Solar Observing
Equipment


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Important Notice:


It is fun to do solar astronomy but it does have one problem,telescopes and binoculars produce a lot of light and heat if you observe with them you will be BLINDED INSTANTLY,even looking at the Sun will blind you.If you have never done solar astronomy before either contact your local astronomy group or contact one of the observing group listed below.

There are many ways to observe the Sun,projection,solar white light filters,then there are narrow band filter or more advanced instruments.In this section I will explain each instrument.
Mounts:
First of all I will talk a little about mounts.There are two main kinds of mounts around and a few other less common kinds.As for all kinds of astronomy you need a steady mount which has a telescope well fixed on it.Altazimuth this has a simple up-down movement as well as a left-right movement.This makes tracking the Sun harder as you need to move the telescope up or down(depending on the time of day) a little and to the right a little.A few solar astronomers use this kind of mount and get on well with it as do I.Equatorial mounts are favoured by most astronomers,as they have a more celestrial movement.This kind of mount has one axis which is tilted towards the north celestrial pole,so allowing you to follow an object by moving one axis.It is possible to get this kind of mount with drives.
Telescopes:
Telescopes for solar observing must be robust.The Sun, gives off radiation across the electromagnetic spectrum,but the Earth's atmosphere stops most of it.Do you remember doing experiments at school using magnifying lenses and how if you focus the image of the Sun you can ignite paper,etc?Well,that is due to the infrared rays being concentrated at the focus.A telescope is just like a magnifying glass,and will do the same thing if paper is placed at the focus of a telescope it will ignite!Think what it could do if you had your eye there.This ability to heat items up is something we must be careful of if we are going to observe the Sun,and it must be in our minds constantly.Light is a problem too,in that there is so much of it!So with this in mind,let's see what telescope can be used for solar observing.
The type of telescope is important,refractor are the best because they are a sealed unit so there is little chance of turbulence within the telescope.The type of refractor to have is the Astronomical Refractor, but not the Terrestrial type. This is because the latter has a number of additional lenses in the telescope to put the image the right way up.The reason you do not want to many pieces of glass as you lose a small amount of light for each pieces of glass the light goes through.It should also have a high f ratio,more than f10 is quite useful for solar observing.Any telescope with a ratio less than 10 should not be used,unless you can cut down the amount of light entering the optical system. Refractor objective lens are the thing you should look for when considering an instrument.The type of telescope you require is an Achromatic, or colour-free lens. If you buy a telescope that has a single, non- achromatic lens, you will get something called Chromatic Abberation.This is colour fringing, and a white object can be surrounded by different colours,which makes the item useless for observation of anything. The other type is the reflectors also known as Newtonian telescopes. They are open at both ends so letting turbulence occur within in the tube of the telescope.Also the Newtonian has a secondary mirror this gets heat and can be damaged.You should never use a reflector at full aperture.A small mask should be made and a hole should be cut of centre(because of the secondary mirror holder called the "spider" ).This means you can use it for projection ,but with the mask it must not be used to view the Sun directly.But if possible you should use some form of filter (glass of Mylar) even with great care it is likely the telescope may get damaged over a long period of solar observing if projection is used
Some telescopes are very sensitive to heat Schmidt-Cassegrain are one of these type of telescope.
DO NOT USE ANY OF THE FOLLOWING TELESCOPES FOR PROJECTION:-
  • SCHMIDT-CASSEGRAIN.
  • SCHMIDT-NEWTONIAN.
  • MAKSUTOV-CASSEGRAIN.
    USE THEM ONLY WITH OVER THE APERTURE SOLAR FILTERS.
    These telescopes are sealed and the build up of heat inside them could damage the telescope.
    Binoculars:
    Binoculars can be used for solar astronomy but you will need to project your image a long way to get a fair size image.You should block off one of the oculars so you do not end up with two images.You could use a camera tripod to keep the binoculars steady.You should still not look at the Sun directly with binoculars it will blind you.
    I will not be talking about costs of the instruments.
    Eyepieces:
    It must be noted here that eyepieces come in various types and some can and others cannot be used on certain telescopes Eyepieces recommended for use for solar observing are the cheap eyepieces called Huygens or Huygen Mittenzway,which are the ones sold with Japanese and other imported telescopes from High Street Shops.These eyepieces can only be used with telescopes of high focal ratio,because they are eyepieces that use lenses which are not cemented (glued) together.The light and heat could damage cemented eyepieces if they are used for solar work for any length of time Orthoscopic eyepieces are universal eyepieces and can be used on any telescope,but they do have cemented lens elements. Other eyepieces such as the Plossl should not be used unless additional filtering is used.
    Click here for the eyeieces I use.
    Eyepiece filters:
    This type of solar filter goes over the eyepiece, this kind of filter is subjected to extreme heat it will creak or shatter at some point,so subjecting the observers eye to the heat and light,causing instance blindness.If you have one throw it away,do not use it!
    Projection:
    This is by far the easiest method for a beginner,as well as one of the safest.This method allows you to use a refractor to see the Sun in white light.The reflector telescope can be used, but long term use of this telescope may damage the mirror on the telescope.If you have this kind of telescope some form of filter should be used.The refractor telescope collects light using its objective lens,then send it down the tube where it comes out of the eyepiece and is projected onto a screen.The person doing projection should not use eyepieces that have cemented elements,should be avoided as the amount of heat going through the eyepiece can damage them see eyepieces.It should also be noted that some eyepiece's have a metal outer casing,if this type is used you may need to let it cool down before you remove it as the heat from the Sun will have heated the case to a high temperature.
    There are may projection screens on the market,all are good for projection.When choosing a screen you should make sure it does not have a reflective surface or glare will make observing hard,if not impossible,if yours does then cover it with plain white paper.You could also use this method if your screen becomes marked which I have done.The only thing you need to do is make sure the paper is pulled tight and keep it flat against the screen.You should also not use the full aperture of the objective lens for anything over 3 inch's.Some telescopes come with the centre of the dust cap cut out so as to get the size of the objective lens down.You can use a circle cut out of paper/card to do the same.
    White light filter:
    There are may producers of white light filter.This type of filter fits over the objective lens.This helps cut out any of the thermal problems caused by projection because the filter greatly reduces the heat that enters the telescope.Most filters let less than 0.1% of light into the observers eye.Two main types of base material are used.Polyester or glass are to two materials,these are then coated with a metal film.
    Glass:
    Glass filters are,plain parallel glass plates,these are coated on the back side with a form of stainless steel(Chromium or Inconel) then these are polished to stop any distortion.On the whole this type of filter can be cleaned.The solar disk appears yellow through this type of filter and the sunspots and faculae are easily seen.


