Discover! - DOCdb

Discover! An observing project of the Deepsky Observing Section of the Astronomical Society of Southern Africa • v.2.0 • http://www.psychohistorian.org • [email protected]

Workbook 1: Naked eye and binocularsDeepsky Observing Checklist

An observing project of the ASSA Deepsky Section

Discover!

Discover the deepsky for yourself

Version 2.0, August 2008


This workbook is ideal for learning all the constellations visible from the southern hemisphere, and for discovering the brighter deepsky objects on your own.

Chart 1 shows the constellations around the south pole. Use the brightest stars – Pointers, Crux, Canopus and Achernar – to orient the chart properly. Charts 2 to 6 show the regions immediately surrounding Chart 1. Chart 7 shows the brighter stars around Orion, a prominent summer constellation. Charts 8 to 13 show the regions surrounding Orion. The remainder of the charts covers the rest of the sky, with generous overlap between charts for easy use. Along the borders of each chart appears the map number of neighbouring charts. For each constellation, a pronounciation guide is given, as well as the English name, genitive and abbreviation. You may want to make photocopies of the star charts, as you will be writing on them, plotting in any objects you discover as you go along. A bonus chart at the end of the workbook illustrates a few San (Bushman) star tales, unique to our African skies.

Use the tables to help plan your observing. The top table lists the charts visible at 21:00 for mid-month, for each month of the year. The next table lists the constellations depicted on each chart, as well as the months during which the charts can be used. The third table lists those constellations that are directly overhead at 21:00 and 02:00 at the beginning of each month.

To use this workbook, you will also need a clipboard, pencil, eraser and a very dim, red-shielded torch – you don’t want to compromise your night vision. Observe from the darkest skies you can safely reach, avoiding bright lights at all costs. Give your eyes sufficient time to dark adapt (about 30 minutes) before starting to observe.

Naked-eye observers can use these charts to learn the constellations. From a dark (rural) observing site, several deepsky objects can be seen with the naked eye. From brighter (sub-urban) skies, many are visible in binoculars. While working with a particular chart, study the sky carefully and mark any non-stellar object you come across on the chart. Make a note of your discovery, describing each object in as much detail as necessary (see below for guidelines; an advanced format is given in the appendix). Sample observing log sheets are given at the end of this workbook.

Binocular observers already familiar with the constellations can use these maps to seek out any non-stellar objects hidden amongst the stars on the maps. Plot all discoveries, number them, and provide descriptions and sketches. A separate record sheet is provided to note the colours of the brighter stars. Once a map has been thoroughly examined, send your annotated star chart and observing notes to the ASSA Deepsky Section, Director: Auke Slotegraaf, Forelle Crescent 8, Die Boord, Stellenbosch, 7600; [[email protected]]. Your observations will be returned along with detailed feedback.

Happy hunting!

PS: For advanced observers, charts down to magnitude 11 are available, covering selected areas of the sky. Contact the Director for details.

How to use this workbookDiscover!Month Charts that can be used (mid-month at 21:00)Jan 1, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 25Feb 1, 2, 4, 5, 7, 8, 9, 10, 12, 13, 14, 16, 17, 25Mar 1, 2, 3, 4, 5, 7, 8, 9, 12, 13, 14, 15, 16, 17Apr 1, 2, 3, 4, 5, 8, 9, 13, 14, 15, 16, 17, 18May 1, 2, 3, 4, 15, 16, 17, 18, 19, 21Jun 1, 2, 3, 15, 17, 18, 19, 21Jul 1, 2, 3, 6, 17, 18, 19, 20, 21Aug 1, 2, 3, 6, 20, 21, 22, 23Sep 1, 2, 3, 6, 20, 21, 22, 23Oct 1, 5, 6, 21, 22, 23, 24, 25Nov 1, 4, 5, 6, 8, 9, 10, 12, 23, 24, 25Dec 1, 4, 5, 6, 7, 8, 9, 10, 11, 12, 24, 25

Which charts to use

For each object you discover, record the date and time of the observation, from where you observed, with what instrument, the sky conditions, and the quality of the observation. When describing the object, keep the following in mind:1. first impressions2. visibility (e.g. obvious/easy/reasonably easy/difficult/challenge)3. size (in arcminutes; either estimated or compared to stars in the field)4. shape (irregular/round/elongated). If elongated, specify the direction of elongation (eg north-west) and the degree of elongation (ratio of width to height)5. prominent stars in the vicinity (specify direction, distance and brightness)

