User Guide
Contents
1. Do it in the dark to better see the patterns You ll need some time to get the right tuning but at the end of the day you ll love that this is to be shown to the kids D D N N laser N Er Mo 650nm Measure the distance x projected on your screen You can then deduct the slit width a with the formula a D 1 x A is the wavelength for your laser in general 650nm or 680nm Here are some values for a laser at 650nm D 50cm 1m 2m 10um 32mm 65mm 130mm a 18um 18mm 36mm 72mm 30um ilmm 22mm 43mm in gt helyak Lhires ITI User Guide English DCOOO4A 12 43 Note that the slit tuning is made manually you ve to untighten the screws move the half slit smoothly very smoothly and tighten back You will be also careful to the slit parallelism this is very easy to control visually by looking at the daylight through the slit Additional slits are available in case you need to frequently change slit width 3 2 Visualize the solar spectrum From now you ll start to see the solar spectrm This important not only because it s beautiful but also because you ll get the exact position angle of the grating for different typical wavelengths IMPORTANTE NOTE There is no danger to look at sun this way without telescope The slit is so small that only a few part of the sun light goes through the instrument and it is very dispersed If2. Dark and Flat files Ensure you do not go over 32767 as SpIRIS only process 16bits signed files If you have 16 unsigned files use the CONVERTSX function I Also ensure all your image are properly oriented red to the right blue to the left If not use the MIRRORX function on all your images Last but not least get the list of hot spots on your dark frame For this LOAD your dark frame and use the FIND HOT COSME 25000 function A cosme lst file will be created in your working directory LOAD altair spectrum image Substract the dark frame SUB dark 0 0 Measure which line the spectrum is located at we will call it YO Find the 6575A telluric line look for the specific pattern below 0 Measure the column where this line is located X0 In our example it is X0 447 e Neon calibration Average the two Neon spectra one before and one after the serie to do a master neon calibration frame for your reference star LOAD your master neon calibration frame I select a frame around the X0 Y0 area m click on the right mouse button m select Fen tre to crop this area O SPiris Version 1 20 c data shelyak hires Fichier Visualisation Geometrie Pretraitement Traiteme A el Statistiques Optimisation du noir pohelyak MENTS Lhires ITI User Guide English DCOOO4A 28 43 m MIRRORXY to reorient it horizontally m select a small frame around this line m ORI will return you th
3. English DC0004A 32 43 7 Spectroscopy introduction 7 1 In the beginning Spectroscopy really started around 1666 when sir Isaac Newton dispersed sunlight with a prism But it s in 1802 that William Wollaston discovered dark absorption lines lines studied later by Joseph von Fraunhofer who published a catalog of several hundred of those lines in 1815 We now have classified thousands of absorption lines in the solar spectra In 1849 L on Foucault studied emission lines produced by a Sodium lap Gustav Kirchoff and Robert Bunsen identified the same lines in the solar spectra in 1857 solar spectra with a Lhires III O Garde 7 2 Different types of spectra Spectrography analyses light from sources away from us It allows the study if the chemical composition temperature pressure and movement Lhires ITI User Guide English DCO004A 33 43 INSTRUMENTS There are three types of spectra following the Kirchoff law 1 Continuous spectra it is emitted by any solid or gazeous body under high presure and high temperature Stars are under first approximation like black body whose continuous spectra has a shape which depends on its surface temperature 2 Absorption line spectra a low pressure low temperature gaz crossed by a continuous light absorbs some photons Spectra then shows dark lines in front of the continuous spectra 3 Emission line spectra a low pressure high temperature gaz
4. 22 5 2 Standard acquisition procedure ueesssnnennnnnnnnennnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn 23 5 3 NOLE ON AUSG EN a ei ne te cu 26 3 4 TAKING Mae MOI asas a a ee en 27 6 Extracting a calibrated 1D spectrum Rss 28 7 Spectroscopy INtrodUcCUO Nissan E a 33 7 1 In the DEODORO 33 7 2 Different types of Decidir een 33 7 5 Message RO OE sd sas 34 7 4 Effective temperature and spectral types 35 20 CCUG he emanadas dead E a Das E pe 35 7 6 Chemical composition and metallicity ro 35 77 DODDITS EOC Correa EE R EE 36 Fo CONCISO eee a E E E AS 36 e PU E 37 8 1 Spector HO la DOY een ad Da near 37 8 2 Jupiter or Saturn rotation nsc r arar rra rr rra rn 38 Suo Radial VOICE EVE a bia aa nan dada donna a a 39 9 4 De OL Siria 40 9 TLOUDIESNOOENG 7 SUPDO micras sra EO Dad 41 LU CT Ol INC CS otra da ee a E a ane 42 LOL BOOKS quant add race 42 10 2 PVV CD WKS ad siste nai dia ada ada O Rd O ds ga 42 SC Cl al PAR RAR ari 42 _ my helyak ir Lhires III User Guide English DC0004A 2 43 SOMA usa dO De pa a ei ra fi a dd 42 Speco ACORDO semanas al IgA Ata LA AD SA IDR a GDE a 43 PRO ICS 7 O CU de de ee ee ee 43 lt la SSshelyak MENTE Lhires ITI User Guide English DCO004A 3 43 1 Introduction This document is made to help you starting in spectroscopy with Lhires III It covers the tuning of the instrument the first steps to acquire and process spectra and some examples of observations Starti
5. 3x3 e Position the slit to the center of your image by adjusting doublet focus if you do not see the slit changing from eyepiece to camera requires some adjustment grating angle I main mirror angle Playing with those three adjustments you should quickly find the ideal positions Eventually try to put the slit closer to one edge to avoid vignetting Shift the mirror screw Slightly toward the slit trappe so the slit image is at 1 3rd of the CCDimage This way you optimize the position and reduce risk of vignetting This is not mandatory but good to do Note where your spectrum is on the CCD this is where you will have to find your star 3 op r ea TEME j Ee a A i 4 Main mirror Screw low adjusting screw Screw high Screw nominal Zero order in gt helyak Lhires ITI User Guide English DCOOO4A 17 43 3 5 Adjusting grating position Before taking a stellar spectra you still have one adjustment to perform It does require patience It s not absolutely mandatory but it will help you afterward Goal is to put grating line parallel to the rotation axis of the grating support when they are not lines will follow a conic curve instead of a cylindric one Projected image on the CCD will shift when changing the wavelength and move eventually out of the CCD camera Ideally your should have the zero order and the full spectra within your CCD and even within a small portion of th