    A white light filter on a Meade 10" LX200.
    The pictures was taken by Nik Szymanek.

    Polyester:
    Polyester filters(mylar) are covered with aluminum.This type of filter may suffer what is known as pinholes,small holes in the film.To check for these you need to hold your filter up to a light bulb,if you see small bight dots then it likely you have pin holes in the film.Some company's use the mylar film to make white light filters.The sun you see is blue in colour.
    Cleaning the filter:
    To clean your glass white light filter you usually use Isopropyl a rubbing alcohol and a soft tissue.You put plenty on the tissue,using a stroking movement across the filter then dry with another tissue.When cleaning mylar filter you can do it the same as glass filter but the mylar filters are easy to damage because they are a plastic film,so great care should be taken.If you are unsure of the cleaning method it is best to contact the manufacturer as some filter may need special cleaning liquids.
    Narrow band filters:
    By narrow band filters we will be talking about H-Alpha filter.Most other filters(H-Beta and Helium to name just two) are out of the price range of many amateur astronomers.An H-Alpha filter will let you see prominence's,filament and flare and so on.There are a lot of H-Alpha filters around now but I will be naming four companies only.One of the newest is the Thousand Oaks filter.Then you have the Lumicon H-Alpha set at 1.5Å.The companies Daystar and Coronado Instruments make narrow band filters. filters.Daystar filters are set at 0.5 Å -0.95Å.Coronado have similar filter pass band to that of Daystar.In most narrow band filters the more pure, (or narrower) the filter bandpass, the higher the contrast of solar features. In fabricating the filter components, the most difficult parameter to control is spectral uniformity which is governed by the quality of the etalon. This sets the limit of the bandpass. Spectrally, the filter must be able to deliver a tightly controlled sub-ångström bandpass over the working aperture. In spite of the many advances in fabricating technology and experience is finding that producing a spectrally uniform etalon seems more like an art than an exact science.
    Coronograph:
    This type of device creates a total eclipse in you telescope.It does this by putting an occulting disk in front of the solar disk only leaving the solar limb visible,if you use a filter set between 2Å and 8Å you will be able to see very fine detail in the prominence's.It would be an advantage to have your telescope set up on an accurately driven mount,because,as the Suns face comes from behind the occulting disk the prominence's become bled out by scattered light,it also will after a short time be damaging to the eye.You will also need a different set of disks for different times of the year as the Suns disk changes it apparent size in the sky.These type of devices are now commercially available.

