2 months to go: time to be serious about observing run preparations

2 months to go: time to be serious about observing run preparations

getting ready for our (any!) observing runhtt

p://cheezburger.com/5797953792

http://glozing.blogspot.com

/2012/09/like-scouts-say-be-prepared.html

http:

//la

bass

lix.c

om/b

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YOU THE OBSERVER should never be the cause of this:

What is the scientific goal?

or …

how did we manage to fool the telescope allocation committee?

questions you should be able to answer• do I know what the point is?

– what astrophysical idea is being considered?– could I explain it to children, friends, other science teachers?

• do I understand if my telescope/instrument can attack this?– have I assembled a reasonable list of stars (or nebulae/galaxies)?– can I observe any/all of these objects?

• observatory location; time of year?• appropriate magnitudes?

• am I comfortable with magnitudes and colors?• can I translate from target star coordinates to where they are in the sky?• do I understand my telescope?

– basic optical configuration?– startup/shutdown, moving between targets, tracking targets?– dangers: mechanical limits of telescope; weather restrictions?

• do I understand my instrument?– optical design (not trivial for our instrument)?– what are its “parameters” (how faint can it go, at what spectral resolution, at what noise level)?– can I tell by looking at an output image whether I have done something stupid?– how do I save the data safely?

• can I interpret a spectrum that is obtained?– what does “interpret” really mean when I am sitting at the telescope at 4AM

• do I know the stuff to be done after the observing run?– extraction of a “clean” spectrum?– analysis to get desired results?

http://astronom

y.sci.ege.edu.tr/ASTRO-W

EB/TR2/

fredhtt

p://astronomy.ege.edu.tr/gstars.izm

ir2013/index.html

fredEge University is in

Izmir, near the western edge of Turkey

Izmir is located in the Aegean province, which, of all the seven geographical regions of Turkey, enjoys the finest climate. In population it is the third city in Turkey.It is located in an area whose magnificent history has made it a tourist centre. It lies at the centre of the most important land, air and sea communication network in the ancient Aegean region.

In June we are observing red giant stars

http://nothingnerdy.wikispaces.com/E5+STELLAR+PROCESSES+AND+STELLAR+EVOLUTION

Thumbnail sketch of stellar evolution

http://nothingnerdy.wikispaces.com/E5+STELLAR+PROCESSES+AND+STELLAR+EVOLUTION

Hydrogen fusion powers most stars

http:

//sp

ot.p

cc.e

du/~

aodm

an/p

hysi

cs%

2012

2/en

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20m

ain%

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The alternate way of H-fusion interests us morehtt

p://

ww

w4.

nau.

edu/

met

eorit

e/M

eteo

rite/

Book

-Glo

ssar

yC.h

tml

Supposed to do the same thing: four H nuclei fuse to form one He nucleus + energy

Cycle doesn’t complete every time; net result is buildup of 13C and 14N

These products get mixed to the stellar surfaces as stars age to become red giants

C and N atoms form molecules, like CH and CN

We can observe these molecules in cool stars, and so we can check out enhancements in N and depletions in C and changes in 12C/13C ratios

The red giant clump is really well-known and understood

http:

//w

ww

.ast

ro.p

rince

ton.

edu/

~bp/

Remember: color is temperature, andabsolute magnitude is luminosity

http:

//si

xday

scie

nce.

com

/cur

ricul

um/t

extb

ooks

/cha

pter

-11/

The red giant clump is really well-known and understood:here is a color-magnitude diagram for nearby stars

http:

//w

ww

.ast

ro.p

rince

ton.

edu/

~bp/

main sequence subgiants

Red giants

The red giant clump is really well-known and understood:so, so … what are these things?

http:

//w

ww

.ast

ro.p

rince

ton.

edu/

~bp/

main sequencesubgiants

Red giants

For very old, low mass stars the clump spreads hotter into the “horizontal branch”

MSTO = main sequence turn-off; RGB = red giant branch; RHB = red horizontal branch; BHB = blue horizontal branch; BSS = blue straggler stars; FG = foreground (ignore)

De Boer et al. 2011, A&

Ap

where the red giant clump should be

A simple question, too long ignored: why are there apparently so many bright RHB stars in the young disk

population surrounding our Sun?D

e Boer et al. 2011, A&ApRGB clump

our target RHB stars

the task: identify true giant stars that are a few hundred K warmer than they should be, and do a detailed analysis of them to see if chemical clues can uncover their secrets …

We will also be studying red giant chemical compostions of open clusters

http:

//m

essi

er.s

eds.

org/

xtra

/ngc

/n08

69.h

tml

http:

//w

ww

.atla

soft

heun

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penc

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htm

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Most open clusters have only a few RGB stars, and it is tough to pick out cluster members from the general Galactic field population

http://www.starobserver.eu/openclusters/hyades.html

Melike is in charge of assembling the target listHer summary of the selection process, and my comments in blue:

The stars we are interested in are RHB stars.

