CCDSPEC User Guide - Elliott Instruments
Contents
1. Cancel Then select which operation you require eg ROI1 ROI2 and press the Set button and the graph will now show the sky subtracted spectrum 16 4 Accurate Measurement of Spectral Lines You can get rough values of the positions of spectral lines by simply putting the cursor on the line and finding the position of the maximum intensity However PCSpectra allows you to measure the position of the line much more accurately by using the centroid method and an example is given here First of all use the mouse and cursor to draw a box ROI around the spectral line of interest and use the Analysis gt SPECTRUM X Axis Projection to get a graph of the intensity of the line File name ic418long fit Mean Intensity Roll 1380 1360 1340 1320 1300 T 850 860 870 880 930 300 Pixel Choose a lower threshold clear of the noise in this case at say 1320 and enter this in the Analysis Set Data Thresholds switch on the lower threshold and press Set m Data Thresholds Lower Threshold Upper Threshold On Minimum hd 1093 26232 Value Value 1320 26232 Cancel Now select Analysis Centroid and Area Measurement and the centre of the line will be displayed m Centroid and Area Centroid Bra rz NE Ade r2 Wavelength No Cal Area Pirels dbz The X value is the centroid of the spectral line and can be as accurate as 0 01 pixels if the data is2. Wave Angstrom 5545 5545 15 5577 34 5666 64 5679 56 5686 21 5710 76 5754 64 5875 64 5978 83 6046 44 6300 3 6312 1 6347 11 6363 78 6371 36 6461 95 6462 13 6548 03 6562 82 6578 05 6583 41 6678 15 6716 47 6730 85 7002 23 7065 28 7111 47 7113 18 7115 17 Ident N N O N Il N II N II N II N II He Si 11 O O I S 111 Si 11 O I Si 11 C II C II N II HI C II N II He S II S II O He C C C 4650 84 4658 1 4661 63 4701 53 4711 37 4713 14 4733 91 4754 69 4769 43 4814 55 4815 51 4861 33 4881 4921 93 4958 91 9006 84 9015 68 9032 43 5041 03 9047 74 9055 98 9056 31 9158 78 2197 9 9200 26 5270 4 9517 71 5537 88 O Fe Ill O Fe Ill Ar IV He Fe Ill Fe Ill Fe Ill Fe S Il HI Fe Ill He O III O III He S 11 Si 11 He Si 11 Si II Fe N I N I Fe Ill CI II CI II 10 Angstr m 1nm 7116 99 7135 78 7155 14 7231 12 7236 19 7254 38 7281 35 7298 05 7318 39 7319 99 7329 66 7330 73 7377 83 7423 64 7442 3 7452 54 7468 31 7499 85 7751 1 7171 94 7782 18 7801 79 7816 13 7837 85 7862 85 7875 99 7959 7 Ar III Fe C II C II O He He O II O II O II O II Ni II Fe N He Ar 11 O V He Co Fe 11 P 11 N 15 2 Calibration Spectra and Line Identifications 300
3. ELLIOTT INSTRUMENTS LTD CCDSPEC User Guide Version 2 2 February 2015 10 11 12 13 14 15 16 17 Contents Introduction Unpacking and checking Getting to know your CCDSPEC Fitting your CCD camera to CCDSPEC Initial alignment of your CCD camera on CCDSPEC Focussing the CCDSPEC Taking Your First Astronomical Spectrum Looking at your first results Plotting your first spectrum Wavelength Calibration Optical Design Specification Amateur Spectroscopy What can amateurs achieve Astronomy Resources lists of possible target objects Spectroscopy Resources Spectra and Wavelength identifications and worksheets Introduction to PCSpectra Software Internet Resources 1 Introduction Elliott Instruments CCDSPEC has been specially designed for amateur astronomers and small observatories to take spectra of astronomical objects from stars and nebulae to the red shifts of galaxies and supernovae The instrument can be used with most astronomical CCD cameras so this is ideal for those amateurs who already have their own CCD camera CCDSPEC has a slit viewing port to enable the star or galaxy to be placed on the slit and to allow guiding for long exposures which are typically needed for faint objects Guiding can be either manual via an eyepiece or by an auto guider attached to the slit viewing port The instrument is essentially Plug and Play apart from focussing as the slit and