    Remeber if in dout do not use the solar filter.Contact your local astronomy group and get thier advice.

    Solar Filter Companies.


    DayStar:For over 25 years DayStar filters have been making narrow band filters,over the last ten or so years,as stated earlier they have moved into the price range of most amateurs. DayStar make three main types of filter.The University series filtering system,The ATM series filtering system and The T-Scanner series filter.Each of this class of filter is explained in detail below.
    The University class filter:
    The University series filtering system represents the finest components manufactured by DayStar.Professional institutions and advanced observers that employ research quality optical systems are encouraged to consider the filtering power of this top quality product. Available in a 0.80Å to 0.50Å bandpass,The University series is designed to handle any focal length system providing an f/30 beam while delivering full aperture spectral uniformity.The resulting visual observations,CCD images and traditional filtergrams are simply stunning.All filtering elements are thermally tuned by a calibrated precision oven and by varying the etalon temperature the observer is able to optimize contrast and engage in Doppler studies.These precision systems are extremely difficult to produce,and may create a variable delivery schedule.
    The ATM class filter:
    The ATM filtering system provides wonderful imaging fidelity at an affordable cost.Informative filtergrams can be made with slight dodging in the darkroom. Smooth spectral uniformity offered by instrument quality etalons will satisfy the needs of most observers.Nominal f/30, ( full aperture or stopped down ) optical systems delivering a focal length up to 2000 mm.will find the spectral uniformity of these filters impressive.The ATM series are available in a 0.95Å to 0.50Å bandpass.If the main stay of the observing program concentrates on filtergrams and CCD imaging, then consider the advantages of the University series.If the main desire is for visual work and taking basic filtergrams,the ATM is an excellent choice.In our manufacturing of a filtering unit each is thermally tuned by a precision factory-calibrated oven to maintain proper bandpass tuning.We are constantly amazed by images delivered by these systems.We continually receive quality filtergrams taken by ATM owners that give the "big boys" a run for their money.
    The T-Scanner class filter:
    T-Scanner series filter assemblies are designed for amateur observers doing remote observations without access to AC power.By taking advantage of fundamental physics relating to thin film coatings,an alternative method of tuning other than controlling the etalon's temperature is tilting the filtering assembly.Tilting the filtering system shifts the bandpass towards the shorter wavelengths.By fabricating the filter a few angstroms longer than the desired observing wavelength, the observer can optimize the contrast simply by tilting the filtering system with a control screw knob.T-Scanners are fabricated to the same quality and safety standards as the University and ATM series.These filters are intended for visual work and available in a 0.80Å to 0.50Å bandpass.Because of the internal tilting mechanism, these filter utilize an aperture of 30 mm. and operate in a nominal f/30 optical system.
    General Information:
    Generally speaking the more pure,(or narrower)the filter bandpass,the higher the contrast of solar features.In fabricating the filter components,the most difficult parameter to control is spectral uniformity which is governed by the quality of the etalon*2.This sets the limit of the bandpass.Spectrally,the filter must be able to deliver a tightly controlled sub-ångström bandpass over the working aperture.In spite of the many advances in fabricating technology,experience at DayStar is finding that producing a spectrally uniform etalon seems more like an art than an exact science.We are proud to place a guarantee on our systems.All DayStar Hydrogen a filters provide clear and exciting images of prominence and surface phenomena.Observers concentrating on prominence work generally prefer a wider bandpass,(0.95Å to 0.80Å ).Those concentrating on subtle surface detail require higher contrast or ultra-narrow bandpass filter systems,( 0.70Å to 0.50Å ).The most common fabrication request is 0.60Å for observing in Hydrogen a.
    Coronado Instrument Group:A new company based in the British Isles,it has two main types of filters on offer to astromomers the HELIOS-1 and the ASP-60 these will allow you two see prominences as well as surface detail such as filaments.for more information visit its we site listed with others below.
    Thousand Oaks filter:For over eighteen Thousand Oaks filter years have manufactured the most popular white light filters in the world. With our white light filter, excellent views of sunspots and granulation are easily seen.