First we did a literature scan and learned about our stars, finding out what temperature and absolute magnitude/luminosity range they have (location on the HR-diagram). We had to understand how temperature and luminosity (theoreticians’ units!) translate into colors and magnitudes (observers’ units!).

Then we used this information to sort out the catalogs, mainly using SIMBAD and HIPPARCOS. These were our basic star information sources.

We threw out the stars outside the temperature and luminosity range (if available) that we are interested in. This is an imperfect process, with uncertainties in all published quantities! We knew that some promising targets would turn out to be duds.

In our case, the Galactic latitudes of the stars are also important since we want to observe stars in the Galactic thin/thick disk and halo.

We used both spectral type and V-K color index in order to determine the temperatures. We also calculated the absolute magnitudes when the distance information was available. As always in astronomy, lack of accurate distances for every target is the biggest limitation for us.

photometric bandpasses? Most of us are familiar with the “UBV” system

http://w

ww

.asahi-spectra.com/opticalfilters/johnson_bessell.htm

lremember for example: V = mV, that is the apparent magnitude in the “visual” (yellowish) bandpass, close to the human eye response

we also used infrared “K” magnitudes

when available

the colors B-V, V-I, and especially V-K are good indicators of temperature

and the V (= mV) magnitude, IF YOU KNOW THE DISTANCE (PARALLAX) can be translated into absolute magnitude MV

http://coursewiki.astro.cornell.edu/Astro4410/BasicObservationalKnowledge

http://simbad.u-strasbg.fr/simbad/sim-fsam

http://simbad.u-strasbg.fr/simbad/sim-fid SIMBAD

HIPPARCOShttp://www.rssd.esa.int/index.php?project=HIPPARCOS

an actual star we need to observe in June!

¡Ay, caramba! Star names can be a headache

RA, Dec, KT, UT, LST, HA

https://dept.astro.lsa.umich.edu/ugactivities/Labs/coords/index.html

http://astunit.com

/astunit_tutorial.php?topic=time

first point of Aries = Vernal Equinox

RA = right ascensionDec = declinationUT = universal (Greenwich) timeLST = local sidereal timeHA = hour angleKT = kitchen (o’clock) time

Galactic coordinates

http://www.atlasoftheuniverse.com/galchart.html

Visualizing Galactic coordinates

http://starplot.org/docs/ch1.html

http://people.physics.carleton.ca/~watson/Physics/Astrophysics/4201_essentials/4201_coordinates.html?id=0

Our Smith Telescope at McDonald Observatory

30.6714° N, 104.0225° W

http://www.laurenceparent.com/portfolios/Texas/lptxmcdonaldob.html

https://w

ebspace.utexas.edu/tsc494/site/autobio/main.htm

l

http://w

ww

.ira.inaf.it/Library/slides-archive/page20.html

Summary of 2.7m Smith Telescope properties

http://www.as.utexas.edu/mcdonald/facilities/2.7m/2.7.html

http://www.as.utexas.edu/mcdonald/facilities/2.7m/2.7.html

The desire is for spectra of our targetswe’ve all seen general stellar spectra before

http:

//pr

ance

r.phy

sics

.loui

svill

e.ed

u/cl

asse

s/10

7/to

pics

/ste

llar_

spec

tra_

exam

ples

/

HαHβHγHδ Na I “D”

Mg I “b”CH “G”

Reminder of basic spectrograph design

http://outreach.atnf.csiro.au/education/senior/astrophysics/spectrographs.htm

l

Echelle spectrographs are a bit more complex

http://www.ucolick.org/~vogt/hires.html

A solar echelle spectrum

http://www.noao.edu/image_gallery/html/im0600.html

A solar echelle spectrum

http://www.noao.edu/image_gallery/html/im0600.html

Telluric O2

Hα

Na I “D”

Mg I “b”

CH

Hβ

Hγ

Our spectrograph: the Tull echelle

circa 1968?? left to right:Harlan Smith, Gerard de VaucouleursBob Tull, Terry Deeming, Frank Edmonds

Very complex drawings designed to make you stop asking questions

What you will see at telescope

http:

//w

ww

.ast

roge

o.va

.it/a

stro

nom

/spe

ttri/

eche

lle_e

n.ph

p

Telluric O2

Hα

Na I “D”

Which you can “display” thusly:

Reduction and analysis: to be continued …

HELP!

http:

//se

arch

netw

orki

ng.te

chta

rget

.com

/fea

ture

/Tec

h-su

ppor

t-I-fo

rgot

-my-

pass

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d

TELESCOPE: http://nexus.as.utexas.edu:8081/obs_sup/man/manuals/TCS/tcs_quick_guide.html

SPECTROGRAPH: http://nexus.as.utexas.edu:8081/obs_sup/man/manuals/2dcoude.html

NIGHT REPORT: http://198.214.229.50:8081/cgi-bin/obs_sup/xrep_form.cgi

WEATHER: http://observatories.hodar.com/mcdonald/

fred