1. rene@astro.su.se Observational Astrophysics II: May-June, 20051 Observational Astrophysics II (L2) http://www.astro.su.se/utbildning/kurser/astro_obs2/

2. rene@astro.su.se Observational Astrophysics II: May-June, 20052 Observational Astrophysics II (L2) Getting our NIRF What do we want to do? 1.Image a selected spiral galaxy in H  6563 (HII/slit position) 2.Spectroscopy of HII regions => los radial velocities 3.Imaging in JHK => isophotes => deprojection => V rad (r) => rotation curve and => stellar population from colours

3. rene@astro.su.se Observational Astrophysics II: May-June, 20053 Spectrograph Slit Radial Distance, r (arcsec to kpc) Error Bars ???! V Galaxy

4. rene@astro.su.se Observational Astrophysics II: May-June, 20054 The Spiral Galaxy M83 in broad band R in narrow band H  H II regions – point likeStellar pop - extended

5. rene@astro.su.se Observational Astrophysics II: May-June, 20055 HH line-to-continuum contrast In narrow band filter continuum U B V R I

6. rene@astro.su.se Observational Astrophysics II: May-June, 20056 Example of long-slit observation (spatio-spectral mapping) 1´´ wide 2´ long spectrograph slit star supersonic jet flow

7. rene@astro.su.se Observational Astrophysics II: May-June, 20057 K-spectrum of Serpens SMM1 jet (VLT-ISAAC) rovibrational H 2 lines Spatial Domain Spectral Domain1´´ slit star 2´ slit S(3) =2-1 S(2) =2-1 R = 400

8. rene@astro.su.se Observational Astrophysics II: May-June, 20058 R = 400 (  v = 750 km s -1 ) R = 100 000 (  v = 3 km s -1 ) Radial velocity measurement

9. rene@astro.su.se Observational Astrophysics II: May-June, 20059 Observing our galaxies 1. ALFOSC H  imaging What Filter? = 6563 (z + 1) Å z (Å) 10 -4 0 10 -3 6570 10 -2 6630 10 -1 7220 http://www.not.iac.es/instruments/instruments.html

10. rene@astro.su.se Observational Astrophysics II: May-June, 200510 Observing our galaxies 2. ALFOSC H  spectroscopy What slit width? http://www.not.iac.es/instruments/instruments.html ALFOSC Slits The following slits are available for use with ALFOSC: Simple, long-slit, covering the full spatial field of view of the instrument (in arcsec): 0.4, 0.5, 0.75, 1.0, 1.2, 1.3, 1.8, 2.5, 5.0, 10.0 Long-slit spectra are oriented vertically on the detector. The 1.8" slit is not very smooth and shows considerable flux variations along the slit.

11. rene@astro.su.se Observational Astrophysics II: May-June, 200511 Observing our galaxies 2. ALFOSC H  spectroscopy What spectral resolution? http://www.not.iac.es/instruments/instruments.html Sun at 8.5 kpc 250 km s - 1  =  v/c R =   v (km s -1 )  (Å) R 300.6510000 3006.51000 300065100 30000> 650< 10

12. rene@astro.su.se Observational Astrophysics II: May-June, 200512 Observing our galaxies 2. ALFOSC H  spectroscopy What integration times? 1. NOT (or ESO) Exposure Time Calculator http://www.not.iac.es/observing/forms/signal/

13. rene@astro.su.se Observational Astrophysics II: May-June, 200513 Exposure Time Calculator Instrument ALFOSC Spectroscopy Detector CCD8 (CCD7) Grism http://www.not.iac.es/instruments/alfosc/grisms/ http://www.not.iac.es/instruments/alfosc/grisms/ Band Bandwidth Slitwidth Source Extended Mag FWHM Exptime Airmass Extinction http://www.ast.cam.ac.uk/~dwe/SRF/camc_extinction.html http://www.ast.cam.ac.uk/~dwe/SRF/camc_extinction.html Sky Brightness B

14. rene@astro.su.se Observational Astrophysics II: May-June, 200514 Observing our galaxies 2. ALFOSC H  spectroscopy What integration times? 2. Manual Estimate Quantify the n s... [ for t =1s and t ~ (S/N) 2 ]

