Discover! Discover the deepsky for yourself

Transcription

1 Discover the deepsky for yourself Discover! An observing project of the ASSA Deepsky Section Workbook 1: Naked eye and binoculars Deepsky Observing Checklist Discover! Version An 2.0, observing August project 2008 of the Deepsky Observing Section of the Astronomical Society of Southern Africa v

2 Discover the deepsky Discover! 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 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 s covers the rest of the sky, with generous overlap between s for easy use. Along the borders of each appears the map number of neighbouring s. 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 s, as you will be writing on them, plotting in any objects you discover as you go along. A bonus 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 s visible at 21:00 for mid-month, for each month of the year. The next table lists the constellations depicted on each, as well as the months during which the s 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 s 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, study the sky carefully and mark any non-stellar object you come across on the. 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 and observing notes to the ASSA Deepsky Section, Director: Auke Slotegraaf, Forelle Crescent 8, Die Boord, Stellenbosch, 7600; [auke@psychohistorian. org]. Your observations will be returned along with detailed feedback. Happy hunting! How to use this workbook PS: For advanced observers, s down to magnitude 11 are available, covering selected areas of the sky. Contact the Director for details. presented by the ASSA Deepsky Observing Section [auke@psychohistorian.org] [ Contents of the s Which s to use Month Charts that can be used (mid-month at 21:00) Jan 1, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 25 Feb 1, 2, 4, 5, 7, 8, 9, 10, 12, 13, 14, 16, 17, 25 Mar 1, 2, 3, 4, 5, 7, 8, 9, 12, 13, 14, 15, 16, 17 Apr 1, 2, 3, 4, 5, 8, 9, 13, 14, 15, 16, 17, 18 May 1, 2, 3, 4, 15, 16, 17, 18, 19, 21 Jun 1, 2, 3, 15, 17, 18, 19, 21 Jul 1, 2, 3, 6, 17, 18, 19, 20, 21 Aug 1, 2, 3, 6, 20, 21, 22, 23 Sep 1, 2, 3, 6, 20, 21, 22, 23 Oct 1, 5, 6, 21, 22, 23, 24, 25 Nov 1, 4, 5, 6, 8, 9, 10, 12, 23, 24, 25 Dec 1, 4, 5, 6, 7, 8, 9, 10, 11, 12, 24, 25 Chart Visibility (21:00) Constellations 01 Jan Dec Apus, Carina, Chamaeleon, Crux, Dorado, Hydrus, Mensa, Musca, Octans, Pavo, Reticulum, Triangulum Australe, Tucana, Volans 02 Feb Sep Centaurus, Circinus, Crux, Musca, Triangulum Australe 03 Mar Sep Ara, Circinus, Lupus, Norma, Triangulum Australe 04 Nov May Antlia, Carina, Pictor, Puppis, Pyxis, Vela, Volans 05 Oct Apr Caelum, Dorado, Horologium, Pictor, Reticulum 06 Jul Jan Grus, Indus, Microscopium, Pavo, Phoenix, Piscis Austrinus, Tucana 07 Dec Mah Auriga, Canis Major, Canis Minor, Columba, Gemini, Lepus, Orion, Perseus, Taurus 08 Nov Apr Orion 09 Nov Apr Canis Major, Columba, Lepus 10 Nov Feb Taurus 11 Dec Jan Auriga, Perseus 12 Nov Mar Eridanus 13 Jan Apr Canis Minor, Gemini, Monoceros 14 Jan Apr Cancer, Lynx 15 Mar Jun Coma Berenices, Leo, Leo Minor 16 Feb May Hydra, Sextans 17 Feb Jul Corvus, Crater, Hydra 18 Apl Jul Virgo 19 May Jul Boötes, Corona Borealis 20 Jul Sep Hercules, Ophiuchus, Serpens 21 May Oct Corona Australis, Libra, Sagittarius, Scorpius, Scutum, Telescopium 22 Aug Oct Aquila, Cygnus, Delphinus, Equuleus, Lyra, Sagitta, Scutum, Vulpecula 23 Aug Nov Aquarius, Capricornus, Piscis Austrinus 24 Oct Dec Andromeda, Aries, Pegasus, Pisces, Triangulum 25 Oct Feb Cetus, Fornax, Sculptor Constellations overhead at 21:00 and 02:00 Month Overhead at 21:00 Overhead at 02:00 Jan Cae, Eri, For, Hor, Phe, Ret, Scl Ant, Car, CMa, Col, Pic, Pup, Pyx, Vel Feb Cae, CMa, Col, Dor, Hor, Lep, Pic, Ret Ant, Crt, Hya, Pyx, Sex, Vel Mar Cae, Car, CMa, Col, Lep, Pic, Pup, Pyx Ant, Cen, Crt, Cru, Crv, Hya Apr Ant, Car, Hya, Pup, Pyx, Vel Cen, Cru, Crv, Hya, Lib, Lup, Nor May Ant, Cen, Crt, Crv, Hya, Pyx, Vel Ara, Lib, Lup, Nor, Sco Jun Cen, Crt, Cru, Crv, Hya, Lup, Vir Ara, CrA, Nor, Sco, Sct, Ser, Sgr, Tel Jul Cen, Lib, Lup, Nor, Sco Cap, CrA, Mic, Sct, Sgr, Tel Aug Ara, CrA, Lib, Lup, Nor, Sco, Sgr, Tel Aqr, Cap, Gru, Ind, Mic, PsA Sep Ara, Cap, CrA, Mic, Sco, Sct, Sgr, Tel Aqr, Cet, Scl, Phe, Gru, PsA Oct Cap, CrA, Gru, Mic, PsA, Sgr, Tel Cet, Eri, For, Hor, Phe, Scl Nov Aqr, Gru, Ind, Mic, Phe, PsA, Scl Cae, Col, Eri, For, Hor, Lep, Pic, Ret Dec Cet, For, Gru, Phe, Scl Cae, CMa, Col, Dor, Hor, Lep, Pic, Pup Discover! Recording your observations & making descriptions 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 impressions 2. 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) An updated (2008 February) Deepsky Observing Checklist is given in the Appendix.