Discover! Recording your observations & making descriptions

presented by the ASSA Deepsky Observing Section[[email protected]] • [http://www.psychohistorian.orgDiscover the deepsky

Month Overhead at 21:00 Overhead at 02:00Jan Cae, Eri, For, Hor, Phe, Ret, Scl Ant, Car, CMa, Col, Pic, Pup, Pyx, VelFeb Cae, CMa, Col, Dor, Hor, Lep, Pic, Ret Ant, Crt, Hya, Pyx, Sex, VelMar Cae, Car, CMa, Col, Lep, Pic, Pup, Pyx Ant, Cen, Crt, Cru, Crv, HyaApr Ant, Car, Hya, Pup, Pyx, Vel Cen, Cru, Crv, Hya, Lib, Lup, NorMay Ant, Cen, Crt, Crv, Hya, Pyx, Vel Ara, Lib, Lup, Nor, ScoJun Cen, Crt, Cru, Crv, Hya, Lup, Vir Ara, CrA, Nor, Sco, Sct, Ser, Sgr, TelJul Cen, Lib, Lup, Nor, Sco Cap, CrA, Mic, Sct, Sgr, TelAug Ara, CrA, Lib, Lup, Nor, Sco, Sgr, Tel Aqr, Cap, Gru, Ind, Mic, PsASep Ara, Cap, CrA, Mic, Sco, Sct, Sgr, Tel Aqr, Cet, Scl, Phe, Gru, PsAOct Cap, CrA, Gru, Mic, PsA, Sgr, Tel Cet, Eri, For, Hor, Phe, SclNov Aqr, Gru, Ind, Mic, Phe, PsA, Scl Cae, Col, Eri, For, Hor, Lep, Pic, RetDec Cet, For, Gru, Phe, Scl Cae, CMa, Col, Dor, Hor, Lep, Pic, Pup

Constellations overhead at 21:00 and 02:00

Chart Visibility (21:00) Constellations01 Jan – Dec Apus, Carina, Chamaeleon, Crux, Dorado, Hydrus, Mensa, Musca, Octans, Pavo, Reticulum, Triangulum Australe, Tucana, Volans02 Feb – Sep Centaurus, Circinus, Crux, Musca, Triangulum Australe03 Mar – Sep Ara, Circinus, Lupus, Norma, Triangulum Australe04 Nov – May Antlia, Carina, Pictor, Puppis, Pyxis, Vela, Volans05 Oct – Apr Caelum, Dorado, Horologium, Pictor, Reticulum06 Jul – Jan Grus, Indus, Microscopium, Pavo, Phoenix, Piscis Austrinus, Tucana07 Dec – Mah Auriga, Canis Major, Canis Minor, Columba, Gemini, Lepus, Orion, Perseus, Taurus08 Nov – Apr Orion09 Nov – Apr Canis Major, Columba, Lepus10 Nov – Feb Taurus11 Dec – Jan Auriga, Perseus12 Nov – Mar Eridanus13 Jan – Apr Canis Minor, Gemini, Monoceros14 Jan – Apr Cancer, Lynx15 Mar – Jun Coma Berenices, Leo, Leo Minor16 Feb – May Hydra, Sextans17 Feb – Jul Corvus, Crater, Hydra18 Apl – Jul Virgo19 May – Jul Boötes, Corona Borealis20 Jul – Sep Hercules, Ophiuchus, Serpens21 May – Oct Corona Australis, Libra, Sagittarius, Scorpius, Scutum, Telescopium22 Aug – Oct Aquila, Cygnus, Delphinus, Equuleus, Lyra, Sagitta, Scutum, Vulpecula23 Aug – Nov Aquarius, Capricornus, Piscis Austrinus24 Oct –Dec Andromeda, Aries, Pegasus, Pisces, Triangulum25 Oct – Feb Cetus, Fornax, Sculptor

Contents of the charts

An updated (2008 February) “Deepsky Observing Checklist” is given in the Appendix.