    A Thousand Oaks white light glass filter.


    Now Thousand Oaks filter have built a H-alpha filter,below there is a short description of this filter. The Thousand Oaks H-alpha filter 1.5Å band-width yields some surface detail including flares.Each system comes complete and ready to attach to telescope. The system includes an energy rejection filter (ERF) and H-alpha filter mounted in a tilting (fine-tuning) mechanism. H-alpha filters generally do not work with Newtonian reflectors as there is not enough focus travel. Piggy-backing a small refractor is recommended since a large aperture is not necessary for solar observation.
    Lumicon Products:Lumicon sell white light filters(I do not know if they make them),they also make solar prominence filters as well as a h-alpha filters set at 1.5Å band-width.
    Kendrick Astro Instruments:Kendrick Astro Instruments are a new company,they are currently designing full aperture and off axis solar filters using the Baader Astro Solar Film.They have two sizes of filters available, a 52 mm for the 6",7" and 8" Kwik Focus and an 82 mm for all other sizes.
    Roger W.Tuthill,Inc:Roger W. Tuthill Solar Skreen Sun Filters has been around for more than 27 years.They are used all around the world by thousands of amateurs and professional solar astronomers.They are made from optical grade Dupont Mylar.
    43°S ASTRO:.These are unique handmade quality metallized film solar filters they consist of the newly patented Baader AstroSolar metallized film,mounted in attractive exotic dark hardwood in New Zealand and multiply-coated with UV-resistant polyurethane.Each filter cell is custom made to fit the telescope barrel,or any other size telescope OTA up to 250 mm,sealed and felt lined.They are shipped in a triple-strength felt-lined cardboard container (bubble-wrap protected) that serves as a long lasting storage box.The solar image is white,with minimum dispersion,black sky background and excellent high-contrast detail of umbra,penumbra, grana and faculae.
    Baader Planetarium:Thomas Baader from Baader Planetarium can supply Coronagraphs.The Baader coronagraph is a commercial version(I believe)of the Lille's coronagraph.

    Please note,I do not work for any of the companies please check my informantion about the filters is correct by visiting thier web sites below.

    Daystar Filters.Daystar filters.
    Coronado Instrument Group.Coronado filters.
     Thousand Oaks Filters.Thousand Oaks filters.
     Lumicon Products.Lumicon products.
    Kendrick Astro Instruments:Kendrick Astro Instruments.
    Solar filters by 43°S ASTRO: Solar filters by 43°S ASTRO
    Roger W.Tuthill,Inc.Roger W.Tuthill,Inc.
    Baader filters. Baader filters
    Thomas Baader.For information about coronagraphs,then contact Thomas Baader at:Baader Planetarium,Zur Sternwarte,8083 Mammendorf,Germany. Tel: (0049) 8145-8802.
    If anyone knows of a solar filter company if you send me an e-mail I will add it to this list.