3 01 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) January December 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) Guide to orienting the Use 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 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 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. Date Jan 1 Feb 1 Mar 1 Apr 1 May 1 Jun 1 Jul 1 Aug 1 Sep 1 Oct 1 Nov 1 Dec 1 18 h 19 h 20 h 21 h 22 h 23 h 00 h 01 h 02 h 03 h 04 h 05 h 06 h 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 R S T Q U P V O W N X M A Crux L Achernar B K C J Canopus D I H E G F

4 02 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 September Triangulum Australe [tri-ang-gyu-lum os-trah-lee], the Southern Triangle. (Trianguli Australis, TrA) Notes

5 03 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 September Triangulum Australe [tri-ang-gyu-lum os-trah-lee], the Southern Triangle. (Trianguli Australis, TrA) Notes

6 04 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) November May Pyxis [PIK-sis], the Mariner s Compass. (Pyxidis, Pyx) Vela [VEE-lah], the Sails. (Velorum, Vel) Volans [VOH-lanz], the Flying Fish. (Volantis, Vol) Notes

7 05 01 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 April Pictor [PIK-tor], the Painter s Easel (Pic, Pictoris) Reticulum [reh-tik-u-lum], the Reticule or Rhomboidal Net (Ret, Reticuli) Notes

8 06 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) July January 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)

9 07 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) December March 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)

10 08 Orion [oh-rye-un], the Hunter. (Orionis, Ori) November April

11 09 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) November April Notes

12 10 25 Taurus [TORR-us], the Bull. (Tauri, Tau) November February Notes

13 11 Auriga [oh-rye-gah], the Charioteer (Aurigae, Aur) Perseus [PURR-see-us], the Champion (Persei, Per) December January 10 Notes

14 12 Eridanus [eh-rid-an-us], the River Eridanus. (Eridani, Eri) November March

15 13 Gemini [JEM-eh-nye], the Twins. (Geminorum, Gem) Canis Minor [KAH-niss MY-ner], the Little Dog. (Canis Minoris, CMi) January April Monoceros [moh-no-ser-us], the Unicorn. (Monocerotis, Mon) Notes

16 14 Cancer [CAN-ser], the Crab. (Cancri, Cnc) Lynx [LINKS]. (Lyncis, Lyn) January April

17 15 Leo [LEE-oh], the Lion. (Leonis, Leo) Leo Minor [LEE-oh MY-ner], the Little Lion. (Leonis Minoris, LMi) March June Coma Berenices [KOH-mah bear-eh-nee-seez], Berenice s Hair (Comae Berenices, Com)

18 16 Hydra [HY-dra], the Water Monster. (Hydrae, Hya) Sextans [SEX-tanz], the Sextant. (Sextantis, Sex) February May Notes

19 17 Hydra [HY-dra], the Water Monster. (Hydrae, Hya) Crater [KRAY-ter], the Cup. (Crateris, Crt) Corvus [KOR-vus], the Crow. (Corvi, Crv) February July Notes

20 18 Virgo [VER-go], the Virgin. (Virginis, Vir) April July Notes

21 19 Boötes [boh-oh-teez], the Herdsman. (Boötis, Boo) Corona Borealis [kor-oh-nah bor-ee-al-is], the Northern Crown. (Coronae Borealis, CrB) May July