• Apus [AY-pus], the Bird of Paradise. (Apodis, Aps)• Carina [ka-RYE-nah], the Keel. (Carinae, Car)• Chamaeleon [ka-MEE-lee-un]. (Chamaeleontis, Cha)• Crux [KRUKS], the Southern Cross. (Crucis, Cru)• Dorado [doh-RAH-doh], the Swordfish. (Doradus, Dor)• Hydrus [HY-drus], the Small Water-Snake. (Hydri, Hyi)• Mensa [MEN-sah], Table Mountain. (Mensae, Men)• Musca [MUSS-kah], the Fly. (Muscae, Mus)

01chart

• Octans [OCK-tanz], the Octant. (Octantis, Oct)• Pavo [PAH-voh], the Peacock. (Pavonis, Pav)• Reticulum [reh-TIK-u-lum], the Reticule (Reticuli, Ret)• Triangulum Australe [tri-ANG-gyu-lum os-TRAH-lee], the Southern Triangle. (Trianguli Australis, TrA)• Tucana [too-KAN-ah], the Toucan. (Tucanae, Tuc)• Volans [VOH-lanz], the Flying Fish. (Volantis, Vol)

January – Decemberα alpha, β beta, γ gamma, δ delta, ε epsilon, ζ zeta, η eta, θ theta, ι iota, κ kappa,λ lambda, µ mu, ν nu, ξ xi, ο omicron, π pi, ρ rho, σ sigma, τ tau, υ upsilon, ϕ phi, χ chi, ψ psi, ω omega

Discover!

18h 19h 20h 21h 22h 23h 00h 01h 02h 03h 04h 05h 06h

O P Q R S T U V W Q R S T U V W X A R S T U V W X A B C D T U V W X A B C D E F U V W X A B C D E F G H I W X A B C D E F G H I J K A B C D E F G H I J K L M C D E F G H I J K L M N O F G H I J K L M N O P H I J K L M N O P Q R K L M N O P Q R S M N O P Q R S T U

Date

Jan 1Feb 1Mar 1Apr 1May 1Jun 1Jul 1Aug 1Sep 1Oct 1Nov 1Dec 1

Guide to orienting the chartUse the small star map on the right to help orient Chart 1. Start by finding the most appropriate date in the left-most column of the table on the right. In the top row, locate the time of observing. Note the letter found at the intersection. Now turn the star chart so that this letter is at the bottom.

Then, stand so that you face South. (To find South, stand so that you are facing the direction where the Sun sets, ie. west. South is then directly towards your left). The chart will now approximately match the position of Crux, the Pointers, Achernar and Canopus in the sky.

Because of the Earth’s motion around the Sun, the sky shifts by one letter each two weeks. Use this fact to interpolate between dates. For example, on January 15 at 21:00, “Q” should be at the bottom.

AB

C

D

EF

GH

I

J

KLMN

O

Achernar

Canopus

Crux

P

QR

ST

U

V

WX

10°


• Centaurus [sen-TOR-us], the Centaur. (Centauri, Cen)• Circinus [SUR-seh-nus], the Compasses. (Circini, Cir)• Crux [KRUKS], the Southern Cross. (Crucis, Cru)• Musca [MUSS-kah], the Fly. (Muscae, Mus)

February – Septemberα alpha, β beta, γ gamma, δ delta, ε epsilon, ζ zeta, η eta, θ theta, ι iota, κ kappa,λ lambda, µ mu, ν nu, ξ xi, ο omicron, π pi, ρ rho, σ sigma, τ tau, υ upsilon, ϕ phi, χ chi, ψ psi, ω omega 02

chart• Triangulum Australe [tri-ANG-gyu-lum os-TRAH-lee], the Southern Triangle. (Trianguli Australis, TrA)

Discover!

Notes

10°


• Ara [AR-uh], the Altar. (Arae, Ara)• Circinus [SUR-seh-nus], the Compasses. (Circini, Cir)• Lupus [LOO-pus], the Wolf. (Lupi, Lup)• Norma [NOR-muh], the Level and Square. (Normae, Nor)

March – Septemberα alpha, β beta, γ gamma, δ delta, ε epsilon, ζ zeta, η eta, θ theta, ι iota, κ kappa,λ lambda, µ mu, ν nu, ξ xi, ο omicron, π pi, ρ rho, σ sigma, τ tau, υ upsilon, ϕ phi, χ chi, ψ psi, ω omega 03

chart• Triangulum Australe [tri-ANG-gyu-lum os-TRAH-lee], the Southern Triangle. (Trianguli Australis, TrA)

Notes

Discover!