4. 15 12 NGC2867 11 37 14 10 NGC6818 11 25 20 6 NGC2440 11 41 17 6 NGC7009 10 98 28 5 6 NGC3918 11 35 19 5 NGC6326 11 75 12 5 5 14 4 Selected Active Galaxies Name Type V mag Z M77 NGC1068 Seyfert 2 10 5 0 003 NGC 4151 Seyfert 1 12 0 003 AGN with NGC4261 SMBH 11 4 0 007 36273 QSO 12 8 0 158 Mrk 79 Seyfert 1 13 4 0 02 NCC 1052 LINER 13 5 0 005 OJ 287 BL Lac 14 BL Lac BL Lac 14 5 0 069 30120 Radio Galaxy 14 6 0 033 15 1 Astronomical Spectral Line Identifications Fraunhofer Lines Element Wavelength nm Fe 302 108 Ti 336 112 Fe 358 121 Fe 382 044 393 368 396 847 Hd 410 175 Ca 430 774 Fe 430 79 Hy 434 047 Fe Fe Fe Mg Fe Fe Mg Fe Hg He Na Na O2 Ha O2 O2 O2 O2 O2 is in Earth s Atmosphere 438 355 466 814 486 134 495 761 516 733 516 891 516 891 517 27 518 362 527 039 546 073 587 562 588 995 589 592 627 661 656 281 686 719 199 37 822 696 898 765 Nebular Emission Lines Wave Angstrom 4009 22 4026 08 4026 21 4068 6 4076 35 4101 74 4120 82 4143 76 4267 15 4303 61 4303 82 4319 63 4326 4 4340 47 4345 56 4363 21 4368 25 4387 93 4437 55 4471 48 4562 6 4571 1 4607 06 4607 16 4621 39 4630 54 4638 86 4641 81 4643 06 4649 13 Ident He N II He 5 II S II C II O O Il O Il O III OI He He He Mg Mg Fe Ill N II N II N II O O N Il O
5. 165688 165 63 168206 190918 191765 192103 192163 192641 193077 1935 6 193793 193928 211853 214419 RA 2 41 11 6 6 54 13 0 18 07 57 0 18 08 28 5 18 19 07 4 20 05 57 3 20 10 14 2 20 11 53 5 20 12 06 5 20 14 31 8 20 17 00 0 20 19 32 4 20 20 28 1 20 21 31 8 22 18 45 6 22 36 54 0 Spectral Type O9 5 O9 5 B1 B7 B7 B8 A0 A1 A2 A5 F2 F5 F8 G2 G8 KO KO K2 K5 MO M2 M6 Dec 56 43 50 23 55 42 19 23 56 21 15 11 11 37 58 35 47 17 36 10 35 36 11 51 38 21 17 36 39 39 37 25 23 38 43 54 43 5117 36 55 13 56 07 35 56 54 21 V Mag 1 79 2 1 9 0 96 1 65 1 35 0 1 1 0 04 1 45 1 25 2 07 2 26 0 35 2 0 3 1 0 08 1 1 5 1 79 0 6 0 85 2 06 0 WC5 WN5 WN6 WC5 WC8 WN4 WN6 WC8 WN6 WC7 WN5 WN5 WC7 WN6 WN6 WN7 8 2 V mag 9 98 6 74 9 81 7 68 9 18 6 78 8 02 8 51 7 44 7 95 8 06 8 27 6 88 9 74 9 03 8 86 Selected P Cyg Stars Name HD 12953 HD 21389 HD 31964 HD 174638 HD 190603 HD 193237 HD 197345 HD 198478 HD 223385 P CYG 14 2 Selected Diffuse Nebulae Name Crab Nebula Orion Nebula Tarantula Nebula Hosette Nebula Carina Nebula Trifid Nebula Lagoon Nebula M16 M17 Cygnus Loop N America Nebula Crescent Nebula Bubble Nebula 14 3 Selected Nebulae Planetary Nebulae listed by surface brightness Name SwST 1 Hb 12 4997 Fg3 Hu 2 1 NGC6644 NG
6. corresponding wavelength scale in nm This process is called wavelength calibration 10 Wavelength Calibration To obtain a graph of spectral brightness against wavelength in nm we need to determine the relationship between the pixel number and the wavelength and this is what wavelength calibration is all about For wavelength calibration your CCDSPEC needs to be mounted on your telescope so the light passes through the telescope optics into the spectrograph To illuminate the telescope beam evenly this is best done by putting a diffuser over the telescope aperture as in Figure 19 and illuminating this with the calibration lamp or by illuminating the inside of the dome or a white card with the calibration lamp and pointing the telescope at the reflected light Using the reflected light method with a calibration lamp that isn t very bright may involve taking a long exposure Figure 19 A tracing paper diffuser on the telescope illuminated by a calibration lamp To obtain an accurate wavelength calibration a number of emission lines of known wavelength and well spaced along the spectrum is needed The spectrum of Helium is ideal for this but other lamps can be used too Examples of various calibration lamps and their wavelength identifications are shown in the section 15 of this manual Take a spectrum of your calibration lamp This can be a cold cathode lamp a camping fluorescent lamp or even a mercury or sodium streetlight observe
7. dispersion are fixed and the input aperture is M42x0 75 T2 mount output is T2 mount or C mount The CCDSPEC is supplied with PCSpectra software for analysis and display of your data 2 Unpacking and checking Please check that all items are present CCDSPEC M42 T mount to C Mount Camera adapter 1 25 Telescope adapter 2 Allen Keys 1 5mm 2 5mm CCDSPEC User Guide PCSpectra User Guide CCDSPEC CD ROM 3 Getting to know your CCDSPEC Most of the CCDSPEC components are pre aligned and locked in place and should need no adjustment There are mounts for telescope CCD Camera and eyepiece or auto guider focus door port slit viewing port Figure 1 Side view of CCDSPEC Figure 2 Camera end of CCSPEC The telescope end of CCDSPEC has an M42 T mount thread which can receive any telescope adapter but is shown here with a standard 1 25 adapter The slit viewing port takes any 1 25 eyepiece or 1 25 auto guider The Focus Port Door gives access to the focus scale drum to allow exact focussing of the spectrum on to your CCD Camera 4 Fitting your CCD camera to CCDSPEC Figure 3 Fitting the T mount adapter Figure 4 Locking the 4 retaining screws The CCD camera is mounted via an M42 T mount to C mount adapter Figure3 The C mount is screwed on to the CCDSPEC camera lens and then the T mount is screwed into the CCD camera Figure 5 Focus Port with door removed 5 INITIAL ALIGNMENT OF CCDSPEC Illuminate