6. giving a spectral dispersion of 0 115 A pixel in the red for a camera using the Kodak KAF 04XX family of CCD chips Audine ST7 Less dispersive gratings are available the groove density falling in proportion to light intensity of weaker and weaker objects in order to obtain a spectrum Grating Lhires III lines mm 2400 1200 600 300 150 Dispersion Ha nm pix 0 012 0 035 0 074 0 149 0 300 Resolving power 17000 5900 2800 1400 700 Radial Velocity Km s 5 17 35 75 150 Field of view nm 8 5 25 55 110 230 All visual domain in images 45 15 7 4 2 Limiting magnitude 5 0 6 8 7 5 8 4 9 2 Table parameters based on grating used ETCL simulation 200mm f 10 telescope 30um slit KAF0400 camera 1h exposure Signal Noise of 100 INSTRUMENTS Lhires III User Guide English DCO004A 43 my helyak MENTE Lhires ITI User Guide English DCO004A 8 43 Tr TT TT 11 TD PT TT TT TT TT yt vega208589240t dat 4300 4800 5300 5800 6300 6800 7300 Comparing spectra of Vega Left low resolution 150 Imp grating Right high resolution 2400 lpm grating The dispersed light from the grating passes back through the lens and is focused on the detector This could be an astronomical cooled CCD camera a DSLR or even a webcam However for most applications in stellar spectroscopy only a cooled CCD camera will have the required sensitivity A few application can m
7. screws 1 pushing and 3 pulling accessible from ouside At this stage you must check that the neon holder can freely move without interferring with the mirror you can check it easily by looking into the spectro from the some position _ my helyak ir Lhires III User Guide English DC0004A 14 43 Fine tuning A fine tuning can be made by materializing the slit center and checking that this part of the slit is seen in the center of the guiding camera field Note materializing the slit center will be reused in next steps e Unmount the slit holder e Put 2 paper small sheets spaced by 2 3mm Use adhesive tape to stick them on the holder not directly on the polished faces of slit Ensure that the 2 3mm gap is well positionned in the mechanical center of the slit This part shows the area where the star beam will have to go e Mount back the slit holder Paper mask I Shelyak INSTRU ENTS Lhires III User Guide English DCO004A 15 43 Mount the spectro on the telescope and point it to the sky not to the sun with no motion Install the guiding camera webcam video camera and visualize the image monitor PC Adjust manually the focus of the camera in order to see the slit acurately Fine tune the mirror in order to put the slit center image in the center of the picture The mirror adjustment is done You can remove the papers but you can also keep them for next steps Guiding
8. the doublet focus carefuly Change the position of the micrometer thus the grating s angle and the position in the spectral domain and repeat the process several times You will obtain a serie of spectra of the sun and you can put them side by side to reproduce a very large spectrum of the sun _ my helyak ir Lhires III User Guide English DC0004A 19 43 Valeur vis microm trique 12 5 13 5 14 5 16 0 17 0 18 0 18 5 19 5 20 0 21 0 22 0 INSTRUM ENTS Spectre du Soleil GIRS R seau de 2400 traits mm apn CANON 20Da 4000 A 23 A 4183 ALOON aaa 2 Fe2p Fel Fel 4357 TC TES A Fel Fel 4527 a O 4 705 Til Cri Ti2 mee cet 4689 A 1 48654 Mgl Hp Til Nil Fel Fel Fel Fel Fel Mg1 5193 A N A PTD NL 33594 Cri 5359 AURA LUN T AE EE EI 5527 4 Fel Fel 5515 TT NET 562 Cal Fel 5676 ADIA EO 052274 Nil Mg1 5825 eo gt gt Nal 5978 Aa MU U DE TR Fel Fel 6120 LU 25 6221 A TT A Fel Atm H20 02 6396 ee A Cal Cal Cal 6533 O E A 6660 A NA A 787 A Fel Nil Nil s787 A HEM TN IL 6905 A Atm 0 6906 a BE HAUL ALE TAL TATO CIE A Atm O 6998A 7055 4 Sil Dispersion de 0 11 pixel 4000 A jusqu a 0 056 A pixel 7000 A Lhires III User Guide English DCOOO4A 2006 Olivier GARDE N O NS D W 5 In the field Once you ve made all adjustments of the instrument you re ready to acquire your first star spect
9. INS TRUMENTS UHTRESE User Guide Shelyak Instruments Les Roussets 38420 Revel France Phone 33 476 413 681 http www shelyak com Email contactOshelyak com Ref DCOOO4A December 2006 lt _ INSTRUMENTS Lhires III User Guide English DCO004A 1 43 Table of Content a il Co e en 4 2 Overview or the Lhires Il agem possas nina Rn aa dar dd iberica 5 2 1 ne Basic Elements asistenta nous 5 2 2 AP CVO Ma CCG quitada aa ad add aa ue di sde De an de US O gaia 10 UNO MAGRA o EE en een 10 LUNING your Enires last ies ros us 12 SS UE WIAEN AA J USE nu anne a nee nennen 12 3 2 Visualize the solar spectrum nsc neun nun neun nun nenn nun nenne 13 3 3 Adjusting guiding mirror cnn rr rr 14 ROUgn ad NUS CSN arras iaa sn 14 PING CAO ee E AS 15 5 AG USEING Mal Ol Ol escaparon a a aa eee 16 Simple AIS EI ya pad 16 PIC a A ee 17 3 5 Adjusting Grating POSITION cccceueceeccssncccunneeenessaccununeesseeuaueennausensenauaegs 18 4 Taking your TIESESDEC ces raras 19 4 1 Reference lamp s SPCCU a een arena 19 DZ SOlAl SD ns ran en cernes 19 D Cle TSI eE E a Dia desista Sadi a aile ana 21 5 1 Operation to be done during daylight cestas 21 Mounting the Lhires III on the telescope nr 21 FOCUSING ne guiding CAMERA sensei asda ana 21 FOCUSING the telescope assuneunnnnnnn nun nn nun neun nun nun nun nnnnun nennen un nun nn nun nn nnnnn 22 Focusing the acquisition CCD camera nun nn nun erre erre