15. rene@astro.su.se Observational Astrophysics II: May-June, 200515 source aha... IS transport diffraction electronics Obs. analysis: Reduction Calibration Informatics telluric atmospheric transport-turbulence spherical coherent - incoherent cow coherent – incoherent detection Plane Wave Two Domains: Above & Below Atmosphere

16. rene@astro.su.se Observational Astrophysics II: May-June, 200516 1. Above telluric atmosphere Photons gained Source  direct emission  scattered into beam Extra-Galactic Background Galactic Background Zodiacal Background Photons lost Source  direct abs/extinction  scattered out of beam Extra-Galactic Extinction Galactic Extinction (IS) Zodiacal Extinction A good emitter is also a good absorber (Kirchoff’s law)

17. rene@astro.su.se Observational Astrophysics II: May-June, 200517 2. Below telluric atmosphere Atmosphere emission extinction scattering Optics emission absorption Detector absorption emission Transmission, T Extinction,  Efficiency,  Detector Noise

18. rene@astro.su.se Observational Astrophysics II: May-June, 200518 Collecting terms: 1. Signal degradation Atmosphere transmission T atm (%) Telescope reflectivity T tel (%) Filter transmission T filter (%) Spectrograph throughput T spec (%) Detector efficiency QE (%) 2. Noise sources Source Photons Poisson Background Photons Sky + Telescope Detector emission Thermal or Dark Current Detector Read Noise Read out noise

19. rene@astro.su.se Observational Astrophysics II: May-June, 200519

20. rene@astro.su.se Observational Astrophysics II: May-June, 200520 Signal = Source flux F tel for given V, E(B-V) Similar can be done at any other filter wavelength, e.g. in the R band

21. rene@astro.su.se Observational Astrophysics II: May-June, 200521 Sky Backgrounds are generally given in mag/arcsec 2 (surface intensity) and are treated similar to source fluxes Dark current and read-out-noise are device specific normally provided externally (manufacturer/observatory) ALFOSC CCD # 8 2048 x 2048 13.5  m pixels image scale 0.19´´/pxl dark current 0.4 e - / pxl / hr ron 5.3 e - / pxl (read time 90 s) conversion * 0.765 e - / ADU (high gain) well capacity 63 000 ADU (~2 16, high gain) non-linearity 0.3 % QE V 0.75 * Analogue-to-Digital Unit

22. rene@astro.su.se Observational Astrophysics II: May-June, 200522 Worked example: NOT-ALFOSC H  image Galaxy R = 13 mag E(B-V) = 0.02 mag  R = 0.02  Airmass = 2  Seeing = 1´´  filter #49  = 50 Å eff = 6607 Å  Line-to-continuum = 1  Sky background = 18 mag

23. rene@astro.su.se Observational Astrophysics II: May-June, 200523 Worked example: NOT-ALFOSC H  image, ctnd. Normally, one makes the computation in electrons and converts at the end. However, at the telescope, the student should watch the ADUs (linearity check).

24. rene@astro.su.se Observational Astrophysics II: May-June, 200524 Obs. Group Filter (type / #) Grism # Slit (arcsec) Object (Name) RA 2000 (h m s) Dec 2000 ( o ´ ´´ ) Proposa l.and. Finder chart (Y/N) 1 Katarina Åsa 22, 78, 49 8, 5, 70.75, 1.0, 1.3, 2.5 5.0 NGC 511213 21 56.4338 44 04.6 Y 2 Kristoffer Sven- Ingmar 7880.5, 0.75, 1.0, 1.2 NGC 587915 09 46.8257 00 02.6 Y 3 Michael Kristina 77, 50, 49, 68 8, 5, 7, 4, 3 5.0, 2.5, 1.0, 0.5, 1.2 NGC 638917 32 39,7716 24 06.4 ALFOSC admits MAX check thickness!!! 7 Filters: UBVRI +2 12 FASU: 6 Grisms: 5 Slits:

25. rene@astro.su.se Observational Astrophysics II: May-June, 200525 Preparing our NIRF http://www.not.iac.es/observing/guide/#preparation http://www.not.iac.es/observing/cookbook Before we go to the mountain...