8. the slit with a spectral calibration light which can be a fluorescent lamp or energy saving lamp which will contain mercury and other elements and will show an emission line spectrum To make sure the slit is evenly illuminated it helps if you place a diffuser over the eyepiece mount Scotch Tape or tracing paper cut to size are perfect for this as shown in the Figure 6 Figure 6 Diffuser on eyepiece mount Switch on your CCD camera and operate it in focussing mode where you can see an image several times a second The CCD display should now show a spectrum which probably out of focus and at some random angle see Figure 7 Figure 7 A spectrum before alignment Remove the Focus Port Door using the 2 5 mm Allen key and rotate the exposed focus vernier drum Figure 5 until the emission lines are approximately focussed Now rotate the CCD camera and the M42 mount in the V groove until the emission lines are exactly lined up so they are parallel to pixels on the CCD It is conventional to have wavelength increasing left to right with pixel number The PC Spectra Software assumes that wavelength increases with pixel number Users of ATIK Artemis software need to select the Camera gt Rotate 180 option for consistency To establish which way round the spectrum is oriented you will need to be able to recognise a spectrum This is most easily done by pointing the CCSDSPEC at sources of light found in the home Da
9. 250 200 150 100 90 350 Helium Wavelength Identifications 400 450 e uo m oo Lo I 900 990 600 Wavelength nm Wavelength nm Figure 31 Helium Calibration Spectrum dL aaa 45 13 f06 52 650 700 150 List of principal wavelengths found in spectral lamps Wave nm Ident 366 33 Hg 388 87 He 404 66 Hg 407 78 Hg 407 78 Hg 410 12 H 434 01 H 435 84 Hg 447 14 He 471 31 He 486 07 H 492 19 He 501 57 He 546 07 Hg 576 96 Hg 579 07 Hg 587 56 He 588 99 Na 589 59 Na 623 44 Hg 656 21 667 81 He 690 75 Hg 706 52 He 728 13 He 15 3 Calibration Wavelength Worksheets CCDSPEC HELIUM CALIBRATION WORKSHEET pixel Helium Wavelengths nm colour 388 87 UV 496 45 447 15 blue 554 81 471 31 blue 604 99 492 19 green 627 5 501 57 green 833 67 587 56 yellow 1029 21 667 81 red 1125 8 706 52 IR 728 13 IR Helium Spectrum pixels CCDSPEC MERCURY CALIBRATION WORKSHEET pixel Mercury Wavelengths nm colour 429 404 66 blue 505 435 83 blue 546 07 green 846 576 96 yellow 851 579 07 yellow pixels pixels 16 An Introduction to PCSpectra Software 16 1 Installation of PCSpectra Software Insert the CCDSPEC CD ROM into your drive and open the folder PCSpectra and run the installation program by double clicking on setup exe and follow the instructions When installed the PCSpectra application can be run by selecting Start gt All Programs gt PCSpectra gt PCSpe
10. C6572 He2 131 IC418 NGC5315 IC4191 BD 30 3639 IC4776 NGC7027 IC4364 NGC6578 NGC6790 RA 2000 0 02 08 40 6 03 29 54 7 05 01 58 1 18 50 04 8 20 04 36 2 20 17 47 2 20 41 25 9 20 48 56 3 23 48 50 2 Type SNR HII Region HII Region HII Region HII Region HII Region HII Region HII Region HII Region SNR HII Region WR Nebula WR Nebula Log HB FI ux 10 33 10 91 10 81 10 9 10 75 10 88 9 72 10 34 9 9 10 6 11 02 10 68 10 69 10 3 10 82 11 53 11 05 Dec 2000 0 Sp 58 25 25 58 52 43 43 49 24 33 21 45 6 32 13 06 9 38 01 58 5 45 16 49 2 46 06 50 9 62 12 52 2 NGC 1952 1976 2070 2237 3372 6415 6523 661 6618 6960 7000 6888 7635 Diam arcsec 1 5 1 1 6 2 2 6 2 6 11 6 12 6 5 res 7 5 14 8 4 4 7 A2 AO F2 B2 1 2 B2 A3 Surface brightness 10000 9918 2910 1513 1265 938 157 610 420 335 183 178 174 123 103 88 87 V mag 5 9 4 8 3 4 3 4 7 4 9 1 3 4 9 5 6 NGC6803 11 32 5 5 76 NGC6884 11 26 6 73 2003 11 8 7 63 NGC6886 11 43 59 NGC6543 10 35 19 5 56 2553 11 05 9 52 NGC6575 11 22 7 6 50 NGC6439 11 62 5 46 NGC6879 11 7 5 38 5873 11 41 7 38 5217 11 47 6 6 37 351 11 48 7 32 4699 11 79 5 31 4593 10 98 13 29 NGC6210 10 83 16 27 2448 11 34 9 27 NGC5882 11 08 14 20 NGC6826 10 58 25 20 NGC6741 11 57 8 20 IC3568 11 39 10 19 NGC6620 11 78 8 12 NGC6891 11 25