10. ake use of a video camera for example one of them being solar observations where the Lhires III can easily be converted into a spectroheliograph for observation of the solar chromosphere Visual observation of spectra with an eyepiece is also equally possible Lhires III therefore can be considered and excellent teaching tool to support the teaching of physics in schools as well as the principles of astronomical optics SOLAR SPECTRUM LHIRES Il 2400 Viewing the solar spectrum through a Lhires III 2 dimensional spectrum of the Be star Gamma Cas The very broad intense line in the centre is the H alpha line in emission The several narrower dark lines on either side are produced by atmospheric water vapour absorption in the Earth s atmosphere td rd Lhires III User Guide English DC0004A 9 43 2 2 Performance Limiting magnitude A spreadsheet had been developped to simulate what would be the expected result with the Lhires III the Exposure Time Calculator for Lhires ETCL This tool is available on internet and on the CD provided with the spectrograph Here are some exemples of performance obtained 2400 I mm Grating Star type BOV CCD KAF 0400 Slit Width 25 um Seeing 4 arcsec Resolving Power R 17000 Sampling KAF 0400 0 115 A pixel Limiting Magnitude Limiting Magnitude S N 50 in 1 h S N 100 in 1 h exposure exposure 1200 mm Grating Star type BOV CCD KAF 0400 Slit Width 25 um Seeing 4
11. al work done on any specific object ADS http adsabs harvard edu abstract_service html This is THE reference where to find for professional articles Thousands articles are scanned and available to the amateur community through that link UVES http www sc eso org santiago uvespop bright_stars_uptonow html see also VisualSpec tutorial http www astrosurf com vdesnoux tutorial8 htm l Software Iris http www astrosurf org buil us iris iris htm SpIRIS http www astrosurf com aras spiris spiris htm VisualSpec http astrosurf com vdesnoux Audela http www astrosurf com aude SpcAudace http bmauclaire free fr astronomie softs audela spcaudace lt my helyak Lhires ITI User Guide English DCO004A 42 43 Prism http www astroccd com prismy fr Spectro heliography Christian Buil http astrosurf com buil sph2 obs htm Jose Ribeiro includes same technic on the Moon http www astrosurf com joseribeiro Eespectrometria htm Robin Leadbeater http mysite wanadoo members co uk astro2 spectra_29 htm Projects Studies Be stars overview http astrosurf com buil us bestar htm COROT Be stars program http www astrosurf org buil corot data htm BeSS not on line at the time this document is printed but look for a link on ARAS home page Stellar disks http www bartol udel edu owocki RDOME Swarthmore Herbig Ae Be stars with a Lhires III http www astrosurf com buil abaur obs htm C amp S sta
12. amera CCD camera SLR camera webcam and orient it so that the spectrum align with the width of your image Protect the instrument from the day light Switch on the neon lamp and put it in front of the slit turning the button e Adjust the grating angle in a region with neon lines The easiest is aroud Ha 6563 A where there are 2 well known lines thanks to Nature During the tuning of your instrument you Should have recorded the micrometer value for Ha e Acquire pictures continuously and identify these lines e Open one of the side doors e Focus the spectrum on the CCD picture by turning the collimation lens holder e If you re in full light you should have to close the side door between each picture because of the parasites e Atthe end tighten smoothly the nylon screw to block the lens holder e At optimum the FWMH should be around 3 to 4 pixels Note this can also be done on solar spectrum but it s less precise Note If you change the observation wavelength you may have to re tune the focus lt _ INSTRUMENTS Lhires III User Guide English DCO004A 22 43 Focus not OK Turning the Doublet Focus OK 5 2 Standard acquisition procedure This is a recommended procedure during a normal night session First focus your spectrograph Point toward a bright star Ensure proper imaging camera orientation spectrum should be along the width Turn on the Neon lamp and fine tune th
13. anged Use the average of the two Neon calibration serie as your main Neon reference spectrum The reference star will be used to calculate the response curve of the full setup telescope spectrograph imaging camera Bias dark and flat field frames will be used to correct images from those defects The only in gt helyak Lhires ITI User Guide English DCOOO4A 23 43 difference in spectrography is for the flat field where we will only use the high frequencies to correct the dust trace but not the overall vignetting of spectral curve of your hallogen lamp Refere to your camera manual on how to get those pre processing frames Here are all images of a typical session with a 2400lines mm grating with each calibration dark bias flat neon already combined to master frames using a median function Reference star Altair Neon serie 1 Altair do are te 2 e TE ti Spectrum Altair in reallity we took 3 of those images Neon serie 2 Altair Target star b ta Auriga Neon serie 1 b ta Auriga Spectrum b ta Auriga in reality we took 3 of those images Neon serie 2 b ta Auriga potelyak Lhires III User Guide English DCO004A 24 43 my helyak ir Lhires III User Guide English DC0004A 25 43 Flat field 5 3 Note on autoguiding Most autoguiding software will work and parameters wi
14. arcsec Resolving Power R 5800 Sampling KAF 0400 0 345 A pixel Limiting Magnitude S N 100 in 1 h exposure a AO A AAA O es ION BE Limiting Magnitude S N 50 in 1 h exposure Lhires ITI User Guide English DCO004A 10 43 INSTRUMENTS 300 I mm Grating Star type BOV CCD KAF 0400 Slit Width 25 um Seeing 4 arcsec Resolving Power R 1300 Sampling KAF 0400 1 493 A pixel Limiting Magnitude a as S N 50 in 1 hexposure N 100 in 1 h exposure INSTRUMENTS Lhires ITI User Guide English DC0004A 11 43 3 Tuning your Lhires III When you ve finished to assemble the instrument you still have to do some tuning This is made during daylight but it requires the full equipement telecsop CCD camera guiding camera In this section we consider that the 2400 g mm grating is used 3 1 Slit width adjusting The slit width is a key point of the instrument It determines the resolution of your spectra Nominal width is 25um If it s bigger you ll decrease the resolution If it s smaller you ll lose some flux Then you should tune this parameter as precisely as possible Measuring a width of 25 um is not obvious you can make it just by looking at light through the slit with some experience but we ve got a more determinist method optics rules say that if you send a laser toward the slit that makes a diffraction pattern with a proportionnal size to the slit width Thanks to the Nature