22 20 Hercules [HER-kyu-leez]. (Herculis, Her) Serpens [SIR-penz], the Serpent. (Serpentis, Ser) (caput, head; cauda, tail) July September Ophiuchus [oh-fee-u-cuss], Ophiuchus the Serpent- Holder. (Ophiuchi, Oph)

23 21 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) May October Telescopium [tel-eh-sko-pee-um], the Telescope. (Telescopii, Tel) Corona Australis [kor-oh-nah os-trah-lis], Southern Crown. (Coronae Australis, CrA)

24 22 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) August October 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)

25 23 Aquarius [ah-kwair-ee-us], Water Bearer. (Aquarii, Aqr) Capricornus [kap-reh-kor-nuss], the Sea-Goat. (Capricorni, Cap) August November Piscis Austrinus [PIE-sis OSS-trih-nuss], the Southern Fish. (Piscis Austrini, PsA)

26 24 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) October December Triangulum [tri-ang-gyu-lum] the Triangle. (Trianguli, Tri) Aries [AIR-eez], the Ram. (Arietis, Ari)

27 25 Cetus [SEE-tus], the Whale. (Ceti, Cet) Fornax [FOR-nax], the Chemical Furnace. (Fornacis, For) Sculptor [SKULP-tor], the Sculptor s Workshop. (Sculptoris, Scl) October February

28 A few San star tales BONUS CHART Procyon (CANIS MINOR) Eland male A beautiful girl once looked upon some people sitting eating together. Transfixed by her looks, they became stars in the sky. (ORION) Betelgeuse Hartebeest female (GEMINI) Pollux Eland females ( CORONA AUSTRALIS ) Aldebaran Hartebeest male Castor (POINTERS) Two male lions (CRUX) Rigel Arrow (ORION) Three lionesses 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. Aldebaran 3 Zebras Betelgeuse Lion Husband µ Eyes of the Lion (SCORPIUS)!Khunuseti Antares Pleiades

29 Observing log Object number: Observer: Location: Date & time: Instrument: Sky conditions: Quality of observation: Description and sketch Discover! Discover the deepsky for yourself. Observing log Object number: Observer: Location: Date & time: Instrument: Sky conditions: Quality of observation: Description and sketch Discover! Discover the deepsky for yourself.

30 Observing log Object number: Observer: Location: Date & time: Instrument: Sky conditions: Quality of observation: Description and sketch Note the size of the field of view sketched, and its orientation. Discover! Discover the deepsky for yourself. Star colour record sheet Star name or identification number Colour (select one) blue yellow light deep light deep orange blue yellow yellow orange orange red red blue yellow light deep light deep orange blue yellow yellow orange orange red red blue yellow light deep light deep orange blue yellow yellow orange orange red red blue yellow light deep light deep orange blue yellow yellow orange orange red red blue yellow light deep light deep orange blue yellow yellow orange orange red red blue yellow light deep light deep orange blue yellow yellow orange orange red red blue yellow light deep light deep orange blue yellow yellow orange orange red red blue yellow light deep light deep orange blue yellow yellow orange orange red red blue yellow light deep light deep orange blue yellow yellow orange orange red red blue yellow light deep light deep orange blue yellow yellow orange orange red red blue yellow light deep light deep orange blue yellow yellow orange orange red red blue yellow light deep light deep orange blue yellow yellow orange orange red red Discover! Discover the deepsky for yourself.

31 Appendix: DOClist NEW! Version 4 overleaf Deepsky Observing Checklist (version 3) 2006 January 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 thoughtconstraining framework, but rather as a tool to make sure you don t forget to note a particular aspect. 1. Identity the object When 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 coordinates (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 first Once 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. Brightness How 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. Size How 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. Shape What 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 profile Most 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. Discover! Discover the deepsky for yourself.

32 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. Sketches A 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 conditions In 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 techniques If 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 conclusion Ignore 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. Discover! Discover the deepsky for yourself.

33 n Oorsiglys vir diepruim weergawe 4, 2008 Februarie waarneming ASSA Deep Sky Obs.Section Newels Wat is jou eerste indruk? Hoe maklik is die voorwerp sigbaar? (helderheid; magnitude) 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. A checklist for observing version 4, 2008 February the deep sky ASSA Deep Sky Obs.Section Nebulae 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 background 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. Sterbondels Wat is jou eerste indruk? Hoe maklik is die voorwerp sigbaar? (helderheid; magnitude) 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 omliggende sterveld? Evalueer jou vertroue in hierdie beskrywing. Star clusters 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.. partially 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.