11. RUM X Axis Projection option as below m SPECTRUM X Axis Projection File name ic418long fit Mean Intensity Hal 1 500 550 600 Wavelength nm Wavelength 5581 Mean Intensity 13505 Close From the file option on the Analysis gt SPECTRUM X Axis Projection the graph can be printed or can be saved as a bitmap or the values in the graph can be saved as a CSV file for further analysis eg by a spreadsheet m SPECTRUM X Axis Projection Display Print Ctrl F Exil Values If you wish to subtract the light pollution lines you can select two regions of interest ROI and subtract one from another First draw the first ROI with the mouse Now pressing the shift key select the second ROI which will have the same dimensions as the first but displaced along the slit as below Regions of Interest Coordinates SPECTRUM X Axis Projection Region af Interest 1 Units Bottom Left Pixel i n 4292 Y 450 File name ic418long fit Mean Intensity Roll Aol 2000 f Wavelength Top Right cogi Operation Hal Rol 2 1500 Region of Interest 2 FESSES 1000 Bottom Left 4282 T S Projections 500 Right Display Mean d B 450 500 LE quu 4 1 550 Bn 650 Wavelength nm Wavelength 666 1 Mean Intensity 22 8 Close Display Sum Close
12. Start PCSpectra and use the File gt Open to open your CCD image which was saved as a fits file ANDY RAY DEVELOPMENTS Ns y P PCSpectra xT Wwawelengh Greyscale Intensi ity Figure 17 The start page of PC Spectra The program will display your CCD image of the spectrum and you can use the Image Set Display Thresholds to adjust the contrast and brightness of the image on the display This does not change any of your data Now using the mouse draw a box around the spectrum you wish to see plotted as a graph and then from the Image Analysis menu select SPECTRUM X axis projection and the program will draw a graph of your spectrum as below File name Fit Mean Intensity Roll 4500 4000 3500 3000 215900 2000 1500 FOO But 300 1000 1100 1200 1300 Pixel Piet Mean Intensity Close Figure 18 The image and graph of the spectrum of a carbon star The graph can be sent to a printer saved as a bit map image or you can export the values of the graph as a csv file so you can use it in a spreadsheet or other program for further analysis Now the graph you have at this stage is a plot of spectral brightness versus pixel value on the CCD If you want to identify the features in the spectrum so you can determine which atoms and or molecules are making the absorption emission lines then you need to convert the CCD pixel scale into a
13. also be saved in other formats such as BMP and JPG but these are only suitable for display purposes 8 Looking at your first results If you take a spectrum of single star it will appear as one continuous band across the CCD all the way from the blue to the red Blue Green Yellow Hed Figure 14 Spectrum of Scheat Beta Peg an M2 spectral type star As the CCDSPEC slit is 5mm in length you can take a 2 dimensional spectrum of quite a large part of the sky in which you may be possible to observe several stars at a time and a nebula too such as shown in the example spectrum of the Orion Nebula in Figure 15 Blue Green Yellow Red Figure 15 A spectrum of the Orion Nebula showing the spectra of stars and the hot gas The spectrum in Figure 15 shows 3 horizontal lines which are continuous spectra of 3 hot stars The vertical lines are emission from the gas in the nebula and are very narrow emission lines at discrete wavelengths So in this one spectrum we have information on both the stars and the gas Figure 16 The Orion Nebula viewed on the slit of the spectrograph lf you want to do any detailed analysis of your spectra you are recommended to save your CCD image as a FITS file 9 Plotting your first spectrum The easiest way to analyse and plot your spectra as graphs Is by using the PCSpectra software provided on the CCDSPEC CD ROM Details of how to install the software are given in the PCSpectra Manual