10°


• Antlia [ANT-lee-uh], the Air Pump. (Antliae, Ant)• Carina [ka-RYE-nah], the Keel. (Carinae, Car)• Pictor [PIK-tor], the Painter’s Easel. (Pictoris, Pic)• Puppis [PUP-iss], the Stern. (Puppis, Pup)

α alpha, β beta, γ gamma, δ delta, ε epsilon, ζ zeta, η eta, θ theta, ι iota, κ kappa,λ lambda, µ mu, ν nu, ξ xi, ο omicron, π pi, ρ rho, σ sigma, τ tau, υ upsilon, ϕ phi, χ chi, ψ psi, ω omega 04

chart

17

02 13

• Pyxis [PIK-sis], the Mariner’s Compass. (Pyxidis, Pyx)• Vela [VEE-lah], the Sails. (Velorum, Vel)• Volans [VOH-lanz], the Flying Fish. (Volantis, Vol)

Discover!

Notes

November – May

10°


• Caelum [SEE-lum], the Chisel (Cae, Caeli)• Dorado [doh-RAH-doh], the Swordfish (Dor, Doradus)• Horologium [hor-oh-LOH-jee-um], the Pendulum Clock (Hor, Horologii)

October – Aprilα alpha, β beta, γ gamma, δ delta, ε epsilon, ζ zeta, η eta, θ theta, ι iota, κ kappa,λ lambda, µ mu, ν nu, ξ xi, ο omicron, π pi, ρ rho, σ sigma, τ tau, υ upsilon, ϕ phi, χ chi, ψ psi, ω omega 05

chart

01

• Pictor [PIK-tor], the Painter’s Easel (Pic, Pictoris)• Reticulum [reh-TIK-u-lum], the Reticule or Rhomboidal Net (Ret, Reticuli)

Discover!

Notes

10°


• Grus [GROOS], the Crane. (Gruis, Gru)• Indus [IN-dus], the Indian. (Indi, Ind)• Microscopium [my-kro-SKO-pee-um], the Microscope. (Microscopii, Mic)• Pavo [PAH-voh], the Peacock. (Pavonis, Pav)

α alpha, β beta, γ gamma, δ delta, ε epsilon, ζ zeta, η eta, θ theta, ι iota, κ kappa,λ lambda, µ mu, ν nu, ξ xi, ο omicron, π pi, ρ rho, σ sigma, τ tau, υ upsilon, ϕ phi, χ chi, ψ psi, ω omega

06chart

• Phoenix [FEE-nicks], the Phoenix. (Phoenicis, Phe)• Piscis Austrinus [PIE-sis OSS-trih-nuss], the Southern Fish. (Piscis Austrini, PsA)• Tucana [too-KAN-ah], the Toucan. (Tucanae, Tuc)

Discover!

July – January

10°


• Auriga [oh-RYE-gah], the Charioteer (Aurigae, Aur)• Canis Major [KAH-niss MAY-jer], the Big Dog. (Canis Majoris, CMa)• Canis Minor [KAH-niss MY-ner], the Little Dog. (Canis Minoris, CMi)• Columba [koh-LUM-bah], the Dove. (Columbae, Col)

α alpha, β beta, γ gamma, δ delta, ε epsilon, ζ zeta, η eta, θ theta, ι iota, κ kappa,λ lambda, µ mu, ν nu, ξ xi, ο omicron, π pi, ρ rho, σ sigma, τ tau, υ upsilon, ϕ phi, χ chi, ψ psi, ω omega

07chart

• Gemini [JEM-eh-nye], the Twins. (Geminorum, Gem)• Lepus [LEE-pus], the Hare. (Leporis, Lep)• Orion [oh-RYE-un], the Hunter. (Orionis, Ori)• Perseus [PURR-see-us], the Champion (Persei, Per)• Taurus [TORR-us], the Bull. (Tauri, Tau)

Discover!

December – March

10°


• Orion [oh-RYE-un], the Hunter. (Orionis, Ori)


chartDiscover!