    Solar Spectral Devices:
    The reason for these devices is they allow you to see the Sun's in different wave lengths of light.The Sun atmosphere is a glowing mix of gases that produce a spectrum with corresponding lines that are linked to atoms and ions to different element which are due to the Sun photosphere,a gas absorbs the elements that it would normally admit.This causes absorption lines which appear as dark lines seen in the solar spectrum.
    Spectroscope:
    This type of device is easy to build,it has four main parts . Light from the Sun goes through a slit where it goes through a collimating lens,then it can pass through a prism or a grating(to produce a Solar spectrum)then it will either be photographed or it will be viewed visually.The amateur who has one of these devices can view or photograph the spectrum and use their photograph or visual observation to work out which wave length of light they are seeing.Each wave length is a key to a different part/height of the solar atmosphere,so also seeing different temperatures.
    Spectroheliograph:
    After a spectroscope was introduced some solar astronomers wanted to record prominence's and other solar detail on film,so attempts were made to move the Sun over the slit slowly and this would record the Sun on photographic film.A spectroscopic device was used to create a spectrum and then this was projected on a surface with a slit,this was placed above photographic film.The only real problem with this is the photographic film must be expose for a long time,so making the viewing of fine detail being picked up on film very hard due to atmospheric turbulence.The Sun is moved across the slit in this kind of device,so there are no mechanical devices but as stated earlier it is a very slow way of recording the Sun in other wave length's of light.It is possible for an amateur to build this kind of device.One way this device could mounted on a telescope switch of the drives and let the Sun track across the film,so recording it on the film.
    Spectrohelioscope:
    This kind of device is much harder for an amateur to build.It involves moving a set of slits across the Sun's disk,this can be done in many different way's.The main problem with this is getting the device to function properly.The main problem with this device is getting all the different part to function together.I have experience of this as I am attempting to build a spectrohelioscope.As you solve one problem another comes to light.My device is all set up,but many problems mean progress is slow.If you do decide to build this kind of device you should first research it well and see what kind of work you need to do.In the case of this kind of device it may be well worth a group of people who have experience in electronics,mechanics and telescope construction together as you do need all of these things to build this kind of device,as well as dedication and patience it may take many years to construct this kind of device.The spectrahelioscope allows you to view the Sun visually as well as to take photographs.
    Additional information:
    There are other devices but I feel that these kinds of items is seldom used by amateur astronomers,so I have opted to add them to this section at present.
    Organizations:
    The B.A.A:
    The BAA is the abbreviation for "The British Astronomical Association" this organization is broken into many sections,the one I add my monthly reports to the BAA solar section.The director of this section is Geoff Elston his e-mail address is     geoff_elston@solarobserver.freeserve.co.uk the Assistant to the Director is Mike Beales,his e-mail address is M_Beales@Compuserve.com. The objectives of the BAA solar section is to get a daily report of the the relative sunspot number.Sunspots are not only thing section members moniter,they also do a report on solar prominences and flares seen,for more information please visit the solar section web pagehttp://ourworld.compuserve.com/homepages/M_Beales. The S.P.A:
    The S.P.A is the abbreviation for the Society of Popular Astronomy. It is similar to the B.A.A, but, it is has been set up to help junior or less experienced amateur astronomer, but it does have some experienced members and directors as well. The S.P.A has a solar section, its director is John Chapman-Smith his e-mail address is jachapmansmith@netscapeonline.co.uk Its solar section counts sunspot numbers as well as sunspot groups. It doescount prominences and filaments as well as flares. It has a 3 monthlymagazine called Popular astronomy and news circulars which has reports onwhat observations the solar section made. It has web page its address ishttp://www.popastro.com. if you what more information please contact the S.P.A director.
    The CV-Helios Network:
    The CV-Helios Network is a group of observers,from all around the world.This group of observer do not count sunspot group or sunspot numbers.They put each group of sunspot groups into its particular group classification,then they use the group class to give it a magnetic value.The group use the McIntosh sunspot group classification method to put each group in to its sunspot group classification.Then using a chart supplied by the CV-Helio give it its value.Here is the CV-Helio web page http://www.cv-helios.net/cvtab1.html,for more information please e-mail Kjell Inge Malde the Coordinator/Director of the CV-Helios Network at Franky.Dubois@digilife.be for more information either contact him of visit the VVS web site http://www.digilife.be/club/Franky.Dubois/werkgroep.htm. Polar faculae are observed by members of the BSO . Feel free to sent your own polar faculae observations to the director of the BSO .More information at http://www.digilife.be/club/Franky.Dubois/polar.htm
    The ALPO:
    The ALPO is the abbreviation for the Association of Lunar & Planetary Observers.The ALPO is divided into several observing programs. The Solar Section studies solar morphology, making high resolution and whole disk solar observations available for professional solar scientists. The Coordinator is Richard Hill, Lunar & Planetary Laboratory, University of Arizona, Tucson, AZ 85721. His E-Mail address is rhill@lpl.arizona.eduGordon Garcia is the Assistant Coordinator for correspondence and new observersgordg@megsinet.net The web site is located at http://www.lpl.arizona.edu/~rhill/alpo/solar.html
    The Astronomer:
    The Astronomer is an organization that is broken into many sections.It has a solar section.The person who runs this section is Nick James his e-mail address isndj@astro1.demon.co.uk. The objectives of "The Astronomer" solar section is to get a daily report of the the relative sunspot number.Sunspots are not only thing section members moniter,they also do a report on solar prominences and flares seen,for more information please visit the solar section web pagehttp://www.demon.co.uk/astronomer/solar.html.
    The A.A V.S.O:
    The A.A V.S.O is the abbreviation for "The American Association of Variable Star Observers" this organization is mainly concerned with Variable Stars,but it does have a solar section.For information on this section you need to contact Committee Chairperson Carl Feehrer his e-mail address iscfeehrer@hotmail.com.The objectives of The A.A.V.S.O solar section has many programs that it members do,for more information please visit the solar section web pagehttp://www.aavso.org/committees/solar/index.stm