14. ctra 2 0 xx or by dragging the application icon on to your desktop and running from the desktop 16 2 Summary of Functions full details in the Reference Manual The main controls are via the following menu options File Image Analysis Help File gt Open This will open and display and image of your spectrum on your PC Image gt Information basic data about the image dimensions and max min etc Zoom allows image to be fitted to window or zoom in or out Invert Display makes the image display a negative set Display Thresholds allows you to change the contrast of the display Display Settings Allows you to save your contrast settings and use them again Analysis gt SPECTRUM X Axis Projection if you use the mouse to draw a box round the image of your spectrum then option this draws an intensity graph of your spectrum which can be printed or saved PROFILE Y Axis Projection draws and intensity graph along the length of the slit Centroid and Area Measurement finds the centre and area on any feature such as a spectral line which is selected by using the mouse to draw a box round the feature and selecting the intensity thresholds Invert Maximum Intensity inverts the spectrum so that an absorption line becomes and emission line for centroid measurement set Data Thresholds to exclude features from the centroid program you can set a threshold in intensity below which the data isn t used to find t
15. d through your telescope The spectral lines in the lamps can be very bright and be very faint in the same lamp so you may need to take several different exposures Save your calibration spectrum and open it with PCSpectra m SPECTRUM X Axis Projection File name hgonscope fit Mean Intensity Rial 20000 15000 16000 14000 12000 10000 08000 06000 04000 02000 L i FAO FOO rh apj eh Pinel Pixel Mean Intensity Figure 20 Spectrum and plot of a cold cathode lamp spectrum Move the cursor on to the emission line peaks and read off which pixel is at the peak of each lines so in this case the peaks are at 429 505 770 846 and 851 pixels You can measure the position of these lines very accurately to 0 01 pixel if you wish using the centroid feature of PCSpectra and this is described in the PC Spectra Manual You can now enter these values into the appropriate Calibration Worksheet which for a cold cathode lamp is the Mercury Calibration Worksheet see Figure 22 which will calculate the relationship between the pixel on the CCD and the wavelength in nm Simply put it calculates the wavelength covered by one CCD pixel and the wavelength at the start of the spectrum in pixel one The worksheet graph displays these values So in this case pixel one on the CCD corresponds to a wavelength of 227 06 nm and every pixel has a width of 0 4138 nm Knowing this we can then calculate the wavelength of any pixel If y
16. egrees 0 5 4x brighter 8 microns 0 17 5mm 100nm mm 1 5nm 400 700nm 50 x 50 x 160 mm 890g 13 Amateur Spectroscopy K H G F E D 400 450 500 550 600 650 700 Wavelength nm Figure 26 the Solar Spectrum showing the Fraunhofer lines Schematic Diagram Fraunhofer in 1817 took a spectrum of the Sun and noticed the dark absorption lines now named after him and labelled them ABC to GHK We now know the lines are due to absorption of different elements in the Sun and the Earth s atmosphere Each element has its own unique atomic fingerprint just like a DNA fingerprint C and F is Hydrogen D is Sodium H amp K are due to Calcium in the Sun We can use these atomic fingerprints to identify the elements in stars nebulae and galaxies What can amateur astronomers achieve Stars Spectral Classification depending on temperature Discover the strange spectra of very hot and very cool stars Identify stars with massive stellar winds 3000 2500 2000 1500 1000 0500 420 440 4 0 480 500 520 540 560 580 600 620 640 Wavelength nm Figure 27 Wolf Rayet Star showing wide emission lines indicating a massive stellar wind Comets amp Planets discover the composition of comets the atmospheres of planets their moons 4000 3000 2000 1000 400 450 500 550 600 650 Wavelength nm Figure 28 Spectrum of Uranus showing deep absorption bands due to methane in its a