15. ational speed First Be star gamma Cas was discovered in 1867 by Secchi There a several Be stars in the Pleiades M45 cluster The emission line is explained by a ring around the star which emits energy to all directions But how this ring is created is still a mystery that professional astronomers are working on exemples of Be stars Ha lines Lhires III with its very high resolution is particularly well adapted to the study of Be star spectra Short term as well as long term evolution will bring more usefull information to professional astronomers A database BeSS Be Star Spectra has even been setup in collaboration with Paris Meudon observatory COROT satellite is another opportunity for such collaboration Amateurs can record spectra while the satellite will do precise photometry of some Be stars Correlation between photometric outburst and spectroscopic line profile changes could be further studied with the help of amateur astronomers with the help of you Be Stars Spectra BELE EE Lhires ITI User Guide English DC0004A 40 43 INSTRUMENTS 9 Troubleshooting Support For any issue with your Lhires III contact us at Phone 33 476 41 36 81 Mobile 33 689 92 74 23 eMail contactOshelyak com Web http www shelyak com Address Les Roussets 38420 Revel France You can also subscribe to the Spectro L internet list where you will find the support of other Lhires ITI users http groups yahoo
16. c doublet as the objective lens The image quality will allow you to obtain a resolving power of 17 000 only in the highest resolution option for Lhires III i e 2400 Ipm grating and a slit width of 25um over a linear 8mm field approximately Connection to the telescope is either by a standard 50 8mm 2 inch adapter or the regular screw adapter for Meade and Celestron SCT s Schmidt Cassegrain Telescopes Ideal input focal ratio is f 10 and the acceptable range is f 8 f 12 For amateurs with faster optical systems a Barlow lens can be employed to increase the f number but you should check that your telescope has sufficient back focus particularly if using a Newtonian reflector The adapter on the camera side is a Pentax type M42 T ring 42mm x 0 75 screw thread There is sufficient back focus with Lhires III so as to allow the use of a DSLR as the detector the T ring is obviously brand dependent as so is not supplied Adapters for the SBIG cameras are supplied with the basic kit as well as a 1 inch 31 75mm adapter for observing spectra with an eyepiece a low light level video camera or with a webcam such as the ToUcam for example Other camera adapters are available as an option The entrance slit to the spectrograph is highly polished and reflective and is inclined at 10 to the optical axis of the telescope The slit plays the role of a mirror for objects whose light is not actually passing through the jaws Light from this polished sur
17. camera IL Slit is OK Slit is not OK 3 4 Adjusting main mirror This adjustment is important for the quality of the spectra produced by your Lhires III You will turn the main mirror so that the light beam dispersed by the grating pass right beside the mirror If the angle is too small mirror will block some light and there will be a vignetting effect if the angle is too large the beam will be too far from the optical axis and spectra will be impacted by the doublet chromatism There are two steps a simple adjusting with naked eye and finetuning with your acquisition camera Simple adjusting e Materialize the center of the slit cf previous paragraph e Put an eye piece on the spectrograph for exemple a 25mm one Note you can perform this on the telescope pointing toward the sky but not the Sun directly or without a telescope and pointing the spectrograph alone toward the Sun e Position the grating angle so that you can vizualize the zero order of the spectra you should have noted this position during your first adjustments It should be around Omm on the micrometer e While looking through the eyepiece adjust the mirror angle screw at the bottom of the chassis so the center of the slit is at the center of the field of view INSTRUMENTS Lhires III User Guide English DCO004A 16 43 Finetuning e Replace the eyepiece with your CCD camera e run continuous exposures around 1sec eventually in binning 2x2 or
18. com group spectro l And regularly look on our website for announcement of technical week ends those are the best way to learn and develop yourself in this wide field that is spectrography Lhires ITI User Guide English DCO004A 41 43 INSTRUMENTS 10 References This is only a few of references that we find useful If you know others do not hesitate to drop us a note contact shelyak com so it can be added in further release of this user guide 10 1 Books Stars and their spectra James B Kaler Cambridge edition Excellent book that goes through the different spectral classes Foundations of Astronomy Michael A Seeds Brooks Cole edition This book talk about lot of astronomical subjects including some related to spectrography 10 2 Web links General Shelyak Instruments http www shelyak com This is our web site where you can find additional information on your Lhires III spectrograph more ideas for projects etc ARAS home page http www astrosurf com aras ARAS is an amateur professional group with objective to promote spectrography Spectro L list http groups yahoo com group spectro Christian Buil web site http www astrosurf org buil Christian s Spectro bookmark http astrosurf com buil us book2 htm CDS Strasbourg http http cdsweb u strasbg fr This is THE reference for any astronomical object Look for key information browse through hundreds of catalogs and link to profession
19. e slant orientation you will need O SPiris Version 1 20 c data shelyak lhires3 userguide ESFERA Fichier Edition Angle 1 393 in our example result if 1 393 e OK now ready to let the software do it all by itself LOAD your first image of Altair select the traitement des spectres Lhires III 2400 in the spectro menu Traitement des spectres LHIRES Ill 2400 Entr e Nom g n rique d entr e limg_altair Nombre d images 3 Pr traitement Carte Offset limg bias Carte Flat field limg_flat Carte Dark lima dark Fichier cosm tique cosme G om trie Angle de slant fi 393 Calibration spectrale M Calibration sur les raies telluriques H20 Position de la raie H20 4565754 1447 Coefficient ordre 2 Coefficient ordre 1 fc 00000 Sortie Nom g n rique altair niveaus Ob Oc 1b fill in all the required data in the processing window INSTRUMENTOS Lhires III User Guide English DCOOO4A OK Annuler 29 43 Check the output window you should get a result such as RMS 0 025604 lambda ref 6522 4277 Pas 0 11570 a2 3 2122e 006 al 0 11868 a0 6522 428 RMS should be as small as possible and indicates the precision you can expect from your spectrum Here it s 0 025A so around 1km sec RMS A c RMS 6563 300000 Pas is the dispersion of the spectrograph with your imaging camera SpIRIS calculated from the tel
