for the whole of my stay at SMAP. The astro image is the first deep sky image taken with this set-up in New Mexico. A large version of this image is shown in the Gallery page of this site (just click the large green button at the top of this page).
After 19 months of imaging with the roll-off it became clear that I was losing around 60% of the clear nights available due to the wind speed alone. I was unable to keep the scope stable in winds over 6 mph. As a result, in March 2010 I decided to order a dome from ScopeDome (Poland) and I travelled to NM to install it with the help of a local contractor and the on-site astronomer. There were fundamental mechanical and electrical problems and it was not possible to commission the dome in the two weeks I was there. Over the next 7 months we were unable to resolve the problems with the manufacturere and ultimately had to fabricate my own solutions to the mechanical issues. I returned on 26th October 2010 to complete the task. The picture in the centre above (foreground dome) shows the new dome design. The remaining problems I had were all concerned with the successful use of sequencing programs and their method of controlling the dome rotation. These were eventually resolved and I had at last achieved direct control and automatic image acquisition from the UK.
The weather monitoring system is mounted on the external wall of the observatory and can be seen in these pictures. The SMAP site has a similar system of its own but it is set up to continuously record the main weather variables and displays them on a 24 hour graph. An All-Sky camera was installed on the SMAP site which also allowed me to see the condition of the sky for myself at any time. This was sensitive enough to pick out the main constellations and covered the whole sky in one continuously refreshed image. The pictures in the Equipment section give some idea of the way the telescope is installed and the arrangement inside the observatory.
I continued to image from New Mexico for nearly 4 years. By this time there had developed a problems with the dome which were seriously limiting my ability to continue. After 4 separate visits from the UK over the last 2 years at SMAP I was unable to find a solution to the unreliable shutter system which was putting my equipment at risk from extreme weather. In November 2012 I withdrew from this beautiful site with great regret. I believe that soon after I left the site, the local support manager had to retire from the position and the site has been closed since. A great shame! that soon after I left the site, the
THIRD OBSERVATORY - AstroCamp, NERPIO, SPAIN
Having sold the dome, the telescope mount and the camera to other amateurs in the USA, I returned with the rest of the equipment to the UK and began to search for an alternative site in easy access distance in Europe which would have reasonably clear, pollution free skies. After 3 months of searching and visiting the site of my choice (there was in fact very little choice) in April 2014 I loaded up my brand new Citroen C4 hatchback with all my new and remaining old equipment and drove to Nerpio in Spain to install it all in a dome. This dome coincidentally was the same type of dome that I used in New Mexico. As it was a later model and had been installed professionally I felt that I had a good chance of making a success of the project. The site was located at the top of a local mountain at around 1200 metres elevation and was set up to operate remotely as before. Seeing was good and clear skies were reasonably frequent and the views were spectacular. The pictures below show how the site was set up generally and my own observatory set-up in particular. The picture on the left shows the site on the summit of the mountain in the far background above Nerpio.
I was keen to change the type of images that I was taking as I had been using the long focal length 400mm diameter Richey-Chretian telescope for the whole of my time at SMAP. I chose to set up the AP155 refractor with the FSQ106N short focus refractor mounted piggy-back. This would give wide field fast optics and allow me to use narrowband filters extensively for the first time. These filters can selectively collect the light of ionised Hydrogen, Oxygen and Sulphur to create images that highlight specific elements rather than a continuum of light in the optical red, green and blue light our eyes are accustomed to.
My stay at AstroCamp lasted from April 2014 until April 2016. Continued problems operating the dome from the UK were never resolved and by that time the site had been filled to capacity. With no other observatory available I had to call it a day after completing only 4 images.
FOUTH OBSERVATORY -ICAstro, Alcalali, SPAIN
A new, temporary, telescope hosting site was found in the Alicante region of Eastern Spain and I moved all my equipment directly to the site from AStroCamp rather than return it to the UK. It was located in the Jalon Valley some 50 Km NW of Benidorm and 90 minutes drive from Alicante Airport. I decided to move there because the site was due to be relocated as soon as planning approval was obtained for a larger and better site. The new site will be quite close to the Spanish National Observatory which is located in Calar Alto, which is on the Northern side of the Sierra Nevada Mountains in Southern Spain. The new site will be over 1200 metres elevation and in a dark sky site. Until then, the less ideal site in Alcalali is a pleasant place to be. There are several telescope systems located in two roll-off roof observatories. The site is the home of the hosting business enterprise co-owner, Colin Cooper who is shown on the image below. Colin provides a top class service to all who use the site. He is also a keen amateur imager with a wealth of experience supporting and maintaining astronomical telescope systems and observatories. The second co-owner is Ian King, who runs an astronomical equipment retail business in Goudhurst, Kent.e second
In the first 4 months I was busy installing the set-up shown above and eventually produced my first serious image from the site between 11 Aug - 23 Sep 2016. I also decided to replace my old ST-11000 camera with a new main imaging camera shown on the smaller of the two telescopes. Most of the equipment was working well, but there were major problems with the replacement camera which lasted from September 2016 to April 2017. It was in April 2017 that I had to replace it. I chose a new Moravian Instruments G3-11002 which was about the same size chip as the old ST-11000. After installing it, I then started to become familiar with the image acquisition software Sequence Generator Pro (SGP) and a new guiding program (PHD). I started taking very deep sky images with this set-up in August 2017 only to find that the new camera had a fault in the imaging chip electronics which only became apparent when taking deep sky, low signal/noise ratio images. The story will continue......... G3-1100
GENERAL PRINCIPLES OF ASTRO-IMAGING
Almost all images are made up from multiple exposures taken sequentially through Red, Green, Blue and Clear filters. Other special filters are sometimes used for deep sky imaging. These "see" only Hydrogen Alpha (Ha), Oxygen III and Sulphur II emissions. These filters also have a very narrow band-pass but they are ideal for imaging nebulae and some planetary nebula. The Ha filter is often used to supplement normal RGB images - Ha emission is in the red end of the visible spectrum. The (Ha), R, G, B and unfiltered luminance (except for infra-red) exposures are later combined to produce the full colour images presented in the Gallery on this web site. Special digital image development software is used to do this frame processing once the raw images have been taken and almost always this is some time after the images were taken. In some cases, the images may be taken over a span of many weeks if the weather is poor and multiple long exposures are needed.
For more detailed information about the equipment and astronomical processing used to produce these images, please see the other pages of this web site or use the eMail link below.
Thank you for your interest.
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