17. f 10 Schmidt Cassegrain Telescope SCT by a 1 25 eyepiece adapter or SCT adapter Light from the telescope is focussed on to the fixed slit which is 50 microns wide by 5mm in length The slit is tilted at 22 5 degrees to the incoming beam and is highly reflective and any light not passing through the slit is reflected intercepted by a folding flat into the slit viewing port and is refocused by a lens at the eyepiece or auto guider The lens de magnifies the image of the slit by a factor of 2 so the image in the guiding port is 4x brighter The slit disk is 10mm in diameter so gives a large acquisition field of view 17 arc minutes with an 8 f 10 SCT Light passing through the slit is focussed by a lens and the collimated beam enters a grism dispersing the light into a spectrum The spectrum is focussed on to the CCD detector by a camera lens which has a vernier focus adjustment which is accessed through the focus port The CCD camera is attached to the CCDSPEC by a special T mount adapter which has the correct spacing for CCD cameras with a back focus in the range 0 17 5mm 12 Specification Construction Input Focal Ratio Minimum Telescope back focus Slit Viewing Field of View Slit Length Slit Width Slit Viewing Magnification Projected slit width at CCD CCD back focus Linear Dispersion Resolution Size Weight CNC machined solid block aluminium f 5 f 30 45mm 10mm omm 50 microns appears as 45 microns at 22 5 d
18. good quality If the data is wavelength calibrated the result will be in wavelength nm 16 5 Absorption lines can also be analysed in this way but they need to be converted into emission lines by using the Analysis Invert Maximum Intensity option 17 Internet Resources Atomic Line List hitp Awww pa uky edu peter atomic index html Interactive Database of Spectral Standard Star Atlases http spectra freeshell org SpectroWeb_ ctrl html Astronomical Almanac Online http asa usno navy mil Club of Amateurs in Optical Spectroscopy http www eso org projects caos The Sun Data http www jgiesen de astro astroJS rs TableWorld index htm Spectral Lamp Data http laserstars org data elements index html Stark Labs supplier of Nebulosity CCD Control Program 60 and PHD guiding software FREE http www stark labs com Copyright Elliott Instruments Limited March 2012 CCDSPEC patent pending 1120579 6 Neither the whole nor any part of the information in this User Guide may be adapted or reproduced in any electronic or material form without the written permission of Elliott Instruments Ltd All information in this User Guide is provided by Elliott Instruments Ltd in good faith for the reader to make use of the CCDSPEC However it is acknowledged that there may be errors or omissions Elliott Instruments Ltd shall not be liable for any loss damage or injury whatsoever arising from the use of any information contained
19. he centre set Region of Interest Size and Position Up to two regions of interest can be specified either by using the mouse or by entering the coordinates via this option The two regions of interest can be added or subtracted so for instance you can subtract the sky background from a spectrum of a star This option also allows you choose to display pixels or wavelength on the spectral graph and either the mean intensity or the summed intensity in the spectrum Display Region of Interest Displays the ROI in it s own window Histogram Intensity Distribution plots a graph of the number of pixels as a function of their brightness Analysis Settings Allows you to save you regions of interest so they can be used again 16 3 Example of Using PCSpectra Here is a spectrum of a planetary nebula as displayed by PCSpectra Values 874 Y 445 Wavelength 588 5 Greyscale 48 Intensity 1386 The planetary nebula is the horizontal line with the bright emission lines on top of the continuum You can also see very long vertical lines which is light pollution At the bottom of the display shows the X and Y coordinates of the cursor and the wavelength as well as the intensity level in the data 0 65536 and the grey scale value of the display 0 255 We can get a graph of spectrum of the planetary nebula simply by using the mouse and cursor to draw round the image of the spectrum and then use the Analysis gt SPECT