20. e chip We will then check that zero order close to Omm and red portion of the spectra around 25mm will be at the same position To correct the position you have to do the following e Dismantle the grating support Adjust the grating as parallel as possible with the support edge or rotate depending on your measurement of the shift Re mount the grating support and control it again After few iterations and some practice you will obtain a perfect tuning Eventually you can now readjust main mirror to put the slit centered on your capteur Bravo all adjusting have been completed now Those adjusting have to be done once for all you will have to do them again if you change the mechanical parts of the instrument or if you change the grating You can now do your first spectra of a star Before do not forget to remove the papers that marked the center of the slit in telyak Lhires III User Guide English DC0004A 18 43 4 Taking your first spectra 4 1 Reference lamp s spectra A good way to get acquainted with your spectrograph is to do some spectra during daylight and inside your home After having set up the acquisition camera you can first take a spectrum of the Neon lamp inside the Lhires III Connect a 12V power supply to the spectrograph input connector switch it on and turn the knob so the Neon lamp is upfront the slit Turn the micrometer so you are in the green area where there is a very bright Ne
21. e focus Then point and center a reference stars such as Altair Castor whose spectra can be found on the UVES database http www sc eso org santiago uvespop bright stars uptonow html see also VisualSpec tutorial http www astrosurf com vdesnoux tutorial8 html Take 3 spectra of Neon switch it off turn the Neon knob Take several bias in 3x3 binning to empty the CCD and remove any remaining trace of Neon Take several spectra of the reference star long exposure of 5min or 10min for example Take 3 spectra of Neon switch it off turn the Neon knob Point and center your first target Take 3 spectra of Neon switch it off turn the Neon knob Take several bias in 3x3 binning to empty the CCD and remove any remaining trace of Neon Take several spectra of the target long exposure of 5min or 10min for example Take 3 spectra of Neon switch it off turn the Neon knob Then repeat this sequence for every target At the end of your session you can record the calibration frames dark frame for spectra images dark frame for Neon spectra bias frame flat field frame A flat field frame in spectrography is done by taking a spectrum of a hallogen whose spectrum is a continuuous one without any absorption line Reason why we take Neon calibration before and after each sequence is because the spectrograph is not stable over temperature and flexion You can check with the two Neon spectra series by how much the wavelength calibration ch
22. ectres LHIRES Ill libre Entr e Mom g n nque d entr e img betaur Nombre d images 3 Fretraitement Carte Offset limg bias Carte Flat field limg flat Carte Dark lima dark Fichier cosm tique cosme G om trie Angle de slant 11 393 Calibration spectrale M Faire la calibration spectrale Longueur d onde de la raie de calibration 6598 95 Position en pixels de la raie de calibration 1657 Spectre du n on img_betaurneon Coefficient ordre 3 0 0000e 000 R seau Coefficient ordre 2 3 2122e D06 1200 traits mm Coefficient ordre 1 10 1 1868 Sorti Mom g n rique beta auriga niveaus Ob Oc 1b Annuler f 2400 traits mm You get again three files for beta auriga The beta auriga 1b DAT file can be opened in VisualSpec 6530 6540 6550 6560 65 0 5580 6590 6600 You notice the telluric lines and of course two absorption lines around Ha This is because b ta Auriga is a spectroscopic binary star Note that before sharing your spectra you need to correct it from the response curve impact of the telescope spectrograph and imaging camera See VisualSpec manual on how to do it We recommend that you subscribe to the Spectro L distribution list to share your first spectra http groups yahoo com group spectro l You will benefit from the support of other spectroscopists and you can get there ideas of new spectrographic projects INSTRUMENTS er Lhires III User Guide
23. emits a light made of few radiations characteristics of the atoms that constitutes this gaz Each chemical element has its own line spectra true identity card of its composition and state An important property of those absoprtion and emission spectra is that lines are emitted at the same wavelength that they are absorbed 7 3 Message from light Spectroscopy was extended to the study of stars and nebulae in which new elements were discovered Sir Norman Lockyer and Jule Janssen discovered in 1868 during a solar eclipse a new element which has been isolated on Earth in 1895 Helium Johann Balmer developed an empiric formula in 1885 for the position of hydrogen emission line Ha Hb Hg This formula was extended to other elements by Johannes Rydberg But it s Niels Bohr who brought in 1820 a theory to the spectral line process The Bohr model is based on quantum theory and electronic clouds around atomic nucleus Astronomy faced a revolution an evolution toward Astrophysics The language of light was just decrypted Coded light is rich of lof of information e on effective temperature at the surface Wien law e on radial rotation and expansion movement Doppler effect e on stellar density and pressure e on chemical composition Lhires ITI User Guide English DCO004A 34 43 INSTRUMENTS 7 4 Effective temperature and spectral types Stars are almost like black bodies They emit energy at all wavelengths wi