November – April

10°


• Canis Major [KAH-niss MAY-jer], the Big Dog. (Canis Majoris, CMa)• Columba [koh-LUM-bah], the Dove. (Columbae, Col)• Lepus [LEE-pus], the Hare. (Leporis, Lep)


chartDiscover!

Notes

November – April

10°


• Taurus [TORR-us], the Bull. (Tauri, Tau)


chart

25

Discover!

Notes

November – February

10°


• Auriga [oh-RYE-gah], the Charioteer (Aurigae, Aur)• Perseus [PURR-see-us], the Champion (Persei, Per)


chart

10

Discover!

Notes

December – January

10°


• Eridanus [eh-RID-an-us], the River Eridanus. (Eridani, Eri)


chartDiscover!

November – March

10°


• Gemini [JEM-eh-nye], the Twins. (Geminorum, Gem)• Canis Minor [KAH-niss MY-ner], the Little Dog. (Canis Minoris, CMi)


chart• Monoceros [moh-NO-ser-us], the Unicorn. (Monocerotis, Mon)

Discover!

Notes

January – April

10°


• Cancer [CAN-ser], the Crab. (Cancri, Cnc)• Lynx [LINKS]. (Lyncis, Lyn)


chartDiscover!

January – April

10°


• Leo [LEE-oh], the Lion. (Leonis, Leo)• Leo Minor [LEE-oh MY-ner], the Little Lion. (Leonis Minoris, LMi)


chart• Coma Berenices [KOH-mah bear-eh-NEE-seez], Berenice’s Hair (Comae Berenices, Com)

Discover!

March – June

10°


• Hydra [HY-dra], the Water Monster. (Hydrae, Hya)• Sextans [SEX-tanz], the Sextant. (Sextantis, Sex)


chartDiscover!

Notes

February – May

10°


• Hydra [HY-dra], the Water Monster. (Hydrae, Hya)• Crater [KRAY-ter], the Cup. (Crateris, Crt)• Corvus [KOR-vus], the Crow. (Corvi, Crv)


chartDiscover!

Notes

February – July

10°


• Virgo [VER-go], the Virgin. (Virginis, Vir)


chartDiscover!

Notes

April – July

10°


• Boötes [boh-OH-teez], the Herdsman. (Boötis, Boo)• Corona Borealis [kor-OH-nah bor-ee-AL-is], the Northern Crown. (Coronae Borealis, CrB)


chartDiscover!

May – July

10°


• Hercules [HER-kyu-leez]. (Herculis, Her)• Serpens [SIR-penz], the Serpent. (Serpentis, Ser) (caput, head; cauda, tail)


chart• Ophiuchus [oh-fee-U-cuss], Ophiuchus the Serpent- Holder. (Ophiuchi, Oph)

Discover!

July – September

10°


• Scorpius [SKOR-pee-us], the Scorpion. (Scorpii, Sco)• Sagittarius [sadge-ih-TAIR-ee-us], Archer. (Sagittarii, Sgr)• Libra [LEE-bra], the Scales. (Librae, Lib)• Scutum [SKU-tum], the Shield. (Scuti, Sct)


chart• Telescopium [tel-eh-SKO-pee-um], the Telescope. (Telescopii, Tel)• Corona Australis [kor-OH-nah os-TRAH-lis], Southern Crown. (Coronae Australis, CrA)

Discover!

May – October

10°


• Delphinus [del-FIE-nus], the Dolphin. (Delphini, Del)• Scutum [SKU-tum], the Shield. (Scuti, Sct)• Equuleus [eh-KWOO-lee-us], Little Horse. (Equulei, Equ)• Vulpecula [vul-PECK-you-lah], the Fox. (Vulpeculae, Vul)


chart• Aquila [uh-KWI-luh], the Eagle. (Aquilae, Aql)• Sagitta [sa-JIT-ah], the Arrow. (Sagittae, Sge)• Cygnus [SIG-nus], the Swan. (Cygni, Cyg)• Lyra [LYE-rah], the Lyre. (Lyrae, Lyr)

Discover!

August – October

10°


• Aquarius [ah-KWAIR-ee-us], Water Bearer. (Aquarii, Aqr)• Capricornus [kap-reh-KOR-nuss], the Sea-Goat. (Capricorni, Cap)


chart• Piscis Austrinus [PIE-sis OSS-trih-nuss], the Southern Fish. (Piscis Austrini, PsA)

Discover!