20. he focus it turned out 1 5 turns from zero then the scale reading is 150 The nominal focus should be about 85 Do not turn the focus more than about 1 7turns out 170 If focus cannot be achieved in the range 0 170 contact El Ltd for advice In Figure 11 the Nebulosity software shows the spectral lines and graph in real time so it is easy to judge the best focus when the lines are clearly resolved Figure 11 Showing the focussing of the mercury doublet using Nebulosity software Once the instrument is focussed re fit the Focus Port Door and replace the door screws using the 2 5 mm Allen key 7 Taking Your First Astronomical Spectrum Before attaching the CCDSPEC to your telescope it is best to focus the slit viewing port Look down the slit viewing port by using an eyepiece webcam or other electronic imaging device and move the eyepiece or other imaging device up or down until you can see the CCDSPEC slit clearly in focus as shown in Figure 12 and then lock in place Attach the CCDSPEC and CCD camera to your telescope by using any suitable T mount adapter For most purposes especially with an equatorially mounted telescope it is best for the slit to be orientated East West which is when the eyepiece mount is upright Make sure the locking screws attaching the CCDSPEC to the telescope are locked tight The combined weight of the CCDSPEC and CCD camera will be typically 1 6 kg but of course the actual weight will depend on y
21. in the User Guide or any errors or omissions in the User Guide Any comments or suggestions or problems with the installation or use of CCDSPEC should be addressed to Dr K H Elliott at the address below ELLIOTT INSTRUMENTS LTD 1 Oak Tree Cottage Lady Hole Lane Yeldersley DE6 1LR UK Telephone 01335 300856 Email sales elliott instruments co uk
22. ou enter these values into a file called SpecCal txt and copy this into the same folder as your CCD images then PCSpectra will display your graphs as plots of spectral brightness against wavelength in nm see Figure 23 SpecCal Notepad File Edit Format View Help 227 05 0 4138 Cold Cathode lamp Mercury lines Starlight press xv H98 3 Feb 2012 Figure 21 File SpecCal txt edited in Notepad CCDSPEC MERCURY CALIBRATION WORKSHEET pixel Mercury Wavelengths nm colour 429 404 66 blue 505 435 83 blue 546 07 green 846 576 96 yellow 851 579 07 yellow Mercury Spectrum Cold Cathode Lamp E D un O D E lt _ LT n D uu O A pixels Figure 22 Mercury Calibration Worksheet File name hgonscope fit Mean Intensity Roll 20000 18000 16000 14000 12000 10000 08000 06000 04000 02000 400 450 500 550 600 Wavelength nm Figure 23 Graph now calibrated in wavelength nm The Mercury Calibration Worksheet and other calibration worksheets can be found on the CCDSPEC CD ROM in the worksheet folder These can be used with Excel or Open Office Spreadsheet programs 11 Optical Design Eyepiece Focus or Auto guider Slit Viewing Lens SLIT at 22 5 Degrees Collimator Grism Camera CCD I Slit Viewing Mirror Figure 24 The optical layout of CCDSPEC The instrument is attached to a telescope typically an
23. our camera and slit viewing device etc You should make sure that your telescope is properly balanced after attaching the CCDSPEC to avoid damage to your drives and mount and also to ensure reliable tracking during long exposures Figure 12 Slit in focus Figure 13 A star nearly on the slit During daylight you can simply take a spectrum of the blue sky and you will see the Fraunhofer absorption lines from the Solar spectrum WARNING NEVER POINT THE CCDSPEC AT THE SUN Centre the object of interest and then use the telescope s focuser to focus the image of the star so that it is in sharp focus on the slit area Use the telescope s guide controls move the object onto the centre of the slit so that the slit goes through the centre of the object Now take a short exposure between say 1 to 10 seconds and look at the captured image You can judge what sort of exposure you will need by seeing how many counts you get in the captured image If the spectrum is overexposed it will be saturated usually with 65k counts and no useful measurements can be made so adjust the exposure so that no pixels are saturated After a little trial and error you should now have a nice image of the spectrum of your object and you should save the image as a FITS file if you want to analyse the spectrum in detail A FITS file records the image as a 16 bit data which is 64 000 grey scales and this is needed for accurate measurements and display The image can