24. f 200mm to 300mm diameter and an S N of 100 can be obtained The spectrograph can be connected to most other standard types of telescope including refractors and Newtonians provided that these instruments are slower than f 8 in order to collect all the light and maintain throughput Several type of reflection gratings are available allowing the user to vary at will the trade off between spectral resolution and the limiting magnitude attainable The nominal configuration for Lhires III is based on a holographic grating with 2400 grooves per mm A 1 as Grating holder can be switched very quickly on a Lhire III spectrograph Oo INSTRUMENTS Lhires III User Guide English DCO004A 5 43 LHIRES is an acronym for Littrow High REsolution Spectrograph A Littrow mounted spectrograph is one where the same optical component in this case a 200mm lens acts as both the collimator to render the light beam parallel and the focusing or imaging lens to bring a focused image of the spectrum onto the detector This design eliminates the need for separate lenses for the collimating and focusing compared to classical spectrograph mountings such as the Czerny Turner or Ebert configurations Lhires III is therefore compact and economical to produce The weight of Lhires III is less than 1 6 kg Inside the Lhires III The usable field where the spectrum is obtained has been deliberately restricted in order to allow the use of a simple achromati
25. face is reflected back to a guide camera not supplied via a 1 inch 31 75mm adapter ring Alternatively it is possible to employ a webcam video camera of a second CCD camera for automatic guiding Lhires ITI User Guide English DCO004A 6 43 INSTRUM ENTS Images from the guiding camera here a Watec 120N The entrance slit is just perceptible as a darker horizontal line against the slighter brighter sky background On the left the star is not on the slit On the right it is correctly positioned on the slit The star s intensity has been strongly reduced since most of the light is now passing through the spectrograph where it should go An algorithm in IRIS software has been developed for guiding on the halo blurred image of a star virtual slit algorithm The spectrograph employs a fixed mirror slit However it can be removed and its width can be varied Additional slits are also available as option so it would be more convinient if you need to often change the width Focused light from the telescope passing through the slit meets the flat 45 mirror and is sent the collimator lens focal length 200mm 30mm diam The collimated beam then passes to the plane reflection grating that is mounted on a pivoting support Varying the spectral range of the spectrograph is achieved by rotation of the grating by adjusting a precise micrometer screw The grating is interchangeable The standard type has 2400 grooves per mm
26. his is the Hertzsprung Russell diagram 7 6 Chemical composition and metallicity Two stars of same class and same type have a different history a different genealogy We note Z the metallicity or the ratio of atom different than hydrogen and helium One can position each star on a 3 dimension HR Z diagram temperature luminosity and metallicity We classify sars in two populations 1 Population I stars rich in metal ie non hydrogen or helium atoms often second or third generation stars Part of their matter has been created during the explosion of a supernova Our Sun and matter that constitutes us is a good exemple 2 Population II stars poor in metal very old We can find them typically in globular clusters gt helyak MENTS Lhires ITI User Guide English DCOOO4A 35 43 7 7 Doppler Effect Doppler effect explained by Christian Doppler in 1842 is a wavelength shift between emitted light and received light when object and observer are moving from each other If they approach themselves shift is toward blue if they are moving away it is toward the red such as the redshift of galaxies Doppler effect allows to measure radial velocity rotational speed and expansion speed It is the key to study binary systems and it has been the key of the discovery of the first exoplanet in 1995 Line profiles are also modified by wave movement at the surface of stars Asterosismology allow to better understand the inter
27. ll depend on your mount But IRIS software includes a special algorythm to guide on a mirror slit Refere to IRIS website for more details Lhires ITI User Guide English DCO004A 26 43 INSTRUMENTS 5 4 Taking flat field As mentionned flat field are slightly different in spectrography Do not try to do it on the skylight as you will then record a spectrum of our Sun Instead take it during the night with an hallogen lamp Use a paper in front of your telescope to diffuse the light as shown in the picture below It is also possible to take the flat field without the telescope Make a hole the size of your f ratio of your telescope In the example below the mask is 140mm in front of the slit and we used a f 10 telescope the size of the mask is then 14mm The hole is filled with a paper to diffuse the light When taking the flat field frame make sure the spectrograph doesn t allow light to get in Cover it with a black tissue if needed Lhires ITI User Guide English DCO004A 27 43 INSTRU MENTES 6 Extracting a calibrated 1D spectrum We will follow here the exemple of SpIRIS software that is provided on our CD ROM But similar technic would work with other softwares that include special function to process spectra AudeLA SpcAudace PRISM Prepare all files you will need O master pre processing files Use individual files and apply a median SMEDIAN to get a single master frame Do it for Bias
28. luric lines in the Altair spectrum the polynomial parameters of the calibration function of the Lhires III a2 al and a0 Now you should have three files in your working directory altair_Ob FIT 2D spectrum of Altair sum of all single frames and corrected from geometrical distorsions altair_Oc FIT 1D spectrum of altair but still in image format and expanded on the Y axis to better allow to see it CC Tr TO I NT 1 nt 6530 6540 6550 6560 65 0 6560 6590 6600 altair_1b DAT this is the spectrum calibrated with the telluric lines You can now load it in VisualSpec software and display the wavelength You can now extract spectra of your target which may be too faint to use those telluric lines SpIRIS will use the Neon calibration spectrum AND the polynomial parameters that were found with your reference spectrum LOAD your neon spectrum for your target star O measure which column is one neon line at the horizontal position of your spectrum In our exemple we will use the line on the right 6598 95A neon line that we measured at column 657 LOAD the first image of your target spectrum serie select a frame around the spectrum select the traitement des spectres Lhires III libre in the spectro menu o fill in the parameters _ my helyak ir Lhires III User Guide English DC0004A 30 43 my helyak ir Lhires III User Guide English DC0004A 31 43 Traitemement des sp