August – November

10°


• Pegasus [PEG-a-sus], Winged Horse. (Pegasi, Peg)• Pisces [PIE-seez], the Fish. (Piscium, Psc)• Andromeda [an-DROH-me-duh], the Chained Woman (Andromedae, And)


chart• Triangulum [tri-ANG-gyu-lum] the Triangle. (Trianguli, Tri)• Aries [AIR-eez], the Ram. (Arietis, Ari)

Discover!

October – December

10°


• Cetus [SEE-tus], the Whale. (Ceti, Cet)• Fornax [FOR-nax], the Chemical Furnace. (Fornacis, For)• Sculptor [SKULP-tor], the Sculptor’s Workshop. (Sculptoris, Scl)


chartDiscover!

October – February

10°


Discover!

BONUSCHART

A few San star tales

Antares

(SCORPIUS)

Eyes ofthe Lion

µ

( CORONA AUSTRALIS )

“A beautiful girl once looked upon some people sitting eating together. Transfixed by her looks, they became stars in the sky.”

Betelgeuse

(ORION)

Rigel

Aldebaran

Pleiades

Lion

!Khunuseti

The !Khunuseti once sent their husband to shoot three zebras, but warned him that if he failed, he was not to return. He went with one arrow, and shot with his bow, but missed. He couldn’t retrieve the spent arrow because it fell near a lion who was also watching the zebras. So the poor man stayed out in the cold veld, too frightened to return home without game.

Husband

Arrow

3 Zebras

(CRUX)

(POINTERS)

Two male lions

Three lionesses

Procyon (CANIS MINOR)

Castor

Pollux(GEMINI)

Betelgeuse

(ORION)

Aldebaran

Eland male

Eland females

Hartebeest female

Hartebeest male

Observing log

Object number: . . . . . . . . . . . . . . . . . . . . . . . . Observer: . . . . . . . . . . . . . . . . . . . . . . . . . . . . Location: . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Date & time: . . . . . . . . . . . . . . . . . . . . . . . . . . Instrument: . . . . . . . . . . . . . . . . . . . . . . . . .

Sky conditions: . . . . . . . . . . . . . . . . . . . . . . . . Quality of observation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Description and sketch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Discover! Discover the deepsky for yourself.

Observing log





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Observing log





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Note the size of the field of view sketched, and its orientation.


Star colour record sheet

Star name or identification number Colour (select one)


blue white red blue yellow light deep light deep orange white white yellow yellow orange orange red












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Appendix: DOClist

1. Identity the objectWhen you set out to describe an object, don’t forget to write down its catalogue number or name! If it’s a well-known object, it should be sufficient to list its NGC number, or any other popular catalogue (e.g. Bennett, Messier, Caldwell etc.). It’s also a good idea to indicate the object’s approximate location within its constellation, just to give a general sense of where it is. Later, when you transcribe your observations from your observing notes to your logbook, look up its co-ordinates (right ascension and declination) and record these.

Sooner or later you’ll start observing more obscure objects – or perhaps even discovering your own. It then becomes particularly import to provide sufficient information so that others can also find the object, and that you can verify later what object was in fact being observed.

2. First things firstOnce you’ve found your target, give a quick summary of what strikes you as most interesting about it. Look at it with an open mind and without preconceptions, and give an overall impression. At a glance, what does it look like? How easy is it to see?

Also pay attention to the surrounding starfield within which the object lies.

3. BrightnessHow bright is the object? You can perhaps use a verbal description, such as “extremely bright – very bright – bright – faint – very faint – extremely faint”.

If possible, estimate the magnitude. This will require experience and reference objects, but is a worthwhile step, particularly for advanced observers.

4. SizeHow big is the object? Estimate its angular size (in degrees, arcminutes or arcseconds).

One way to estimate the size is to compare it to the size of the field of view of the eyepiece you are using.

A more accurate method is to compare the object’s size to the distance between two stars in the field. Note

which stars you have used, and (with a star atlas or computer program) determine the distance between them.