24. tmosphere Nebulae find out the properties of the hot gas and measure the expansion of supernova remnants BD 4000 2000 350 400 450 Sut 550 B 650 00 Wavelength nm Figure 29 The spectrum of the Orion Nebula showing the emission lines of Hydrogen Oxygen Nitrogen and Sulphur The three horizontal lines are the spectra of very hot stars which are so hot they show almost no absorption lines Galaxies and Quasars Identify active galaxies and measure the redshift Z Figure 30 The spectrum of Active Seyfert Galaxy M77 showing emission lines of OIII and velocity broadened H alpha line The vertical lines are spectral lines of light pollution from Sodium and Mercury lights 14 Astronomy Resources List of possible target objects 14 1 Stars Selected Stars for Spectral Type Determination Common Name Alnitak Mintaka Spica El Nath Regulus Rigel Vega Sirius Deneb Procyon Polaris Capella Pollux Dubhe Arcturus Alderbaran Mirach Betelgeuse Mira Constellation Zeta ORI Delta ORI Alpha VIR Beta TAU Alpha LEO Beta OHI Alpha LYR Alpha CMA Alpha CYG Alpha OPH Beta CAS Alpha CMI Alpha UMI Alpha CEN Alpha AUR Beta GEM Alpha UMA Alpha BOO Alpha TAU Beta AND Alpha ORI Omicron CET Selected Wolf Rayet Stars Name WR 4 WR 6 WR110 WR111 WR113 WR133 WR134 WR135 WR136 WR137 WR138 WR139 WR140 WR141 WR153 WR155 HD 16523 90896
25. ust scattered sunlight and so contains the Solar spectrum which includes many Fraunhofer absorption lines as shown in Figure 8 below 3 FA i Figure 8 The daylight spectrum showing the Fraunhofer absorption lines in the Sun Simply adjust the focus vernier until the narrow absorption lines are well focussed in the middle of the spectrum 6 2 Energy Saving lamps Many of the energy saving lamps used in your home have complex spectra showing many emission lines and these can be used too Simply look at the spectrum in real time and adjust the focus vernier until any fine line features are sharply focussed An energy saving lamp spectrum which is well focussed is shown below in Figure 9 Figure 9 Spectrum of a domestic energy saving lamp 6 3 Mercury Yellow Doublet Probably the best way to focus the CCDSPEC is to look at a very close doublet spectral line such as the yellow Mercury doublet For this you will need a mercury lamp but many fluorescent lamps and cold cathode lamps use mercury vapour so these can be used too The spectrum will look similar to the one below from a cold cathode lamp Figure 10 Spectrum of a cold cathode lamp showing the mercury lines violet blue green yellow doublet Using your CCD acquisition program in its focus mode where you can see the spectrum in real time rotate the focus vernier to get the best focus and record the reading of the vernier The focus control is scaled 0 100 If t
26. ylight has the characteristic spectrum of the Sun with the many Fraunhofer Absorption lines but energy saving lights computer monitors TV displays and even l phones display characteristic spectra Some power indicator lamps in mains adapters use Neon lamps which have many lines although some now use red LED lamps Figure 7a below shows a picture of the spectrum of many common light sources found in the home to allow you to check that you have your CCD camera aligned the correct way round which is with the BLUE part of the spectrum on the LEFT and the RED end of the spectrum to the right Daylight Energy saving lamp Fluor lamp l phone white Blue LED Red LED Neon lamp Torch bulb tungsten Ultra Violet lamp BLUE TV TV RED BLUE HED Figure 7a The spectra of various light sources to show correct alignment of CCD camera Once the CCD is aligned with the spectrum tighten up all 4 locking screws using the 1 5mm Allen key See Figure 4 6 FOCUSSING of CCDSPEC There a few simple ways to do the final focussing of the CCDSPEC Each require you to operate the CCD in its focus mode so you can see the spectrum in real time with frames typically being displayed a few times a second We recommend the use of Nebulosity software from Stark Labs as it has an excellent focus option This may be downloaded from hitp www stark labs com nebulosity html 6 1 Daylight Daylight is j
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