29. nal structure of stars Even if one can t see the star surface visually their light brings us a message full of learning 7 8 Conclusion Spectrography is like archeology or a criminal case study With clues included in spectra the astrophysist tries to go back to the root of the phenomena Almost all professional observations are done today in spectrography Large telescope are equiped with powerful spectrographs to analyse large spectral domain and several targets at once But now spectrography is evolving within the amateur astronomy community High resolution spectrography the message from the stars is now accessible to you with your Lhires III lt SSshelyak ir Lhires III User Guide English DC0004A 36 43 8 Applications There are a lot of projects that can be done with such spectrograph as the Lhires III specially as you can change to several resolution We only gives some exemples here and we recommend you subscribe to the Spectro L mailing list where new projects are described by other Lhires III owners Check also our web site http www shelyak com where those projects are documented 8 1 Spectro Heliography Spectro heliography was so far reserved to home improvement people building their own instrument With the Lhires III and a small video camera or webcam it is now possible to record video of spectra while scanning the solar surface After some processing the solar image can be rebuilt As y
30. ng in spectroscopy can be impressive since there are several elements to put under control But thanks to this guide you will see that none of them is very complex and just some rigour is required to make things working together We hope that you will enjoy spectroscopy with Lhires III Join the increasing Lhires III s users and amateur spectroscopist community on Spectro L http groups yahoo com group spectro l to keep us informed of your progress and results But most importantly enjoy spectrography Olivier Thizy olivier thizy shelyak com Fran ois Cochard francois cochard shelyak com Lhires ITI User Guide English DCO004A 4 43 INSTRUM ENTS 2 Overview of the Lhires III 2 1 The Basic Elements Lhires III is a spectrograph optimized for high resolution spectroscopy with amateur sized telescopes The resolving power expressed as MAA is around 17 000 in the red and is therefore capable of resolving spectral details smaller than 0 4 Angstrom units in the vicinity of the hydrogen H alpha line A neon calibration lamp is also integrated in the spectrograph for reference emission line comparison e Telescope entrance micrometer to set wavelength gt Guiding hole Access to the mirror slit Access door to focus doublet Neon lamp knob Gel Spectrum imaging hole Lhires III spectrograph With a 1 hour exposure the spectra of stars down to visual magnitude 6 to 8 with the popular SCTs o
31. on emission line Check you have proper focus and adjust he doublet if necessary Take a spectrum with enough dynamic but be careful not to to saturate Your acquisition software may have a statistic command or status so you can check the maximum level while taking the spectrum Turn the Neon lamp off and remove it from the slit entrance by turning the Neon lamp knob Try several lamps you have at home and take spectra of them Try an energy saving lamp where you Should see two green emission lines in that area otherwise turn the micrometer to see them and redo a Neon lamp calibration spectrum Those are Mercury Hg element lamp and you can also see a very bright yellow line and two lines around blue violet Those spectra are a good practice to extract the profile and calibrate in VisualSpec Refere to this software manual for more details 4 2 Solar spectra Ideally with a SLR camera using the proper T ring adapter or with a CCD camera point the Lhires III spectrograph toward the sun Do not mount it on a telescope and put a blurry transparent paper in front of the spectrograph to diffuse the light in Caution looking the sun through a telescope can cause pemanent dammage to your eyes Do not look the sun directly through a telescope nor with the spectrograph at the zero order where the grating acts like a mirror In low resolution mode look at the blue or cloudy sky instead of the sun directly Take images of the spectra and adjust
32. ou can position the grating to any wavelength you want in the visible range you have not one but thousands filters available to you Select the area you want to look at Hydrogen Calcium Helium Iron Magnesium each will show you something different White ligth Video recording take a range around the selected wavelength By substracting the images you can see the solar surface shifting with Doppler effect map the speed field and study the complex solar surface Halpha 0 36 A Dopplergram Fe lines Check our web site for some references about spectro heliography This technic is powerful but complex to implement INSTRUMENTS Lhires III User Guide English DCO004A 37 43 8 2 Jupiter or Saturn rotation Planet rotation is a very easy project which can be done with a Lhires III spectrograph A single spectra will unveil the tilted line by the Doppler effect Measure the tilt dX as shown Calculate your dispersion D gt using a Neon spectrum for exemple and calculate dA D dX In the exemple above we found dX 8 and D 0 115A pixel so dA 0 92A Doppler formula is dA A v c so you can measure the linear radial velocity v c dA A The exemple above is around Ha so A 6563A and v 300000 0 92 6563 42km s patel yak Lhires ITI User Guide English DCO004A 38 43 The actual speed of Jupiter edge is a of this calculated speed e 1 because you measure both sides together shown as blue
33. ra This section describes the operations to do at every observation 5 1 Operation to be done during daylight As often is spectro a part of the preparation operations can be done during daylight it s even preferable We consider that your telescope is ready and you CCD camera as well Mounting the Lhires III on the telescope Be sure that the instrument is strongly attached to the telescope using the 2 50 8mm or SCT adapter Secure it so it can t slide down Check the total weight capacity of your mount if needed Position the spectro in order to have the slit parallel to the RA movement if you don t know it yet you ll make that later And of course balance your setup very carefully Focusing the guiding camera e Point the telescope to the sky not to the sun e Slide the guiding camera up to have a focused image of the slit Turn the camera to have the slit horizontal e Move the camera and tighten it in order to have the slit center in the center of the image lt _ my helyak Lhires III User Guide English DC0004A 21 43 Focusing the telescope e Point the telescope to the horizon line our exemple here is Chamrousse ski ressort in the French Alps e Focus the telescope up to get an accurate picture of the horizon trees moutains Note during this adjustment the slit remains focused so do not touch the guiding camera focus Focusing the acquisition CCD camera e Mount your imaging c