5. ShapeWhat is the general shape of the object? How you answer this question will depend a lot on what type of object it is. Galaxies and planetary nebulae often have well-defined shapes, whereas open clusters and nebulae are more difficult to pin down and are often just “irregular”.

If the object has a regular shape, is it round or elongated (oval)? If it is elongated, to what extent? The degree of ellipticity can be indicated in words such as “very slightly oval – clearly elongated – extremely extended into a ray”. Preferably, estimate the size of the minor (shortest) and major (longest) axis. For an elongated object, you also need to specify its orientation, to indicate the direction in which the object lies. Usually, it is sufficient to use compass directions, for example: “The galaxy is elongated northwest by southeast”. More advanced observers may estimate the “position angle” (PA). A position angle of 0° means the object is positioned on the north-south axis; PA=45° is northeast by southwest; PA=135° is northwest by southeast, etc.

6. Brightness profileMost “fuzzy” objects – galaxies, globular clusters, planetary nebulae, etc. – are not equally bright all over. Many have a central nucleus that is brighter than the outer regions. The brightness profile describes how the object’s brightness changes as you look towards the centre. Note by how much, and how quickly, it brightens. In some cases there is a sudden rise in brightness (sharp concentration) at the centre, and in other cases the brightness profile rises gradually. Some objects, galaxies in particular, grow brighter towards the centre at varying rates.

7. Specific things to look out for In addition to the general features above, different types of objects have unique characteristics that can be noted.

These guidelines will help you to get the most out of your observing sessions by providing a checklist of things to look out for when you examine a deepsky object. The checklist is not meant as a rigid thought-constraining framework, but rather as a tool to make sure you don’t forget to note a particular aspect.

Deepsky Observing Checklist (version 3)2006 January


NEW! Version 4 overleaf

7.1 open clusters(a) relation to the surrounding field stars (cluster not

separated, well detached, etc.)(b) how many stars are there? (make an estimate, but

preferably count the stars within a fixed diameter)(c) range of brightness (most stars of nearly the same

brightness … bright and faint stars mixed)(d) how are the stars concentrated? (not at all, slightly,

strongly, etc.)(e) look for prominent empty spaces / starless patches(f) are there clumps/chains of stars?(g) is there a glow of unresolved stars/nebulosity?(h) is there an obvious central or other prominent

individual stars? (magnitudes? colours?)(i) any striking double stars resolved?(j) do any of the stars have a particular colour?

7.2 globular clusters(a) are individual stars seen? (unresolved – granular

– partially resolved – well resolved)(b) how are the stars concentrated towards the

nucleus?(c) estimate the size of the nucleus (compare with the

size of the halo)(d) are there clumps/chains of stars?(e) look for prominent empty spaces / starless patches

7.3 planetary nebulae (a) is a disk seen? (if so, at what magnification)(b) is the edge sharply defined?(c) what colour is the nebula?(d) is there a central star?

7.4 galaxies(a) what does the galactic nucleus look like?(b) are there stars very near by, or within the galaxy?(c) are there darker areas within the galaxy?(d) are there areas of uneven brightness?

7.5 bright nebulae(a) are there areas of uneven brightness?(b) dark lanes/patches?(c) any other structure visible?

7.6 dark nebulae(a) how well does the nebula stand out from the

background?(b) is it isolated, or part of a larger complex?(c) how dark is it? (d) are the edges sharp or diffuse?(e) are there stars superimposed on the nebula?

8. SketchesA sketch done with care rather than in a hurry can make a fine addition to your observing records. Phil Harrington, veteran deepsky observer, wrote: “A picture is worth a thousand words, except in observational astronomy, when it is worth ten times that much! The drawing need not be extravagant; just a simple sketch giving a feel for scale and orientation. It is important that the astro-artist note the direction of the four cardinal points plus include at least a few of the field stars.”

9. Personal details and observing conditionsIn your logbook, record your assessment of the quality/accuracy of the observation, and perhaps indicate a difficulty level: how much of a challenge the object was.

Record the location of your observing site and the date of the observation. Describe the instrument used: type (e.g. binoculars, reflector, refractor) aperture and f/ratio. For each eyepiece you use, give its focal length and field size.

Note any relevant weather details, including the clarity of the sky. Give an indication of the seeing (stars are fuzzy – stars appear disk-like – images are sharp at medium power – sharp images at high magnification). Seeing is often measured as the size, in arcseconds, of a stellar image.