    Solar E-Mail List and Newsgroups:


    There is an e-mail discussion group set up on egroups.com for the purpose of discussing various forms of solar observation, equipment, techniques and for the posting of important announcements regarding solar activity. Visit http://www.egroups.com and subscribe. Once you have subscribed the URL ishttp://www.egroups.com/group/solar-observers..
    As well as this there is a newsgroup used to talk about solar astromomy it is called "alt.astronomy.solar" it can be found on most server's newsgroup lists.Take look at this web page it will show you some of the subjects to talked aboutalt.astronomy.solar

    My Solar Observing
    Equipment.


    Introduction:
    I have been observing the Sun for 9 years,I became interested in solar astronomy when I went to Hawaii to see the 1991 total eclipse.I was amazed at what I saw,we were lucky at that eclipse we were graced by to large prominences,this made me want to observe the Sun and I have been doing so ever since.
    My Telescopes:
    I have a 3 inch Vixen telescope,which I used to do projection.


    My Vixen in it's projection setup.


    The Vixen setup for projectionI have a second telescope this is a 2.4 inch Pronto which is setup for my Daystar filter.I use the Pronto for the Daystar filter and this telescope is not used for any other type of observations.
    Filters:
    I have one filter it is a Daystar set at 0.7Å this is a nice filter to have,it is used to see the Sun in H-Alpha which allows me to see prominences,filament as well as other detail,not able to be seen in white light.Since having it fitted to the Pronto telescope the image quality has increased by 15%,the reason for this is that all the extra fitting I also bought were designed to used with the telescope and Daystar filter.The detail I can now see on the Sun is very good as well as allowing me to take pictures.


    My Daystar filter.


    Eyepiece.
    I use four eyepieces at present. They are 32mm, 26mm, 20mm and a 15mm plössl. I have found that a plössl type eyepiece work's best with my Daystar filter and Pronto telescope.


    32mm plössl.

    26mm plössl.

    20mm plössl.

    15mm plössl.



    A CDD picture taken by Nik Szymanek and Anthony Seal.

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