34. red sides in the previous picture e because the Doppler effect happens twice on a planet 1 when the solar light hits Jupiter 2 when the reflected light leaves Jupiter surface So the actual speed is V 10 5km s Knowing that Jupiter rotates in P 9 92 hours 357005 you can calculate the diameter of the planet Diam V P n 10 5 35700 3 14 120 000 km Book gives 140 000 km so our measure is close We could improve it by improving the telescope tracking and by ensuring the slit is exactly at Jupiter s equator Give it a try Same method can also be used on Saturn and on the rings 8 3 Radial velocity Stars are moving into space and their spectra appear shifted compared to the same lines in laboratory Exemple here is SAO104807 which is moving toward us at a speed of 100km Sec and SAP112958 which is moving away at the spedd of 99km sec With the Lhires III high resolution you even have to correct from the Earth movement to do a proper calculation Shift in the spectra of those two stars taken with a Celestron 11 and a Lhires III is easily visible compared to Alair spectra This is an easy and highly educational project 6545 6550 6555 6560 6565 65 0 6575 6580 Lhires III User Guide English DCO004A 39 43 INSTRUMENTS 8 4 Be Stars Be stars are hot B stars which shows or has shown emission line in its spectra they are much more luminous and more massive than our Sun They also have high rot
35. rs http astrosurf com aras papers c s stars htm c INSTRUMENTS Lhires III User Guide English DCO004A 43 43
36. s about 20 turns and hundreds of absorption lines How great is spectro isnt it e Then to complete this color trip look for the zero order around position O of the micrometer You ll see a single line very bright it s better to point slightly beside the sun In this position the grating works as a mirror and what you see is the image onf the slit Record precisely the micrometer position for each recognized wavelength Note If the weather is bad you also can do all this step with the neon lamp In this case prevent any parasit from daylight See the image of the neon spectrum Note lines are curved and it s normal This is because we work in 3D and not in a 2D plan We are working slightly off axis thus a line deformation 3 3 Adjusting guiding mirror The guiding mirror is made to redirect skyfield to the guiding camera This adjustment have no effect on the spectrum quality but it facilitates the guiding even autoguiding of the telescop during the acquisition The adjutment can be made in two steps Rough adjustment In a first time it can be adjusted roughly with the same kind of method used to tune the collimation of a telescope Just put the Lhires III on a table and look at it from the top your eye takes place of the telescope When the position is OK you should see the guiding camera lens picture and the slit black line well centered in the spectro You can adjust the position of the mirror by turning the 4
37. th a continuous spectra Its shape is a Planck curve whose maximum is directly linked to the effective temperature of the surface stellar atmosphere this is the Wien law 10000K KAREN 3000K 3000K 5500 6500 7500 8500 Continuous spectra of several black bodies Our Sun has an effective surface temperature around 6000K visible stars to us have temperature between 3000K and 30000K Stars are classified based on their temperature with historical letters O B A F G K M Stars with O type are the hottest while M type are the coolest We memorize this sequence with the famous Oh Be A Fine Girl Guy Kiss Me Types R S and N have been added later one Right Now Sweetheart Annie Jump Cannon was one of the most famous assistant of Edward Charles Pickering in Harvard She was an expert in stellar classification For the Henry Drapper catalog she classified more than 300000 stars an example of productivity 7 5 Spectral class If the spectral type is a characteristic of the surface temperature a more precise classification should take into account their luminosity In Yerkes William Morgan Philip Keenan and Edith Kellman MMK established a classification I to V which takes into account the shape of some absoprtion lines characteristics of gravity forces Class I stars are super giants while class V like the Sun are sub giants stars Astrophysists position stars on a graph based on their temperature and luminosity T
38. you put the spectrograph on a telescope then point the blue sky or a cloud to see the solar spectra do not look directly toward focused solar spectrum INSTRUMENTOS pohelyak Lhires ITI User Guide English DCO004A 13 43 Put the eye piece mount and an eyepiece on the spectro Adjust the micrmeter to about 20mm Adjust the main mirror to the middle position screws M4 on the bottom face of the Lhires III e Open a side door and put the collimation lens holder at medium position e Choose a sunny day or find a powerful light but for sure the sun is much better e Point the spectro towards the sun the slit must receive direct light from sun e Then you should be able to see your first high resolution spectrum of the sun This is a large band whose color depends ont the region you r looking at At this stage you can focus the collimation lens Then you ll see a lot of absorbing lines across the spectrum e It s possible that you also see deep black lines in the direction of the spectrum dispersion This very probably the effect of dust in the slit or small defects on the slit edge e Move the grating angle by turning the micrometer to explore the full solar spectrum You ll should recognize major lines such as Ha 6563 A in my case micrometer position is 21 64mm sodium doublet in may case 19 38mm and so on The full spectrum goes roughly from 13 5mm deep purple to 23 5mm dark red which make
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