Rate the sky darkness by indicating the limiting magnitude, i.e. the brightness of the faintest star visible through the telescope.

10. Other techniquesIf you have a selection of eyepieces, use each one. A variety of magnifications can bring out additional details and objects often look subtly different at different magnifications. Also, comparing objects as seen through different-sized telescopes can be instructive.

If you have access to filters (UHC, O-III, Light Pollution, etc.) note the visibility of the object with and without filters. If you have a spectroscope or diffraction grating, the spectral lines of bright nebulae and emission stars can be studied.

11. In conclusionIgnore all these guidelines. Or use some of them. The important thing is to enjoy what you are doing, and to capture the essence of each deepsky object in such a way that others, reading your description and looking at your sketch, can share in that enjoyment.



Newels

’n Oorsiglys vir diepruim waarneming

Sterbondels

Wat is jou eerste indruk?Hoe maklik is die voorwerp sigbaar? (helderheid; mag-nitude)Wat is die vorm van die newel?Hoe groot is die newel?Hoe verander die verloop van die helderheid, van buite na binne? (helderheidprofiel)Is daar ’n kern?Is die rante skerp of onduidelik?Is daar donkerder dele, of areas van onewe helderheid?Hoe goed staan die newel uit teen die agtergrond?Watter kleur, indien enige, het die newel?Is daar sterre baie naby, of binne, die newel?Wat is die verband tussen newel & omliggende sterveld?Evalueer jou vertroue in hierdie beskrywing.

Wat is jou eerste indruk?Hoe maklik is die voorwerp sigbaar? (helderheid; mag-nitude)Wat is die vorm van die sterbondel?Hoe groot is die sterbondel?Is individuele sterre sigbaar? (onopgelos .. korrelrig .. gedeeltelik opgelos .. goed opgelos, ens.)Hoe bymekaargetrek is die sterre (glad nie .. effens .. sterk gekonsentreerd, ens.)Hoe verander die verloop van die helderheid, van buite na binne? (helderheidprofiel)Hoeveel sterre is sigbaar? (maak ’n skatting; tel die aantal binne ’n bepaalde grote area)Wat is die bestek van helderheid? (almal ewe helder .. groot verskeidenheid; skat die magnitudes)Is daar ’n ooglopende middelster of ander prominente ster betrokke?Het enige van die sterre ’n opvallende kleur? Is enige van die sterre dubbel?Is daar kettings, rye, of klossies sterre? Is daar opvallende sterlose kolle?Is daar ’n agtergrond gloed? (onopgeloste sterre/newel)Wat is die verband tussen die sterbondel en die om-liggende sterveld?Evalueer jou vertroue in hierdie beskrywing.

Nebulae

Star clusters

What are your first impressions?How easy is it to see? (visibility; brightness; magnitude)What shape is the nebula?How big is the nebula?How does the brightness change from edge to centre? (brightness profile)Is there a nuclear region?Are the edges sharp or diffuse?Are there darker parts or areas of uneven brightness?How well does the nebula stand out from the back-ground field?What colour is the nebula?Are there stars very near, or within, the nebula?How does it relate to the surrounding star field?Rate your confidence in this observation.

What are your first impressions?How easy is it to see? (visibility; brightness; magnitude)What shape is the cluster?How big is the cluster?Are individual stars seen? (unresolved .. granular .. par-tially resolved .. well resolved, etc.)Are the stars concentrated towards the centre? (not at all .. slightly .. strongly, etc.)How does the brightness change from edge to centre? (brightness profile)How many stars can you see? (make an estimate; count the number within a specified diameter)What is the range of their brightness? (nearly the same .. mixed; estimate magnitudes)Is there an obvious central or other prominent star?Do any of the stars have a particular colour?Are any of the stars double?Are there chains, rows, or clumps of stars?Are there prominent empty spaces or starless patches?Is there a background glow (unresolved stars/nebulosity)?How does the cluster relate to the surrounding star field?Rate your confidence in this observation.

A checklist for observing the deep sky ASSA Deep Sky Obs.Section

version 4, 2008 FebruaryASSA Deep Sky Obs.Sectionweergawe 4, 2008 Februarie

Discover! - DOCdb

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